international rice research newsletter vol12 no.4

IRRN — growing and changing

The International Rice Research Newsletter is in its 12th year of publication. In its first issue, October 1976, the IRRN objective was stated as:

“To expedite communication among scientists concerned with the development of improved technology for rice and for rice-based cropping systems. This publication will report what scientists are doing to increase the production of rice, inasmuch as this crop feeds the most densely populated and land-scarce nations in the world , . . IRRN is a mechanism to help rice scientists keep each other informed of current research findings.” That remains our objective. To meet that objective in the

expanding and increasing complexity of the rice research world, we are initiating some changes, effective with the 1988 publication year. The family of rice researchers is growing exponentially. We distributed 6,000 copies of IRRN Vol. 1, No. 1; we will distribute close to 13,000 copies of Vol. 12, No. 4, to individual scientists and to the libraries of research institutions. The first issue totaled 24 pages; some issues this year totaled 54 pages. The number of research brief reports being submitted has more than doubled, and grows daily.

For IRRN to continue to meet its objective efficiently and with increased quality, the categories of research reported are being expanded to include new specializations and topics now being researched. The Guidelines for Contributors have been expanded and specified more precisely. Criteria for reviewers emphasize the global nature of rice research work reports that will be accepted.

The concise reports contained in IRRN are meant to encourage rice scientists and workers to communicate with one another. In this way, readers can obtain more detailed information on the research reported.

Please examine the new categories and the new guidelines that follow.

If you have comments or suggestions, please write the editor, IRRN. We look forward to your continuing interest in IRRN.

Guidelines for contributors to IRRN

The International Rice Research Newsletter is a compilation of research briefs on topics of interest to rice scientists all over the world. Contributions to IRRN should be reports of recent work and work-in- progress that have broad interest and application. Please observe these guidelines in preparing submissions:

• The report should not exceed two pages of double-spaced typewritten text. No more than two figures (graphs, tables, or photos) may

accompany the text. Do not cite references or include a bibliography. Items that exceed the specified length will be returned.

research objectives and project design. The discussion should be brief, and should relate the results of the work to its objectives.

• Report appropriate statistical analysis.

• Provide genetic background for new varieties or breeding lines.

• Specify the environment (irrigated, rainfed lowland, upland, deep water, tidal wetlands). If you must use local terms to specify landforms or cropping systems, explain or define them in parentheses.

transplanted, wet seeded, dry seeded).

• Specify seasons by characteristic weather (wet, dry, monsoon) and by months. Do not use national or local terms for seasons or, if used, define them.

• When describing the rice plant and its cultivation, use standard, internationally recognized designators for plant parts and growth stages, environments, management practices, etc. Do not use local terms.

studies, be sure to include standard soil profile description, classification, and relevant soil properties.

diseases, insects, weeds, and crop plants; do not use common names or local names alone.

• Survey data should be quantified (infection percentage, degree of severity, sampling base, etc.).

• When evaluating susceptibility, resistance, tolerance, etc., report the actual quantification of damage due to stress used to assess level or incidence. Specify the measurements used.

• Use international measurements. Do not use local units of measure. Express yield data in metric tons per hectare (t/ha) for field studies and in grams per pot (g/pot) or per row (g/row) for small-scale studies.

• Express all economic data in terms of the US$. Do not use national monetary units. Economic information should be presented at the exchange rate $:local currency at the time data were collected.

• Use generic names, not trade names, for all chemicals.

• When using acronyms or abbreviations, write the name in full on first mention, following it with the acronym or abbreviation in parentheses. Thereafter, use the abbreviation.

• Define in a footnote or legend any nonstandard abbreviations or symbols used in a table or figure.

• Include a brief statement of

• Specify the type of rice culture (e.g.,

• When reporting soil nutrient

• Provide scientific names for

IRRN: categories of research reported

GERMPLASM IMPROVEMENT genetic resources genetics breeding methods yield potential grain quality and nutritional value disease resistance insect resistance drought tolerance excess water tolerance adverse temperature tolerance adverse soils tolerance integrated germplasm improvement research techniques data management and computer

modeling IRTP seed technology

CROP AND RESOURCE MANAGEMENT

soils and soil characterization soil microbiology and biological N

physiology and plant nutrition crop management soil fertility and fertilizer management INSFFER disease management insect management weed management managing other pests integrated pest management water management farm machinery environmental analysis postharvest technology farming systems ARFSN research methodology data management and computer

fertilizer

modeling

SOCIOECONOMIC AND ENVIRONMENTAL IMPACT

environment production livelihood

EDUCATION AND COMMUNICATION

training and technology transfer

communication research information storage and retrieval

research

Criteria for IRRN research reports • has international, or pan-national,

• has rice environment relevance • advances rice knowledge • uses appropriate research design

and data collection methodology • reports appropriate, adequate data • applies appropriate analysis, using

appropriate statistical techniques • reaches supportable conclusions

relevance

Contents

GENETIC EVALUATION AND UTILIZATION

Overall progress 5 TPS2 — variety for Kanyakumari 5 Dominant dwarf mutants in rice induced with fractionated dose of

6 TNAU80030 - a promising medium-duration rice for Tamil Nadu 6 IR18348-36-3-3, a promising rice for irrigated and slight acid sulfate soil

7 Metica I released in Brazil

gamma rays

in Vietnam

Germplasm 7 A simple and convenient method to preserve seed of rice germplasm

Agronomic characteristics 8 Response of new rice varieties to N 9 Performance of overage seedlings at different N levels

Grain quality 9 Two promising scented rice varieties for the Mekong Delta

10 Molecular basis for puffing quality of rice 10 High-yielding aromatic rice variety GR101 11 Physicochemical properties as a basis for identifying preferred cooking

12 Effect of time of evaluation on alkali spreading values 12 High density grain index among primary and secondary tillers of short-

quality

and long-duration rices

Disease resistance 12 Sugars and phenolic compounds in rice leaves in relation to varietall

13 Field screening IRRI lines against tungro (RTV) disease in Lanrang 13 Manoharsali, neck blast-resistant variety 14 Reaction of varieties and selections to green leafhopper (GLH) and

14 Ragged stunt virus (RSV) concentration in tolerant rice 14 Symptoms and yield reduction in tolerant varieties infected with ragged

15 Incidence of rice kernel smut (KSm) in Pakistan 15 Reaction of selected varieties to tungro (RTV) and green leafhopper

resistance to bacterial blight (BB) pathogen

tungro (RTV) in the greenhouse

stunt virus (RSV)

(GLH) Insect resistance

16 Tolerance of some rice varieties for gall midge (GM) Orseolia oryzae

17 Stem borers (SB) in dryland and wetland rice 17 Screening of rice accessions against leaffolder (LF) Cnaphalocrocis

18 Screening rice varieties for resistance to mealybug

Wood-Mason

medinalis

Drought tolerance 18 Evaluation of drought-resistant upland rice accessions

Adverse soils tolerance 19 A breeding method for tolerance for acid sulfate soil 19 Performance of coarse and fine rice varieties on alkali soils 20 Vyttila 3, a new rice variety for acid saline areas

Temperature tolerance 20 Chhomro — a promising cold-tolerant traditional rice variety for rainfed

21 Low temperature tolerance of traditional Vietnamese varieties wetlands in western hills in Nepal

Hybrid rice 21 Potassium nutrition in hybrid rice 22 Test cross for restorer genes using three male sterile lines

Tissue culture 23 Influence of position of rice anthers at plating on callusing and plant

23 Somatic embryogenesis in rice Oryza sativa, cultivar IR40 24 Somatic embryogenesis in wild rice Oryza perennis Moench

regeneration

PEST CONTROL AND MANAGEMENT

Diseases 25 Trichoderma in Philippine ricefield soils 25 Interaction in vivo between virulent and avirulent cultures of rice

bacterial blight (BB) pathogen 26 Fungicidal control of rice sheath blight (ShB) 27 Damage by rice root-knot nematode 27 Detection of seedborne rice fungi by blotter method 28 Cost comparison of neem oil and an insecticide against rice tungro virus

29 Ufra threatens deepwater rice in Majuli, Assam 29 Ufra problem in low-lying areas of Bangladesh 30 Weed hosts of ragged stunt virus (RSV) 30 Frequency and timing of insecticide application to control rice tungro

31 Sheath blotch (SBL) of rice 32 Effect of Azolla hipinnata soil amendment on reduction in viability of

32 Pestalotia oryzae — a new rice fungus in India 33 Effect of grain spotting on rice quality 33 Distribution of rice seedling damping-off in Bangladesh 33 Relationship between tungro transmission by individual Nephotettix

34 Incidence of rice panicle stalk blast (Bl) in Manipur

(RTV)

virus (RTV)

sclerotia of rice stem rot (SR) fungus

virescens, mode of feeding, and life span

Insects 35 Predators of rice insect pests in Chhattishgarh region, Madhya Pradesh,

35 Effect of insecticides on eggs of Brevennia rehi (Lindinger) 35 Insect pests on main and ratoon rice 36 Electronically recorded waveforms associated with brown planthopper

37 Strepsipteran parasites of rice leafhoppers and planthoppers in the

38 Nymphula africalis (Lepidoptera: Pyralidae), a pest of azolla in Nigeria 39 Minimum levels of three commonly used insecticides to control five insect

40 Biotype shift in a brown planthopper (BPH) population on IR42 41 Control of tungro (RTV) and yellow stem borer (YSB) in rice by synthetic

India

(BPH) feeding activity

Philippines

pests of rice in the Philippines

pyrethroids 41 Rice thrips infestations in West Bengal 42 Nymphula africalis, azolla pest in Nigeria 42 Occurrence of a predatory mite Pyemotes ventricosus on Sitotroga

42 Effect of 8 insecticides on rice bug eggs 42 Rice leaffolder (LF) species in North Arcot District, Tamil Nadu 43 Persistence of quinalphos in rice 43 Insecticides to control rice hispa 43 Egg parasites of Scirpophaga incertulas (Walker) in Sri Lanka 44 Diluted quinalphos and fenthion and control of whitebacked planthopper

44 Nisaga simplex caterpillar on rice in western Orissa 44 Rice leaffolder (LF) infestations in West Bengal 45 Biochemical changes in rice plants infested with mealybug

cerealella Oliv.

(WBPH)

Weeds 45 Effect of frequent cultivation on Rottboellia cochinchinensis density 46 Weed control in irrigated wet and dry seeded rice in medium-textured

47 Ricefield weeds in South Andaman, India 47 Response of upland rice to weed control methods 48 Weed control in hybrid rice

soils of northwestern India

Other pests 48 Pomacea snails in the Philippines

SOIL AND CROP MANAGEMENT 49 Puddling methods for lowland rice 49 Effect of spacing and seedlings per hill 49 Performance of rice varieties on floating rafts 50 Effect of land preparation on control of Paspalum distichum 50 Effect of modified urea materials and N levels on transplanted rice 51 Nitrogen management for increasing N efficiency in transplanted rice 51 Nitrogen sources for flooded rice 52 Effect of transplanting date and N application on yield 52 Effect of slow-release nitrogen fertilizers on lowland rice 53 Constraints to rice yields in Punjab, Pakistan 53 Effect of soil N on rice yield in Punjab 54 Rapid and sensitive method to estimate salinity tolerance of Azolla

54 Effect of azolla and inorganic N combined 55 Effect of cultivation method on the rice crop and the mechanical

55 Efficiency of nitrogen fertilizers and a nitrification inhibitor

pinnata

impediment of Vertisols

56

56 57 57 58 58 59 59 59 59 60 60

60

Effect of plant density and fertilization on rice yield and fertilizer efficiency Effect of method of applying Azospirillum brasilense on rice yield Effect of urea on decomposition of azolla Induction of callus from leaf explants of Azolla pinnata Cultural practices to reduce winter damage to rice Effect of slow-release nitrogen fertilizers on rice yield Damaged seedling roots and grain yield Performance of long-duration CR1009 with aged seedlings Preservation of Azolla pinnata germplasm Ammonia volatilization loss in rice soils of Cauvery Delta Response of upland rices to nitrogen Relationship between organic N fraction and N uptake of rice in submerged soil Effect of nitrogen on rice in an alkali soil

CONSEQUENCES 61 Energy management in rice production

RICE-BASED CROPPING SYSTEMS 63 Effect of soil amendments on rice and wheat yields in salt-affected soils 63 Rice - fish cultivation in the hilly region of Karnataka, India 64 Rice-based crop rotations for upland fields 64 Zinc required for a rice - wheat sequence in alkali soils

ANNOUNCEMENTS 64 World Food Prize to Swaminathan 64 IRRI-CIMMYT honored 64 New IRRI publications

Guidelines and Style for

IRRN Contributors

Articles for publication in the International Rice Research Newsletter (IRRN) should observe the following guidelines and style.

Guidelines • Contributions should not exceed two pages of

double-spaced typewritten text. Two figures (graphs, tables, or photos) may accompany. each article. The editor will return articles that exceed space limitations.

• Contributions should be based on results of research on rice or on cropping patterns involving rice.

• Appropriate statistical analyses should be done.

• Announcements of the release of new rice varieties are encouraged.

• Pest survey data should be quantified. Give infection percentage, degree of severity, etc.

Style • For measurements, use the International

System. Avoid national units of measure (cavan, rai, etc.).

measure when they follow a number. For example: 20 kg/ha, 2 h/d.

• Express yield data in tonnes per hectare (t/ha) With small-scale studies, use grams per pot

• Express time, money, and common measures in number, even when the amount is less than 10. For example: 8 min, $2, 3 kg/ha, 2-wk intervals.

• Write out numbers below 10 except in a series containing 10 or higher numbers. For example: six parts, seven tractors, four varieties. But There were 4 plots in India, 8 in Thailand, and 12 in Indonesia.

• Write out numbers that start sentences. For example: Sixty insects were put in each cage. Seventy-five percent of the yield increase is attributed to fertilizer.

• Place the name or denotation of chemicals or other measured materials near the unit of measure. For example: 60 kg N/ ha, not 60 kg/ha N; 200 kg seed / ha, not 200 kg/ ha seed.

• Use common names — not trade names — for chemicals.

• The US$ is the standard monetary unit in the IRRN. Data in other currencies should be converted to US$.

• When using acronyms, spell each out at first mention and put the specific acronym in parentheses. After that, use the acronym throughout the paper. For example: The brown planthopper (BPH) is a well-known insect pest of rice. Three BPH biotypes have been observed in Asia.

• Abbreviate names of months to three letters: Jun, Apr, Sep.

• Define in the footnote or legend any nonstandard abbreviations or symbols used in a table or figure.

bibliography.

• Abbreviate names of standard units of

(g/pot) or g/row.

• Do not cite references or include a

Genetic Evaluation and Utilization OVERALL PROGRESS

TPS2 - a new variety for Kanyakumari

S. Kalaimani, O.R. Pillai, W. W. Manuel, and M. Subramanian, Tamil Nadu Agricultural University, Coimbatore 641003, Tamil Nadu, India

TPS2, a derivative of IR26/CO 40 developed at the Thiruppathisaram Rice Research Station, has been released. The semidwarf (90-95 cm) with 125 d

duration is suitable for second season (Sep-Oct) sowing. In testing at the research station and in adaptive research trials over the entire Kanyakumari district, it had 16.6-31.4% increases in grain yield and 27.6-48.8% increases in straw yield over IR20 (see table).

TPS2 is moderately resistant to brown planthopper, leaffolder, and white tip nematode. It is nonlodging and nonshattering. Grain is bold, with a 1,000-grain weight of 23.5 g.

Characteristics of TPS2 in Kanyakumari, India, 1979-86.

Grain yield Straw yield

t/ha % increase t/ha % increase Variety

Duration (d)

TPS2 IR20

TPS2 IR20

TPS2 IR20

4.6 3.5

4.1 3.4

4.2 3.6

Station trials a

31.4 6.4 – 4.3

Adaptive research trials, 1982-83 20.1 10.8

– 8.2

Adaptive research trials, 1983-84 16.6 7.4

– 5.8

48.8 –

31.7 –

27.6 –

125 125

125 125

123 123

a Mean of 1979-86.

Dominant dwarf mutants in rice induced with fractionated dose of gamma rays

C. R. A. Kumar, S. R. Sree Rangasamy, School of Genetics, Tamil Nadu Agricultural University, Coimbatore, Tamil Nadu, India

Presoaked seeds (24 h in distilled water) of TKM6 were exposed to gamma rays

of 35 kR in split or fractionated treatments with 4-h intervals between each exposure. The treatments were 0, 35 kR in a single dose, 30 + 5 kR, 25 + 10 kR, 20 + 15 kR, 15 + 20 kR, 10 + 25 kR, and 5 + 30 kR. In the first generation (M 1 ), plants survived from only 3 treatments: 5 + 30 kR (3 plants), 30 + 5 kR (5 plants), and 20 + 15 kR

Table 1. Performance of dominant dwarf mutants of TKM6 in the M 1 . Coimbatore, Tamil Nadu, India.

Plant

(cm) (cm) (g)

Tillers Panicle Yield/ Treatment height length plant (no.)

5 + 30 kR 30 + 5 kR 20 + 15 kR Control

84 84 85

150

11 15 17 12

22.9 21.5 20.9 23.3

6.2 20.9 19.6 9.2

IRRN 12:4 (August 1987) 5

Nguyen Van Luat, Bui Ba Bong, and Pham Cong Voc, Cuu Long Delta Rice Research Institute (CLRRI), Omon. Hau Giang, Vietnam

(5 plants). All plants were dwarf, irrespective of treatment (Table 1).

When the plants were forwarded to the M 2 , the dwarf nature was

maintained, with increase in tiller number and per-plant yield (Table 2).

The dwarf plants were crossed with TKM6 in direct and reciprocal

combinations. The F 1 exhibited the dwarf nature (82.8 cm to 91.3 cm), confirming the dominant nature of the mutation.

IR18348-36-3-3, a cross of IR5657-33-2- 2 and IR2061-425-1-5-5, was selected at CLRRI from the International Rice Yield Nursery in early 1983. It has 100- 115 d maturity, 95-110 cm height, and good grain quality, and is suitable for irrigated, slight acid sulfate soils.

Table 2. Performance of dwarf mutants in M 2 . Coimbatore, Tamil Nadu, India.

Plant height (cm) Tillers (no.) Panicle length (cm) Yield/plant (g) Treatment

Mean ± SE Range CV Mean ± SE Range CV Mean ± SE Range CV Mean ± SE Range CV

5 + 30 kR 80.00±1.33 71.5- 85.0 2.35 9.66±1.15 5-16 16.84 18.24±1.19 17.5-21.4 9.23 13.57±2.29 5.1-28.7 24.04 30 + 5 kR 79.66±0.56 75.5- 81.0 0.99 9.42±0.60 6-12 9.03 20.44±0.48 18.4-22.7 3.32 12.57±1.11 7.6-16.0 12.49 20 + 15 kR 80.11±1.16 75.0- 89.0 2.05 9.33±0.85 8-14 12.88 18.38±0.43 16.4-21.2 3.31 10.37±0.76 7.2-14.9 10.36 control 161.99±0.49 155.0-163.0 0.43 9.40±0.38 8-11 5.12 25.74±0.51 22.5-26.6 2.8 8.73±0.61 7.5-10.3 9.88

TNAUB80030 - a promising medium- duration rice for Tamil Nadu

S. Palanisamy, G. A. Palanisamy, K. Natarajamoorthy, and R. Velusamy, School of Genetics, Tamil Nadu Agricultural University, Coimbatore, Tamil Nadu 641003, India

We evaluated several breeding lines for yield potential and field tolerance for brown planthopper. IR13240-82-2-3-2, a derivative of IR30/ Babawee/ / IR36, was found most promising. It was designated TNAU80030 for testing at the Paddy Breeding Station, Coimbatore, and was advanced to multilocation trial.

In 10 locations, TNAU80030 ranked first in four and tied with P837 in two

Yield of TNAU80030 in multilocation trials. Tamil Nadu, India, Sep-Oct 1985.

Location Yield (t/ha)

TNAU80030 P837 CO 43 IR20

Aduthurai Coimbatore Tirur Ambasamudram Madurai Pondicherry Tirupathisaram Trichy Paiyur Bhavanisagar

Mean

4.4 5.4 4.7 5.2 2 .7 6.4 4.1 3.8 5.2 5.1 4.7

3.9 4.6 4.4 5.0 2.9 8.9 2.1 4.5 5.1 5.7 4.7

3.3 5.2 3.2 4.7 2.5 6.9 3.6 6.6 4.3 5.2 4.5

3.3 4.7 4.5 4.9 2.7 5.8 3.4 3.7 4.7 4.4

4.2

and with CO 43 in one location (see TNAU80030 is semidwarf with a table). TNAU80030 has been advanced medium slender grain type and field to adaptive research trials in farmers' tolerance for brown planthopper, blast, fields. and rice tungro virus.

IR18348-36-3-3, a promising rice for irrigated and slight acid sulfate soil in Vietnam Table 2. Reaction of IR18348-36-3-3 to insects

and diseases at CLRRI.

Variety BPH B1 BB ShB

Reaction a to

Table 1. Yield of IR18348-36-3-3 in 1984-86 dry and wet seasons. Omon, Hau Giang, Vietnam.

Dry season Wet season

1984 1985 1986 1983 1984 1985 Variety Average

IR18348-36-3-3 (OM89) 5.5 5.4 5.4 6.1 5.6 5.3 5.5 NN3A (check) 4.4 5.5 5.3 4.8 5.7 4.3 4.9 NN6A (check) 4.8 5.3 5.2 5.2 5.6 5.5 5.2

cv (%) 24.5 – 20.4 13.3 – 26.8 LSD 5%

1.3 1.9 0.6 1.1 0.5 0.2

IR18348-36-3-3 3-5 4-5 5-7 7 (OM89)

NN6A 3 7-9 7 7 NN3A 3 7-9 7 7 Resistant check b 3 1 2 3 Susceptible check c 9 9 8 7

a By the Standard evaluation system for rice

planthopper (BPH), IR8 for blast (BI), Compo- scale. b Resistant check was IR36 for brown

selak for bacterial blight (BB), Tapochoz for sheath blight (ShB). c Susceptible check was TN1 for BPH, NN7A for B1, IR8 for BB, and IR36 for ShB.

6 IRRN 12:4 (August 1987)

Irrigated rice is about 30% of the total area planted to rice in Brazil and 40% of total rice production. The most important areas for irrigated rice are located in the south, but lately emphasis has been placed on developing varieties for the tropical region.

In 1981, the National Research Center for Rice and Beans (EMBRAPA/ CNPAF) introduced Metica 1 from the International Center for Tropical Agriculture (CIAT), Cali, Colombia. Beginning in 1982, this variety was evaluated in several Brazilian states and in 1986 was released for commercial use in four states.

Average yields of Metica 1 were 14 – 50% higher than local checks' (see table), with similar grain quality. However, Metica 1 was found to be susceptible to brown spot and rice blast, primarily where water control was not adequate. The figure shows the area currently planted to irrigated rice in the states where Metica 1 was released.

In 1984-86 trials, the line yielded consistently higher than NN3A and NN6A (Table 1). It is moderately

biotype 2 and susceptible to bacterial and released for large-scale cultivation in blight and sheath blight (Table 2). the Mekong Delta. IR18348-36-3-3, was

In 1986, IR18348-36-3-3 was named released by the Philippine Seed Board as resistant to blast and brown planthopper OM89 by the Ministry of Agriculture IR64 in 1985.

Metica 1 released in Brazil

P. H. N. Rangel, E. P. Guimarães and V. dos A. Cutrim, National Research Center for Rice and Beans (EMBRAPA/CNPAF) - Caixa Postal 179, 74000 Goiânia, Goias, Brazil

Area (ha) planted to irrigated rice in states where Metica 1 was released, Goiania, Brazil.

Days to flowering and grain yield of Metica 1. a Goiâna, Brazil.

Yield

State flowering Metica 1 Cica 8 De Abril increase

(check) (check) (%)

Rio de Janeiro (RJ) 115 4.9 – 4.3 14 Piaui (PI) 80 6.9 6.0 – 16 Goiâs (Go) Mato Grosso (MT) 95 6.2 4.1 – 50

Mean (PI, GO, MT) – 7.0 5.6 – 25

Grain yield (t/ha) Days to

90–115 8.0 6.7 – 19

a Av of 29 trials.

Genetic Evaluation and Utilization GERMPLASM

A simple and convenient method to preserve seed of rice germplasm

Chang–Xiang Mao, Hunan Hybrid Rice Research Center, Changsha, Hunan, China

More than 500 samples of rice seed harvested in autumn 1976 were sealed with indicating silica gel in glass ampules (see figure). The sealed ampules were

sorted in boxes placed in an ordinary room where the average monthly temperatures are about 5°C, 6°C, 11 °C, 17°C, 22°C, 26°C, 29°C, 29°C, 24°C, 18°C, 12°C, and 10°C Jan– Dec. After 10 yr, the seeds still have desirable germination abilities. Average moisture content before sealing was about 12%; it is now 7–8%. Average germination rate is about 90%. Seedlings

derived from the germinated seeds grow well in the field.

preservation method are 1. Well–sealed conditions. The ampule

was sealed by melting the glass tip, the relative humidity was very low and, with adequate silica gel, continuously becomes lower and lower.

The characteristics of this


Rice seed samples in glass ampules. Hunan, China, 1987.

2. Ease in operating. It is very easy to seal the ampule vials using a bunsen burner and a pair of tweezers.

3. Ease in keeping. The ampule is made of glass, which cannot be affected by moisture, insects, and rats. It can be stored in normal conditions.

4. Low cost. The ampules are very cheap. One 2-ml ampule can store 20- 30 rice seeds, enough to use for breeding parents. A 20-ml ampule bottle can hold 500 rice seeds.

5. Use for other crops. Glass ampules can be used for other small-seed crops, such as wheat, vegetables, and rapeseeds.

Individuals, organizations, and media are invited to quote or reprint articles or excerpts from articles in the IRRN.

Genetic Evaluation and Utilization AGRONOMIC CHARACTERISTICS

Response of new rice varieties to N Grain yield, N uptake, and yield parameters of 3 rice varieties at different levels of N application, Punjab, India, 1986 summer.

M.S.Maskina, yadvinder-singh and Bijay- Singh,Soils Department, Punjab Agricultural University, Ludhiana 141004, India

Rice variety PR106 covers about 80% of the area under rice in punjab. Recently, yield at experimental farms and in farmers’ fields have dropped markedly Susceptibilityof cultivars to a number of plant dieases was ofund to be the major reason. Two new varieties with high yield potential — PR108 and PR109 — are more resitant to plant pathogens. Because Punjab soils are inherently deficient in organic matter N, a subtanstial response of the three varaties to applied N is expected.

We studied the response of thr three varaties to four N level during 1986 summer.Treatment were laid out in a slit-plot design with three replicantion Soils (pH8.4 EC 0.16 dS/m, 0.30%

8 IRRN 12:4 (August 1987)

Variety No N 90 kg N/ha 120 kg N/ha 150 kg N/ha Mean

Grain yield (t/ha) PR106 2.7 5.5 5.8 6.2 5.0 PR108 3.3 6.0 6.3 6.7 5.6 PR109 3.1 5.7 6.1 6.4 5.3

Mean 3.0 5.7 6.1 6 .4 LSD (P=0.05): N levels = 0.27, varieties = 0.31, NXV = ns

Effective tillers/plant PR106 8.4 9.4 9.7 10.7 9.6 PR108 8.5 9.5 11.5 11.9 10.4 PR109 8.7 9.1 10.6 11.5 10.0

Mean 8.5 9.3 10.6 11.4 LSD (P=0.05): N levels = 0.5, varieties = 0.4, NXV = ns

Filled spikelets/panicle PR106 92 97 99 112 100 PR108 109 115 122 127 118 PR109 94 107 109 117 107

Mean 98 106 110 119 LSD (P=0.05): N levels = 7, varieties = 8, NXV = ns

PR106 39 106 125 138 102 N uptake

PR108 61 127 140 150 120 PR109 53 113 132 142 110

Mean 51 115 132 143 LSD (P=0.05): N levels = 9, varieties = 8, NXV = ns

organic C, 0.04% total N) of the after transplanting. A basal dose of 13 table). Yield components also were experimental field was loamy sand kg P and 12 kg K/ha was applied at last highest in PR108. PR108 matures 6-8 d (Typic Ustochrept) with an average puddling. earlier than PR106, an advantage for percolation rate of 4 mm/ h. All the 3 varieties responded up to early sowing of wheat in a rice - wheat

splits: at transplanting and 21 and 42 d outyielded PR106 at all N levels (see N as urea was applied in 3 equal 150 kg N/ha. PR108 significantly cropping system.

Performance of overage seedlings at different N levels

D. M. Maurya and M. P. Yadav, N. D. University of Agriculture and Technology, Crop Research Station, Masodha, Faizabad, U. P., India

We studied the effect of N level on grain yield and yield parameters using overage seedlings of four transplanted rice varieties - Mahsuri, Sarjoo 52, Ratna, and Saket 4 in a randomized block design with four replications. Experimental plot soil was sandy loam with pH 7.5, EC (1:2) 0.09 mmho/cm, 0.42% organic C, 17.5 kg available P/ ha, and 135 kg available K/ha. Fifty- five-day-old seedlings were transplanted 10 Aug 1983 at 2-3 seedlings/hill at 20- × 10-cm spacing. Urea was applied at 0, 50, and 100 kg N/ha. Single superphosphate and muriate of potash at 18 and 32 kg/ ha were basally applied.

Each increment of N significantly increased panicle number, panicle

Yield and yield attributes of overage seedlings of 4 varieties as influenced by N level. Masodha, India.

Panicle 1000-grain Plant Grain Treatment Panicles/m 2 weight weight height yield

(g) (g) (cm) (t/ha)

N level (kg/ha) 0

50 100

CD (0.05) Variety

Mahsuri Sarjoo 52 Ratna Saket 4

CD (0.05)

35 44 52

7.0

42 35 41 54

4

1.6 1.7 2.0 0.2

1.7 2.3 1.7 1.3

0.3

20.3 20.9 21.7

0.3

15.2 27.1 21.6 20.1

0.4

73 82 90

3

94 77 79 77

3

1.5 2.4 2.9 0.1

2.6 2.3 2.1 1.9 0.1

weight, test weight, plant height, and Sarjoo 52 and short Ratna and Saket 4. grain yield (see table), but average N use Although Sarjoo 52 yields higher than efficiency was low, 17.7 kg grain/kg N other varieties under normal conditions, with 50 kg N/ha and 14.1 kg grain/kg N Mahsuri performed better under these with 100 kg N/ha. In general, grain conditions, probably because its longer yield and yield parameters were duration gave sufficient growth and adversely affected by planting overage development time to overcome late seedlings, which resulted in low grain seedling planting. N application was yields for all varieties. Long-duration beneficial to grain yield, even with Mahsuri performed better than medium overage seedlings.

Genetic Evaluation and Utilization GRAIN QUALITY

Two promising scented rice varieties for the Mekong Delta

Nguyen Xuan Hien and Nguyen Zhu Ha, Plant Breeding Department, Institute of Agricultural Technology of South Vietnam, Ho Chi Minh City, Vietnam

Two promising scented rice varieties — Nang-thom sel. and Nang-huong-ran sel. — have been released for specific areas in the Mekong Delta. The varieties are suitable for the early Jul - late Dec crop in various waterlogged ricefields.

Nang-huong-ran sel. is distinguished

Table 1. Agricultural characteristics and grain quality of promising scented varieties. Ho Chi Minh City, Vietnam.

Character Nang-thom sel. Nang-huong-ran sel.

Culm length (cm) 141.8 145.6 Growth duration (d) 160.3 165.3 Panicles/plant 10.6 7.3 Panicle length (cm) 23.7 23.6 Fully filled spikelets/panicle 108.0 131.3 1000-grain wt (g) 23.4 24.9 Grain yield (t/ha) 3.85 4.88 Culm strength b 5-7 1-3 Brown rice length (mm) 7.03 6.62 Brown rice length-to-width ratio 3.36 Chakiness b 1

3.22 1

Scent b 2 1

a Av of 4-yr trials. b Standard evaluation system for rice codes.


by strong culms and large and dark green leaves. It grows well in light acid sulfate soils, but has a rather long growth duration. Nang-thom sel. meets all the requirements of Asian rice consumers (Table 1). Gross income for Nang-thom sel. is about 50% higher than that for Nang-huong-ran sel. and other common scented rices.

More than 40 samples of 22 scented varieties were collected from 11 provinces in the south and screened in a 4-yr project.

The two new varieties confirmed yield and grain quality superiorities over cultivars in testing in relatively large areas during two recent seasons (Table 2).

Table 2. Yields of scented varieties in on-farm trials in Vietnam.

Yield (t/ha) Cooperative

Nang-thom sel. Nang-huong-ran sel. Check a

Thanh Loc (Ho Chi Minh city) 3.6 3.9 (135) (150)

2.6 (100)

An Lac (HCM city)

An Phu Tay (HCM city)

3.4 (118)

–

3 .0 (125)

3.5 (137)

(100) 2.9

(100) 2.4

My Le (Long An Province) 3.3 3.8 2.9 (115) (131) (100)

a Local scented varieties. Figures in parentheses are % of local check.

The International Rice Research Newsletter and the IRRI Reporter are mailed free to qualified individuals and institutions engaged in rice production and training. For further information write: IRRI, Communication and Publications Dept., Division R, P. O. Box 933, Manila, Philippines.

Molecular basis for puffing quality of rice

B. Thayumanavan, Biochemistry Department, Tamil Nadu Agricultural University, Coimbatore 641003, India

High-amylose varieties such as Bhavani and IR50 are preferred for making puffed rice. We compared the molecular properties of amylose and amylopectin in Bhavani and IR50 with those in CO 25, ASD7, and Ponni, which are preferred for making rice flakes, idli, and cooked rice.

longer chain than the other varieties studied (Table 1). The chain length of amylose was not determined.

from these varieties were treated with

The amylopectin of Bhavani showed a

The amylose and amylopectin isolated

Table 2. Percentage hydrolysis of amylose and amylopectin by salivary a -amylase at different time intervals. a Coimbatore, India.

Percentage hydrolysis at indicated time

30 min 60 min 120 min 240 min 360 min Variety Component

Bhavani A AP

IR50 A AP

Ponni A AP

ASD7 A AP

CO 25 A AP

LSD A AP

51.8 50.0 49.7 48.2 4 1.4 48.2 43.5 38.3 21.8 38.3

62.1 59.6 65.3 50.4 53.6 48.9 51.8 43.5

34.7 44.2

0.7 (between varieties) 0.8 (between varieties)

66.2 59.6 79.0 51.8 65.0 49.4

60.1 49.4

43.3 52.2

86.0 61.9 84.9 56.2 79.7 55.7 66.2 56.9

50.8 59.0

93.2 65.3 88.0 65.3 83.9 62.1

66.2 57.9

54.9 66.2

a Each value represents the average of duplicate analysis. A = amylose, AP = amylopectin.

alpha-amylase and the amount of other varieties (Table 2). For reducing sugars released was measured amylopectin, the rate of release of across time. The rate of release of reducing sugars was faster for

Table 1. Amylose percentage and chain length of amylopectin in rice varieties. a Coimbatore, Bhavani and IR50 was faster than in the

reducing sugars from the amylose of Bhavani.

India.

Chain length Variety Amylose (%) (no. of glucose/

branch) High-yielding aromatic rice variety material of IR8/Pankhali 203 cross, was GR101 released in 1986. The new variety has

maintained its superior performance at Bhavani 30.0 26 IR50 27.6 23 CO 25 27.3 22 N. D. Desai, S. Raman, M. U. Kukadia, and all locations (Table 1). It has yielded 4.1 Ponni 27.2 22 M. R. Patel, National Agricultural Research t/ ha, 83.6% more than Pankhali 203. ASD7 29.5 21 Project, Gujarat Agricultural University, GRl0l has long, slender, fine grains

LSD 0.48 0.95 Navsari 396453, Gujarat, India with an oily translucent kernel and mild a Each value represents the average of triplicate analysis. GR 101, selected from segregating

aroma (Table 2). It has resistance to neck blast.

10 IRRN 12:4 (August 1987)

Table 1. Average yield data and yield characteristics of promising scented cultures. Gujarat, India, 1980-83.

Grain Flowering Plat 1000-grain Length Breadth Classification rice

Milled Variety height weight (mm) (mm) Individuals, organizations, and media are

excerpts from articles in the IRRN. (t/ha) (d) (cm) (g) recovery invited to quote or reprint articles or

(%)

GRl0l 4.1 105 101 19.3 9.52 2.24 Fine 69.63 Pankhali 203 2.2 92 140 17.2 8.43 2.30 Fine 53.78 (check)

Table 2. Quality characteristics of GR101.

Variety Kernel

Water Alkali Alkali Protein Moisture Starch Length Breadth uptake spreading clearing (%) (%) value (mm) (mm)

After cooking Taste

(%) Appearance Cohesiveness Tenderness

GRl0l 6.5 1.9 295 Completely Collar 7 13 21 Whole Well- Firm and Scented dispersed cleared smooth separated chewy

grain grain Pankhali 203 (check) 5.7 1.9 185 Collar Collar 7 13 6 Indistinct Sticky Firm and Scented

incomplete cottony broken chewy grain

Physicochemical properties as a influence the cooking quality of milled basis for identifying preferred rice. We measured physicochemical cooking quality parameters of 40 popular rice varieties

B. Thayumanavan, Biochemistry Department, Tamil Nadu Agricultural University, Coimbatore 3, India cooking quality on the basis of total

(Table 1). The varieties were classified as rices with high, medium, and low

points (Table 2). Many physicochemical properties

Table 1. Cooking quality of physicochemical characteristics of milled rice. Coimbatore, India.

Cooking quality

High Medium Low Characteristic

Pericarp Single grain weight (mg) Length (mm) Shape L/B/T a

Surface area (cm 2 /g) Alkali disintegration value Cooked volume for 100 g rice (CC) Elongation ratio in length Elongation ratio in shape (L/B) Amylose content (%)

Red >23

<5 <1.2

<15.0 >6.0

<1.4 <2.4

<20.00

<260

White 18.0 –22.9 5.0 – 5.99 1.21– 1.59

15.1 –16.9 3.1 – 5.99 261–279 1.40– 1.59 2.41– 2.99

20.00–24.99

– <18

>6 >1.6

>17.0 <3.0

>1.6 >3.0

>280

>25 a Length-breadth-thickness.

Complete slide sets of photos printed in Field problems of tropical rice, revised 1983, are available for purchase at $50 (less developed country price) or $60 (developed country price), including airmail postage and handling, from the Communication and Publications Department, Division R, IRRI, P.O. Box 933, Manila, Philippines. No orders for surface mail handling will be accepted.

Table 2. Total evaluation points of rice varieties and cultures. a Coimbatore, India. Variety or culture Total IR20 28 Ponni 28 IR60 28 B havani 27 IR50 CO41

27 27

White Ponni 27 ADT36 27 IR62 CO 44

26 26

IR42 25 NLR CO 37

25 23

ADT27 CO 43

23

CO 25 23 23

ASDl5 22 Ponmani 21 IR8 TKM9

17 17

ASD1 ASD7

16

TNAU801790 15

TNAU831293 28

TNAU801793 26

AD85001 26

TNAU80042 26

TNAU80058 25

AS25370 25

TNAU80030 25

AD9408 23

AS13744 23 21

BS8 IET7301

20

IET7590 20

AS28883 20

IET7303 20

BC367-4 20

TM8089 20 19

a High = >25, medium = 20-24, law = <20.

IRRN 12:4 (August 1987) 11

yield

High density grain index among primary and secondary tillers of short- and long-duration rices

S. P. Rao, Directorate of Rice Research, Rajendranagar, Hyderabad 500030, A. P., India

We conducted a multilocation field experiment using two short-duration and two long-duration varieties during 1985 wet season in a randomized b1ock design with four replications. Test plots were fertilized 80-13-25 kg NPK/ ha.

Tillers were sequentially labeled during crop growth and 50 panicles/replication were sampled at harvest. Density was measured by immersing the grain in a 1.20 specific gravity salt solution. The percentage of submerged high density grain from primary and secondary or tertiary tillers was recorded.

In early varieties. the high density grain index was higher for primary tillers than for secondary and tertiary tillers (see table). In late varieties, the indexes were equal.

Sugars and phenolic compounds in rice leaves in relation to varietal resistance to bacterial blight (BB) pathogen

B.N. Mahto, R.N. Singh, C.P. Anasthi, and A.B. Abidi, Narendra Dev University of Agriculture and Technology, Kumarganj, P. O. District Faizabad 224229 (U. P.), India

A few reports establish a relationship between phenolic and sugar constituents of rice leaves and resistance or susceptibility of a variety to BB caused

by Xanthomonas campestris pv. oryzae (Ishiyama) Dye.

Following standard procedures, we analyzed for total phenol, total sugar, and reducing sugars from alcoholic and aqueous extracts Of apparent1y hea1thy rice leaves. The leaves were from plants that had been inoculated with the local BB isolate and showed resistant, moderately resistant, and highly susceptible disease reactions.

Highest total phenol, 278.26 mg/100 g of fresh leaves, was found in IR20, a resistant variety; the lowest, 100 mg/100

Effect of time of evaluation on alkali spreading values

A. A. Vidal and J. J. Marassi, Estación Experimental Ins. Agr. Julio Hirschhorn, Facultad de Agronomía, Universidad Nacional de la Plata, La Plata, Buenos Aires, Argentina

The gelatinization temperature of the endosperm starch, a test of rice cooking quality, is estimated by the extent of spreading and clearing of milled rice treated with a 1.7% solution of potassium hydroxide for 23 h at 30 °C. Grain with low gelatinization temperature dissolves completely; the endosperm of grain with intermediate gelatinization temperature spreads partially; rices with high gelatinization temperature are essentially unaffected.

We studied the effect of time of exposure in the alkali test using 41 Argentinian and United States varieties and lines of rices with alkali spreading values ranging from 2.62 to 7 in a random split-plot design with 3 replications. The alkali test was evaluated at 6, 12, 18, and 23 h following the original method. No significant difference in the varietal reaction was noted between alkali exposure at 18 and at 23 h (see table).

Effect of soaking time on mean alkali spreading value of milled rice of 41 varieties.

Time (h) Alkali spreading value

6 5.27 c 12 5.66 b 18 5.94 a 23 5.91 a

Tukey 5% 0.07 Tukey 1% 0.1

Mean values with the same letter are not significantly different from each other.

The International Rice Research News- letter (IRRN) invites all scientists to contribute concise summaries of significant rice research for publication. Contributions should be limited to one or two pages and no more than two short tables, figures, or photographs. Contributions are subject to editing and abridgment to meet space limitations. Authors will be identified by name, title, and research organization.

12 IRRN 12:4 (August 1987)

High density grain index (%) of primary and tertiary tillers of short and long-duration varieties. Hyberabad, India, 1985 kharif.

High density grain index

Hyderabad Chinsurah Kanpur Kapurthala Maruteru Variety

Short duration Rasi Ratna Long duration Mahsuri IET5656

CD (0.05) CV (%)

Early Rasi Ratna Late Mahsuri IETS 65 6

CD (0.05) CV (%)

71.6 55.7

I 5 3.0 61.8

5.2 4.3

64.6 50.4

55.1 61.8

3.5 3.0

Primary tillers

85.9 66.5 72.8 71.2

83.6 81.2

2.4 1.5

– –

ns 9.8

Secondary. and tertiary tillers

80.0 60.4 71.5 38.0

81.3 76.1

– –

1.4 10.3 1.3 5.8

86.5 79.0

– –

ns 5.1

65 .0 75 .0

– –

6.4 2.6

60.0 29.0

75.0 90.0

4.1 3.3

53.0 23.0

80.0 91.0

2.5 2.1

Genetic Evaluation and Utilization DISEASE RESISTANCE

g of fresh leaves, in Anand, the highly susceptible check. This trend is reflected in reducing and total sugars as well.

The amount of phenol and sugars present in the leaves of resistant varieties varied considerably, but was always higher than that present in moderately susceptible Bhagalpuri, which in turn was higher than that present in highly susceptible Anand (see table).

These findings establish that higher amounts of phenols and sugars keep BB lesion size smaller by generating a resistant reaction to the BB pathogen.

Field screening IRRI lines against tungro (RTV) disease in Lanrang

M. Sudjak S., A. Muis, S. Sama, W. Wakman, Agency for Agricultural Research and Development, Maros Research Institute for Food Crops, P. O. Box 173, Uung Pandang, Indonesia

To obtain sources of resistance to RTV for the breeding programs in Indonesia, we screened IRRI lines in the field in Lanrang substation during the 1986 wet monsoon season.

Lines tested were transplanted in 2 rows of 20 hills/row. Susceptible check variety TNI was transplanted between each two rows. All test lines and TNI were transplanted at 20- × 20cm spacing.

The trial was fertilized with urea and triple superphosphate at 90 kg N/ ha and 26 kg P/ ha. RTV symptoms were measured at 4, 6, and 8 wk after

Manoharsali, neck blast-resistant variety

Y. Rathaiah and G.R. Das, Regional Agricultural Research Station, Assam Agricultural University, Titabar 785630, Assam, India

During the 1986 Jul-Dec season, a severe neck and nodal blast (BI) incidence throughout Assam offered an opportunity to screen rice varieties against neck B1. Infection was assessed

Total phenol and reducing and total sugar content in apparently healthy leaves from BB inoculated resistant (R), moderately resistant (MR), and highly susceptible (HS) rice varieties. Kumarganj, India.

Variety level a Reaction Resistance Total phenol b Reducing sugars b Total sugars b

(mg/100 g) (mg/100 g) (g/l00 g)

IR20 1 R 278.26 Anjani III 1 R 126.08 Damodar 1 R 121.73 Randhuri 1 R 117.39 Getu 1 R 113.04 Zeerabatti 1 R 113.04 Bishunbhog 1 R 112.50 Bhagalpuri 5 MR 104.34 Anand 9 HS 100.00

a Standard evaluation system for rice (1980). b Fresh weight basis.

114.40 113.90 114.30 114.00 114.00 113.90 113.80 113.70 113.50

1.1085 1.1080 1.1059 1.1070 1.1060 1.1069 1.1058 1.1050 1.1048

Field screening of IRRI lines against tungro disease in Lanrang, Indonesia.

Line SES rating

4 WT 6 WT 8 WT IR1352 0 0 1 IR1354-21-2-3-3-2-2 0 0 1 IR31868-64-2-3-3-3 0 1 1 IR11288-B-B-60-1 0 1 3 IR14437-Kn-6-0-0-5-3 0 1 3 IR15864-430-3-1-2-3 0 1 3 IR19743-43-2-3-3 0 1 3 IR1975-5-2-3-1 0 1 3 IR21567-18-3 0 1 3 IR28224-3-2-3-2 0 1 3 IR28228-119-2-3-1-1 0 0 3 IR29692-99-3-2-1 1 1 3 IR31851-96-2-3-2-1 0 1 3 IR35546-2-1-3-2 0 1 3 IR37218-24-2-2 0 1 3 IR38784-137-2-6-6 0 0 3 IR4432-28-5-30Kr-b-Mr-3 0 1 3 IR4432-28-5-40Kr-b-Mr-9 1 3 3 IR18348-36-3-3 1 3 5 IR28128-45-3-3-2 0 3 5 IR29658-69-2-1 1 3 5 IR29925-22-3-3-3 1 3 5 IR31082-48-2-2 1 3 5 IR33450-25-2-1-1-2-2 1 3 5 IR35664-42-1-2-2-2-2 1 3 5

transplanting (WT) on the Standard evaluation system for rice (SES).

Of 400 lines tested, 18 were resistant and 7 moderately resistant (see table).

Complete slide sets of photos printed in Field problems of tropical rice, revised 1983, are available for purchase at $50 (less developed country price) or $60 (developed country price), including airmail postage and handling, from the Communication and Publications Department, Division R, IRRI, P. O. Box 933, Manila, Philippines. No orders for surface mail handling will be accepted.

Incidence of neck Bl in 5 varieties in Assam, India.

Variety Disease score a

Manoharsali 0 Kmj 1-17-2 0 B iraj 3 IET7 25 1 9 Pusa 2-21 9

a Standard evaluation system for rice.

on 20 randomly selected hills of 5 promising varieties grown in adjacent plots.

Manoharsali and Kmj 1-17-2 were totally free of neck Bl (see table). Manoharsali also showed complete resistance to B1 in farmers' fields. This variety has been grown in Assam for 20 yr.

Kmj 1-17-2 is a derivative of the cross Manoharsali/IR8 and might have inherited resistance from Manoharsali.

Manoharsali also is tolerant of bacterial leaf blight and sheath blight and resistant to brown planthopper. It is susceptible to brown spot.

IRRN 12:4 (August 1987) 13

Reaction of varieties and selections to green leafhopper (GLH) and tungro (RTV) in the greenhouse

L. M. Sunio and E. H. Tryon, Entomology Department, IRRI

We evaluated selected varieties and lines for resistance to GLH and RTV.

Six-day-old seedlings were infested with 4 second- and third-instar GLH nymphs/ seedling, using the no-choice seedling bulk test. Damage was rated at 7 d after inoculation, when susceptible check TN1 died. The experiment was repeated 3 times with 8 replications of 15 seedlings/ variety.

For RTV inoculation, ten 2-wk-old seedlings of each variety were separately exposed for 24 h to 2 adult GLH which had 2-d acquisition feeding on RTV- infected TN1 plants. Infected plants were counted 14 d after inoculation.

Varieties and selections were categorized as 1) resistant to both insect and virus, 2) resistant to insect but susceptible to virus, 3) susceptible to insect but resistant to virus, and 4) susceptible to both insect and virus (see table).

Reaction of selected varieties and lines to GLH and RTV. IRRI, 1986.

Variety GLH rating RTV (%)

Resistant to GLH and RTV Pankhari 203 3 0 IR29725-109-1-2-1 3 30 IR32307-107-3-2-2 3 30 IR32429-47-3-2-2 3 30 IR32453-20-3-2-2 3 20 IR33043-46-1-3 3 20

Resistant to GLH, susceptible to RTV Ptb 18 1 70 ASD7 1 90 Palasithari 601 3 90 IR28222-9-2-2-2-2 3 100 IR28224-3-2-3-2 1 70 IR28228-199-2-3-1-1 3 70

Susceptible to GLH, resistant to RTV Utri Rajapan 9 0 Utri Merah 7 0 ARC11554 7 10 Naria Bachi 9 30 ARC10342 7 50 Basmati 7 60

Susceptible to GLH and RTV ARC10980 7 70 IR22 7 100 IR42 7 80 TN1 9 100

14 IRRN 12:4 (August 1987)

Ragged stunt virus (RSV) concentration in tolerant rice

A. Parejarearn and H. Hibino, Plant Pathology Department, IRRI

Seven-day-old seedlings of Sitopas, Ptb 18, Tetep, and Lemo, which have symptomatic resistance (tolerance) to RSV, and several nontolerant varieties were individually inoculated with RSV and transplanted in pots. Uninoculated seedlings were transplanted as a check. Five RSV-infected and 3 uninoculated plants of each variety were individually tested for height and RSV concentration at 30 and 45 d after infection (DI).

Whole plants except roots were separately homogenized with buffer solution and the sap at 1/5 dilution was directly tested in ELISA. For ELISA, Micro ELISA Plate (Dynatech) was coated with immunoglobulin to RSV at

2 µg/ ml and immunoglobulin-alkaline phosphatase conjugate was diluted 300 times. RSV concentration in sap was indicated by absorbance value at 405 nm. In ELISA, absorbance of uninfected plant sap was below 0.05 throughout the tests.

Infected seedlings of all varieties showed typical RSV symptoms. Plant height reduction at 30 DI was high in RSV-infected plants of all varieties (see table). At 45 DI, height reduction was less in Sitopas, Lemo, and TN1. RSV concentration in Sitopas and Ptb 18 was consistently lower than in other varieties. Although RSV concentration was generally lower in tolerant varieties than in nontolerant varieties at 45 DI, the difference was not significantly large. Resistance to RSV in the varieties tested may not be due solely to their resistance to RSV multiplication.

Plant height reduction and RSV concentration at 30 and 45 DI in plants of 10 rice varieties infected at 7 d after soaking. IRRI, 1985.

RSV concentration a Height reduction (%) Variety

30 DI 45 DI 30 DI 45 DI

Sitopas 0.86 ± 0.19 0.84 ± 0.01 34 2 Ptb 18 0.89 ± 0.09 0.87 ± 0.00 33 15 Tetep 1.13 ± 0.03 1.04 ± 0.09 35 16 Lemo 1.00 ± 0.02 0.95 ± 0.20 28 Ptb 21

0 0.94 ± 0.00 1.10 ± 0.13 24 11

Utri Rajapan 0.93 ± 0.08 1.01 ± 0.10 21 11 Khao Mali 1.06 ± 0.01 1.06 ± 0.01 21 8 Khao-Tah-Haeng 1.07 ± 0.17 1.20 ± 0.19 28 46

TN 1 Kirikara 1.15 ± 0.06 1.10 ± 0.13 26 16

1.24 ± 0.03 0.94 ± 0.09 26 4

a Indicated by absorbance at 405 nm of sap at 1/5 dilution in ELISA.

Symptoms and yield reduction in Plant height, major symptoms, and tolerant varieties infected with grain yield were noted for each plant. ragged stunt virus (RSV) Seedlings inoculated at 7 and 15 DAS

developed symptoms characteristic of A. Parejarearn and H. Hibino, Plant RSV about 2 wk after inoculation. Pathology Department, IRRI Emergence of new leaves was delayed

Seedlings of 10 selected varieties were and darker in color. At 1 mo after transplanted 7 d after soaking (DAS), in inoculation, newly developed leaves 16- × 16- × 19-cm pots with fertile soil were less abnormal in all varieties. At 2 at 3 seedlings/pot. Seedlings were mo after inoculation, many varieties inoculated at 7, 15, 30, 45, and 60 DAS. showed vein swelling and occasional Uninoculated plants served as control. ragged or twisted leaves, but less Trials were established Sep 1984 and stunting (Table 1). The symptoms were Nov 1985, with three replications each. especially milder in Sitopas, Ptb 18, and

and leaves were short, ragged or twisted,

Table 1. Symptoms a and plant height reduction at 30 and 60 d after infection in 10 rice varieties infected with RSV 7 d after soaking. Sep 1984, IRRI.

30 d after infection 60 d after infection

Symptoms Height Symptoms Height Variety

reduction reduction (%) (%)

Sitopas R +++ , Tw, V + 24 Tw, V 7 Ptb 18 R + , TW, V + 29 R + , V ++ 17 Tetep R + , Tw, V + 29 R ++ , V + 22 Lemo R + , Tw 57 R ++ , Tw, V + 36 Ptb 21 R + , Tw 59 V ++ 20 Utri Rajapan R + 52 R + , Tw, V + 21 Khao Mali Tw 43 V ++ 21 Khao-Tah-Haeng R + , Tw, V + 45 R ++ , V + 43 Kirikara R + , Tw, V + 68 R + , Tw, V ++ 34 TN 1 R + , V + 56 R ++ , Tw, V ++ 25

a R = ragged leaves, Tw = twisted leaves, V = vein swelling. +, ++, +++ = degree of severity from low to high.

Table 2. Yield reduction in 10 rice varieties infected with RSV at different days after soaking. IRRI, Sep 1984.

Yield reduction (%)

7 DAS 15 DAS 30 DAS 45 DAS 60 DAS Variety

Sitopas 41 55 28 35 3 Ptb 18 a 38 65 28 21 Tetep 22 58 30 46 5 Lemo 57 – 33 –28 –21 Ptb 21 99 53 –10 –3 –22 Utri Rajapan 100 59 35 5 –39 Khao Mali 80 79 32 47 –16 Khao-Tah-Haeng 100 100 15 28 52 Kirikara 77 96 34 52 20 TN1 84 90 78 65 2

a Percentage yield reduction was calculated based on the yield of plants inoculated at 60 DAS.

–

Tetep. The symptoms in plants infected at 30 DAS were milder and those in plants infected at 45 DAS were not clear in any varieties except Kirikara and TN1.

high in plants of almost all varieties infected at 7 or 15 DAS (Table 2). Sitopas, Ptb 18, Tetep, and Lemo have significantly less yield reduction than other varieties infected at the seedling stages. In the second trial, flowering was delayed and yield reduction was less than in the first trial in all varieties. Yield reduction in many varieties inoculated at 30 DAS was higher than in plants inoculated at 7 or 15 DAS. Sitopas, Ptb 18, Lemo, and Ptb 21 had significantly lower yield reduction.

Sitopas, Ptb 18, Lemo, and Tetep developed milder symptoms and sustained less damage when infected with RSV at seedling stage. Their tolerance for RSV was due to their high ability to recover after severe infection at an early stage.

In the first trial, yield reduction was


Incidence of rice kernel smut (KSm) in Pakistan

M.A. Akhtar and M. Sarwar, Pakistan Agricultural Research Council, NARC, POB 1031, Islamabad

Sixteen rice varieties were evaluated at Gujranwala and Sheikhupura district research farms against KSm by the partial vacuum method using the chlamydospores of Tilletia barclayana. Sporidia1 cultures were prepared on potato dextrose agar for inoculation of 20 panicles of each variety at anthesis. Percentages of infected panicles were recorded at maturity.

at both locations. Disease incidence ranged from 5.25 to 95.25% at Sheikhupura and 6.25 to 97.25% at Gujranwala. C622 developed the lowest

Varieties showed differential reaction

Reaction of rice varieties to Tilletia barclayana. Islamabad, Pakistan.

Disease incidence (%) Variety Reaction

Sheikhupura Gujranwala

Bara, Basmati Pak, Dokri Basmati, >50 >50 Susceptible Jhona 349, Kangni, Melha 364, Motia, Mushakan, Palman, Ratria, Red rice, Sathra 278 Basmati 370, Sada gulab >10 >10 Intermediate C622, IR579 <10 <10 Resistant

infection, followed by IR579 and None of the varieties appeared to be Basmati 370 (see table). immune.

Reaction of selected varieties to tungro (RTV) and green leafhopper Seven-day-old seedlings of ASD7, (GLH) ARC11554, Gam Pai 30-12-15,

Kataribhog, TKM6, TN1, and Utri E. R. Tiongco, Z.M. Flores, and H. Hibino, Rajapan were individually exposed to Plant Pathology Department, IRRI one or five RTV-viruliferous adult

IRRN 12:4 (August 1987) 15

GLH. Longevity of adult GLH on the seedlings also was evaluated. Plants were scored 3 wk after inoculation for symptoms and assayed by latex test for the presence of the rice tungro bacilliform (RTBV) and spherical (RSTV).viruses.

ARCl 1554, Gam Pai 30-12-15, Kataribhog, and Utri Rajapan showed low level of apparent RTV infection but were mostly infected with RTBV alone, regardless of the number of insects used for inoculation (see table). Average vector longevity was shorter on ARCl 1554 and Gam Pai 30-12-15, indicating resistance to GLH, and longer on Kataribhog and Utri Rajapan, indicating low resistance. TKM6 and ASD7 showed apparent RTV symptoms even when infected with RTBV.

Longevity of adult GLH, percentage of seedlings with apparent symptoms, and infection by RTBV and RTSV of rice varieties exposed to 1 or 5 RTV-viruliferous GLH. IRRI, 1987.

Seedlings infected a (%)

GLH 1 insect/seedling Variety longevity

5 insects/seedling

(d) With By latex test With By latex test apparent apparent

symptoms RTBV+ RTBV RTSV symptoms RTBV+ RTBV RTSV RTSV RTSV

TN1 TKM6 Gam Pai 30-12-15 ASD7 Utri Rajapan ARC11554 Kataribhog

9.4 1.3 4.9 3.8 8.4 4.1 9.4

13 47 13 33

4 0

28

43 0 0 7 2 0 5

33 48 19

7 11 73

38

4 0 0 4 0 0 2

74 39 13 46 7

11 25

61 3 0

25 3 0

14

32 46 49 47 22 22 60

2 0 0 2 0 0 0

a Av of 2 trials. Plants scored and assayed by latex test 3 wk after inoculation.

Kataribhog had low infection on the basis of symptoms but had high RTBV

infection, indicating symptomatic resistance (tolerance) to RTV.

Genetic Evaluation and Utilization INSECT RESISTANCE

Tolerance of some rice varieties for gall midge (GM) Orseolia oryzae Wood-Mason

P.S. P. Rao, Central Rice Research Institute (CRRI), Cuttack 753006, Orissa, India

Thirty-day-old seedlings of 15 varieties were transplanted singly at 15- × 15-cm spacing in two 18- × 3-m plots per entry

on 29 Jul 1982 to synchronize the vulnerable tillering stage with high GM infestation. The varieties were grown with 80 + 20 kg N, 18 kg P, and 33 kg K/ ha.

protected with granular diazinon applied to soil water at 1.50 kg ai/ ha on 10, 25, and 40 d after transplanting (DT). Because the experimental field tended to

One plot of each variety was

be invaded by other insects (leaffolder, yellow borer, etc) from 40 DT, all plots were sprayed with 0.4 kg ai phosphamidon/ha at 40, 50, 60, and 70 DT.

Twelve 9-plant samples were marked at random in each plot. Percent silvershoots (SS) was estimated at 50 d after treatment and grain yields were recorded at harvest.

Vikram, PTB10, and CR94-MR1550

GM incidence and yield losses in some rice varieties. CRRI, Cuttack, 1982 wet season.

Seed to GM incidence (%) Regression Reaction a to pest

Variety 50% flowering equation for Regression % yield loss/ based on Lowest Highest Mean expected yield ( r ) value incidence (d) (24 samples) (kg/ha) Incidence Yield loss

GEB24 Pankaj

Vijaya Sona Jaya

Padma Bala Leuang 152 Vikram

PTB10 CR1014 Jagannath

CR94R-MR1559

CR58-MR1538

CR94-MR1550

116 113 104 96 96

90 85 82 65

138 96 95 70

121 113

0 10 14 17 11 11 10 18 10 0 0 0 3 0 0

95 91 94 93 88 90 62 91 40 0

39 46 24 78 80

50 46 59 54 56 60 29 49 25 0

13 8 9

34 35

3161 – 19.6 × 1301 – 59.1 × 3119 – 34.1 × 4099 – 21.8 × 3321 – 11.3 × 5913 – 55.2 × 5658 – 62.6 × 2194 – 14.2 × 2405 – 23.5 ×

– 6072 – 32.2 × 5588 – 28.0 × 2112 – 1.6 × 2569 + 1.3 × 4798 – 12.8 ×

–0.747** –0.900** –0.699** –0.777** –0.802** –0.887** –0.747** –0.625** –0.450*

– –0.282 –0.215 –0.151 +0.342 –0.457*

0.62

0.93 0.68 0.52 0.93 1.1 1 0.5 1 0.98

0.5 3 0.50 0.35

0.27

0.81

–

–0.06

S S S S S S S S S HR R R R S S

LT LT LT LT MT LT LT MT LT – – –

HT HT

–

a Percent silvershoots. S = susceptible, R = resistant, HR = highly resistant, LT = least tolerant, MT = moderately tolerant, HT = highly tolerant.

16 IRRN 12:4 (August 1987)

unit %

irrigated wetland field planted to indica varieties and in a dryland field planted to japonica varieties. The experimental fields were planted the same day.

At 2 wk before harvest, 150 tillers/variety were dissected. SB infestation was higher in the japonica varieties (see figure). SB species found in

rated resistant, with means of 8-13% SS; CR1014 to 1.1% in CR58-MRl538. Leuang 152 was highly resistant (no SS). Based on yield losses, susceptible entries

The correlation of incidence with could be tentatively classified for yield was negatively linear except for tolerance as follows: CR1014. In 10 varieties, the regression coefficient was significant or highly significant (see table).

Yield loss ranged from -0.06% in

Highly tolerant : CR1014,

Moderately tolerant : Sona, Padma (0-0.30%) Jagannath

(0.31-0.60%)

Stem borers (SB) in dryland and wetland rice

A. T. Barrion and J. A. Litsinger, Entomology Department; E. Sison and M. Arraudeau, Plant Breeding Department, IRRI

We compared SB infestation in an

Relative abundance of rice SB in japonica varieties planted in dryland fields and indica varieties planted in wetland fields. IRRI farm, 1985 wet season.

Least tolerant : GEB24, Pankaj, (0.61%–higher) CR94-MRl559,

Vijaya, Jaya,

Bala CR58-MR1538,

As yield loss varied widely among varieties, economic injury and threshold levels also varied.

wetland indicas and dryland japonicas also differed.

environments: Chilo suppressalis (Walker), C. auricilius Dudgeon, Scirpophaga incertulas (Walker), Maliarpha sp., and Sesamia inferens

(Walker). Species abundance in the indicas was S. incertulas > C. auricilius > C. suppressalis > S. inferens > Maliarpha sp. In the japonicas, it was C. suppressalis > C. auricilius > S. inferens > Maliarpha sp. > S. incertulas.

The indicas had fewer whiteheads (1-4%) and SB (4-12 larvae) than the japonicas (1-12% whiteheads and 0-130 SB larvae). Four Brazilian japonica varieties — Japones, Maranhao Vermelho, Manteiga, and Poupa Preguica — had the highest infestation.

Five SB sp. were collected in both rice

Screening of rice accessions against leaffolder (LF) Cnaphalocrocis medinalis

R. Rajendran and R. Velusamy, Centre for Plant Protection Studies, Tamil Nadu Agricultural University (TNAU), Coimbatore 641003, India

We screened 32 rice accessions from the All-India Coordinated Rice Improvement Project for resistance to LF during 1986 wet season, using a seedling screening technique.

Pregerminated seeds of accessions were sown 6 cm apart in 6 rows in 50- × 40- × 10-cm wooden seedboxes. Each accession was planted across the width of the seedbox to maintain at least 5 hills (3 plants/hill)/row. One row of susceptible check TN1 and one row of resistant check Ptb 33 were sown at

IRRN 12:4 (August 1987) 17

random in the seedboxes. At 7 d after seeding, the seedboxes were transferred to iron trays (60 × 40 × 15 cm) filled with 5 cm water. At 20 d after seeding, the plants in the boxes were covered with nylon net cages into which LF moths collected in the field were released at 20 moths/ cage (1 male to 1 female). A cotton swab soaked in 1% sugar solution was hung inside the cage as food for the moths. Moths were allowed to oviposit for 3-4 d. At 15 d after release of moths, LF damage was assessed as percent damaged leaves in each row and accessions were rated according to the Standard evaluation system for rice.

The same accessions were screened in the field at the Paddy Breeding Station, TNAU.

Reaction of rice accessions to LF. Coimbatore, India.

Accession Cross Damage rating a

Greenhouse Field

BKNBR1088-83 IR2030-203-3-1/RD 1 RP1579-43

3 3 Phalguna/ARC6650 3 3 Phalguna/TKM6 3 3 Phalguna/TKM6 3 3

F'TB12 (donor) – 3 3

RP2199-41-25-30-55 RP2199-249-209

RP2035-48-54-6 Phalguna/IR50 3 3 RP2235-85-62-8 Phalguna/IR50 3 3 RP2235-115-75-40 Phalguna/IR50 3 3 RP2235-136-65-10 Phalguna/IR50 3 TNAULFR83 1324

3 Bhavani/IR4707-106-3-2 3

TNAULFR832042 3

Bhavani/ARC10550 3 3 T2005 (donor) 3 3 TNl (susceptible check) 9 9 PTB33 (resistant check) 3 3

a By the Standard evaluation system for rice.

Twelve accessions were identified as resistant in the greenhouse and in the field (see table).

Screening rice varieties for with 3 replications. Twenty hills were 19% to 58% (see table). IET8616 had the resistance to mealybug selected for each entry and the number fewest infested plants; AD85001 was

of mealybugs/ tiller and percentage highly susceptible. ACM10 had the M. Gopalan, N.C. Radja, and infested plants on 20 hilIs/entry were highest number of mealybugs/ tiller. G. Balasubramanian, Centre for Plant recorded at 15-d intervals beginning 15 d Mealybugs/ tiller and percentage Protection Studies, Tamil Nadu Agricultural after transplanting. University, Coimbatore 641003, India

infestation were positively correlated Mealybug infestation ranged from ( r = 0.9786).

We evaluated 17 varieties for resistance to mealybug Brevennia rehi Lindinger. Experimental plots were 4 × 2 m with 2 seedlings/ hill at 15- × 10-cm spacing

Mealybug infestation on 17 rice varieties. a

Coimbatore, India.

Variety Infested plants Mealybugs (%) (no./tiller)

PY 3 31.2 (33.1) a-d 43.4 (19.7) b CO 37 23.4 (28.6) a-c 43.1 (19.6) b CO 41 36.8 (36.7) b-e 41.7 (19.2) b ADT31 31.9 (35.9) a-e 58.6 (23.0) c ADT36 28.2 (31.9) a-d 61.0 (23.2) c IR20 29.2 (42.4) c-e 64.2 (24.0) c IR50 31.5 (34.0) a-d 92.7 (28.9) de ACM9 45.7 (42.5) c-e 101.2 (30.1) d-f ACM 10 51.0 (45.6) de 107.6 (31.0) f IET8616 19.1 (25.7) a 32.7 (17.1) a AS20665 19.8 (26.3) ab 39.6 (18.9) b

Genetic Evaluation and Utilization DROUGHT TOLERANCE

Evaluation of drought-resistant upland rice accessions 10 cm within rows.

Rainfall during the cropping period P.G. Nayagam, G. Soundrapandian, S. was 474.4 mm in 20 rainy days, with a Natarajan. Agricultural Research Station 16-d drought spell during the vegetative (ARS), Paramakudi, India phase. Drought tolerance and recovery

We evaluated 53 early-maturing rice Standard evaluation system for rice. accessions against local checks Oct 1986- Two drough)-resistant varieties were Feb 1987. Seeds were sown directly in 1- identified: IRAT 170 and IR21018-97-1 m2 plots at 20 cm between rows and (see table).

percentage were scored using the

AS24956 48.4 (44.0) c-e 92.0 (28.7) d A528838 55.0 (47.9) de 102.2 (30.2) ef AD85001 58.0 (49.7) e 96.7 (29.5) de Performance of promising upland rice varieties under moisture stress. Paramakudi, India. AD85003 53.1 (46.8) de 101.1 (30.2) ef

TNAU831175 52.7 (46.6) de 101.7 (30.1) d-f IRAT 170 IRAT13/Palawan 3 3

a Means of 3 replications. Figures in parentheses IR21018-97-1 BG34-8/RP825-70-7-1//IR36 3 3 are arc sine transformed values. In a column, Nootripathu (local check) – 3 5 means followed by a common letter are not PMK1 (improved check) Co 25/ADT31 3 3 significantly different (P = 0.05) by DMRT.

TNAU831146 43.7 (41.2) c-e 98.6 (29.7) d-f Variety cross Drought tolerance Drought recovery

18 IRRN 12:4 (August 1987)

Genetic Evaluation and Utilization ADVERSE SOILS TOLERANCE

A breeding method for tolerance for acid sulfate soil

Dao The Tuan and Pham Van Chuong, Vietnam Agricultural Science Institute, Hanoi, Vietnam

Tolerance for acid sulfate soils is related to tolerance for Al toxicity, Fe toxicity, and P deficiency. Local varieties have all three characteristics, modern varieties or lines only one or two.

We crossed high-yielding varieties with local tolerant varieties and modern varieties with different tolerances. Crossing modern varieties with different tolerances gave quicker and more effective results because negative traits of local varieties did not need to be eliminated.

Among six crosses, the cross NN75- 2/V12 gave the best performance. NN75-2 is an intermediate variety with tolerance for Al toxicity and P deficiency, V12 is a high-yielding

Tolerance for acid sulfate soils among different varieties and crosses. Hanoi, Vietnam.

Score a

Al toxicity P deficiency Fe toxicity Acid sulfate soils tolerance tolerance tolerance tolerance

IR8 Bau V12 NN75-2 IR2151-9-6 IR2153-2-6 IR8/Bau V12/NN75-2 NN75-2/V12 (V14) IR8/NN75-2 V12/IR2151-9-6 V12/IR2153-2-6

7 1 3 1 1 1 1 1 1 5 1

1-3

5 1 5 1 1 1 1 1 1 1 1

1-3

5 1-2 3-5 5

3-4 5 3 3 3

5-7 3-5 5

5-1 1

3-5 2-3 1-2 2-3 1-3 1-3 1

3-5 1-3 5

a By the Standard evaluation system for rice.

semidwarf variety with relatively high tolerance for Fe toxicity.

with good plant type, large panicles, moderate resistance to blast, and high cold tolerance. With these traits, VI4 could be grown in the spring on acid

From this cross, we selected line V14,

sulfate soils in the north. In varietal testing in different soil

types, V14 gave 10–15% higher yield than NN75-2, a variety adapted to acid and acid sulfate soils, and yield similar to that of IR8 on nonacid soil (see table).

Performance of coarse and fine rice varieties on alkali soils

K. K. Mehta, Central Soil Salinity Research Institute, Karnal 132001, India

In 1986 we evaluated selected varieties in 40 farmers' fields in 7 villages of the Operational Research Project for reclamation of alkali soils. Soils were highly alkali (pH > 10.0), sandy loam in

texture, and are classified as Natrustalfs (see table).

The fields were bunded and leveled and gypsum (30 mesh) applied Jun–Jul 1986. For IR8, PR106, PR107, and Basmata varieties, 120 kg N/ ha and 6 kg Znl ha were applied. For B370 and Basmati Desi, N was reduced to 80 kg/ha.

Maximum yield was with IR8 (4.6 t/ha) followed by PR106, PR107,

Grain yield of different rice varieties in first year of reclamation of alkali soils. Karnal, India, 1986.

Fields Av pH Gypsum Grain Sale Gross

(t/ha) yield price a

($/t) return a

($/ha) Variety (no.) 1:2 applied

IR8 PR106 PR107 Basmata Basmati (B370) Basmati Desi

1 6 3

16 10 4

10.2 10.2 10.1 10.1 10.0 10.2

10.5 10.5 10.0 10.5 10.0 10.5

4.6 4.5 4.4 4.0 1.6 1.5

128 135 135 220 384 340

589 605 592 881 631 506

a Converted at the rate of $1 = Rs 12.49.

Basmata, B370, and Basmati Desi. Basmata, with an average yield of 4.0 t/ ha, had the maximum return — $881/ha — because of its higher sale price (see figure).

B-370 (Basmati) and Basmata varieties of rice have similar grains but differ in yield potential. Karnal, India, 1986.

IRRN 12:4 (August 1987) 19

Vyttila 3, a new rice variety for acid saline areas

T. U. George, P. J. Tomy, and R. G. Pinhero, Rice Research Station, Vyttila, Kerala, India

Vyttila 3 has-been released for acid saline areas of Kerala. The Vyttila 1 / Taichung Native I cross yields 200 kg/ ha more than improved pureline selection Vyttila 1.

Vyttila 3, with 115 d duration, is

Performance of Vyttila 3 in farmers’ fields, Kerala, India.

Yield (t/ha)

Vyttila 1 Vyttila 3 Location

Parur Vyttila Maradu Panangad Chellanam Kandekadavu Kannamali

Mean

0.9 3.6 2.4 3.7 4.5 4.3 4.5 3.4

1.3 3.8 2.4 4.0 5 .0 4.1 4.9 3.6

suitable for May-Jun to Sep-Oct (pokkali season) cultivation. It is 166 cm tall with 3.6 t/ ha average yield potential and 5 t/ha maximum yield potential (see table). Kernels are red with good cooking quality; protein content is 7.8%.

The variety is photoperiod insensitive and tolerant of major diseases and most insect pests (except stem borer, leafroller, and rice bug).

Genetic Evaluation and Utilization TEMPERATURE TOLERANCE

Chhomro — a promising cold-tolerant traditional rice variety for rainfed wetlands in western hills in Nepal

B. R. Sthapit, Lumle Agricultural Centre (LAC), P.O. Box 1, Pokhara, Kaski, Gandaki Zone, Nepal

No improved rice varieties have yet been identified for temperate regions, particularly for elevations above 1,500 m. We evaluated 57 local varieties and 367 exotic materials during 1985-86. Local rices were collected from the altitude range 1,000-2,300 m in the western hills. Major sources of exotic materials were the International Rice Cold Tolerance Nursery (IRCTN), the National Cold Tolerance Rice Nursery (NCTRN), and an initial evaluation trial (IET) carried out in collaboration with the National Rice Improvement Programme (NRIP), Parwanipur.

were established at LAC (1,500 m). Mean air temperatures during early

Cold tolerance screening nurseries

Table 1. Comparative performance of selected cold-tolerant rice varieties identified in different nurseries. LAC, 1985-86.

Grain yield Sterility d Cold injury Trial or nursery Best yielding varieties (t/ha) at 12%

(%) at seedling stage e

moisture content (1-9 scale)

Farmers’ field, Chhomro local 5.3 0 1 1985 (n= 13) Banahu local 5 .05 3

Ghara local 3.4 15 3 NCTRN, 1985 Laisika-F 4.2 20 3 (n = 30) WR10072-79-1-2-3 2.4 25 3

IRCTN, 1985 Laisika-I 5.1 5 3 (n = 184) K39-96-1-1-1-2 4.9 5 4 NCTRN, 1986 Chhomro local 4.8 0 1 (n = 22) NR10073-167-3-1-3 4.1 30 4

Phalame 3.4 60 4 LRCTN a , 1986 Chhomro local 5.0 2 1 (n = 52) Seto Bhakunde 3.9 2 2

Kalo Patle 3.2 1 2 Raksali 3.1 5 3

PON b , 1986 Banahu local 4.1 6 2 (n = 50) Chhomro local 4.0 5 1

Raksali 2.8 10 3 SFT c , 1986 Chhomro local 4.1 0 1 (n = 36)

on Chhomro local. d Spikelet sterility was estimated by eye and by grasping the panicle. e Measured a Local Rice Cold Tolerance Nursery. b Preliminary Observation Nursery. c Spacing × Fertility Trial

according to the procedures mentioned in the IRRI Standard evaluation system for rice scale.

NR10068-60-3-2 2.2 25 4

seedling growth (Jun-Jul) were 16.2- 17.1 °C minimum and 22.6-22.8 °C maximum. During ripening (Oct-Nov),

Table 2. Comparative performance of 2 best cold-tolerant local varieties of rice at an altitude of 1500 m. a LAC, 1985-86.

minimum temperature was 9.9-15.2 °C Variety Plant Tillers/ Panicles/m 2 Grain yield b

and maximum was 16.7-20.1 °C stand/m 2 plant (t/ha) Maximum water temperature was Chhomro local 46.6 ± 3.27 7.0 ± 1.05 256.6 ± 34.71 4.798 ± 0.475 20.1 °C in Jul and 14.0 °C in Oct. Cold Raksali local 29.4 ± 4.48 5.6 ± 0.70 263.3 ± 52.30 2.359 ± 0.794 tolerance of local and exotic varieties Difference 17.2 ns 1.4 ns 6.7 ns 2.439*** was measured by leaf discoloration at (P = 0.05) seedling stage, spikelet sterility, and grain yield.

a Yields were estimated from 1 m 2 crop cuts (n = 10) from seed multiplication block. b At 12% moisture content.

20 IRRN 12:4 (August 1987)

We evaluated the cold tolerance of 475 traditional Vietnamese rice varieties from the International Rice Germplasm Center to identify possible donor parents for breeding.

The entries could be grouped into five categories: 1) glutinous (mostly japonica), 2) mountain area, 3) winter rice, 4) wet season rice in the north, and 5) wet season rice in the south (Table 1).

Low temperature tolerance of traditional Vietnamese varieties

The mountain and winter varieties include many japonicas. Both north and south wet season varieties are indica types.

Varieties were tested at the seedling stage (10°C for 4 d), panicle initiation (I7°C for 15 d), and anthesis (17°C for 10 d). At the seedling stage, 39 entries — many of them winter rice varieties — showed cold hardiness (Table 1). A large number of the varieties used in the mountains did not have cold tolerance at the seedling stage. Some glutinous varieties showed cold tolerance at the seedling stage.

Winter rices usually are divided into six subgroups on the basis of morphological characteristics. The Tep group had the highest number of cold- tolerant varieties (Table 2).

The rice plant is most sensitive to low temperature at meiosis or panicle initiation. The outstanding Vietnam entry tolerant of 17°C air temperature at panicle initiation was Bong Sen (Acc. 10861) with a score of 1 ; Tep Trang and Ba Ren were relatively tolerant at

No injuries from cold temperatures were observed in traditional varieties Chhomro and Raksali at the seedling stage; most improved lines had either discolored leaves or stunted yellowish growth. Chhomro and Raksali consistently performed better than the exotic cold-tolerant materials for 2 yr. Spikelet sterility on exotic lines was

D. Duc, Vietnam Agricultural Science Institute. Van Dien Thanhtri. Hanoi, Vietnam, and R. M. Visperas and B.S. Vergara, IRRI

About 2.5 million ha of rice in Vietnam is subjected to low temperature. In the north, low temperature killed 27,110 ha of rice seedlings in 1976.

The first crop Nov–Jun is subjected to low temperatures Nov–Mar (5.0 to 11.0°C minimum temperature), coupled with low sunshine hours (1.3–4.5 h/d). The most common cold injury symptoms are seedling stunting, leaf wilting or even death, spikelet degeneration, poor grain filling, high sterility, and delayed growth.

Table 1. Response of Vietnamese rice groups to low temperature at the seedling stage. Hanoi, Vietnam.

Varieties (no.) with cold tolerance at

seedling stage

Good Poor Total Group

Glutinous 9 28 37 Mountain area 4 30 34 Winter rice (Chiem) 14 77 91 Wet season (north) 0 92 92 Wet season (south) 12 209 221

Total 39 436 475

large (25–100%); no sterility was noticed in Chhomro (Table I). Yields of Chhomro were significantly superior to those of Raksali in 1986 (Table 2). Widely grown Raksali suffered some spikelet sterility and yielded relatively less than Chhomro.

Most of the exotic lines from

NCTRN and IRCTN failed to set grain at Lumle. Chhomro yields ranged from 4.8 to 5.3 t/ha under rainfed wetland conditions.

Chhomro's cold tolerance could be utilized in developing suitable cold- tolerant rice varieties for temperate areas of Nepal and elsewhere.

Table 2. Winter season Vietnam varieties (Chiem) and their response to low temperature at the seedling stage. Hanoi, Vietnam.

Group

Varieties (no.) with indicated cold

tolerance

Good Poor Total

Te (nonglutinous rice) 3 4 7 Tep (fine, short grain) 4 Cut (round grain)

5 9 0 6 6

Bau (large grain) 2 10 12 Saiduong (brown glume) 3 3 6 Other Chiem varieties 29 23 52

panicle initiation and at the seedling st age.

Most of the varieties had relatively poor tolerance at anthesis. The most tolerant are Bong Sen, Nep Da, Nep Den (Acc. 24149), Bat Ngoat (Acc. 24193), Ba Ren, Tep 62, and Khau Mua Venh.

Ba Ren and Tep 62 are the most promising. Scores for the other Vietnamese varieties are available from the IRGC data bank.

Genetic Evaluation and Utilization HYBRID RICE

Potassium nutrition in hybrid rice

Fan Mingxieng and Ge Dangzhi, Hunan Agricultural College; and fiang Longyin, Hunan Hybrid Rice Research Centre, China

We studied hybrid rice Vu 35 at different K levels on a Quaternary red clay soil with pH 6.0, 2.76% organic matter, 70 ppm available K, 240 ppm

slowly available K, and 0.188% N. Conventional variety Xiang 9 was the check.

KC1 was applied at 0, 110, 220, and 440 kg/ ha in main plots with 350 kg urea and 550 kg superphosphate/ ha. All the P, 2/3 N, and 1/3 K were applied before transplanting, 1/3 N and 2/3 K at tillering. The 2 varieties were transplanted in 4- × 8-m subplots with 3

IRRN 12:4 (August 1987) 21

Test cross for restorer genes using three male sterile lines

O. Watanesk and S. Sa-nguansaj, Chainat Rice Experiment Station, Chainat 17000, Thailand

We tested crosses for restorer genes for the Thailand hybrid rice breeding program in 1982. Now we have 8 varieties and 10 elite breeding lines that are effective restorers for V20A. In 1985, we received male sterile lines IR46828A and IR46829A from IRRI and crossed 5 varieties and 10 elite breeding lines as male parents with 3 CMS lines — V20A, IR46828A. and IR46829A (which are the same WA type) — to identify their restorers (see table).

The F 1 hybrids were grown in the field. Spikelet fertility was evaluated visually for each plant. Varieties showing more than 80% spikelet fertility were classified as restorers. those

replications. Samples were taken at transplanting, tillering, panicle initiation, full heading, and maturity for soil, plant, and yield analyses.

Increased K increased K content in plant and absorbed K increased with increased K fertilizer at all stages for both varieties; however, Vu 35 was more sensitive to K supplied from panicle initiation to heading and needed more K. The leaf area index was significantly correlated with plant N content ( r = 0.91*) at early growth stages and with plant K content ( r = 0.94) at late growth stages. Total photosynthetic area and net assimilation rate had increased significantly at heading and maturing stages, which led to 13-44% increase in dry matter production with K application (Table 1).

Grain yield of Vu 35 increased 3-8% with K level, but increase/ kg K applied declined (Table 2), resulting in lower K economic efficiency at higher K levels. Yield of Xiang 9 was significantly lower than that of Vu 35 and did not show obvious response to K fertilization.

O 2

Table 1. Effect of K level on growth of hybrid rice Vu 35. a Hunan, China.

K level (kg KCl/ha) Tillering Panicle initiation Full heading Maturity

Leaf area index 0 1.63 4.51 6.69

1.52 2.19

4.80 1.68

8.39** 3.64** 4.88 8.44**

1.71 4.04 9.71** 4.34** 4.10**

Net assimilation rate (A Dry matter mg/dm 2 per h) 10.5 12.3 1.9 13.3 8.6 9.5

110 220 440

0 110 220 440

8.1 7 .0 9.0 9.3

11.0 8.9 13.2 11.4 8.9 10.9

0 Dry matter weight (g/plant)

110 2.73 8.13 19.47 2.73

27.17 8.27

220 26.10* 34.93*

2.96 8.30 21.97 440 3.23 8.30 28.10* 35.27*

33.73*

a Significance at the 5% (*) or 1% (**) levels by Duncan’s multiple range test.

Table 2. Effect of K fertilization on yield and K absorption by hybrid rice and a conventional variety. Hunan, China.

K level Yield Variety (kg KCl/ha) (t/ha)

K absorbed K depleted (kg/ha) (kg/t grain)

Grain increase (kg/kg K 2 O)

Vu 35 0 8.5 107.8 12.72 100 8.7 147.9 16.92 220 8.8 198.4 22.54 440 9.2 250.9 27.42 3.0

110 7.6 144.2 18.88 6.6 220 7.4 440

190.3 25.68 1.3 7.6 195.3 25.80 1.6

4.8 2.9

Xiang 9 0 7.3 88.95 12.25

Restorers and maintainers a for CMS lines V20A, IR46828A, and IR46829A in Thailand, 1986.

Variety V20A IR46828A IR46829A

IR11418-19-2-3 PR SPRLR75007-16-3-1 PR SPRLR76037-2-164-1-1 M CNTBR71011-59-2-2-2 PR SPRLR76035-PSL-16-1-2 PR SPRLR80187-21-1-1 PR

PR PR M PR PR PR

PR PR M PR PR PR

BKNLR77011-31-1-1-1-1 PR PR PR SPRLRl7034-PSL-17-1-1-1 R PR PR SPRLR75055-352-2-1 R, PR PR PR BKNLR77003-PSL-9-1-1 R

R R R R

IR36 R RD7

R

RDll M M

RD23 PR PR R R

C4-63 (green) R M M

a R = restorer (>80% spikelet fertility), PR = partial restorer (5- 80% spikelet fertility), M = maintainer (<5% spikelet fertility), – = damaged seedlings.

- -

showing 5-80% as partial restorers. and restorers only for V20A. SPRLR76037- those with less than 5% as maintainers. 2-164-1-1 was an effective maintainer for

RD23 and IR36 were effective all CMS lines. RD7 and C4-63 (green) restorers for all 3 CMS lines. RD11, were effective restorers for V20A, but SPRLR77034-PSL-17-1-1-1, and maintainers for IR46828A and SPRLR75055-352-2-1 were effective IR46829A.

22 IRRN 12:4 (August 1987)

Somatic embryogenesis in rice Oryza sativa, cultivar IR40

Man Si Wang and F.J. Zapata. Tissue Culture Laboratory, Plant Breeding Department, IRRI

Somatic embryogenesis is a preferred method of plant propagation in vitro. It allows rapid production of a large

number of true-to-type plants. Plants derived through embryogenesis are unicellular in origin, and are likely to be

mutation research. more suitable for genetic, breeding, and

We studied the efficiency of O. sativa regeneration through this pathway. Dehulled mature seeds and young panicles of rice variety IR40 were sterilized and used as explants. The

Genetic Evaluation and Utilization TISSUE CULTURE

Influence of position of rice anthers at plating on callusing and plant regeneration

S. T. Mercy and F.J. Zapata. Tissue Culture Laboratory, Plant Breeding Department, IRRI

We studied the effect of anther orientation at plating on callusing response and plant regeneration in japonica rice variety Taipei 309. Callus induction from anthers was according to standard IRRI procedure.

Anthers were plated on semisolid E10 (modified B5 medium, each liter containing 1 mg 2,4-D, 0.5 mg BAP, 0.5 mg IAA, 20 g sucrose, and 5 g glucose). Sixty anthers were inoculated at random (specific positioning of anthers is extremely difficult because of their small size). Microscopic examination showed that anthers were naturally positioned approximately half on edge (one lobe touching the medium) and half flat (both lobes in contact with the medium).

Plates were incubated at 26-29°C in dim light and scored for callusing 40 d after plating. Some calli of both flat and edge-oriented anthers were transferred for regeneration in MS medium (1 mg each NAA and kinetin/liter and 30 g sucrose/ liter) under continuous light. Percentage of green plant regeneration was recorded.

d of plating, liberating a large part of the pollen grains on the medium. None of the liberated pollen grains developed into calli. Calli from pollen grains held within the anther started appearing about 25 d after inoculation.

Of the 2,160 anthers plated, 518 (24%) produced calli. Of the anthers with calli, 60% were plated on edge (see figure) and 40% flat. Most of the anthers plated flat callused on both lobes, but callusing on one lobe was also observed. Most anthers plated on edge produced callus on the upper lobe. Only rarely did

Most of the anthers dehisced within 5

Callusing response of anthers. 1= Anther positioned on edge callusing from upper lobe. 2 = One anther on edge at left and the other flat at right, both callusing. 3 = Anther flat, callusing from both lobes. 4 = Anther flat, callusing from only one lobe. 5 = Anther on edge, callusing from upper and lower lobes. 6 = Anther on edge, callusing from lower lobe only. Note calli from lower lobes growing into the medium.

anthers plated on edge produce callus IR5, Basmati 370, and Pankaj showed from both lobes or from the lower lobe the same anther callusing response. only. No special anther inoculation

About 15% of the calli transferred for technique is needed to get satisfactory regeneration produced green or green callusing response in rice except to see and albino plantlets. that anthers are not buried in the

Observations made on rice varieties medium.

IRRN 12:4 (August 1987) 23

Plant regeneration at different durations in culture of calli derived from young inflorescences and seeds of IR40. IRRI, 1987.

Young inflorescence-derived callus Seed-derived callus

Passage Calli Calli Av green plant Calli Calli plated responding production b plated responding

Av green plant production b

(no.) no. % a (no.) (no.) no. % a (no.)

5 44 7 15.9 4.1 25 4 16.0 6 0 0 0 0

3 .0

7 24 11 45.8

25 3 12.0 3.0 5.1

20 8

3 15.0 25

4.3 6 24.0

9 5.0 15 1 6.7 4.0

20 3 15.0 4.0 20 0 0 0

a Total no. of calli responding x 100 Total no. of calli plated for regeneration

b Plants produced/calli-producing plant.

materials were inoculated on Murashige and Skoog (MS) medium with 2 mg 2, 4-dichlorophenoxyacetic acid (2,4- D); liter, 0.2 mg benzyl adenine (BAP)/liter, 3% sucrose, and 0.8% Difco Bacto agar (MS 3 ) at pH 5.8–5.9. MS 3 has been found optimum for callus induction in young rice panicles. The cultures were incubated in darkness at 26-27 °C. Induced calli were subcultured every 4 wk (1 passage).

From passages 5 to 9, embryogenic calli were transferred to a regeneration medium: MS medium supplemented

with 4 mg BAP/liter, 0.5 mg/ indoleacetic acid (IAA)/ liter. 0.5 mg naphthalene acetic acid (NAA)/ liter, 500 mg casein hydrolysate/ liter, 3% sucrose, 0.8% Difco Bacto agar, pH 5.8–5.9 (MS 18-1 ). The cultures were incubated in continuous light, 3,000 1x intensity, at

Data on regenerated plants were gathered after 4 wk in MS 18-1 medium.

Regenet ation efficiency decreased with the number of passages (see table). The decrease was more pronounced in

26–27 °C.

Somatic embryogenesis in wild rice Oryza perennis Moench

Man Si Wang and F. J. Zapata, Tissue Culture Laboratory, Plant Breeding Department, IRRI

Wild rice species O. perennis Moench is tolerant of stagnant flooding and acid sulfate soils and has desirable floral characteristics for outcrossing.

We sterilized and cultured young inflorescences and the scutellum of mature seeds of O. perennis. Embryogenic calli (E-callus) and nonembryogenic calli (NE-callus) were initiated from both explants (see figure). E-callus induction frequency was higher in young inflorescences (62%) than in mature seeds (44%). The embryogenic nature of the callus cultures from both explants was maintained over 14 subculture passages (about 16 mo).

Two types of callus formed from scutellum of mature seed after 4 wk in culture.

Regeneration frequency and average green plant production of the callus derived from young inflorescences decreased with time in culture (see table).

clear trend in the percentage of calli responding. However, average green plant production showed a decreasing trend. Generally, a decline in

In seed-derived callus, there was no

24 IRRN 12:4 (August 1987)

Longitudinal section of an embryoid showing synchronous development of coleoptile (CL) and coleorhiza (CR). SC = scutellum. IRRI, 1987.

seed-derived callus. Plants from inflorescence-derived cultures could still be regenerated after passage 9. Seed- derived callus regenerated only through passage 8. The explants did not differ in average plant production.

The longitudinal section shows that germinated embryoids were bipolar with scutellum, coleoptile, and coleorhiza, indicating that plant regeneration was through embryogenesis (see figure).

regeneration capacity of the callus and in average green plant production was observed.

Although the regeneration capacity of both explants did not differ significantly, from a practical point of view mature seed is a more convenient source of explant than a young inflorescence because it can be stored and is more readily available any time of the year.

The effect of different concentrations of BAP (2, 4, 6, and 8 mg/liter) on plant regeneration at passage 8 was determined. The optimum level was 4 mg/ liter, which gave the highest callus response and average green plant regeneration in both explants.

embryogenesis was proven by longitudinal section and scanning electron microscopy. Structures of somatic embryos resembled those of IR40.

Plant regeneration through somatic

Plant regeneration at different durations in culture of calli derived from young inflorescences and seeds of O. perennis a IRRI, 1987.

Young inflorescence-derived callus Seed-derived callus

Passage Calli Calli Total Av green Calli Calli Total Av green (mo in plated responding b plants plant plated responding b plants plant culture) (no.) (%) produced production c (no.) (%) produced production c

(no.) (no.) (no.) (no.)

6-8 25 80 117 5.8 20 75.0 97 6.5 7-9 20 65 78 6.0 20 50.0 58 5.8 8-10 20 60 62 5.2 15 66.7 60 6.0 9-11 25 60 64 4.3 12 58.3 35 5.0

10-12 20 60 42 3.5 43 69.8 132 4.4 11-13 34 58.8 70 3.5 20 65.0 52 4.0 12-14 34 35.3 43 3.6 20 70.0 57 4.1 13-15 20 40 24 3.0 30 66.7 65 3.3 14-16 20 45 20 2.2 30 53.3 17 1.1

a Computed after 4 wk in culture on MS 18-1 medium. b Total no. calli responding × 100

Total no. calli plated for regeneration c Plants produced/calli-producing plant.

This is the first report on somatic embryogenesis from a wild rice species. Young inflorescences and scutellum of mature seeds appear to be appropriate explants for establishing wild rice species plants via somatic embryogenesis.

The International Rice Research News- letter (IRRN) invites all scientists to contribute concise summaries of significant rice research for publication. Contributions should be limited to one or two pages and no more than two short tables, figures, or photographs. Contributions are subject to editing and abridgment to meet space limitations. Authors will be identified by name, title, and research organization.

Pest Control and Management DISEASES

Trichoderma in Philippine ricefield soils

A. Nagamani and T. W. Mew, Plant Pathology Department, IRRI

Common soil fungus Trichoderma can control several soil-borne pathogens. To assess its potential as a biocontrol agent in disease management of crops planted after rainfed rice, we collected 200 soil samples from 23 Philippine provinces Oct 1985 - Dec 1986.

plate and soil plate techniques using Trichoderma medium E.

Trichoderma populations in 90% of the samples ranged from 0.5 to 8.5 × 103 CFU/g of soil. The survey recorded 13 species, including 7 new to the Philippines and 2 unidentified. Dominance and occurrence of species varied with culture type (see table).

Our study showed wide distribution and variation in dominance of different species. All species were antagonistic to rice sheath blight fungus in vitro. The potential isolates belonging to different species could be used as biocontrol agents in crop disease management.

Trichoderma was isolated by dilution

Occurrence of Trichoderma species in lowland and upland rice fields in the Philippines, 1985-86.

Species Culture type

Dominant 70-40% Common 20-39% Uncommon 2-5% Very rare 1-2%

Upland T. aureoviride or T. piluliferum T. koningii a

T. harzianum T. fongibrachiatum Trichoderma b I Trichoderma b II

Lowland T. pseudokoningii or T. harzianum T. koningii T. aureoviride T. piluliferum a Trichoderma sp I

T. longibrachiatum Trichoderma sp. II

a Species not previously reported in the Philippines. b Species unidentified.

T. pseudokoningii T. hamatum a

T. glaucum a

T. polysporum a

T. viride a

T. reesei a

T. glaucum T. hamatum T. polysporum T. viride T. reesei

Interaction in vivo between virulent induced only dark brown discoloration and avirulent cultures of rice bacterial at inoculated sites. Microscopic

blight (BB) pathogen examination did not reveal characteristic

J. C. Durgapal, Division of Mycology and The cultures were identified as Plant Pathology, Indian Agricultural avirulent (AV) forms of the bacterium. Research Institute, New Delhi 110012, India The AV cultures were morphologically

and culturally identical to virulent (V) When tested for virulence, some cultures cultures except that they grew faster on of the BB pathogen Xanthomonas culture medium. camptestris pv. oryzae failed to cause We studied the interaction between V typical disease symptoms in the leaves of and AV cultures on TNl plants. susceptible variety TN1. The cultures Standard aqueous suspensions of

bacterial streaming in those leaves.

IRRN 12:4 (August 1987) 25

young, actively growing cultures of virulent (V 1 , V 2 ) and avirulent (AV 1 , AV 2 ) types, each consisting of about 10 9

cells/ ml, were mixed in different proportions (see figure) and inoculated separately by pin-prick (PP) and leaf- tip-cut (TC) techniques in flag leaves of the host. Disease intensity (DI) — average leaf lesion length (cm) of 3 replications — was recorded 15 d after inoculation. Disease increase or reduction over check was assessed as average DI of PP and TC inoculations, expressed in percentage.

The disease-producing ability of V cultures was noticeably reduced when the AV cultures were mixed. Qualitative and quantitative disease suppression was detected. Necrosis induced by the V + AV inoculum developed slowly and was characteristically discontinuous and less intensive than in the checks. Although lesion length reduction (DI) occurred even in leaves inoculated with less than 50% of the AV culture, it was significant where inoculum had 50% or more of AV culture. Inoculation with V 1 + V 2 combinations, however, did not show significant increase or decrease of

Fungicidal control of rice sheath blight (ShB)

Y.J.P.K. Mithrasena, D. L. Wickramasinghe, and W.P. Adikari, Regional Agricultural Research Centre, Bombuwela, Sri Lanka

ShB caused by Rhizoctonia solani Kuhn (Thanatephorus cucumeris) is a serious disease in the wet rice-growing areas of Sri Lanka. No suitable chemicals for its control have been recommended. Since a variety resistant to ShB has yet to be found, the effectiveness of some fungicides was tested in vitro and in vivo.

tested against R. solani in PDA medium, using the filter paper disc technique. The medium in the plates was divided into four equal parts and filter paper discs dipped in fungicide solutions were placed in each quarter. A single sclerotium of R. solani was placed in the center of the plate. The inhibition zone

Ten concentrations, 10-100 ppm, were

26 IRRN 12:4 (August 1987)

Percentage of increase or reduction in disease intensity over checks (inoculated with single virulent culture) at varying concentrations of virulent (V 1 , V 2 ) plus avirulent (AV 1 , AV 2 ) and V 1 plus V 2 cultures in inoculum.

infection over checks. the pathogen suggests that occurrence of The fact that the AV forms of X. c. AV forms is important in the

pv. oryzae interfere with the disease- epidemiology of the disease. producing ability of the V population of

Effectiveness of fungicides on rice ShB disease incidence and grain yield. a Bombuwela, Sri Lanka.

Application

inoculation Fungicide time after

50% benomyl 24 h 2 wk

Triphenyltin hydroxide 24 h 2 wk

25% pencycuron 24 h 2 wk

Control (no fungicide) –

CV (%)

Disease incidence Grain yield (t/ha)

1984/85 maha 1985 yala 1984/85 maha 1985 yala

3.88 a 3.22 a 3.2 3.6 3.12 ab 2.55 bc 3.5 3.6 2.50 b 2.29 c 3.6 3.5 3.26 ab 2.80 ab 3.6 3.6 2.38 b 2.30 c 3.6 3.6 2.48 b 2.52 bc 3.6 3.4 3.63 a 2.85 ab 3.1 3.2

18.8 9 11.5 11.7

a Av of 3 replications. In a column, values followed by the same letter are not significantly different at 5% level by DMRT.

around each disc for each concentration fertilizers were applied. Standard plant was measured as the fungus grew. protection measures were taken.

Benomyl, triphenyltin hydroxide, and The inoculum, 7-d-old R. solani pencycuron were used for field tests for cultured on rice grain, was spread evenly two seasons in a randomized complete on the water surface at panicle initiation. block design with three replications. Plot Fungicides were sprayed 24 h and 2 wk size was 6 × 3 m. Rice variety BW288-1- after inoculation at 0.5 kg ai/ha for 3 was broadcast. Recommended benomyl and triphenyltin hydroxide,

tillers, M = moderately infected tillers, S

and 0.25 kg ai/ha for pencycuron. pencycuron at 30 ppm. Disease incidence was assessed at 1 = severely infected tillers, Disease incidence and yield in two

harvest as follows: and S 2 = very severely infected tillers seasons are given in the table. In both (flag leaf dried and killed). seasons, the lowest disease incidence was

inhibitory zones were shown only with inoculation.

Disease incidence = 1(H) + 2(L) + 3(M) - 4(S 1 ) + 5(S 2 )

Of fungicides tested in PDA medium, with pencycuron applied 24 h after

H = healthy tillers, L = lightly infected triphenyltin hydroxide at 10 ppm and

Total no. of tillers

Damage by rice root-knot nematode

N. C. Patnaik and N. N. Padhi, College of Agriculture, Orissa University of Agriculture and Technology, Bhubaneswar 751003, India

Healthy seedlings of rice variety PTBl0 were transplanted in 10-cm-diameter earthen pots containing sterilized soil (500 g/ pot). At 6 d after planting, 0, 1, 4, and 16 Meloidogyne graminicola egg masses/ plant were introduced in the root zone. The treatments were in 8 replications in a randomized block design. Symptoms of infestation on foliage and external symptoms and gall formation on the root system were recorded.

Disease caused by the root-knot nematode affected the entire rice plant, producing damage symptoms on foliage and roots.

On the foliage, tip drying was observed at all levels of inoculum. Leaf bronzing developed from the tip downward and from the margin toward the midrib of the leaf blade. Plants were chlorotic. There was considerable distortion in leaf emergence and growth. The leaves were crinkled (Fig. 1). New tillers had reduced height. Severely

Detection of seedborne rice fungi by blotter method

T.S. Singh, Horticulture and Soil Conservation Department, Manipur, Imphal Pin 795001, India

Seed samples of Ratna, Jaya, IR24, Pusa 2-21, Phouren, and Moirangphou that had been collected 2-3 mo after harvest were kept in polythene bags in desiccators. Glass petri dishes and semitransparent plastic petri dishes were

1. Symptoms on plants showing crinkled appearance of leaves.

infected plants flowered and matured early. Emerging panicles were crinkled, grain setting was poor, and chaffiness was observed in the panicles.

Characteristic knots appeared in a string on the fibrous roots (Fig. 2). Roots showed profuse development of small, slender, lateral roots, resulting in a hairy root system.

Galls were beaded, club- or spindle- shaped. In cases of heavy infection, they coalesced and formed peculiar shapes. The minimum-size galls, which appeared 4 d after inoculation, were 300-550 mµ long and 150450 mµ wide. Each gall

used. Twenty-five seeds/petri dish were plated on three 11-cm diameter circles blotter paper moistened with water. Plates were incubated 6 d in B.O.D. incubators fitted with daylight tubes. Intact growths of fungal pathogens were examined with a stereoscopic microscope. Four hundred seeds/ variety were tested under the following conditions:

Temperature. 17°C, 22 °C, 27°C, and 32°C with 12 h light. Temperature had a significant effect on percentage

2. a) Root system of an infected plant. b) Different shapes of galls.

was as big as 13 mm long and 2.29 mm wide after egg production.

infection of most fungi (Table 1). Higher infection percentages of Pyricularia oryzae, and Nigrospora spp. at 22°C were detected, higher infection percentages of Drechslera oryzae, Trichoconis padwickii, and Curvularia spp., at 27°C.

percentages of most fungi were detected at 12 h/d exposure to light (Table 2).

Substrate moisture. Eight to 10 ml water were optimum to detect maximum infection percentages of most

Light. Maximum infection

IRRN 12:4 (August 1987) 27

Use of streptomycin. When 100 ppm concentration streptomycin solution was used as substrate moisture, higher infection of D. oryzae, T. padwickii, and Phoma spp. could be detected, but growth and detection of P. oryzae were

reduced. 2,4-D. Use of low concentrations 2,4-

D (0.05%–0.10%) in the substrate moisture restricted root growth and facilitated detection of most of the important fungi.

seedborne rice fungi. pH level. Infection percentages were

higher at substrate moisture at pH 5-6. Type of container. Higher infection

percentages were detected in semitransparent plastic petri dishes than in glass petri dishes.

Table 1. Effect of incubation temperature on infection percentage of seedborne rice pathogens by blotter method. Imphal Pin, India.

Infection detected (%) Temperature

(°C) D. oryzae P. oryzae T. padwickii N. oryzae Curvularia spp. Alternaria spp. Phoma spp. Fusarium dimerum Stemphylium sp.

17 13 8 16 12 21 2 9 11 2 22 18 22 16 16 20 6 10 18 4 27 18 15 20 13 21 4 10 15 2 32 19 5 27 11 27 1 10 17 0 CD (0.05) 4 4 4 3 5 3 ns 3 2

Table 2. Effect of light on infection percentages of seedborne rice pathogens. Imphal Pin, India.

Mean infection percentage transformed into angles a

D. oryzae P. oryzae T. padwickii N. oryzae Curvularia spp. Alternaria spp. Phoma spp. F. sernitectum Stemphylium sp. Light h/d

0 (24 h

4

8

12

16

20

darkness)

CD (0.05)

15.83 (7.44) 22.38

(14.50) 23.42

( 15.80) 24.69

(17.45) 25.36

(18.34) 23.75

(16.25) 3.50

12.91 (5.0) 16.66 (8.22) 20.04

(11.74) 22.68

(14.86) 21.57

(13.51) 21.34

(13.24) 3.32

14.86 (6.57) 21.26

(13.15) 24.38

(1 7.04) 26.17

(19.45) 26.78

(20.30) 25.66

(18.75) 6.39

24.17 28.34 22.62 18.76 6.99 13.46

26.76 33.25 24.03 21.06 7.60 13.45

27.35 33.59 25.57 21.48 8.24 11.19

27.66 35.73 27.13 21.25 8.69 11.32

27.17 34.72 25.85 21.83 13.66 11.43

27.47 33.23 26.46 21.60 11.91 12.83

(22.53)

(30.07)

(30.61)

(34.00)

(32.43)

(30.03) ns 3.81 ns ns ns ns

a Figures in parentheses indicate values transformed back to percentages.

Cost comparison of neem oil and an insecticide against rice tungro virus (RTV)

A. Abdul Kareem, R.C. Saxena, and H.D. Justo, Jr., Entomology Department, IRRI

The potential of neem oil (NO) mixed with custard-apple oil (CAO) was evaluated in three consecutive croppings 1984-85. A 50% NO:CAO mixture in 4:1 proportion at 8 liters/ha was sprayed with an ultralow volume (ULV) applicator at weekly intervals from seedling to maximum tillering stages. The treated control was sprayed with BPMC at 0.75 kg ai/ha and the untreated control with 1.66% Teepol- water solution (emulsifier). Incidence of

Comparative RTV control, yield, and net gain in ricefields sprayed with neem oil and insecticide. a

IRRI, 1987.

RTV Yield (%) (t/ha)

Value of cost of Net gain Treatment yield

($) treatment (value of yield less

($) cost of treatment b )

Jan-Apr 1984 NO:CAO 5 a 6.1 a 1068 44 1024 BPMC 4 a 6.1 a 1068 125 943 Control 7 a 5.6 a 980 12 968

NO:CAO 4 a 5.1 a 892 44 848 BPMC 6 ab 4.7 a 822 125 697 Control 9 b 4.6 a 8 05 12 793

NO:CAO 29 a 3.1 a 542 44 498 BPMC 56 b 2.5 b 438 125 313 Control 52 b 2.3 b 402 12 390

and BPMC were applied 8 times during each cropping season. Means followed by a common letter a Av of 4 replications/cropping season. Cost of palay = US$0.175/kg (NFA price). NO:CAO mixture

are not significantly different at the 5% level by DMRT. b Cost of treatment includes labor and materials. Control treatment cost included labor (US$l0) and 8 pc DC batteries (US$2) for applying 1.66% Teepol-water solution (emulsifier) using an ULV-spray applicator.

Jun-Oct 1984

Nov 1984-Mar 1985

28 IRRN 12:4 (August 1987)

Ufra problem in low-lying areas of Bangladesh

A. H. Mondal and S. A. Miah, Plant Patho1ogy Division, Bangladesh Rice Research Institute (BRRI), Joydebpur, Gazipur, Bangladesh

We surveyed the disease situation of five low-lying areas during the 1986 aman (Apr–Dec). Three zones in the south, where ricefields are subjected to tidal submergence twice every 24 h, were found to be ufra prone (see figure).

Tidal water helps spread ufra

RTV and yield are shown in the table. Jan-Apr 1984, RTV incidence was

negligible and yields were high in all treatments. Jun–Oct 1985, plots treated with the oil mixture had significantly less RTV infection than the untreated

control (9% RTV), but yields were not significantly different. Nov 1984-Mar 1985, RTV incidence was significantly less in plots treated with the oil mixture than in insecticide-treated and untreated control plots. Yield was significantly

higher in plots treated with the oil mixture.

Net gain was consistently higher in plots treated with NO:CAO than in untreated or insecticide-treated plots.

Ufra threatens deepwater rice in Majuli, Assam

Y. Rathaiah and G. R. Das, Regional Agricultural Research Station. Assam Agricultural University, Titabar 785630, Assam, India

Ufra disease caused by stem nematode Ditylenchus angustus was severe in deepwater rice on Majuli, the river island of Brahmaputra in Assam. About 2,000 ha was badly damaged. Symptoms observed included the characteristic white patches of barren rice plants, panicles of many plants that did not emerge, or only half emerged, and stems of many plants that produced aborted skeletons of deformed panicles (see

figure). Variety Padmapani appeared to its early maturity (Nov). Popular variety escape the disease, probably because of Rangabao was severely affected.

Aborted panicles of rice due to stem nematode. Assam, India. Outbreak of ufra disease in Bangladesh.

IRRN 12:4 (August 1987) 29

Weed hosts of ragged stunt virus (RSV)

G. Z. Salamat, Jr., A. Parejarearn and H. Hibino. Plant Pathology Department, IRRI

We collected young weed plants of different species commonly found in ricefields and transplanted them individually in pots. Each plant was exposed to 50 RSV-viruliferous brown planthopper (BPH) for 2 d.

One month after inoculation, the 2 youngest leaves of each plant were homogenized with 2 times (by weight) 0.02 M PBS-Tween. Extracts were tested in ELISA for the presence of RSV antigen. Extracts of uninoculated weed plants served as the control. Absorbance values at 405 nm of test extracts above 2 times mean absorbance value of control extracts were considered positive.

Echinochloa glabrescens, Eleusine indica, Monochoria vaginalis, and Paspalum distichum gave positive ELISA; Commelina benghalensis, Echinochloa colona, Echinochloa crus- galli, Ischaemum rugosum, and Ludwigia octovalvis negative (see table). That result indicates that some weed

species can be hosts of RSV. BPH nymphs given a 1.5-d

acquisition access on some of the plants

gave positive ELISA. Nymphs fed on healthy rice seedlings for 8 d, then tested for infectivity, did not transmit RSV.

nematode. Most of the ufra-prone areas grow broadcast aman (B. aman) rice Apr-Nov, followed by boro rice Nov - Mar. That helps the ufra nematode survive throughout the year.

Repeated cultivation of highly susceptible varieties Kaladhan, Dudhomona, and Kaligacha has contributed to the development of ufra. These varieties also act as sources of secondary and tertiary inocula.

About 60-70% of the areas, covering about 200,000 ha, was infested.

Digha variety was found to be resistant in one zone, probably because it escaped the disease because of its early maturity. Khalni was moderately resistant. In the two other zones, local B. aman varieties Rayanda (Rayada) and Keora were resistant. Other minor diseases observed during the survey are given in the table.

Disease distribution in deepwater rice areas of Bangladesh, with existing cropping pattern and varieties cultivated. Bangladesh, 1986.

Zones of Cropping Varieties cultivated Bangladesh pattern a Major Minor

Diseased b Ufra Varieties infestation resistant

(%) to ufra c

Pabna BA or rabi/boro

Barisal BA or TA/rabi/ boro

Faridpur BA or rabi/ Khulna boro

Sylhet BA or rabi/

Comilla BA or rabi/ Noakhali boro

fallow

Sharshari, Boron, ShB (only Dhaldhigha, Bhawalia

in one

Chikon, Mota, location) Ufra

Pajam d , Dudhmona d , Gorcha, Asfal d , Khalni, Digha, BR11, IR5, Joina d

Grkajal d , Kaladhad Ufra Digha d , Joina, Khaiya motor d

Rayanda, Marchan Karkati, Badal, Bazail, Biron Kaligacha d , Ufra Barwa d , Keora, Aman, Hirbain

–

BB, B1 BS, ShR

BB, B1

ShR, ShB LSc,

BS, ShR B1

ShR, BB

ShR

– –

40-50% Digha (R) Khalni (MR)

60-70% Rayanda (R)

– –

80-90% Keora (R)

a BA = broadcast aman, TA = transplanted aman. b BB = bacterial blight, B1 = blast, BS = brown spot, ShR = sheath rot, ShB = sheath blight, LSc = leaf scald. c R = resistant, MR = moderately resistant. d Highly susceptible to ufra.

Detection of RSV by ELISA in weeds inoculated with RSV.

Average absorbance at Inoculated Infected

Weed species samples samples 405 nm a

(no.) (no.) Infected Control

Echinochloa glabrescens 23 4 0.42 0.19 Eleusine indica 33 3 0.90 0.02 Monochoria vaginalis 35 10 0.58 0.07 Paspalum distichum 23 6 0.32 0.09

a Value above 2 × absorbance value of control considered positive.

Frequency and timing application to control virus (RTV)

of insecticide We conducted two trials during the rice tungro 1986 wet season to test insecticide timing

and application frequency. IR64 (resistant) and TN1 (susceptible to green

S. L. Valencia and O. Mochida, Entomology leafhopper and RTV) were planted in 5- Department, IRRI × 7-m plots with 4 replications. The

When vector populations are high, using prevent early RTV infection. In the first insecticides to control RTV infection in trial, cypermethrin (0.05 kg ai/ha) and moderately resistant and susceptible monocrotophos (0.4 kg ai/ ha) were cultivars requires increasing the number applied 4 times at 10-d intervals starting of applications. More precise timing of at 1, 5, or 10 d after transplanting (DT). insecticide application could reduce the RTV infected hills were recorded at 60 number of applications needed. DT.

seedbeds were covered by mesh to

30 IRRN 12:4 (August 1987)

1. Effect of insecticide applica- t ion t iming in prevent ing RTV IRRI, 1986 WS.

2. Effect of frequency of insecticide application in pre- venting RTV. IRRI, 1986 WS.

RTV incidence was significantly lower Cypermethrin at 0.05 kg ai/ha and on IR64 and TN1 with cypermethrin monocrotophos and MIPC at 0.41 kg applied within 5 DT (Fig. 1). ai/ha were sprayed 2, 3, and 4 times at Monocrotophos applied 1 DT gave 10-d intervals starting 5 DT. Three control only on the resistant cultivar. applications protected the seedlings

were used on moderately resistant IR42. In the second trial, three insecticides (Fig. 2).

Sheath blotch (SBL) of rice

S.C. Ahuja and U. Bhan, Rice Research Station, Kaul 132021, Haryana, India

We studied the host range of Pyrenochaeta oryzae, the cause of SBL, and the effect of infection on germination, seedling vigor, and yield parameters on potted plants and inoculated grains of four crops.

Plants of Zea mays, Oryzae barthii, Echinochloa crus-galli, and Sorghum vulgare were inoculated by inserting a hypha piece between the sheath and culm. P. oryzae could infect Z. mays and O. barthii, causing brown- olivaceous spots 4 d after inoculation. Pycnidia formed after 17 d only on O. barthii.

Rice varieties HKR101, Palman 579, RP2151-33-4, RP2151-76-1, RP2151-27- 1, RP2151-40-1, IET7662, 7688, and HAU47-6045-1 were inoculated at booting by injecting mycelial suspension prepared from oat grain culture. Grains and enclosing sheaths of all varieties showed lesions. Initially, glumes assumed a blood red color, which

Table 1. Effect of P. oryzae infection on seedling characteristics. Haryana, India.

Reduction a (%)

Root Shoot Germination length length

Variety

Palman 579 38.3 7.0 0 RP2151-76-1 43.4 47.8 26.7 RP2151-40-1 15.6 5.1 20.0 RP2151-27-1 6.7 11.2 6.7

a Compared to healthy seedlings. Av of 3 replications.

Table 2. Effect of SBL on yield parameters. Haryana, India.

Reduction or increases (%)

Parameter Jaya Pusa 2-21

Affected plants (%) 2 12 1000-grain wt 0 4 Filled grains/panicle 33 69 Unfilled grains/panicle 2 b 18 Discolored grains/panicle 51 b 52 Panicle length (cm) 4 5

over healthy panicles. a Av of 3 replications, 5 panicles each. b Incease

IRRN 12:4 (August 1987) 31

turned into the color of clotted blood. Rice varieties could not be graded on panicle infection.

Germination and seedling vigor of discolored and healthy grains of 4 selected varieties were tested in petri plates at 30± 1°C. Varieties differed in reduction of percent germination and

root and shoot length (Table 1). Reduction was maximum in RP2151- 76-1 and minimum in RP2151-27-1. Although germination in discolored seeds of Palman 579 was not affected, root length reduction was noticed.

Affected and healthy panicles from six plots of Jaya and Pusa 2-21 were

collected to study the effect of SBL on yield parameters. Number of filled grains was reduced and number of unfilled and discolored grains was higher in affected panicles (Table 2). Infection was more pronounced on Pusa 2-21 than on Jaya.

Effect of Azolla bipinnata soil amendment on reduction in viability of sclerotia of rice stem rot (SR) fungus

S. Hussain, S. M. Haroon Usmani, and A. Ghaffar, Botany Department, University of Karachi, Pakistan

A greenhouse pot experiment examined the effect of Azolla bipinnata used as an organic substrate on the survival of sclerotia of the SR fungus Sclerotium oryzae. Soil artificially infested with sclerotia of S. oryzae at 5 sclerotia/g of soil was amended with fresh azolla at 0, 0.1, 0.5, and 1% wt/ wt. The soil in 7- cm-diameter pots was adjusted and maintained at 50, 75, and 100% moisture-holding capacity by watering daily. At 0, 10-, 20-, 40-, and 80-d intervals, sclerotia were separated by wet sieving and their viability tested on water agar supplemented with streptomycin sulfate and penicillin at

Table 1. Reduction in viability of sclerotia of Sclerotium oryzae in soil amended with Azolla bipinnata at different moisture levels. Karachi, Pakistan.

Reduction in viabilitya

Azolla Moisture (%) treatment (%)

10 d 20 d 40 d 80 d

Control

Azolla 0.1 %

Azolla 0.5%

Azolla 1.0%

50 75

100 50 75

100 50 75

1 00 50 75

100

4 5 0

10 0

14 4

12 5 1

13 12

3 4

10

3 14 13 12

0 8

18 8

16

3 8

13

9 8 4

8 13 17 5

13 14

0 4

13 5

13 17 25 14 35 29 18 26

a Zero reduction at 0 d.

32 IRRN 12:4 (August 1987)

Table 2. Analysis of variance for the viability of sclerotia of Sclerotium oryzae.

Source of variance SS df MS F ratio

Treatments (T) Moisture (M) Time (D) TX M TX D MXD TX MXD Residual

Total

1045.51 1 625.328

4220.755 306.91 1

1152.045 670.128

1853.533 10938.667

20812.978

*P<0.05

3 2 4 6

12 8

24 120

179

**P<0.01

348.50 312.69

1055.19 51.15 96.00 83.77 77.23 91.15

3.82** 3.43*

11.58** 0.56 1.05 0.92 0.85

3,000 ppm each.

sclerotial viability was observed with azolla at 0.5% wt/ wt (Table 1).

at different time intervals showed significant reduction in viability of sclerotia (Table 2). Moisture also was significant. Interactions among

Maximum reduction, up to 35%, in

Azolla at different concentrations and

amendment, moisture, and time were not significant. Presumably soil incorporation of azolla and the decomposition of organic matter generate anaerobic conditions and/ or accumulation of fungitoxic substances due to increased microbial activity, resulting in a reduction in viability of S. oryzae sclerotia.

Pestalotia oryzae - a new rice fungus in India

N. I. Singh, Botany and Plant Pathology Department, Manipur Agricultural College, Iroisemba, Imphal 795001, India

A severe glume spot disease of rice was found in Manipur for the first time in

Symptoms appeared first as small, pale brown spots which gradually increased to 2 mm in size. The center of the spot is gray-brown with a dark brown margin and bears minute fruiting bodies of the fungus.

Diseased grains were collected in separate bags from different rice- growing valley areas during the crop season. The causal organism was isolated and maintained on potato

1985-86.

Panicle stage and susceptibility to Pestalotia oryzae. Iroisemba, Manipur, India, 1985-86.

Panicles Panicles Panicle stage inoculated infected

(no.) (no.)

Just emerged Milk Dough Mature

30 30 30 30

2 30

6 0

dextrose agar (PDA) medium. Pathogenicity of the fungus was proved by inoculating young panicles with 7-d- old cultures.

The fungus failed to infect the living leaves. However, it could easily infect dead rice leaves.

The isolated pathogenic fungus has been identified as Pestalotia oryzae Hara. This is the first record of its

Severity of rice seedling damping-off in 11 districts of Bangladesh. winter, 1987.

Seedbeds Severity District affected (0-9 scale a ) (%)

Bogra Comilla Chittagong Dinajpur Gazipur Jamalpur Mymensingh Pabna Rajshahi Rangpur 60 3–9 Tangail 20 3–5

30 5–7 25 5–7 25 5–7 40 5–7 30 5–9 70 5–9 30 5–7 30 5 –7 40 3–5

a 0 = no incidence, 3 = 11–20% damage. 4 = 21– 30% damage, damage, 7 = damage, and 9

5 = 31–40% damage, 51–60% damage, 8

= 81–100%

6 = 41–50% = 61–70%

damage.

lines sown were affected, with up to 80% seed or seedling mortality.

min, and grain volume after cooking measured.

All varieties showed grain spotting (see table). Infected seeds weighed less

than healthy seeds. Infected husk also weighed less. Healthy grains expanded more than spotted grains with cooking.

occurrence on rice glumes in India. cells having 2–3 hyaline apical bits of the fungus were prepared from 7- The fungus produces hyaline, appendages. Size of conidia is 30–35 × d-old culture and sprayed on rice grain

caenocytic mycelium. Conidiophores are 7–10 µ m µm with appendages 20-35 at different stages. The milk stage was short and simple. Conidia are dark and long. found to be most susceptible to fungal 5-celled, with hyaline and pointed-end During pathogenicity tests, mycelial infection (see table).

Effect of grain spotting on rice quality

V.S. T. Murty, B.S. Chandrakar, A. K. Singh, and R. K. Misra, J. N. Agricultural University Campus, Bilaspur (M. P.), India

Grain spotting is caused by several microorganisms (Trichoconis spp., Helminthosporium oryzae, Pyricularia oryzae, Aspergillus spp., Alternaria padwickii, Curvularia spp., etc.). Symptoms (distinct black dots, sometimes brown blackish blotches) vary with the degree of infection.

We sampled grain lots of 21 varieties and measured grain spotting incidence.

Twenty-five healthy and 25 infected seeds of each variety were selected at random, dehusked, and the husk and grain weighed.

Ten healthy and 10 infected seeds were dehusked and the grains placed in 15- × 1-cm test tubes with 10 ml water each tube. Grain volume was measured. The tubes were placed in a 500-ml beaker with 200 ml water, heated for 30

Loss to grain spotting. Bilaspur, India.

Loss (g) in Difference in Cooking Variety Infection (%) husk 1000-grain expansion

weight weight (g) difference (ml)

Jaya

Bd 200 Ratna

BPT1235 Surekha

Saket-4 IR36 Chatri Mahsuri IET4094

Phalguna Pankaj Kranti Pusa IET3273 Jagriti Garima Patel 85

R-35-2752

RP9-4

R-2384

6.2 7.3 3.4 9.1 6.2 4.6 5.4 5.8

10.3 10.4 1.6 5.2

11.7 4.1 4 ..0 6.9 7.3

11.5 4.7 4.5 4.8

0.26 0.18 0.1 1 0.5 1 0.31 0.21 0.1 2 0.30 0.30 0.53 0.1 1 0.28 0.06 0.1 3 0.10 0.17 0.1 1 0.39 0.27 0.12 0.21

1.79 3.27 2.0 1 0.78 4.33 1.80 2.84 3.62 0.26 0.07 3.44 5.96 3.94 3.75 2.09 0.20 3.99 0.65 1.70 1.86 2.73

0.12 0.12 0.00 2.19 1.95 0.48 0.24 1.09 0.73 1.09 0.36 1.09 0.36 0.45 0.00 0.61 0.6 1 0.36 0.24 0.36 0.73

Distribution of rice seedling damping- off in Bangladesh

M. M. Rahman, A. H. Mondal, and S.A. Miah, Bangladesh Rice Research Institute (BRRI), Joydebpur, Dhaka, Bangladesh

Rice seedling damping-off caused by Achlya sp. was first identified in Bangladesh in 1978. The disease is soil borne and is disseminated through both soil and water. The pathogen affects seeds or young seedlings during the winter (Nov–Feb). The fungus forms a gray/ brown/ black-colored tangled mass of hyphae covering the surface of the infected seeds.

During 1978, severe seed or seedling damage occurred in the seedbed at the BRRI farm. Almost all rice varieties or

We surveyed the distribution and intensity of the disease in different districts during Jan 1987. The disease was prevalent in all 11 districts visited, with damage as high as 70% in seedbeds kept submerged during and after sowing (see table).

Relationship between tungro transmission by individual Nephotettix virescens, mode of feeding, and life span

G. Dahal and H. Hibino, Plant Patholagy Department, IRRI

A green leafhopper (GLH) Nephotettix virescens colony collected from

IRRN 12:4 (August 1987) 33

Transmission of RTBV, RTSV, and RTBV +RTSV on IR54, IR36, and TN1 by GLH, area of acidic and basic honeydew excreted during inoculation feeding, and survival of GLH on the respective cultivars. IRRI, 1986.

Koronadal, South Cotabato, and reared on TN1 for 5-6 overlapping generations was used in this study. About 3-4 d after molting, adult GLH were given 4-d acquisition access to plants infected with both rice tungro bacilliform (RTBV) and rice tungro spherical viruses (RTSV). The GLH then were tested individually on IR36, IR54, and TN1 for virus transmission, feeding behavior during inoculation feeding, and survival on seedlings.

Feeding behavior was monitored by the reaction of honeydew spots on bromocresol-green treated filter paper discs. Blue color spots (basic honeydew) indicates phloem feeding and orange or brown color spots (acidic honeydew) indicates xylem feeding. Inoculated plants were indexed by latex serology. After inoculation feeding, each GLH was caged on about 3-wk-old plants of the respective cultivars to determine life span.

Leafhoppers fed on both phloem and xylem on all test varieties. They excreted less basic honeydew on GLH-resistant IR36 and IR54, survived fewer days, and transmitted viruses at lower rates (see figure). On susceptible TN1, the GLH excreted more basic honeydew, survived longer, and transmitted viruses at higher rates.

There was a significant correlation between percent virus transmission and, the average areas of basic honeydew spots, and the average life span of GLH on the test varieties. However, there was

34 IRRN 12:4 (August 1987)

Transmission of RTBV and RTSV on 3 cultivars by individual GLH and their feeding behavior during inoculation access. a IRRI, 1987.

GLH Transmissions GLH (no.) that fed on Cultivar tested (no.)

(no.) by GLH Phloem Phloem and xylem Xylem

IR36 30 RTBV+RTSV 10 RTBV 7 RTSV 1 None 12

IR54 30 RTBV+RTSV 3 RTBV 9 RTSV 0 None 18

TN1 30 RTBV+RTSV 18 RTBV 6 RTSV 2 None 4

0 0 0 0 0 0 0 0 0 0 1 0

7 5 1 1 2 2 0 3

16 6 1 2

3 2 0

11 1 7 0

15 2 0 0 2

a GLH fed on plants infected with RTBV and RTSV were individually given a 1-d inoculation access feeding on seedlings.

no correlation between the areas of basic honeydew spots excreted by the individual leafhoppers during inoculation feeding and life span on the

Incidence of rice panicle stalk blast (BI) in Manipur

same variety.

indicating that GLH which Agricultural College (MAC), Iroisemba, predominantly excreted more basic Imphal 795001, India honeydew transmitted the viruses at higher rate. But on IR36 and TN1, Internodal culm Bl of rice was found for GLH which excreted more basic the first time in experimental plots of honeydew transmitted the viruses. MAC and in many rice-growing areas in Irrespective of variety, a high proportion Manipur in 1985; the incidence was of GLH which fed on both phloem and severe in 1986. xylem transmitted the viruses (see table). Punshi and KD 2-6-3, varieties widely About one-third of the GLH that fed on cultivated in Manipur, suffered 60–100% xylem alone transmitted the viruses. yield loss.

The results indicate that virus The disease attacked rice plants from transmission occurs even when GLH anthesis on. Symptoms were numerous feed predominantly on xylem. white, empty panicles. But the

N. Iboton Singh, Botany and Plant On IR54, there was no clear tendency Pathology Department, Manipur

uppermost leaf sheath enclosing the fields. pathogenicity proved. infected internode remained healthy. When microscopically examined, The sudden spread of the disease Sections of tissues of the uppermost diseased samples collected from different seems to have been influenced by internode rotted and were covered with rice-growing valley areas in the State cultivation of high-yielding, susceptible sooty spore masses. In late infection, consistently showed Pyricularia oryzae rice varieties and by a long dry spell grains developed poorly. The disease Cav. The pathogen was isolated on rice during late growth stage. was more severe in dry fields than in wet straw extract agar medium and its

Pest Control and Management INSECTS

Predators of rice insect pests in 20-30 °C temperature during the Jun- We counted natural enemies of Chhattishgarh region, Madhya Sep monsoon. Monsoon rice cultivation monsoon rice pests in 1984-86 (see Pradesh, India favors insect multiplication. table).

D. Bhardwaj and A. D. Pawar, Central Biological Control Station, Raipur, Madhya Pradesh, India

Madhya Pradesh is situated between latitude 17° and 26°N and longitude 74° and 84°E. Rice is the predominant crop in Chhattishgarh, which has mixed red and yellow soil, 1,400-1,600 mm average rainfall, 85-95% average humidity, and

Predators of rice insect pests in Chhattishgarh region, Madhya Pradesh, India, 1984–86.

Effect of insecticides on eggs of Brevennia rehi (Lindinger)

M. Gopalan, N. C. Radja, and G. Balasubramanian, Centre for Plant Protection Studies, Tamil Nadu Agricultural University, Coimbatore 641003, India

We tested the ovicidal action of 11 insecticides in the laboratory (see table).

For each treatment, 50 eggs were

placed in a petri dish lined with moist filter paper and sprayed with 1 ml spray solution, using an atomizer.

Eggs that hatched were counted every 15 min for 3 d. Data were converted into arc sin values and corrected for natural mortality using Abbott's formula.

BPMC 0.25 kg ai/ha delayed hatching most, and crawlers that hatched, died.

Predators Prevalence Effect of insecticides on hatchability of B. rehi eggs. a Coimbatore, India.

I Araneida Tetragnathidae

Lycosidae Tetragnatha mandibulata

Lycosa pseudoannulata II Orthoptera

Tettigonnidae Conocephalus longipennis

III Odonota Coenagrionidae

Ischnura sp. Agriocnemus pygmaea

IV Coleoptera Carabidae

Ophionea nigrofasciata Casnoidae indica

Coceinella arcuata Menochilus sexmaculata Scymnus postpinctus

Coccinellidae

High

Moderate

Moderate

Low High

Moderate

Low

Moderate Low Low

Insecticide Rate (kg ai/ha) Hatchability (%) Mortality (%)

Endosulfan 0.33 11 def 31 de Phosphamidon 0.25 13 efg 22 f Monocrotophos 0.20 10 def 36 de Fenthion 0.50 11 cde 34 de Chlorpyrifos 0.35 12 efg 22 f Methyl demeton 0.125 10 c 39 d Dimethoate 0.15 8 cd 51 c Phosalone 0.35 12 efg 23 f Biphenyl methyl carbamate 0.25 2 a 88 a Deltamethrin 0.01 14 fg 14 Carbaryl 0.5 7 b

g

Control – 14 g –

followed by a common letter are not significantly different (P = 0.05) by DMRT. a Mean of 3 replications. Figures in parentheses are arc sin transformed values. In a column, means

58 b

Staphylinidae Paederus fuscipes High Insect pests on main and ratoon rice 0.1-m nursery beds. Seedlings were

V Hemiptera transplanted 2 Aug 1984 in 64-m 2 plots Miridae High A. K. Chakravarthy, Regional Research and 13 Jul 1985 in 66-m 2 plots with 4 Cyrtorhinus lividipennis Gerridae Moderate

Limnogonus sp. To supplement natural buildup of Microvelia sp. Moderate Intan, a popular irrigated rice variety in insect population, 15-20 20-m-long rows Tropiconabis capsiformis Moderate the hilly region of Karnataka, was sown were maintained on each side of the

5 Jul 1984 and 7 Jun 1985 in 8- × 1- × experimental field. No insecticides were

Station, Mudigere 577132, India replications.

Nabidae

IRRN 12:4 (August 1987) 35

used. The crop was harvested on 31 Dec 1984 and 25 Nov 1985 leaving 8-cm stubble. The ratoon crop was fertilized with 45 kg urea 30 d after main crop harvest.

Insects were sampled on main crop and ratoon crop using a sweep net. Ten criss-cross sweeps were made at the top of the canopy on each plot and selected species counted. Plants also were examined for noticeable damage. In 1985, natural enemies were also sampled following the same sampling methods.

significantly higher numbers of orange- headed leafhopper Thaia subrufa (Motsch.) and green leafhopper Nephotettix virescens (Distant) than the main crop in both 1984 and 1985 (see figure). Brown planthopper Nilaparvata lugens (Stål) had significantly higher numbers on the ratoon crop in 1985.

Whorl maggot Hydrellia griseola (Fallen), caseworm Nymphula depunctalis (Guenée), leaffolder Cnaphalocrocis medinalis (Guenée), gall midge Orseolia oryzae (Wood-Mason), and thrips Stenchaetothrips biformis

The ratoon crop recorded

(Bagn.) did not increase. Stem borers Scirpophaga incertulas (Walk.) and S. innotata (Walk.) damaged both the main and ratoon crops.

natural enemies that can play a crucial role in suppressing insect pests.

Both main and ratoon crops harbored

Electronically recorded waveforms associated with brown planthopper (BPH) feeding activity

D. Kilin, Bogor Research Institute for Food Crops, Cimanggu Kecil 2, Bogor, and K. Sogawa, Indonesia-Japan Joint Programme on Food Crop Protection, Directorate of Food Crop Protection, P. O. Box 36 Pasarminggu, Jakarta, Indonesia

We analyzed the feeding activity of BPH by an electronic measurement system constructed with a power supply unit, variable oscillator, logarithmic amplifier, and stripchart recorder. BPH behavioral components associated with feeding activity were recorded as different voltage fluctuation patterns.

36 IRRN 12:4 (August 1987)

Insect pests on main crop and ratoon crop of lntan at Mudigere, India. OHLH = orange- headed leafhopper, WM = whorl maggot, CW = caseworm, LR = leafroller, T = thrips, GM = gall midge, SB = stem borer, GLH = green leafhopper, BPH = brown planthopper.

Six spiders, 2 odonatans, 2 wasps, 1 neuropteran, 16 Cyrtorhinus sp., and 12 Microvelia sp. bugs were recorded per 10 clumps on the main crop. On the ratoon crop, one spider, two odonatans, one neuropteran, six Cyrtorhinus, and two Microvelia spp. were recorded.

A brachypterous female was tethered with a 10-µm-diameter gold wire leading to the input of the electric current detection amplifier using electric conductive paint Dotite D-550 and allowed to feed on a potted rice plant electrified by applying a 500 Hz, 5 V alternative current from the oscillator. The plant and BPH were confined in a copper net cage during measurement to shut off electric noise.

BPH is a phloem feeder, with stylet sheath feeding. Its feeding process consisted of probing and sucking phases that elicited distinct waveforms. When the BPH started to penetrate the plant epidermis, an abrupt upsurge of electric current appeared. This is possibly due to excretion of a bulk of sheath material

on and into the plant tissues. Subsequent stylet probing along with stylet sheath formation produced an irregular jagged pattern with gradual drop of voltage (P).

Once the BPH went into sustained sucking from sieve elements in the phloem, confirmed by excretion of honeydew rich in sucrose, stable voltage output with micro vibrations in amplitude continued (S). Between the probing (P) and sucking (S) waveforms, two types of brief but characteristic waveforms registered: a regular pulsation pattern (A) and a small plateau formed by a vertical rise of voltage (B) similar to an intermittent sucking waveform. The A and B waveforms are possibly related to sensory responses of the BPH for

1. Examples of waveforms produced by biotype I females on resistant variety IR26, Indonesia, 1987. The upper chart shows that sucking from a sieve element after a P-A- B-A sequence was discon- tinued shortly. The lower chart shows a very short sucking waveform between the A-waveforms.

localization of sieve elements within the phloem, such as pulsatory emission of watery saliva for gustatory sensing and trial sucking.

commonly recorded when BPH fed on susceptible rice varieties is P-A-S, P-B- A-S, or P-A-B-A-S. The same waveforms also were produced on resistant varieties.

briefly, if at all on resistant varieties (Fig. 1). They lasted for a long time on susceptible varieties (Fig. 2).

resistance to BPH is attributed to gustatory blockage of sustained sucking on sieve elements.

The sequences of waveforms

The sucking waveform appeared only

This reconfirms that the varietal

2. Examples of waveforms produced by biotype 1 females on susceptible variety Pelita I/1, Indonesia, 1987. The upper chart indicates a process going into a sustained sucking from a sieve element after a sequence of P-A- S-A waveforms. The lower chart shows that a P-B-A sequence occurred during sustained sucking, indicating a change of sucking sites from one sieve element to another without withdrawal of the stylets from the plant. Letters A, B, P. and S indicate A, B, probing, and sucking waveforms, respectively. Arrow indicates a voltage upsurge at time of stylet insertion.

Strepsipteran parasites of rice leafhoppers and planthoppers in the Philippines

A. T. Barrion and J. A. Litsinger Entomology Deparment, IRRI

Strepsiptera are highly host-specific parasites of auchenorhynchous Homoptera. Host records can be determined by dissecting specimens. In 1985-86, we collected leafhoppers and planthoppers by D-Vac suction machine from dryland ricefields and adjacent grasslands of Caliraya in Laguna and Claveria in Misamis Oriental and from wetland ricefields in Koronadal in South

Cotabato, Calauan in Laguna, and Zaragoza in Nueva Ecija.

Two new host records for the Philippines were found, bringing the total to six (see table). The earlier record of Halictophagus yiperi Bohart on its sole host Cofana longa Merino was not detected. Elenchus yasumatsui Kifune et Hirashima parasitizes nymphs and adults of brown planthopper Nilaparvata lugens and is newly recorded on N. bakeri, H. spectrus Yang attacks only Cojana spectra and H. munroei Hirashima et Kifune only green leafhoppers Nephotettix spp.

H. bipunctatus Yang, recorded in Japan and China, was observed on N.

IRRN 12:4 (August 1987) 37

Parasitization of rice leafhoppers and planthoppers in the Philippines. a IRRI, 1985-86.

Parasitization (%) Specimen

(no.) Host dissected Halictophagus Elenchus

spectrus munroei bipunctatus b yasumatsui ?japonicus b

Cicadellidae Nephotettix virescens

N. nigropictus (Stal) Cofana spectra (Distant)

Nilaparvata lugens (Stal) N. bakeri (Muir) b

Sogatella furcifera (Horvath)

S. longifurcifera (Esaki & Ishihara)

S. kolophon (Kirkaldy) Sogatodes pusanus

(Distant)

Delphacidae

(Distant)

1884

3621 1875

4666 430

5 045

238

175 5730

– 0.1

– – 10 –

– – – – – –

– –

– – – –

0.3

0.1 –

– – –

–

– –

–

– –

9 0.7 2.1

–

3.2 –

–

– –

–

8

3.4

1.1

–

11

a H. piperi and its host C. longa were not collected. b New records.

virescens and N. nigropictus. E. nr. japonicus Esaki et Hashimoto was taken from the whitebacked planthopper complex Sogatella and Sogatodes.

Parasitization by strepsiptera is low, 0.1-11%, but supplements that of other nymphal-adult parasites, such as Tomosvaryella and Pipunculus, in regulating populations of rice leafhoppers and planthoppers. Strepsipterans cause castration or stylopization on the host genitalia. Usually they occur as wormlike or pupiform structures with their cephalothorax exserted between the dorsal or ventral abdominal segments of hoppers. An infested host usually has two to three adult strepsiptera embedded in its abdomen.

Nymphula africalis (Lepidoptera: Pyralidae), a pest of azolla in Nigeria

M.S. Alam, International Institute of Tropical Agriculture (IITA), Oyo Road, PMB 5320, Ibadan, Nigeria

In China, six moths, one beetle, and a snail are considered major pests of azolla. Information on insect pests of azolla in Africa is scarce. In West Africa, two pests (snail Limnea natalensis and caseworm Nymphula sp.)

are reported to have quickly destroyed the inoculum of Azolla pinnata var. africana.

In Sep-Oct 1986, azolla in an irrigated ricefield at Ibadan was infested with caseworm Nymphula africalis Hampson. The adult N. africalis is a dull-colored moth about 10 mm long with 4 distinct wavy bands on its forewings and a 15- to 18-mm wing span (Fig. 1). Newly hatched larvae feed on azolla leaf buds.

After a few days, they conceal themselves in cases made from azolla

1. Adult moth of Nymphula africalis.

38 IRRN 12:4 (August 1987)

2. a) Larval case, b) full-grown larva, and c) pupal case of Nymphula africalis.

fronds, which they carry with them as they move about for food. Larvae stretch their heads and thoraxes from the cases to feed. A full-grown larva is 15-16 mm long and will consume 9-14 azolla leaves a day.

The larval cases are about 20 mm long. Mature larvae spin cocoons inside the cases for pupation. A pupal case is about 14 mm long (Fig. 2). Pupae are brown and about 9 mm long. Adult moths emerge from cocoons within a week.

Minimum levels of three commonly used insecticides to control five insect pests of rice in the Philippines

R.F. Macatula and O. Mochida, Entomology Department, IRRI

The recommended foliar insecticide rate to control rice insect pests in the Philippines is 0.75 kg ai/ ha. We tested monocrotophos, MIPC, and chlorpyrifos + BMPC at 0.3, 0.4, and 0.5 kg ai/ ha on the IRRI farm. IR22 seedlings were transplanted at 21 d old in 6.0- X 5.2-m plots with 4 replications. Insecticides were sprayed 5 times at 14-d intervals from 5 to 61 d after transplanting. Populations of Nephotettix virescens (GLH), Hydrellia philippina (RWM), Cnaphalocrocis medinalis (LF), Chilo suppressalis (SB), and Leptocorisa oratorius (RB) were monitored.

There was no difference between dosages of the effective insecticides (see table). Monocrotophos or chlorpyrifos + BMPC were effective against LF. None of the insecticides lowered RWM incidence below 50%. Monocrotophos at 0.4 kg ai/ha was effective against RB. None of the insecticides gave better than 50% control of SB deadhearts. Monocrotophos at 0.3 kg ai/ha or chlorpyrifos + BPMC at 0.5 kg ai/ ha

prevented whiteheads. Significantly fewer rice tungro virus

(RTV) infested hills were observed on plots treated with monocrotophos.

Monocrotophos or MIPC at 0.3 kg

ai/ha was as good as higher dosages against GLH adults and nymphs. Chlorpyrifos + BPMC at 0.4 kg ai/ ha was effective on adults and at 0.75 kg ai/ ha on nymphs (see figure).

Effect of 3 insecticides applied as foliar spray at different rates on GLH. IRRI, 1985–86. In a row, means followed by different letters show that the average populations of adults and nymphs were significantly different at the 5% level by DMRT.

Rate (kg ai/ha)

Field evaluation of minimal levels of commonly used insecticides to control insect pest complex. a IRRI, 1985–86.

Insecticide b LF damaged RWM damaged leaves (%) c leaves (%) c

Hills (%) Stem borer

symptoms Deadhearts Whiteheads Rate showing RTV

RB e

(no./m2) (kg ai/ha) 20 DT 70 DT 65 DT (%) 60 DT (%) 5 DBH d at milk stage

Chlorpyrifos + BPMC 3 1.5 EC 0.3 0.4 0.5 0.7

MIPC 50 WP 0.3 0.4 0.5 0.7

Monocrotophos 30 EC 0.3 0.4 0.5 0.7

Control -

6 a 7 a 5 a 5 a

13 b 14 b 12 b 14 b 7 a 6 a 6 a 5 a

14 b

24 bc 23 abc 25 bc 20 ab 25 bc 27 bc 24 bc 22 abc 20 ab 24 bc 20 ab 18 a 32 d

13 de 9 cde

11 de 8 bcd 9 cde

10 cde 10 cde 8 bcd 5 abc 3 a 7 abcd 4 ab

12 de

15.4 cd 13.3 bcd 15.0 cd 13.5 bcd 14.7 cd 13.7 bcd 14.9 cd 14.5 cd

12.4 abc 9.6 a 9.4 a

10.9 ab 17.1 d

1.1 abc 5.3 bcde 1.2 bc 4.8 abcd 0.9 ab 4.3 abc 0.8 ab 5.0 bcde 2.8 d 5.8 cde 2.8 d 6.3 cde 2.5 d 8.8 de 1.9 cd 4.5 abcd 0.8 ab 5.3 bcde 0.6 ab 2.3 abc 0.4 ab 1.0 ab 0.3 a 0.7 a 2.5 d 9.2 e

a DT = days after transplanting. In a column, means followed by a common letter are not significantly different at the 5% level by DMRT. b Insecticides were applied at 5, 19, 33, 47, and 61 DT. Spray volume was 300–500 liters/ha. c Data based on 20 sample hills. Av of 4 replications. LF = leaffolder, RWM = rice whorl maggot. d Days before harvest. e Rice bug.

IRRN 12:4 (August 1987) 39

Biotype shift in a brown planthopper (BPH) population on IR42

K. Sogawa and D. Kilin, Indonesia-Japan Joint Programme on Food Crop Protection, Directorate of Food Crop Protection, P.O. Box 36, Pasarminggu, Jakarta, Indonesia.

IR42, with bph 2 gene for resistance to BPH, was introduced in Indonesia in 1980. However, its BPH resistance has been defeated rather easily by the development of a new biotype in North Sumatra in 1982 and in Central Sulawesi and Riau in 1983.

biotype was reproduced in the laboratory at Bogor Research Institute for Food Crops. The field BPH population was collected on susceptible variety Pelita I/1 at Jatisari Field Laboratory, West Java. The Jatisari population is biotype 1. First-instar nymphs hatched on Pelita I/1 plants were individually introduced into test tubes (1.5 × 16 cm) containing 2 IR42 seedlings. Seedlings were changed weekly.

Nymphal development and mortality were recorded daily. Adults that emerged were immediately transferred to Pelita I/1 plants to mate and produce progeny. Nymphs that hatched on the Pelita I/1 plants were again subjected to individual rearing on IR42 seedlings. These procedures were applied for five consecutive generations.

The Jatisari population of the BPH became compatible with IR42 or shifted from biotype 1 to biotype 3 within five generations. Adult emergence on IR42 increased logarithmically, from 19.3 to 82.5%. The average nymphal period was shortened from 17.1 to 12.4 d, and the growth index improved from 1.13 to 6.65 (see table). Adults of the 4th and 5th generations were able to reproduce significantly to maintain the population on IR42 plants at tillering.

During the first 2 generations, nymphal duration on IR42 ranged from 12 to 22 d. However. after the third generation, the variation in duration was gradually reduced to a binomial

The developmental process of the new

40 IRRN 12:4 (August 1987)

Gradual improvement in the Jatisari BPH population nymphal growth during a course of selection on IR42. Jakarta, Indonesia.

Nymphs Adult Mean Generation tested emergence nymphal

(no.) (%) period (d) Growth

index

Brachypterous females

(%)

1 2 3 4 5

197 59 54 58 40

19.3 22.0 48.1 70.0 82.5

17.1 ± 2.9 16.4 ± 3.6 14.1 ± 1.5 13.5 ± 1.3 12.4 ± 0.9

1.13 1.34 3.42 5.36 6.65

62 100 100 100 100

Change in frequency distribution of nymphal period of the BPH Jatisari population for 5 consecutive generations selected on IR42 seedlings, Jakarta, Indonesia.

distribution pattern (see figure). About 40% of the females were macropterous

in the first generation; after the second generation, all were brachypterous.

Complete slide sets of photos printed in field problems of tropical rice, revised 1983, are available for purchase at $50 (less developed country price) or $60 (developed country price), including airmail postage and handling, from the communication and Publications Department, Division R, IRRI P.O. Box 933, Manila, Philippines. No orders for surface mail handling will be accepted.

Control of tungro (RTV) and yellow stem borer (YSB) in rice by synthetic pyrethroids

P.S.P. Rao, G. Bhaktavatsalam, and A. Anjaneyulu, Central Rice Research Institute, Cuttack 753006, Orissa, India

Resurgence of insect pests following repeated insecticide applications has become widespread. We evaluated foliar application of available synthetic pyrethroids in controlling RTV vector green leafhoppers (GLH) Nephotettix virescens (Distant) and N. nigropictus Stål and YSB Scirpophaga incertulas Walker.

Two field experiments were conducted in wet season (Jul-Nov) 1984 using rice variety Ratna, which is tolerant of both RTV and YSB. Thirty- d-old seedlings were transplanted in 3- × 3-m plots at 20- × 15-cm spacing (300 hills) late in the season (12 Sep) to synchronize the RTV-vulnerable, early tillering stage with emergence of GLH in mid-Sep to mid-Oct and the flowering stage YSB (end of Oct to mid-Nov). The crop was grown with 100-18-33 kg NPK/ha. Five days after transplanting (DT), 2 m around each plot was transplanted with RTV inoculated seedlings in the glasshouse.

In the first experiment, decamethrin

Control of RTV, GLH, and YSB by some synthetic pyrethroids. a Cuttack, India, 1984 kharif.

Green leafhopper/10 hills

Insecticide Dose (ai/ha) Adult Nymph

30 DT 42 DT 30 DT 42 DT

A. Decamethrin 200 g 0.3 a 3.0 ab 0.3 a nil a 100 g 1.3 ab 3.7 ab 1.3 ab 0.3 a 50 g 0.7 a 4.0 b 3.0 b nil a 25 g 0.3 bc 5.0 b 3.7 b 0.7 ab 12 g 2.7 bc 5.0 b 3.0 b 1.0 ab 6 g 6.7 d 9.7 c 10.3 c 3.0 b

Cypermethrin 100 g 1.3 ab 1.7 a 2.0 ab nil a Carbofuran (treated check) 2 kg 4.3 cd 5.0 b 20.3 d 2.0 ab Control (untreated check) – 16.0 e 34.7 d 98.3 e 53.3 c

B. Synthetic pyrethroids Decamethrin + bufrofezin 100 g 11.7 bcde 8.0 ab 4.3 ab 3.0 abc

Tralomethrin 10 g 6.3 ab 9.7 ab 6.7 b 5.0 bc 200 g 8.7 abcd 6.0 a 2.3 a 1.3 a

20 g 5.0 ab 8.3 ab 2.3 a 1.0 a S. 399 125 g 30.0 g 18.0 cd 41.0 a 15.3 d

250 g 18.7 efg 14.0 ab 27.0 d 12.3 d S. 423 500 g 20.0 fg 6.3 a 13.0 c

l000 g 15.7 def 12.7 bc 5.0 c

6.3 ab 2.0 a Decamethrin 12 g 6.3 abc 8.3 ab 3.3 ab 1.0 a Cypermethrin 50 g 2.7 a 7.0 ab 3.0 ab 1.7 a Carbofuran (treated check) 2 kg 13.7 cdef 9.0 ab 13.7 c 2.3 ab Control (untreated check) – 29.3 g 21.0 d 59.0 f 37.3 e

and cypermethrin were sprayed six times. In the second experiment, synthetic pyrethroids decamethrin + bufrofezin, tralomethrin, S.399, and S.423. decamethrin and cypermethrin were sprayed four times. Adult and nymph populations were monitored at 30 and 42 DT and RTV disease at 49- 51 DT. Stem borer infestation at heading (%, whiteheads) was estimated from 4 random samples of 20 hills each.

Treatments differed significantly (see table). In both experiments, synthetic pyrethroids gave good to excellent control of both RTV and its vector, but were not effective against YSB.

Disease (%)

(49-51 d) Whiteheads Angular

YSB infestation at heading

(%) value

1.7 a 1.9 a 3.7 b 4.5 bc 4.7 bc 5.2 bc 2.1 a

11.6 d 43.6 e

3.9 12.0 14.6 13.9 11.6

8.6 15.6

1.6 7.7

11.34 ab 20.21 cdef 22.36 ef 21.90 def 19.87 cde 16.97 cd 23.02 ef

6.82 a 15.80 bc

8.4 bc 10.6 18.79 cd 5.9 ab 8.2 16.40 bcd 9.5 c 9.5 17.90 cd 4.1 a 11.0 19.27 cd

38.9 f 7.2 15.47 bc 23.8 e 8 .0 16.36 bcd 14.5 d 7.1 15.43 bc 8.3 bc 8.4 16.68 bcd 5.2 ab 8.0 16.46 bcd 4.6 a 12.6 20.54 d

10.6 cd 0.03 6.03 a 42.3 f 4.9 12.75 b

a Within a group, means in a column followed by a common letter are not significantly different at the 5% level by DMRT.

Rice thrips infestations in West Bengal

P.B. Chatterjee, Rice Research Station, P.O. Chinsurah R.S. 712102, Hooghly, West Bengal, India

Rice thrips Stenchaetothrips biformis (Bagnall) is essentially a pest of young rice plants. On wetland or monsoon

season rice (kharif), maximum infestation is found Jul-Aug when rice is in nursery beds or at tillering in the field. However, a severe outbreak occurred at late tillering in West Bengal in Sep 1986. An estimated 60,000 ha was affected. A prolonged dry spell from Aug to the third week of Sep in the middle of the rainy season may have been one of the causes.

Another thrips species, Haplothrips gunglbaueri Schmutz, commonly known as rice ear thrips, damages the inflorescence of early varieties. It is polyphagous and has been recorded on other crops. On rice, adults and nymphs congregate on the emerging inflorescence, lacerate the lemma and palea of the spikelet, and suck the content. Symptoms include ear

IRRN 12:4 (August 1987) 41

Rice leaffolder (LF) species in North Arcot District, Tamil Nadu

S. Jaganathan and N. Chandramohan. Tamil Nadu Agricultural University Research Centre, Vellore, Tamil Nadu, India

Rice LF has been a major pest in Tamil Nadu for 15 yr. We surveyed North Arcot District during Sep-Jan (late samba) to identify LF species on rice.

In each division, 100 larvae were collected and reared in the glasshouse.

distortion and spikelet whitening and sterility.

H. ganglbaueri has been found in Hooghly, .Midnapore, Burdwan, and 24 Parganas districts of West Bengal. On wet season rice, damage occurs Sep-Oct; on dry season rice, maximum thrips concentration occurs in Mar-Apr.

Nymphula africalis, azolla pest in Nigeria

M. N. Ukwungwu, S.O. Fagade, and E. Fagbohun, National Cereals Research Institute, Badeggi, P.M. B. 8, Bida, Nigeria

Insect damage reportedly limits azolla production as a supplementary N source for rice in many Asian countries. We observed high infestations of caseworm Nymphula africalis Hampson on Azolla pinnata in the 1986 wet season in multiplying tanks at Badeggi, Nigeria. We also observed high incidence on the Institute's farm at Badeggi.

The larvae were reared in the laboratory and the adult identified by the Commonwealth Institute of Entomology, London, as Nymphula africalis.

This is the first report of this species on azolla in Nigeria. Nymphs and adults of Tramea sp. (Odonata: Libellulidae) were predators of both larvae and adults of N. africalis.

Occurrence of a predatory mite Pyemotes ventricosus on Sitotroga cerealella Oliv.

A. Dakshinamurthy, P. Karuppuchamy, and M. Mohanasundaram, Agricultural Entomology Department, Tamil Nadu Agricultural University. Coimbatore 641003, India

A predatory mite P. ventricosus (Newport) has been reported to prey on the larvae of rice moth Corcyra sp., Angoumois grain moth Sitotroga cerealella Oliv., satin moth Stilpnotia salicis L., peach twig borer Anarsia lineatella Zeller, bud moth Spilonota ocellana Schiff, and coconut caterpillar

42 lRRN 12:4 (August 1987)

Opisina arenosella (Wlk). Females feed by piercing the integument with their chelicerae. Mite eggs develop inside the female which gives birth to nymphs. The mite reproduces parthenogenetically.

P. ventricosus mites were mounted in Hoyer's medium on microscopic slides and kept in a hot air oven at 50°C for 2 d. Taxonomic characters were examined under a phase contrast microscope.

In the genus Pyemotes, the idiosoma are oval-shaped and the anterior edge of the dorsal propodosomal shield partially

overhangs the gnathosoma. In the female, legs I have five free segments terminating in a claw. Legs I1 to IV terminate in two claws and a pretarsus. In the male, tarsus IV bears a single claw. P. ventricosus characters agree with this description.

This mite has been a problem in maintaining insect cultures in the laboratory and is said to cause dermatitis in people handling infected storage materials.

cylindrical polyester cages. The leaf portions containing eggs were clipped and 30 eggs placed on moist filter paper

Effect of 8 insecticides on rice bug eggs

R. Rujendran and S. Chelliah, Centre for Plant Protection Studies, Tamil Nadu Agricultural University, Coimbatore 641003, India

Twenty adults each sex of rice bug Leptocorisa oratorius (Fabricius) were collected from the field and released on flowering rice plants confined in

in a petri dish. Insecticide was sprayed with an atomizer at a pressure of 0.7 kg/cm 2 . Treatments were replicated three times. Nymphs that emerged were counted daily from 6 to 10 d after treatment.

Fenthion had the maximum ovicidal action, with 74% reduction in hatching followed by chlorpyrifos (see table).

Ovicidal effect of insecticides. Coimbatore, India.

Rate (kg ai/ha)

Egg hatch reduction a Insecticide Formulation

(%)

Fenthion Chlorpyrifos Phosphamidon Phosalone Monocrotophos Quinalphos Malathion Endosulfan

100 EC 20 EC 85 SC 35 EC 36 SC 25 EC 50 EC 35 EC

0.50 0.20 0.50 0.35 0.40 0.38 0.25 0.35

74 a 60 ab 55 bc 44 c 29 d 22 de 18 de 11 e

a Means followed by a common letter are not significantly different at 5% level, Duncan's multiple range test. Mortality corrected by Abbott's formula.

Rice LF genera in North Arcot District, Tamil Nadu, India.

Generic composition (%) Division

Cnaphalocrocis Marasmia medinalis patnalis

Arakonam 34 66 Cheyyar 64 36 Gudiyatham 79 21 Thiruvannamalai 83 17 Vaniyambadi 31 69 Vellore 74 26

Mean 53 Walajah 7

47 93

Emerging adults were identified on the basis of wing markings.

Two species were found: Cnaphalocrocis medinalis and Marasmia patnalis. C. medinalis accounted for 53% and M. patnalis for 47% of the population (see table). M. patnalis predominated in Walajah, Thiruvannamalai, and Arakonam divisions; C. medinalis in the other divisions.

Persistence of quinalphos in rice

A. K. Pal, H. K. Senapati, and N. Panda, Pesticide Residue Laboratory, Soils and Agriculture Chemistry Department, Orissa University of Agriculture and Technology, Bhubaneswar 751003, Orissa, India

We studied the persistence of quinalphos in rice variety Lalat following foliar spraying during 1984-85 kharif and rabi. Quinalphos was sprayed at 0.5 kg ai/ ha and 1.0 kg ai/ ha, with 3 replications. Plant samples were extracted by chloroform, cleaned by celite:MgO:charcoal column, and

Table 1. Quinalphos residue in rice, 1984-85 dry season (rabi), Bhubaneswar, India.

Days Quinalphos residue a (ppm) after

treatment 0.5 kg ai/ha 1.0 kg ai/ha

0 5

10 15 20

5.3 9.5 2.5 3.1 0.5 1.0 n.d. 0.25 n.d. n.d.

50% residue 3 3 level (d)

a n.d. = not detectable.

Table 2. Quinalphos residue in rice, 1985 wet season (kharif), Bhubaneswar, India.

Days Quinalphos residue (ppm) after

treatment 0.5 kg ai/ha 1.0 kg ai/ha

0 4.23 6.53 5 1.74 2.71

10 0.27 0.69 15 20

n.d. 0.34 n.d. n.d.

50% residue 2.5 3.0 level (d)

estimated by spectrophotometric nondetectable levels within 15-20 d after method. Recoveries from fortified treatment during the dry season samples were 80-85% (Table 1) and within 15-20 d after

plant samples were reduced to 2). Initial deposits of quinalphos in rice treatment during the wet season (Table

Insecticides to control rice hispa Live grub population from 10 hills/ plot was recorded before insecticide

P. V. Krishnaiah, P. Seshagiri Rao, P. Sanjeeva Rao, N. H. P. Rao, and V. Narasimham, I. C. O. R. P. Project, Agricultural Research Station, Warangal, Andhra Pradesh, India

We evaluated eight insecticides against rice hispa Dicladispa armigera (Oliv.) in a duplicated farmer’s field trial during kharif 1986. Plot size was 100 m 2 .

application and 1 wk after. Adult beetle population and percent leaf damage on all leaves in 10 hills/plot were assessed 2 wk after insecticide application.

Monocrotophos at 0.06% was most effective against hispa grubs, closely followed by quinalphos at 0.07%. Adult beetle population also was checked by monocrotophos followed by quinalphos (see table).

Chemical control of rice hispa in Warangal district, Andhra Pradesh, India. a

Treatment Grubs/hill % reduction Adults/hill at % leaf

Before 7 d after of grubs 14 d after damage application application application

Carbofuran 3G @ 25 kg/ha Phorate 10G @ 10 kg/ha Monocrotophos 40EC @ 0.06% Chlorpyriphos 20EC @ 0.06% Endosulfan 35EC @ 0.09% Fenvalerate 20EC @ 0.01% Phosalone 35EC @ 0.09% Quinalphos 25EC @ 0.07% Untreated control

F test CD (0.05)

12 9

11 7

12 10 10 10 10 ns –

l a 3 a l a 2 a 6 b 2 a l a l a

11 c **

2

87 a 60 ab 94 a 69 ab 42 b 83 ab 89 a 92 a –8 c

** (26)

0.4 ab 1.2 b 0.2 a 0.6 ab 6.8 d 2.5 c 0.8 ab 0.3 ab 7.0 d

** 1.0

0.1 ab 0.9 ab 0.3 ab 0.0 a 8.0 c 1.8 b 0.4 ab 0.1 ab 8.4 c

** (5.70)

a In a column, values followed by the same letter do not differ significantly. Figures in parentheses are transformed values.

Egg parasites of Scirpophaga incertulas (Walker) in Sri Lanka for YSB oviposition. The experiment

was repeated four times in two seasons.

D. Ahangama, Faculty of Agriculture, University of Peradeniya, Sri Lanka, and F.E. Gilstrap, Entomology Department, Texas A & M University, College Station, Texas 77843, USA

We studied the yellow stem borer (YSB) Scirpophaga incertulas (Walker) in Mar and Jul 1982 at the Dryzone Agricultural Research Station, Maha Illuppallama, Sri Lanka. After transplanting, experimental plots were covered with mesh cages. Two weeks after transplanting, plots were exposed

Hatched egg masses were collected on day four, remaining egg masses were collected on day eight and held in glass vials in the laboratory. Number of parasites emerging from each egg mass was recorded. Then, egg masses were soaked in 5% HCl and separated into individual eggs and number of hatched eggs, unenclosed dead larvae, and unemerged parasites recorded. Parasites were sent to the Commonwealth Institute of Entomology for identification.

Telenomus sp. and Tetrastichus

IRRN 12:4 (August 1987) 43

Hairy caterpillar Nisaga simplex Wlk. (Eupterotidae: Lepidoptera) regularly damages upland and medium ricefields in various locations of Kalahandi and Koraput districts in the wet season Jun- Dec. Moths emerged in Jun with the onset of the monsoon and oviposit on weedy growth of scrubby jungles and on adjoining ricefields. Incubation lasted 7- 9 d. In the laboratory, 8 larval instars were completed in 68-76 d. Pupation took place in soil. Caterpillars fed

voraciously on the leaf lamina, leaving only the midrib.

In its natural habitat, the pest pupated in loose lateritic soil, often as deep as 30 cm, in Oct and overwintered to the following Jun. The caterpillars shunned water and did not migrate to lowland fields. The moths are poor fliers.

Weedy fields attracted higher populations than weeded fields. The caterpillars also attacked maize, sorghum, finger millet, sugarcane, and these weed species: Brachiaria mutica, Cynodon dactylon, Dactyloctenium aegyptium, Digitaria ciliaris, Echinochloa colona, E. crus-galli, E. glabrescens, Eleusine indica, Ischaemum rugosum, Leersia hexandra, Leptochloa chinensis, Panicum repens, Paspalum conjugatum, P. clistichum, and P. scrobiculatum.

Rice leaffolder (LF) infestations in West Bengal

P. B. Chatterjee, Rice Research Station, P.O. Chinsurah R.S. 712102, Hooghly, West Bengal, India

Rice LF generally appears as a minor pest of rice in West Bengal. However, it

infested over 67,000 ha in 11 districts in 1986, causing appreciable damage to standing wet season rice. All the districts experiencing massive infestation were located on the south and southwest sides of the river Ganges.

Cnaphalocrocis medinalis (Guenée) was the most dominant LF species;

schoenobii Ferriere were the only egg parasites obtained from 193 egg masses (1,070 eggs) of S. incertulas (see table). Although Telenomus sp. caused a higher percentage of parasitization than T. schoenobii in all four generations ( S. incertulas completes two generations each cropping season in Sri Lanka), the difference was not significant.

Diluted quinalphos and fenthion and control of whitebacked planthopper (WBPH)

J. Singh and S.S. Malhi, Plant Breeding Department, Punjab Agricultural University, Ludhiana, India

Two experiments with two insecticides (quinalphos and fenthion) were conducted to evaluate diluted insecticides in controlling WBPH Sogatella furcifera at Bhupindra Rice Research Substation, Rauni, 1985 wet season.

quinalphos and fenthion was diluted with water to apply 250, 375, and 500 liters/ha. A randomized block design with four replications for quinalphos and three for fenthion was used. Plot size was 300 m 2 .

WBPH counts at 2 and 8 d after application for quinalphos and 2 d after application for fenthion showed no significant differences among treatments (see table).

Effect of diluted insecticides on WBPH incidence. Punjab, India, 1985.

Recommended rate (0.5 kg ai/ ha) of

WBPH a (adults + nymphs)/l0 hills

Pre- 2 d after 8 d after treatment b application application

Treatment

Quinalphos 25 EC 250 174 a 11 a 80 a 375 171 a 9 a 84 a 5 00 174 a 4 a 101 a

Control 184 a 200 b 273 b Fenthion 1000 EC

250 211 a 11 a 375 189 a 9 a 500 175 a 10 a

– – –

Control 182 a 294 b – a For each group of insecticide treatments, means in a column followed by a common

by DMRT. b 30 Aug for quinalphos and 5 Sep letter do no differ significantly at the 5% level

for fenthion.

44 IRRN 12:4 (August 1987)

Parasitization of S. incertulas eggs by Telenomus sp. and T. schoenobii. Maha Illuppallama, Sri Lanka, May and Jul, 1982.

Parasitization (%) Generation Eggs (no.)

Telenomus sp. T. schoenobii Total

1 st 2d 3d 4th

208

345 195

322

27 .0 27.4 36.3 35.3

17.3 44.3 16.0 43.4 24.5 60.8 23.3 58.6

Nisaga simplex caterpillar on rice in western Orissa

N. C. Patnaik, Entomology Department, Orissa University of Agriculture and Technology (OUAT), Bhubaneswar - 3; B. Mohanty, Regional Research Station (RRS), Bhawanipatna; and A. K. Parida, AICRP on Weed Control, OUAT; Bhubaneswar - 3, India

Leaves damaged by LF, maximum and minimum temperatures, and rainfall in different months. a

West Bengal, India.

Damaged Mean monthly temperature (°C) Month leaves Rainfall (mm)

(%) Maximum Minimum

May 3.6 34.5 (–1.9) 22.3 (–2.7) 178.8 (+63.4) Jun 5.5 34.3 (+0.4) 26.6 (+l.l) 278.6 (+30.0) Jul 12.6 31.5 (–0.2) 25.9 (+0.2) 249.5 (–40.2) Aug 31.3 32.7 (+1.4) 26.3 (+0.6) 98.2 (–404.4) Sep 73.6 31.4 (–0.1) 25.1 (–0.4) 750.0 (+513.5) Oct 31.9 30.6 (–0.4) 22.1 (–0.8) 104.3 (–8.0) a Mean of 20 samples. Figures in the parentheses indicate deviations from normal.

however, Marasmia exigua (Butler) also caused damage. Their relative proportion was 80:20.

Wet season rice usually is transplanted Jul–Aug and harvested in Nov. But an unusual drought in Aug– Sep caused setbacks. Stray incidences of LF were observed in May on broadcast rice seedlings sown in Apr. Gradually the pest population built up. Percentages of damaged and folded leaves/m 2 of sample plots were recorded May-Oct 1986. The sample was 20 randomly selected plots in each district. Data with rainfall, temperature, and deviations from normal are presented in the table.

Four overlapping LF broods were observed. Cotesia sp. and Temelucha philippinensis (Ashm.) were the common larval parasites.

combined with other bioecological factors favored the outbreak. After superabundant rain 22 Sep-8 Oct (a record 503 mm rainfall was recorded in 12 d at Chinsurah), the infestation gradually waned.

It appears the unusual dry conditions

Biochemical changes in rice plants infested with mealybug

M. Gopalan, N. C. Radja, and G. Balasubramanian. Centre for Plant Protection Studies, Tamil Nadu Agricultural University, Coimbatoire 641003, India

We studied the contents of reducing and nonreducing sugars, total phenols, and amino acids in healthy rice plants and those infested with mealybug Brevennia rehi Lindinger. Fifty mealybugs were placed on each tiller of 20-d-old IR20 seedlings, and allowed to feed 40 d. Samples were drawn 60 d after treatment from healthy and infested seedlings with three replications.

A 10-g sample of plant material was plunged into boiling 80% ethyl alcohol and extracted for 10 min. The extract was decanted, the tissues ground with a pestle and mortar and reextracted with another aliqout of ethanol, then strained through cheesecloth. Extracts were pooled to make up a desirable volume

Effect of mealybug infestation on biochemical contents of rice. a Coimbatore, India.

Biochemical constituent Content (mg/g dry weight)

Healthy Infested

Change (%)

Total phenol Total sugar Reducing sugar Nonreducing sugar Total N Amino acid (mg/100 g dry weight)

Histidine Lysine Serine Tyrosine Alanine Glycine Tryptophan Arginine Isoleucine Proline Threonine Hydroxyproline

Total

3.9 16.9 6.4

10.5 10.7

28 54 25

199 –

47 127

29 31 52 37

202 838

4.0 32.6 12.9 19.7 6.8

34 62 29

221 8

60 142

37 87

140 39

297 1156

+ 2.6 + 92.9 +101.6 + 87.6 – 36.7

+ 21.4 + 14.8 + 16.0 + 11.1 + 11.3 + 27.7 + 11.8 + 27.6 +180.6 +169.2 + 5.4 + 47.0

37.9

a Mean of 3 replications.

to use in estimating total and reducing sugars and total phenols and for chromatographic estimation of individual amino acids.

unidimensional descending chromatographic technique for qualitative analysis and estimated quantitatively by Demetriades’ method. The nitrogen was estimated on dry

The amino acids were separated

plants by Humpries’ method. Feeding injury by mealybugs resulted

in a marginal increase in total phenolic content (see table). Total sugar, reducing sugar, nonreducing sugar and total amino acid contents increased phenomenally. Among the amino acids, isoleucine and proline contents increased more.

Pest Control and Management WEEDS

Effect of frequent cultivation on Rottboellia cochinchinensis density

D.C. Navarez, E.M. Castin, and K. Moody, IRRI

Rottboellia cochinchinensis (Lour.) W.D. Clayton (syn. R. exaltata) is a major weed in upland rice, maize, sugarcane, and legumes in the Philippines. We tested the effect of cultivation frequency (every 2, 3, and 5 wk) on R. cochinchinensis emergence in a fallow field at IRRI Aug 1983 - Jul 1985. Weeds were counted monthly in two 50- × 50-cm random quadrats per 48-m 2 (6 × 8 m) plot.

Initial weed density was 285 plants/m 2 , with R. cochinchinensis comprising 30% of the population. After 1 yr, R. cochinchinensis population declined substantially (see figure). Reduction was associated with more frequent cultivation. By the end of the second year, R. cochinchinensis had been practically eliminated with cultivation every 2-3 wk; only a few plants grew in plots cultivated every 5 wk. This indicates that seeds of this weed either have very short dormancy or no dormancy or are short-lived.

Decline in the R. cochinchinensis population was not necessarily accompanied by an overall reduction in

IRRN 12:4 (August 1987) 45

46 IRRN 12:4 (August 1987)

were the predominant weed flora. (see table). Combining propanil at 2 kg Among the preemergence herbicides,

oxadiazon at 0.6 kg ai/ ha resulted in the best weed kill, with yields of 4.1 t dry seeded rice and 4.6 t wet seeded rice/ha

ai/ha with butachlor or pendimethalin was more effective than when the preemergence herbicides were applied alone.

Weed control in irrigated wet and dry seeded rice in medium-textured soils of Northwestern India

B.B. Bhol and K.N. Singh, Division of Agronomy, Indian Agricultural Research Institute (IARI), New Delhi 110012, India

Eight weed control treatments were tested to control weeds in direct seeded rice when sprouted seeds were sown on a puddled field and when dry seeds were sown on an unpuddled bed. The trial was in a split-plot design with three replications during 1983 and 1984 monsoon seasons.

The field was well-drained sandy clay loam soil. Pusa 33, 105-110 d duration and photoperiod insensitive with high yield potential, was the test variety. The crop received 100-22-42 kg NPK/ha. Preemergence herbicides like oxadiazon, pendimethalin, and butachlor were applied 4-5 d after seeding (DAS); propanil was applied 21 DAS. Echinochloa colona and E. crus-galli

Effect of frequency of cultivation on density of Rottboellia cochinchinensis and all weed species. IRRI, Aug 1983-Jul 1985.

total weed density. Cyperus rotundus L. populations decreased in plots that were frequently cultivated but increased with less frequent cultivation. Densities of Eleusine indica (L.) Gaertn. and Portulaca oleracea L. also increased.

reduced in the plots rototilled every 5 wk. However, R. cochinchinensis was replaced by less competitive weeds.

Total weed density after 2 yr was not

Complete slide sets of photos printed in Field problems of tropical rice, revised 1983, are available for purchase at $50 (less developed country price) or $60 (developed country price), including airmail postage and handling, from the Communication and Publications Department, Division R, IRRI, P. O. Box 933, Manila, Philippines. No orders for surface mail handling will be accepted.

Delhi, India, 1983-84. Effect of herbicide schedule and seeding method on grain yield of direct seeded rice. IARI, New

Grain yield (t/ha) Weed wt (g/m 2 )

Dry seeded Wet seeded Dry seeded Wet seeded

Oxadiazon 0.6 pre + propanil 2 post 4.3 4.7 19 20 Oxadiazon 0.6 kg pre 4.1 4.6 18 19 Hand weeding + propanil 2 post 3.8 3.9 36 36 Pendimethalin 1.5 pre + propanil 2 post 2.1 3.0 71 61 Butachlor 1.0 pre + propanil 2 post 1.9 2.2 73 69

Treatment a

Pendimethalin 1.5 pre 1.4 2.5 88 73 Butachlor 1.0 pre 0.9 2.0 101 81

0.5 1.3 125 105 CD for weed control treatment 0.3 6 means for the same method of seeding CD for method of seeding means 0.3 for the same level of weed control

6

a Pre and post = preemergence and postemergence applications. Herbicide measurements are in kg ai/ha.

Weedy check

Response of upland rice to weed control methods

M. R. Deshmukh, K.K. Trivedi, and J. P. Tiwari, Agronomy Department, JNKVV, Jabalpur, (M. P.), India

We evaluated 14 treatments to manage the complex weed ecosystem in upland rice. Each treatment was replicated four times in a randomized block design. Pusa 33 seed at 100 kg/ha was drilled in 20-cm-wide rows the first week of Jul. Fertilizer was 100-26-33 kg NPK/ ha. All P and K and 1 / 2 N were applied at sowing; the remaining N was applied in 2 equal splits at 20 and 40 d after sowing (DAS).

Cyperus iria, C. rotundus, Commelina diffusa, Echinochloa crus-galli, Digitaria ciliaris, Paspalum distichum, Cynodon dactylon, Eclipta prostrata, and Alternanthera sessilis were the major weeds in the experimental field. The weed biomass was determined at harvest.

Weed biomass was lowest with oxadiazon 0.75 kg ai/ha plus 1 hand weeding at 30 DAS (see table).

Effective tillers were highest with oxadiazon 0.75 kg ai/ha + 1 hand weeding at 30 DAS. Crop biomass was highest (13.7 t/ha) with thiobencarb 1.5 kg ai/ha + 1 hand weeding 30 DAS.

Highest grain (4.39 t/ ha) and straw (9.29 t/ ha) yields were observed with thiobencarb 1.5 kg ai/ha + 1 hand weeding at 30 DAS. The same treatment gave the highest profit ($241.46/ ha).

IRRN 124 (August 1987) 47

Ricefield weeds in South Andarnan, India

D. Singh and B. Gangwar, Central Agricultural Research Institute, Port Blair 744101, India

We surveyed weeds in 103 randomly selected ricefields in 14 locations of South Andaman during Oct 1986. Percentage cover for all weed species was assessed in 51 clay loam soil and 52 clay soil fields between heading and

flowering.

families were identified: 30% were Cyperaceae and 27.5% Poaceae (see table). Thirty-nine species were found in clay loam fields, 38 in clay fields; 37 were common to both conditions. Eleocharis dulcis was not found in clay loam fields; Ageratum conyzoides, and Spilanthes paniculata were not found in clay fields.

predominant in all the clay loam and

Forty weed species belonging to 13

Fimbristylis miliacea was

94% of the clay fields surveyed. Echinochloa colona, Ludwigia hyssopifolia, Torenia violacea, and Cyperus rotundus were almost equally important in both soil types.

Scirpus juncoides and Monochoria vaginalis in clay fields and Cyperus difformis in clay loam fields were also important.


Percentage of fields infested with weeds and severity of infestation in transplanted upland and lowland rice in South Andaman.

Clay loam a Clay soil b

Weed species Family Field Cover Field Cover infested (%) infested (%)

(%) (%)

Fimbristylis miliacea (L.) Vahl Echinochloa colona (L.) Link Ludwigia hyssopifolia (G. Don) Exell Torenia violacea (Azaola ex Blanco) Pennell Cyperus rotundus L. Scirpus juncoides Roxb. Monochoria vaginalis (Burm.f.) Pres1 Cyperus difformis L. Lindernia antipoda (L.) Alston Cynodon dactylon (L.) Pers. Echinochloa crus-galli (L.) Beauv. Cyperus iria L. Cryptocoryne Ciliata (Roxb.) Schott Setaria verticillata (L.) Beauv. Eclipta prostrata (L.) L. Eleusine indica (L.) Gaertn. Fuirena umbellata Rottb. Phyllanthus amarus Schum & Thonn. Bacopa monnieri (L.) Pennell Cyperus javanicus Houtt. Axonopus compressus (Sw.) P. Beauv. Amaranthus viridis L. Ageratum conyzoides L. Euphorbia hirta L. Eleocharis dulcis (Burm. f.) Henschel Fimbristylis alboviridis C. B. Clarke Aponogeton natans (L.) Eng & Kr. Hedyotis umbellata (L.) Lam. Marsilea quadrifolia L. Spilanthes paniculata Wall. ex DC. Paspalum conjugatum Berg. Paspalum scrobiculotum L. Ischaernum indicum (Houtt.) Merr. Ischaemum rugosum Salisb. Panicum repens L. Cyperus kyllinga Endl. Murdannia nudiflora (L.) Brenan Cyperus halpan L. Cyperus sanguinolentus Vahl Commelina benghalensis L.

Cyperaceae Poaceae Onagraceae Scrophulariaceae

Cyperaceae Cyperaceae Pontederiaceae Cyperaceae Scrophulariaceae Poaceae Poaceae Cyperaceae Araceae Poaceae Asteraceae Poaceae Cyperaceae Euphorbiaceae Scrophulariaceae Cyperaceae Poaceae Amaranthaceae Asteraceae Euphorbiaceae Cyperaceae Cyperaceae Aponogetonaceae Rubiaceae Marsileaceae Asteraceae Poaceae Poaceae Poaceae Poaceae Poaceae Cyperaceae Commelinaceae Cyperaceae Cyperaceae Commelinaceae

100 84 80 64

64 64 80 84 56 53 53 55 53 53 39 29 37 35 33 31 31 29 29 29 – 23 23 27 23 27 12 10

2 8 4 2 2 4 2 4

27.6 94 23.0 7.4 75 1.8 2.1 71 2.5 2.7 75 6.3

8.2 63 5 .0 2.3 79 21.2 2.3 69 4.9 53 1.6 51 2.3 51 2.1 51 1.6 55 9.1 53 1.3 34 4.5 50 2.4 34 2.5 52 0.2 29 1.3 38 0.5 29 0.6 29 0.5 29 0.3 – 1.9 23 – 29

0.1 23 0.3 23 0.3 6 0.4 23 0.3 – 0.3 4 0.1 12 0.6 12 1.9 6 0.5 12 0.3 8 3.4 6 1.1 4 0.3 4 0.4 2

4.6 2.9 4.1 1.6 1.6 1.5 7.7 0.5 2.3 1.1 2.2 0.1 1.2 0.2 0.3 0.3

1.5 0.2 0.1 0.2 0.1 0.7

>.l 0.1 0.1 >.1 0.1 0.1 >.1 >.l >.l >.1

–

–

a Drained soils located on the lower edge of hills. During rainy season, these soils remain wet. b Clay soils of valley areas. Water stagnates up to 15-20 cm during the rainy season. With short dry spells, the soils become dry. Rice transplanting is common in both clay loam and clay soils in Andaman, Nicobar Islands.

Influence of various weed control treatments on weed control efficiency, growth, and yield of upland rice. Jabalpur, India.

Weed Effective Straw Grain Crop biomass tillers/ biomass yield yield

Treatment

(t/ha) plant (t/ha) (t/ha) (t/ha) ($/ha) ($) cost b Treatment a Profit c

Thiobencarb 1.5 + 1 HW 30 DAS 0.2 2.7 13.7 9.3 Oxadiazon 0.75 + 1 HW 30 DAS 0.1 3.8

4.4 93.45 241.46

Pendimethalin 1 + 1 HW 30 DAS 12.9 8.8 95.45 203.43

0.2 4.1

3.0 11.6 Hand weeding 20 and 40 DAS

7.5 0.2

4.1 3.1 11.7

90.00 195.10

Oxadiazon 1.0 0.3 7.6 4.1 190.90

3.1 12.7 8.7 4.0 40.90 238.91 92.84

Thiobencarb 1.5 1.4 3.0 10.8 7.0 3.8 Oxadiazon 0.75 0.9

29.81 3.1 11.6 7.9 3.7 31.81

208.88

Thiobencarb 1.5 + 2,4-D EE 1.0 1.8 2.8 10.3 6.8 195.85

Hand hoeing 20 and 40 DAS 2.5 2.7 3.6 40.27 165.65

Thiobencarb 2.0 10.0 6.6 3.5

1.2 2.5 3.1 39.45 104.97 50.90

10.5 137.60

7.4 Pendimethalin 2.0 2.3 2.4 8.6 5.2 3.0 48.63 Pendimethalin 1.0 + 2,4-D EE 1.0

60.18 1.6 2.2 9.4

Weedy check 3.4 6.5 2.9 35.90

2.0 74.87

Pendimethalin 1.0 7.4

3.1 2.2 5.3 2.2

7.1 5.2 1.9 26.36 –64.94 CD at 5% 0.853 0.76 3.117 2.22 1.286

– –

a Herbicide measurements are in kg ai/ha. HW = hand weeding. EE = ethyl ester. b Cost of herbicide and labor: thiobencarb = $1 7.45/liter, pendimethalin (G) = $21.81/kg, oxadiazon = $36.36/liter, 2,4-D EE = $9.54/kg, application charges = $4.54/ha, Cost of hand weeding 1 = $127.27/ha, cost of hand weeding 2 = $63.63/ha, cost of hoeing 1 = $31.81/ha, cost of hoeing 2 = $19.09/ha, hand weeding after herbicide application = $63.36/ha, price of rice = $136.3/t, and price of straw = $8.18/t. c Profit = grain yield + straw yield minus treatment cost.

Weed control in hybrid rice

M. Yasin HG, P. O. Box 173, Ujung Pandang, Indonesia

We evaluated some herbicides to control weeds in hybrid rice Shen Zhan 97A/Saddang in the 1985-86 wet season. Herbicides were applied 3 d after transplanting.

tillering and plant height. MCPA-K salt, oxadiazon, thiobencarb, and 2,4-D were not significantly different in controlling broadleaves, grasses, and sedges (see table). Piperophos + 2,4-D was not significantly different from hand weeding, especially for controlling grasses. Highest yield was with hand

The herbicides did not influence

Effect of some herbicides on tillering, plant height, weeds, and grain yield in hybrid rice. Maros, Indonesia, 1985-86 wet season.

Tillers Plant Dry weed a (g/m 2 )

(no.) (cm) Broad- Grasses Sedges leaves

Treatment kg ai/ha

MCPA K salt 0.40 12 70 2.8 bc Oxadiazon 0.50 10 60 3.4 c Piperophos + 2,4-D 0.33 + 0.17 13 71 1.5 b Thiobencarb 1 .00 12 67 3.5 c

Hand weeding 7 and 35 DT b 12 70 0.6 a Unweeded control 10 70 8.9 d

2,4-D 0.85 12 66 3.1 c

CV (%) 20 7 16.4

2.0 b 2.4 b 1.1 a 2.3 b 2.8 b 0.4 a 5.1 c

21.5

1.2 bc 1.5 cd 0.9 b 1.0 bc 1.3 cd 0.0 a 2.9 d

23.6

Grain yield (t/ha)

3.3 c 3.4 c 4.2 b 3.2 cd 3.4 c 5.2 a 2.3 d

12.0

a Means followed by a common letter are not significantly different at the 5% level by DMRT. Data transformed to log (x + 1). b Days after transplanting.

weeding, then with piperophos + 2,4-D. Thiobencarb increased yield 35%.

Pest Control and Management OTHER PESTS

Pomacea snails in the Philippines frequently confused, were determined by

O. Mochida, IRRI Family: Pilidae (Ampullariidae) Pomacea canaliculata (Lamarck)

Pomacea snails indigenous to South Ampullaria canaliculata America were recently introduced for Ampullarium insularum Hamada human food in Taiwan (China), Japan, et Matsumoto 1985 (nec and the Philippines. Scientific names, d’Orbigny 1839)

Habe as follows:

48 IRRN 12:4 (August 1987)

Ampullarius insularus Chang 1985 (nec d’orbigny 1839)

Ampullarius insularus. Miyazaki 1985 (nec d’Orbigny 1839)

Ampullarius insularus Miyahara et al. 1986 (nec d’Orbigny 1839)

Pomacea gigas (Spix) Ampullaria gigas

height

Performance of rice varieties on floating rafts

V. K. Sasidhar, M.A. Salam, and V. R. Nair, Kerala Agricultural University, Vellayani 695522, India

Rice cultivation on floating rafts, a technique developed at the College of Agriculture, is suitable for flooded areas (see figure). The system saves the labor and electricity needed to drain an area for a single dry season rice crop. Rice

Effect of puddling method on grain yield and return. Tamil Nadu, India.

Grain yield (t/ha)

Cost of cultivation ($/ha)

Net income ($/ha)

Puddling method Kharif Winter Kharif Winter Kharif Winter

Puddling 3 times with iron plow (conventional)

Puddling twice with iron plow and once with helical blade puddler

Puddling twice with country plow and once with helical blade puddler

Puddling once with iron plow and 5.7 4.4 327 313 604 401 twice with helical blade puddler

CD (0.05) 0.6 0.4

6.0 4.7

6.4 5.0

5.4 4.2

353 339

321 329

337 323

625 424

701 492

562 354

Three sources introduced Pomacea P. gigas from Florida (USA) to leopordivillensis d’Orbigny, was also spp. in the Philippines: Makati, Metro Manila, 1983. introduced from Taiwan. P. cuprina

P. canaliculata via Taiwan from Pomacea snails directly from (Reeve) is also found in the Argentina to Lemery, Batangas, Luzon, Argentina to Asturias, Cebu, in 1984. Philippines. 1982. An African snail, Pila

Soil and Crop Management

Puddling methods for lowland rice

S. Purushothaman, P. Jayapaul, and R. Kandasamy, Agricultural College and Research Institute, Tamil Nadu Agricultural University, Madurai 625104, India

We studied the effect of puddling methods on lowland rice (Paiyur 1 variety) during Jun-Sep kharif and Oct- Jan (winter) seasons 1982-83. Puddling twice with an iron plow followed by one puddling with a helical blade puddler produced the highest grain yield and net income (see table).

Effect of spacing and seedlings per hill

S. Ramasamy, B. Chandrasekaran, and S. Sankaran, Tamil Nadu Rice Research Institute, Aduthurai 612101, India

We studied the effect of spacing and seedlings per hill in the 1985 dry season. Short-duration rice variety ADT36 was transplanted at 60 d after seeding.

The experiment used 3 spacings (12.5 × 10.0 cm with 80 hills/m 2 , 15.0 × 10.0 cm with 66 hills/m 2 , and 20.0 × 10.0 cm with 50 hills/m 2 and 2, 4, 6, and 8 seedlings per hill in a randomized block design. NPK at 75- 17-3 1 kg/ ha were applied. N was split: 50% as basal, 25% 15 d after transplanting (DT), and 25% 30 DT.

within 21 DT, but these panicles shattered before harvest.

weight, and number of filled spikelets/panicle, 12.5- × 10.0-cm spacing produced significantly higher

The primary tillers produced panicles,

In spite of reduced tillers/ hill, panicle

Effect of spacing and seedlings/hill on yield parameters of short-duration rice. a Tamil Nadu, India, 1985 dry season.

Tillers/ Tillers/ hill m 2

Panicle weight Spikelets/

panicle Grain yield Treatment

(g) (t/ha)

Spacing 12.5 × 10.0 cm 6.6 b 528 a 1.41 a 46 b 4.0 a 15.0 × 10.0 cm 7.0 a 425 b 1.44 a 51 ab 3.6 b 20.0 × 10.0 cm 7.3 a 371 c 1.48 a 53 a 3.3 c Seedlings/hill 2 7.4 a 466 a 1.81 a 62 a 4.8 a 4 6 8

a In a column within each group, means followed by the same letters are not significantly different at the 5% level.

6.9 ab 442 b 1.38 b 50 b 3.6 b 6.7 ab 422 c 1.35 b 47 b 6.6 b 416 c 1.21 c 41 c 2.9 c

3.1 c

grain yield, mainly because of higher seedlings/ hill had an adverse effect. All numbers of tillers/unit area (see table). yield parameters were reduced with

Increasing the number of more than 2 seedlings/hill.

IRRN 12:4 (August 1987) 49

can be raised year round with this system.

Bamboo platforms were attached to two large airtight oil drums. The tops of the rafts were covered with damaged gunny sacks and a thin 7.5-cm layer of rice soil was spread over the surface.

We compared the performance of 10 short-duration rice varieties on 3- × 3-m floating rafts with 3 replications. Seedlings were transplanted 18 d after seeding in Jun 1985 (wet season).

Crop growth was satisfactory (see table).

Growth characteristics, yield attributes, and yield of rice varieties grown on floating rafts. Vellayani, India, 1985 kharif.

Variety Height Tillers/ Productive Percentage Panicle Filled Grain Straw

hill panicles/hill (cm) panicle (t/ha) (t/ha) (cm) hill tillers/ of length grains/ yield yield

Cul. 170 Cul. 8 Karthika Mo-5 Pavizham

Triveni Bhadra Kochuvithu Cul. 93

Mo-4

62 92

102 90 95

100 102

82 110 105

28 27 25 28 21 11 21 18 14 23

26 23 22 22 16

9 18 16 10 20

93 85 88 78 76 82 82 89 71 87

14 36 18 30 20 30 19 32 18 25 19 22 19 39 17 32 20 21 20.5 43

4.0 6.9 4.0 6.7 2.0 5.0 2.7 6.8 2.1 6.1 1.7 6.9 4.6 6.4 2.7 6.8 2.0 5.5 4.7 8.7

Effect of land preparation on control of Paspalurn distichurn

F.F. Fajardo and K. Moody, IRRI

We tested tillage to control perennial grass weed Paspalum distichurn L. in transplanted rice in Guimba, Nueva Ecija, Philippines.

plots was highest with 1 plowing + 3 harrowings by hand tractor; Echinochloa glabrescens Munro ex Hook. f. accounted for the bulk of the weed growth (see table).

The intensive soil turning by the hand tractor reduced growth of P. distichum, but not significantly. It could have brought seeds of E. glabrescens to the

Total dry weed weight in unweeded

surface or scarified them, resulting in increased germination and growth. Or, an allelopathic substance that might be released by P. distichum reduces growth of E. glabrescens. Tall-growing annual grass E. glabrescens also might have competed with and reduced growth of shorter P. distichum.

The significant yield reduction was the result of weed competition, probably because of increased growth of E. glabrescens. No significant yield differences were found in the plots treated with butachlor or hand weeded. This indicates that P. distichum can be reduced with good land preparation and the annual grass population that may increase can be checked by butachlor.

Total weed weight and weight of Echinochloa glabrescens and Paspalurn distichum in the unweeded plots as affected by tillage levels, and grain yield as affected by different weeding regimes. a Nueva Ecija, Philippines.

Weed weight (g/m 2 ) Grain yield (t/ha)

Tillage treatment Echinochloa Paspalum Total No Hand weeding Butachlor glabrescens distichum weeding (21 and 35 DT) (0.6,3 DT)

1 plowing + 3 harrowings 180 a 30 a 274 a 2.1 a 2.7 a 2.6 ab (within 1 mo before transplanting) 1 plowing + 3 harrowings 159 a 37 a 259 a 1.9 a 2.6 a 2.2 b (within 2 mo before transplanting) 1 plowing + 3 harrowings 418 b 8 a 578 b 0.9 b 2.4 a 2.6 ab (harrowing by hand tractor)

2 plowings + 3 harrowings 53 a 60 a 141 a 2.3 a 2.0 a 2.3 b (animal) 1 plowing + 5 harrowings 127 a 62 a 214 a 2.3 a 2.6 a 3.0 a (animal)

a In a column, means followed by the same letter are not significantly different at the 5% level by DMRT. DT = days after transplanting.

Effect of modified urea materials and N levels on transplanted rice

S. S. Tomar, Sukhadia University, Agricultural Research Station, Borkhera, Kota 324001 (Rajasthan), India

Split application of urea and modified urea materials was tested in 1985 kharif.

In a field experiment laid out on a deep Vertisol (pH 7.5, 0.61% organic C, CEC 20.6 meq/ 100 g, 25.3 kg available P (Olsen)/ ha, 4.6 meq exchangeable K/ 100 g, 0.2 ppm available Zn and silty clay texture). At the last puddling, 26.4

Effect of modified urea and N level on tram- planted rice. Kota, India, 1985 kharif.

Treatment a Grain Panicles yield (t/ha)

(no./m2)

Control (no N) 2.2 181.3 58 kg N/ha PU-BS 3.9 214.8

PU-SS 3.9 213.3 SCU-basal 4.0 237.5 USG-placement 4.1 270.0 MPCU-basal 3.9 219.0

87 kg N/ha PU-BS 4.6 241.5 PU-SS 4.5 238.3 SCU-basal 5.9 269.8 USG-placement 6.1 270.3 MPCU-basal 4.8 249.8

116 kg N/ha PU-BS 6.0 287.8 PU-SS 5.8 296.3 SCU-basal 6.0 316.8 USG-placement 6.1 329.0 MPCU-basal 5.6 268.5

CD (0.05) 0.3 38.3

prilled urea, standard split, SCU-basal = sulfhr- a PU-BS = prilled urea, local best split, PU-SS =

coated urea, USG-placement = urea supergranules, and MPCU-basal = Mussooriephos- coated urea.

50 IRRN 12:4 (August 1987)

kg P/ha and 33.2 kg K/ha were applied. 58, 87, and 116 kg N/ha were evaluated produced significantly higher yields than Prilled urea was applied as basal in 2-3 against local best split (1/2 basal + 1/4 standard best split urea and MPCU at cm standing water. at maximum tillering + 1/4 at panicle 87 and 116 kg N/ha. USG and SCU

Root zone placement (10-12 cm) of initiation) and standard best split (2/3 also produced significantly more urea supergranules (USG) and basal basal + 1/3 at panicle initiation). panicles/m 2 than MPCU at 116 kg sulfur-coated-urea (SCU) and Maximum grain yield was with USG N/ha. Mussooriephos-coated urea (MPCU) at and SCU at all N levels (see table). USG

Nitrogen management for increasing N efficiency in transplanted rice

S. K. Shrivastava, Jr., R. Singh, B.R. Chandrawanshi, and H.P. Agrawal, J.N. Krishi Vishwa Vidyalaya, Zonal Agricultural Research Station, College of Agriculture, Raipur, M.P. 492012, India

We compared the efficiency of a single application of sulfur-coated urea (SCU), urea supergranules (USG), and split application of prilled urea (PU) at

varying levels of N during 1983 kharif. The experiment was in a randomized block design with three replications. Treatments were SCU, USG, and PU at 29, 58, 87, and I16 kg N/ha. Medium- duration, dwarf variety Usha was the test crop. Soil was a Vertisol (clay-loam, with 210.11 kg available N, 12.50 kg available P, 225 kg available K/ ha, 0.20 mmho EC, 0.60% organic C, and pH

Growth and yield-contributing characters were significantly superior with SCU and USG (see table). Grain

6.5-7.5).

Grain yield and ancillary characters as influenced by sources and levels of N. Raipur, India, 1983 kharif.

Nitrogen Sources and methods yield Grain Straw Effective Panicle Panicle Sound

(g) (cm) panicle (kg/ha) of N application (t/ha) (t/ha) yield tillers/m 2 weight length spikelets/

0 Check 29 Urea, best split 29 SCU, broadcast and

incorporated in soil 29 USG placed at 10-12

cm soil depth Mean

58 Urea, best split 58 SCU, broadcast and


cm soil depth Mean

87 Urea, best split 87 SCU, broadcast and


cm soil depth Mean

116 Urea, best split 116 SCU broadcast and

incorporated in soil

116 USG placed at 10–12 cm soil depth

1.9 2.30 190 2.6 2.94 206 3.2 3.51 259

3.2 3.77 257

3.0 3.40 240 3.0 3.15 243 3.8 4.35 304

3.7 4.97 303

3.5 4.16 283 3.3 3.50 277 4.2 5.30 344

4.1 5.84 340

3.9 4.88 320 3.7 4.32 335 4.5 6.24 409

4.3 6.97 405

1.3 17 1.7 18 2.1 20

1.8 19

1.9 19 1.9 19

2.2 21

2.1 20

2.1 20 1.9 19 2.3 21

2.2 21

2.2 20 2.1 20 2.5 22

2.4 22

48 62 69

66

65 67

76

70

71 68 79

76

75 72 82

80

Mean 4.2 5.84 383 2.3 21 78

CD (0.05) for forms 0.2 0.40 9 0.1 0.4 5.7 for levels 0.2 0.46 10 0.2 0.5 6.6

and straw yields were significantly different with different forms and levels of N.

Maximum grain yield was with SCU, followed by USG. SCU and USG were similar in N efficiency. USG produced a significantly higher straw yield than SCU and PU.

high grain and straw yields. N at 116 kg/ ha produced significantly

Nitrogen sources for flooded rice

H. Singh and B. Mishra, Soil Science Department, G. B. Pant University of Agriculture and Technology, Pantnagar 263145, (U. P.), India

We evaluated prilled urea (PU), neem cake coated-urea (NCU), lac-coated urea (LCU), didin-coated urea (DCU), and urea supergranule (USG) at 40, 80, and 120 kg N/ ha for transplanted rice in the 1983 and 1984 wet seasons. Experi- mental field soil was a fine, silty, mixed, hyperthermic, Typic Hapludoll with pH

Effect of N source and N level on yield. Pant- nagar, India, 1983 and 1984 wet seasons.

Grain yield (t/ha)

1983 1984 Mean Treatment

N sources PU NCU LCU DCU USG

SE CD (0.05)

N levels (kg/ha) 0

40 80

120 SE CD (0.05)

3.67 3.71 3.69 4.36 4.57 4.46 3.79 4.14 3.96 3.71 4.11 3.91 4.70 4.73 4.72 0.06 0.06 – 0.16 0.16 –

2.25 2.42 2.33 3.36 3.55 3.45 4.11 4.36 4.24 4.66 4.91 4.78 0.04 0.04 – 0.12 0.12 –

IRRN 12:4 (August 1987) 51

7.6, 1.2% organic C, 44 kg available P/ha, and 3 13 kg available K/ha. The experiment was laid out in a randomized block design.

One-half the PU was applied at transplanting and one-half equally divided into two topdressings at tillering and panicle initiation. NCU, LCU, and DCU were applied one-half at

Effect of transplanting date and N application on yield

M.S. Maskina, Bijay-Singh, and Yadvinder- Singh, Soils Department, Punjab Agricultural University, Ludhiana 141004, India

Under optimal water and minerals, applied N absorption by rice and its translation into grain yield are limited by such climatic factors as light and temperature. Transplanting date and crop duration seem to be important. We studied yield response to applied N at different transplanting dates.

The experiment was in a Fatehpur loamy sand (Typic Ustipsamment) with pH 8.5, 0.24% organic C, and 0.03% total N. Four levels of N (0,60, 120, and 180 kg/ ha) were used in a split-plot design. PR106 seedlings at 45 d were transplanted on 9 Jun, 30 Jun, and 21 Jul at 15- × 15-cm spacing. Field plots were submerged 2 d before the

Effect of transplanting date on lowland rice response to N. Ludhiana, India.

52 IRRN 12:4 (August 1987)

transplanting and one-half at tillering. USG was placed 8-10 cm deep in the center of 4 hills 1 wk after transplanting. All plots received 17.4 kg P and 33.3 kg K/ ha. Two seedlings per hill of rice variety Jaya were transplanted at 20- × 20-cm spacing. The field was flooded (5 cm ± 3 cm) by rain or irrigation from

transplanting. Crop durations were 121, 112, and 101 d.

Although response to applied N was significant, transplanting date had a pronounced effect on the nature and extent of the response (see figure). Rice transplanted 9 Jun and 30 Jun and harvested at 121 and 112 d exhibited quadratic response curves that were almost flat with 180 kg N/ha. Rice transplanted 21 Jul matured in only 101 d and responded linearly, with lower yields than the crops transplanted in Jun, at least up to 180 kg N/ ha. The influence of transplanting date and N was reflected primarily in tiller density and spikelet number.

The interaction between N level and date of transplanting was significant. Yield similar to those with 180 kg N/ha and 21 Jul transplanting could be obtained with 120 kg N/ha and 30 Jun transplanting or 60 kg N/ha and 9 Jun transplanting.

transplanting to milk stage. N levels and N sources significantly

influenced yield (see table). All amended N fertilizers except DCU in 1983 performed better than PU in both years. USG outyielded other N sources, with 28% higher yield than PU in 1983 and 27.5% higher in 1984.

Effect of slow-release nitrogen fertilizers on lowland rice

B.K. Jena, P.K. Mahapatra, and G.K. Patro, Orissa University of Agriculture and Technology, Bhubaneswar 751003, India

We studied five sources of N during the 1984 wet season (WS) in a split-plot design with three replications. N levels were in the main plots and sources in the subplots. The soil was lateritic and sandy loam, pH 5.8, EC 0.112 dS/m, 0.73% organic C, 0.07% total N, 20 kg available P, and 140 kg available K/ha. Rice varieties were Lalat (135 d) during the WS and Jajati (120 d) during the dry season (DS). Spacing was 15 × 10 cm.

All N sources were applied in a single dose at transplanting except for prilled urea, which was split-applied: 25% at transplanting, 50% at tillering, and 25%

Effect of N source on yield and BB intensity. Bhubaneswar, India, 1984-85.

Treatment

Grain yield (t/ha) BB a

WS DS WS DS

N level No N 56 kg/ha 84 kg/ha 11 2 kg/ha

CD (0.05) CV (%)

Source Prilled urea split application Urea gypsum Rock phosphate- coated urea

Urea supergranule Urea nitro-humic acid

CD (0.05) CV (%)

1.9 2.2 2 2 2.9 2.7 3 2 3.0 2.8 4 3 3.3 2.7 4 3 0.3 0.3 – – 45 – –

3.0 2.5 3 2

3.0 2.8 3 2 3.0 2.6 3 2

3.3 2.9 4 2 3.0 2.8 3 2 0.2 0.3 – – 6 6 – –

a Standard evaluation system for rice scale.

Contribution of test factors to yield gap. Punjab, Pakistan.

at panicle initiation. The WS crop received 17 kg P and 33 kg K/ha.

All the treatments received 50-22- 42 kg NPK/ha during the DS to study residual effects of N.

All N levels were superior to the control during both seasons (see table).

Constraints to rice yields in Punjab, Pakistan

M.S. Zia, M. Ashraf, and M. Munsif, Pakistan Agricultural Research Council, National Agricultural Research Centre, Soil Science Section, P. O., N.I. H., Park Road, Islamabad, Pakistan

We analyzed the contribution of various factors to the gap between potential and actual yields in farmers’ field trials. The recommended inputs were land preparation by 2 plowings in dry soil and 4 plowings and 2 plankings in standing water, transplanting with 30-d- old seedlings, fertilizer at 110-26 kg NP/ ha, plant density of 250,000 hills/ha, 2 kg Zn/ha, insect control using carbofuran (3G) at 16 and

N at 56 kg/ ha equaled 84 kg N/ ha; with N levels as well as sources during 112 kg N/ha was best during the WS. DS . USG gave the highest yields, 3.3 t/ ha in Bacterial blight (BB) intensity the WS and 2.9 t/ha in the DS. DS increased with increasing N, and was yield was low because of a hailstorm at higher in the WS than in the DS with harvest. Residual effect was pronounced respect to levels as well as sources.

20 kg/ ha, and hand weeding at 20 and 30 d after transplanting.

Farmer’s inputs were land preparation with 2 plowings and 1 planking in standing water, transplanting with 50-d- old seedlings, plant population of 125,000 hills/ ha, fertilizer at 50-13 kg NP/ ha, no Zn, no insect and weed control.

The contribution of plant density to the yield gap was 43-45% for IR6 and 55% for Basmati 370 (see figure). The contribution of fertilizer was 33-39.5% for IR6 and 27% for Basmati 370. Other test factors’ contributions follow: land preparation for IR6, 22.6%; insect control (for Basmati 370), 18%; weed control, 10-17%; and seedling age (IR6), 9.7%.

Effect of soil N on rice yield in Punjab

N.S. Dhillon, R.K. Gupta, and G. Dev. Soils Department, Punjab Agricultural University, Ludhiana, Punjab, India

We conducted 15 experiments in farmers’ fields using 0, 50. 100, and 150 kg N/ ha as urea, replicated twice. Surface soil samples of Typic Ustochrepts (0-15 cm) collected before transplanting were loamy sand to loam in texture, alkaline (pH 7.4 to 8.8), nonsaline (EC 0.06 to 0.48 dS/ m), and low to medium in organic C (0.14 to 0.68%). The mean and range of soil test

Table 1. Status of nitrogen in rice growing soils. Punjab, India.

N content (µg/g soil)

Range Mean Soil N fraction

Total N 392-952 643 Hydrolyzable N 233-699 468 Hydrolyzable amino acid N 60-168 106 Hydrolyzable hexosamine N 14-56 28 Hydrolyzable NH 4 -N 42-140 94 Nonhydrolyzable N 112-309 220

Table 2. Relationships of soil N fractions with yield and N uptake by rice. a Punjab, India.

Soil N fraction Relative Relative

uptake yield

Total N 0.54* 0.68** Hydrolyzable N 0.52* 0.66** Hydrolyzable amino acid N 0.43 0.60* Hydrolyzable hexosamine N 0.61* 0.60* Hydrolyzable NH 4 -N 0.64** 0.72** Nonhydrolyzable N 0.55* 0.67**

a Significance at the 5% (*) and 1% (**) levels.

IRRN 12:4 (August 1987) 53

N

Relative yield/ relative uptake

= Yield or uptake without N Maximum yield or uptake

with N

× 100.

values for various forms of soil N (0-15 cm depth) before transplanting are given in Table 1. The values show that a major part of organic N was present in acid hydrolyzable N form (59–74%) and nonhydrolyzable N constituted 26–41% of the total N present. Hexosamines represented 1.9–7.1% and amino acids 10.7–16.7% of total N. Hydrolyzable

NH4-N constituted 10.6–13.9% of total N present.

nonhydrolyzable N correlated significantly with yield and N uptake by rice variety PR106 (Table 2). Among the forms of hydrolyzable N, NH4-N showed the highest significant relationship with relative yield ( r =

Total N, hydrolyzable N, and

0.64*) and relative N uptake ( r = 0.72**), followed by hexosamine N ( r = 0.61*, 0.60*) and amino acid N ( r = 0.60*, 0.43). Results show that forms of both hydrolyzable N and nonhydrolyzable N supply N to rice plants. Among the various fractions of soil N, hydrolyzable NH 4 -N seemed to be more important.

Rapid and sensitive method to estimate salinity tolerance of Azolla pinnata

K. Rajarathinam and M.A. Padhya. Botany Department, The M. S. University of Baroda, Baroda 390002, India

We have developed a rapid, nondestructive but sensitive method for assessing the salinity tolerance of different strains of Azolla pinnata. Pigments (chlorophyll and phycocyanin) are measured by their fluorescence in the heterocysts and the vegetative cells of Anabaena azolla isolated from sodium chloride-treated azolla, using Leitz fluorescence microscope. Chlorophyll and phycocyanin were reduced in both types of cells (see figure). The acetylene reduction activity of the Azolla- Anabaena complex also showed reduction, which correlated with that in the pigments of the endophyte.

Measuring the chlorophyll and phycocyanin content of Anabaena isolated from salt-treated azolla can be used to estimate the salinity tolerance of Effect of salinity on chlorophyll and phycocyanin of Anabaena azollae, and a particular strain of azolla. on acetylene reduction activity, Baroda, India. Sodium chloride levels: 1 =

10 mM, 2 = 20 mM, 3 = 30 mM, and 4 = 40 mM.

Effect of azolla and inorganic N combined

V. Chandrasekharan, G. S. Thangamuthu, and P. Balasubramaniyan, Agronomy Department, Tamil Nadu Agricultural University, Coimbatore 641003, India

We studied the effect of azolla and inorganic N on growth and yield of lowland rice variety Co 43 during 1983- 84 wet and dry seasons. Soil was clay loam, with 261 kg available N/ ha,

15.9 kg P/ha, 460.7 kg K/ha, and pH 7.9. The design was a randomized block with four replications. Seedlings were transplanted at 30 d at 20- × l0-cm spacing.

supergranules (USG) alone or in combination with azolla at 75:25 were compared. N rate was 100 kg/ ha for all the treatments except control. PU was split-applied: 50% basal, 25% at tillering, and 25% at panicle initiation stages;

Prilled urea (PU) or urea

54 IRRN 12:4 (August 1987)

USG was applied all basal, point placed, 1 wk after transplanting. Superphosphate at 22 kg P/ha and muriate of potash at 42 kg K/ha were basally applied. Azolla was incorporated 1 wk before transplanting.

USG at 100 kg N/ha or azolla at 25 kg N/ha with USG at 75 kg N/ ha were equal in increasing dry matter production, number of panicles, grain numbers, and grain and straw yields in both seasons (see table).

Effect of azolla and inorganic N on rice. a Coimbatore, India, 1983-84

1983 wet season 1983-84 dry season

Treatment b Dry matter Panicles Filled Grain Straw Dry matter Panicles Filled Grain Straw production (no./m 2 ) grains yield yield production (no./m 2 ) grains yield yield

(t/ha) (no.) (t/ha) (t/ha) (t/ha) (no.) (t/ha) (t/ha)

Control (no N) 6.4 d 245 d 69 d 2.5 d 4.0 d 6.1 d 212 d 63 d 2.3 d 4.0 d

25 kg N-azolla + 11.0 c 413 c 88 c 5.0 c 6.4 c 10.7 c 397 c 80 c 4.5 c 6.2 c 100 kg N-PU 13.4 b 502 b 91 b 5.9 b 7.7 b 13.1 b 483 b 83 bc 5.5 b 7.6 b

75 kg N-PU 100 kg N-USG 15.2 a 618 a 100 a 7.0 a 9.0 a 14.8 a 598 a 87 ab 6.5 a 8.4 a 25 kg N-azolla + 15.1 a 565 a 100 a 7.0 a 8.9 a 14.6 a 560 a 89 a 6.4 a 8.4 a

75 kg N-USG

a Means followed by the same letter are not significantly different at the 5% level by DMRT. b N rate = 100 kg/ha.

Effect of cultivation method on the rice crop and the mechanical impediment of Vertisols

B.L. Ganjir and R.P. Rajput, Soil Science and Agricultural Chemistry Department, J.N. Agricultural University, Jabalpur 482004, M.P., India

Puddling for transplanted rice facilitates transplanting, maintenance of submergence, and weed control. But in Vertisols, with low infiltration rates, puddling disturbs the soil physical condition and creates problems for field preparation of dry season wheat.

We studied the influence of different cultivation methods on the rice crop and soil mechanical impediment. Treatments — direct drilling (DD), direct transplanting (DT), bullock puddling (BP), and tractor puddling (TP) — were in a randomized block design with four

Table 1. Effect of puddling on penetration force. Jabalpur, India, 1985.

Penetration force

Treatment Depth (kg/cm 2 )

(m) Tillering Milk stage stage

Direct 5 1.49 4.61 drilling 10 4.93 6.26

15 6.49 7.36 Direct 5 2.15 4.85 transplanting 10 5.30 6.24

15 6.39 7.49 Bullock 5 1.37 2.74 puddling 10 3.31 6.01

15 4.37 7.35 Tractor 5 1.02 2.80 puddling 10 4.47 6.18

15 6.02 7.43

Table 2. Effect of method of cultivation on growth and yield of paddy. Jabalpur, India, 1985.

Treatment Yield (t/ha) Plant

height Tillers/ Panicle length

Plant Grain Straw (cm) (cm)

Direct drilling 4.2 10.6 76.8 6.3 20.8 Direct transplanting 3.3 8.4 75.6 6.4 21.2 Bullock puddling 3.7 9.2 77.8 6.4 21.2 Tractor puddling 3.4 9.4 72.0 6.3 21.3

CD at 0.05 0.7 cv (%) 28 19

1.5 ns ns no – – –

replications. Rice variety Ratna was milk stage was attributed to reduced sown 7 Nov 1985. Fertilizer was applied moisture content. at 120-60-40 kg NPK/ha. Tillers/ plant, plant height, and

length, and grain and straw yields were (Table 2). DD gave the significantly recorded. Penetration force at tillering highest grain and straw yield. The and milk stages was measured by differences among DT, BP, and TP penetrometer. were not significant. A similar trend was

impediment (MI), and TP the lowest, Reduced yield due to puddling is irrespective of growth stage (Table 1). attributed to deterioration of physical The increased magnitude of MI at the conditions of the soil.

Plant height, tiller numbers, panicle panicle length did not differ significantly

DD gave the highest mechanical found with straw yield.

Efficiency of nitrogen fertilizers and a nitrification inhibitor

Yadvinder-Singh, Bijay-Singh, and M.S. Maskina, Soils Department, Punjab Agricultural University, Ludhiana 141004, India

We studied the relative efficiency of urea, ammonium sulfate, and potassium nitrate during 1986 kharif (Jun-Sep). Nitrification inhibitor 4-amino-1,2,4- triazole (ATC) was applied at 5% by weight of urea. To restrict NH 3 volatilization, urea-nitrification inhibitor and urea alone treatments were applied

in bands (3 cm below surface) between the rows. N at 110 kg/ ha was applied in 3 equal splits: 7, 21, and 42 d after transplanting with no standing water.

Soil of the experimental field was Fatehpur loamy sand (Typic Ustipsamment) with pH 8.5, 0.23% organic C, 7 kg Olsen’s P/ha and 71 kg ammonium acetate extractable K/ha. Soil percolation rate was about 6 mm/h. Treatments were laid out in a randomized complete block design with four replications. Six-week-old seedlings of rice variety PR106 were transplanted the third week of June.

IRRN 12:4 (August 1987) 55

Urea and ammonium sulfate topdressed in three equal splits did not differ significantly (see table). Band application slightly increased grain yield and N uptake over topdressing. Additional benefit with band placement was probably due to the low rate of nitrification.

Application of ATC, a water-soluble chemical recommended for nitrification inhibition, did not influence yield and N uptake of rice, even at higher rates. This may be due to ineffective coating and leaching of the chemical from the bands. Potassium nitrate was the most

Effect of plant density and fertilization on rice yield and fertilizer efficiency

M.S. Zia, National Agricultural Research Centre, Islamabad, Pakistan

We studied fertilizer efficiency at different N P levels and different plant densities, with IR6 as the test variety.

significantly affected yield (see table). The highest yield was at 20- × 20-cm spacing (250,000 hills/ha) and the lowest at 40- × 25-cm spacing (100,000 hills/ ha). The highest yield was with

Plant density and NP level

Effect of method of applying Azospirillum brasilense on rice yield

G. Gopalaswamy and P. Vidhyasekaran, Tamil Nadu Rice Research Institute (TNRRI), Aduthurai 612101, India

Azospirillum brasilense Tarrand et al. fixes atmospheric N in soil. We studied methods of applying bacterium to increase yield. Peat-based A. brasilense inoculum (6 kg/ ha) containing l0 8

bacteria/g of peat soil was used for all treatments.

For seed treatment, 60 kg of seeds were soaked for 24 h in 60 liters water containing 6 kg peat-based inoculum. The seeds were allowed to sprout, then sown in the nursery. For seedling treatment, seedling roots were dipped in

56 IRRN 12:4 (August 1987)

Influence of N source and a nitrification inhibitor (ATC) on yield and N uptake of wetland rice. Ludhiana (Punjab), India, 1986 kharif.

Treatment Yield (t/ha) N uptake

(kg/ha)

Apparent N recovery

Grain Straw (%)

Ammonium sulfate (topdressed) 7.6 8.8 124.5 11.8 Urea (topdressed) 7.2 8.8 113.2 61.5 Potassium nitrate (topdressed) 4.8 6.3 80.6 37.9 Urea (banded) 7.8 9.2 122.6 76.1 Urea + ATC (banded) 7.7 9.3 119.8 13.5

LSD (P = 0.05) 0.6 0.8 5.4 –

Control (no N) 2.5 3.5 38.9 –

inefficient N source. Recovery of N that from ammonium sulfate and from potassium nitrate was about half urea.

Effect of plant density and fertilizer level on rice yield and fertilizer efficiency. Muridke, Pakistan.

N efficiency (kg rice/ Mean for

plant (kg/ha) level density density a (kg rice/

0-60 60-60 90-60 120-60 (t/ha) 60-60 90-60 120-60 kg N)

Yield (t/ha) at indicated Mean for kg N) at indicated NP plant Spacing Plant density NP (kg/ha) level

(cm) (hills/ha)

40 × 25 100,000 3.2 5.7 5.9 6.3 5.2 c 42 30 26 33 25 × 25 160,000 3.2 6.0 6.1 6.7 5.5 b 44 32 28 35 20 × 25 200,000 3.5 6.2 6.4 6.9 5.7 ab 45 33 29 36 20 × 20 250,000 3.7 6.4 6.7 7.2 6.0 a 46 34 29 36

Mean for fertilizer a 3.4 c 6.1 b 6.3 b 6.8 a 44 32 28

a Means followed by a common letter are not significantly different from each other.

120-26 kg NP/ha. gradually with decreased fertilizer. Fertilizer efficiency was lowest at the Fertilizer efficiency was highest at higher

highest level of fertilization, increasing plant densities.

Method of application of Azospirillum on rice yield. TNRRI, Aduthurai, India.

Azospirillum Plant Productive Straw Grain application height tillers yield yield

method (cm) (no./hill) (t/ha) (t/ha)

Seed 87 8 8.0 4.9 Seedling 86 7 1.2 4.8

Seed + seedling 88 7 8.8 5.6 Seed + soil 89 7 1.4 4.8 Seedling + soil 86 7 8.3 5.5 Seed + seedling + soil 89 8 9.3 6.5 Uninoculated (control) 84 6 6.3 4.4

CD 3 1 1.4 1 .0

Soil 86 7 1.5 4.6

400 liters water containing 6 kg was split into two doses and given as inoculum for 20 min and transplanted. seed + seedling treatment or seed 4- soil Soil application of the bacterium was treatment or seedling + soil treatment. done by mixing 6 kg inoculum with In the last treatment, inoculum was split 15 kg sand and broadcasting in the main into three doses and given as seed + field before transplanting. Inoculum also seedling + soil treatment.

Cultivar ADT36 was grown during 70 kg available P/ ha, and 92 kg Jun-Oct 1986. Plot size was 25 m 2 in a exchangeable K/ ha. Maximum and split-plot design replicated 3 times. Soil minimum temperatures during growth was clayey loam with pH 7 and CEC were 31-39 °C and 22-28 °C. Total 36 meq/ 100 g. It had 0.13% total N, rainfall was 324 mm.

Effect of urea on decomposition of azolla

medium was kept in plastic tubs and 30 g Azolla pinnata, A. microphylla, and A. filiculoides inoculated and

S. Subramani and S. Kannaiyan, Agricultural Microbiology Department, Tamil Nadu Agricultural University, Coimbatore 641003, Tamil Nadu, India

We applied urea as a foliar spray over the azolla mat in a pot culture experiment to study azolla decomposition. One liter soil extract

maintained. Urea was added directly to the soil extract solution at 50, 100, 250, 500, 1,000, and 2,000 ppm or sprayed at 3 d after inoculation.

At 5 d after urea treatment, the decayed biomass was filtered in muslin and the moisture content removed by placing the mass on tissue paper.

With increased urea concentration,

Influence of foliar spray of urea on the decomposition of azolla. Tamil Nadu, India.

Urea concentration

(ppm)

50 100 250 500

1000 2000

CD

Weight on 5th day after spraying

A. pinnata A. filiculoides A. microphylla

g

13.7

11.2 14.8 13.3 10.8

1 2.8

% decrease from initial inoculum

54 57 63 51 56 64

g

20.8 20.0 18.0 15.9 13.9 12.0

% decrease from initial inoculum

31 33 40 47 54 60

g % decrease from initial inoculum

18.1 40 15.4 49 15.0 50 12.5 58 10.5 65 10.0 67

0.7 0.9 1.2

Split application of A. brasilense inoculum through seed, seedling, and soil gave the highest grain and straw yields, plant height, and number of productive tillers (see table).

azolla decomposition increased (see table). Urea at 2,000 ppm caused considerable weight reduction in all the 3 species of azolla. Weight reduction was highest in A. microphylla. Urea incorporated into the soil extract significantly activated decomposition (see figure).

Induction of callus from leaf explants of Azolla pinnata

B.K. Sarma and P. C. Deka, Plant Breeding and Genetics Department, Assam Agricultural University, Jorhat 785013, India

Callus from root and leaf explants of Azolla pinnata var. imbricata, Jorhat strain, was induced on two standard media: MS (Murashige and Skoog, 1962) and SH (Schenk and Hildebrandt, 1972) as such and with certain modifications in type and concentration of the hormones and cytokinins. Callus induction from leaf explants was achieved in the modified SH medium supplemented with IAA (1.0 mg/ liter),

Effect of adding urea to soil extract medium on the decomposition of Azolla. Tamil Nadu, India.

Callus induced from Azolla pinnata, after 8 wk in culture, Jorhat, India.

IRRN 12:4 (August 1987) 57

In the tank-fed areas of southern Karnataka India, cold temperature- sensitive rice varieties planted after the first week of Sep fail to produce any grain. The main cause is high susceptibility to low temperature at flowering. Local cold-tolerant varieties S705, S317, and Mangala fail because of heavy disease pressure. We tested postponing flowering time by cutting tillers to 10 cm at varying times after transplanting. Six varieties with varying maturities were sown 11 Sep 1985 and transplanted 10 Oct 1985.

Cutting up to 74 d after seeding (DAS) did not delay flowering because the primordia was unaffected (Table 1). Cutting 84 and 96 DAS markedly

delayed flowering because the stem tip was pruned. Flowering delay due to cutting date varied by genotype. 11315579-135-3 could be delayed a

maximum of 19 d, ES18 could be delayed 37 d.

Plant height and tiller production did not vary because of pruning (Table 2).

NAA (0.5 mg/ liter), 2,4-D (1.0 mg/ liter), and benzyl aminopurine (0.5 mg/liter) without kinetin.

Temperature was maintained at 25 + 10 °C. Callus first appeared 22 d after inoculation.

Callus induction and development were more effective at 1,000 1x. Well- developed callus was 20% and poor callus, 66.6% when cultures were grown with light; they were 0% and 53.33% when cultures were grown in darkness,

indicating that light has some effect on callus induction. Further growth and development was measured weekly. After 8 wk in culture, the callus grew sufficiently for subculturing.

Subculturing was done in the same medium. Initially, growth was slower, with a callus doubling time of about 8 wk. But with frequent subculturing, callus doubling time was reduced to 5 wk.

Under the microscope, no Anabaena cells were found in mature callus cells (see figure). This indicates that Anabaena -free Azolla pinnata cultures can be produced through tissue culture of leaf explants. It could be possible to isolate Anabaena -free Azolla protoplast from these calli which could be utilized for future somatic cell fusion experiments with improved N2-fixing Anabaena cells.

Cultural practices to reduce winter damage to rice

M. Mahadevappa and Nagaraju, Seed Technology Department, Agricultural College, University of Agricultural Sciences, Bangalore, India

Table 1. Effect of pruning on days to 50% flowering of winter rices. Bangalore, India, 1985.

Days to 50% flowering

No cutting 54 DAS 64 DAS 74 DAS 84 DAS 96 DAS Entry

ES18 94 100 100 110 127 131 Mangala 104 110 111 113 126 131 IR19743-25-2-2 100 103 107 110 114 126 IR18476-55-2 100 104 107 110 114 127 IR15579-135-3 114 126 126 127 131 133 IR9202-25-1-3 110 117 121 124 127 131

Table 2. Effect of pruning of winter rices on tillering. Bangalore, India, 1985.

Tillers (no.)

No cutting 54 DAS 64 DAS 74 DAS 84 DAS 96 DAS Entry

ES18 14 16 15 19 18 15 Mangala 16 20 39 25 14 20 IR19743-25-2-2 19 18 14 17 16 15 IR18476-55-2 14 10 8 13 11 8 IR15579-135-3 12 10 9 14 13 12 IR9202-25-1-3 15 14 11 15 12 11

Effect of slow-release nitrogen fertilizers on rice yield

A. K. Chakraborty and B. Bhattacharya, Agriculture Department, Calcutta University, India

We studied the effect of slow-release N fertilizers on grain yield, total N uptake, and fertilizer efficiency using Ratna variety during the 1983 and 1984 wet seasons.

with pH 6.7, 0.35% organic C, and Soil was Gangetic alluvial clay-loam

Effect of slow-release urea materials on yield and fertilizer efficiency. Calcutta, India.

Grain Straw Total Fertilizer Treatment yield yield N uptake efficiency

(t/ha) (t/ha) (kg/ha) (%)

Control 2.0 2.9 34.28 Urea 2.9 3.9 58.31 24.03 Urea supergranule 3.0 3.9 60.69 26.41 Neem cake urea mixture 3.3 4.3 70.41 36.13 Lac-coated urea 3.3 4.3 77.48 43.20 Sulfur-coated urea 3.9 4.9 94.89 60.61 Bitumen-coated urea formaldehyde 3.9 4.8 93.64 59.36 Sawdust urea formaldehyde 3.7 4.6 85.76 51.48 Urea formaldehyde 3.6 4.5 84.60 49.37

Mean 3.3 4.2 70.81 43.45 SE (±) 0.66 0.69 6.82 5.13 CD (0.05) 0.37 0.37

–

– –

58 IRRN 12:4 (August 1987)

Damaged seedling roots and grain yield

H. Om, R. K. Joon, and O. P. Singh, Haryana Agricultural University. Rice Research Station, Kaul 132021, India

We studied the effect of seedling root damage on grain yield during kharif 1985 and 1986. The treatments follow: roots were handled carefully to avoid injury, roots trimmed from the base, seedlings uprooted from semidry soil with the help of a spade.

Thirty-day-old Jaya seedlings were transplanted the first week of July and fertilized with 120-26-50-6 kg N-P-K- Zn/ha. All of the P, K, and Zn were applied basally at transplanting. N was applied in 3 equal splits: basal, 21 d after transplanting (DT) and 42 DT. Experimental field was clay loam with pH 8.1, low N, and medium P and K.

Root injury did not affect grain yield (see table). In transplanting rice, uprooting seedlings with the help of a spade may minimize labor costs.

(samba season), transplanting of widely cultivated 165-d duration CR 1009 is sometimes delayed because of delayed receipt of water in the canal. We tested the performance of late-planted CR1009 during 1985-86 samba. Seedlings were transplanted 30, 40, 50, and 60 d after

seeding. Plant height, panicles/ hill, panicle

weight, grain weight/panicle, 100-grain weight, and grain yield were not affected by planting up to 50 d after sowing (see table). Later planting reduced yield parameters and yield.

0.078% total N. Available P, K, and Zn were 11.8 kg/ ha, 368.5 kg/ ha, and 1.68 kg/ha (DTPA extractable Zn). Soil CEC was 21.80 meq/100 g.

design with nine treatments and three replications.

All plots except control and urea

The trial was in a randomized block

Effect of root injury on grain yield, Kaul, India.

Panicles Grains Grain Treatment (no./ (no./ yield

hill) panicle) (t/ha)

All roots intact 10 120 5.6 Roots 100% cut 9.5 128 5.5 Seedlings uprooted 10 125 5.7

with spade

Performance of long-duration CR1009 with aged seedlings

P. Balasubramaniyan, Tamil Nadu Rice Research Institute, Aduthurai 612101, India

In the Cauvery delta during Aug-Feb

supergranule (USG) treatments received highest grain yield, N uptake, and one basal application of 100 kg N/ha fertilizer efficiency (see table). In our during puddling. USG was applied laboratory, bitumen is used to coat immediately before transplanting by ureaform. Results are comparable to pressing the granules below the surface those with SCU. Ureaform formulations soil with the foot. also showed a significant increase in

Sulfur-coated urea (SCU) gave the fertilizer efficiency.

Performance of late-planted CR1009 in 1985-86 samba, Aduthurai, India. a

Seedling Plant Panicle Grain 100-grain Grain age height hill weight weight/panicle weight yield (d) (cm) (g) (g) (g) (t/ha)

30 92 a 8.5 a 4.1 1 a 3.82 a 2.38 a 5.40 a 40 89 a 8.9 a 4.27 a 3.92 a 2.30 a 5.49 a 50 88 a 9.3 a 4.09 a 3.72 a 2.25 a 5.65 a 60 87 a 7.5 b 3.54 b 3.24 b 2.18 a 4.43 b

a In a column, numbers followed by a common letter are statistically identical at the 95% level of confidence.

Preservation of Azolla pinnata with cool white fluorescent light for a germplasm 16/8 light/dark cycle.

Growth of azolla was extremely slow K. Rajarathinam and M.A. Padhya, Botany compared to growth in a liquid medium Department, The M.S. University of Baroda (see table). The fronds remained green Baroda 390002, India for more than 3 mo and, when

transferred to a N-free liquid medium, Senescence and death of azolla during continued to grow and develop faster. the summer is common in tropical areas. Viability of the fronds transferred to We have developed a technique to liquid medium was 100%. The azolla preserve germplasm of Azolla pinnata. cultures also were easy to transport.

Surface-sterilized fronds were inoculated on sterilized N-free medium solidified with 0.9% agar. Cultures were incubated at 25 ± 1°C and illuminated

Growth of Azolla pinnata in solid and liquid medium. Baroda, India.

Period

(wk) Solid medium Liquid medium

Fresh weight (mg)

0 1

300 ± 20.0 300 ± 20.0

2 398 ± 20.6 698 ± 29.8

3 518 ± 22.1 1258 ± 34.0 780 ± 39.1 2638 ± 73.2

Ammonia volatilization loss in rice soils of Cauvery Delta

A. Saravanan, V. Velu, and K. M. Ramanathan, Tamil Nadu Rice Research Institute (TNRRI), Aduthurai, India

We quantified NH 3 loss using different sources of N with basal and split application of 90 kg N/ha in Jun-Sep 1984. Experimental field soil was a clay

IRRN 12:4 (August 1987) 59

Panicles/

loam textured Entic Chromustert with Volatilization loss of N. TNRRI, Aduthurai, India, 1984. KMnO 4 -N 110 ppm, 0.75% organic C, and pH 7.4. Test crop was ADT36, Loss of N (kg/ha)

grown in 20-m 2 plots replicated 3 times Treatment Phase I Phase II Phase III in a randomized complete block design. 0-15 d 16-30 d 31-45 d

A 12.5- × 35-cm cylindrical frame 2.82 2.24 0.80 5.85 covered with a polythene bag was placed Urea all basal 3.13 1.28 0.50 4.95

Cumulative loss of N

kg/ha

Urea best split (½ + ¼ + ¼)

between rows immediately after fertilizer application. A petri dish containing 100 ml of 0.1 N H 2 SO 4 was suspended inside the frame. The dish was emptied at 3-d intervals and the contents distilled for NH 3 . Ammonia volatilization loss was calculated 15 d after basal application and after each topdressing (see table). Values are after deducting loss in control plots. Correlations were worked out for pH, temperature, and NH 4 -N content of floodwater with volatilization loss.

The cumulative N loss ranged from 3.44 to 5.85 kg/ ha. The highest was with urea split application, followed by split- applied lac-coated urea. Green manure

Lac-coated urea (LCU) basal 2.89 Neem cake coated urea (NCU) basal 2.78 Green manure + urea (1 : 1) basal 2.20 LCU split (½ + ¼ + ¼) 2.34 NCU split (½ + ¼ + ¼) 1.71 Green manure + urea split (½ + 1/8 + l/8) 1.18

Mean CD

2.37

% loss to the total loss 52

and urea combination had relatively lower loss than other N sources. Basal application showed higher losses than topdressings. Of the total volatilization loss, 52% occurred within 15 d, 36% between 15 and 30 d, and 12% between 3 1 and 45 d. NH 3 loss correlated with

1.35 1.19 1.11 2.15 1.88 1.79 1.62

36

0.48 0.47 0.47 0.57 0.74 0.48 0.57

12

4.72 4.39 3.78 5.06 4.33 3.44

0.47

100

morning floodwater pH ( r = 0.45**), evening floodwater pH ( r = 0.55**), morning floodwater temperature ( r = 0.49**), evening floodwater temperature ( r = 0.61**), and NH 4 -N content of floodwater ( r = 0.43**).

Response of upland rices to organic matter, and pH 5.4. N as nitrogen ammonium sulfate was applied at 0, 30,

and 60 kg N/ ha, half at planting and J. K. Kehinde and S. O. Fagade, National half 60 d after. P and K were applied Cereals Research Institute, Rice Research Programme, PMB 5042, Ibadan, Nigeria

basally, each at 30 kg/ha.

randomized complete block design with Three upland rice varieties (Faro 11, three replications. Plot size was 12 m 2 .

loam soil with 0.09% total N, 1.63%

Treatments were laid out in a

E425 and R66) were planted on sandy Plant spacing was 30 × 30 cm.

Table 1. Effect of N level on yield, yield components, and growth of rice. a Ibadan, Nigeria, 1984.

N level Yield Lodging b Whiteheads Wt of 10 p1ant Tillers b

(kg/ha) (kg/plot) (%) (no./plot) panicles (g) (no./hill)

0 1.64 b 0 31 b 46 b 102 b 14 b 30 1.94 a 31 41 b 50 b 111 a 15 b 60 1.98 a 78 91 a 62 a 113 a 16 a

ht b

(cm)

Application of 60 kg N/ha did not significantly increase grain yield over 30 kg N/ ha (Table 1). Stem borer damage and lodging percentage were higher with 60 kg N/ha.

parameters examined (Table 2). Varieties tested were similar in all

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a Mean of 3 replications. b Recorded at maturity. In a column, means followed by a common letter are not significantly different at the 5% level.

Table 2. Varietal differences in yield, yield components, and growth of rice. Ibadan, Nigeria, 1984.

Variety Yield Lodging Days to 50% Whiteheads Wt of 10 Plant ht Tillers (kg/plot) (%) flowering (no./plot) panicles (g) (cm) (no./hill)

Faro 11 1.87 39 87 55 52 107 15 E425 1.93 36 88 53 53 108 15 R66 1.78 33 88 54 52 110 15

LSD (0.05) ns – – ns ns ns ns

Relationship between organic N fraction and N uptake of rice in submerged soil

B.S. Mahapatra, K. C. Sharma, and G. L. Sharma, Agronomy Department, G. B. Pant University of Agriculture and Technology, Pantnagar, Nainital, U. P. 263145, India

A field experiment during the 1983-84 wet season showed that hydrolyzable

60 IRRN 12:4 (August 1987)

production in relation to farm size in six randomly selected villages of Karnal district, Haryana State, north India. The farm households were categorized into five Strata on the basis of operational holding size (Cumulative Frequency Square Root method). Input-output data on the rice crop were gathered from I19 farmers (10% of the total population) representing the strata: 31

CD (0.05) 0.09 0.03 0.06 0.04

P, and adequate K in the 0–15 cm layer. Spacing was 15 × 15 cm with 3

seedlings/ hill. N as urea was applied one-third at transplanting and the remainder as 2 equal splits at 25 and 50 d after transplanting; zinc sulfate was applied at 5.5 kg Zn/ ha. The rice was harvested 17 Nov 1981 and 16 Nov 1982.

organic N (6 N HC1 extractable) is

Yield attributes and grain and straw yields significantly increased with N level (Table 1). Grain and straw N also increased significantly up to 120 kg N/ha (Table 2). Soil pH was not

ultimately responsible for N in submerged soil. Hydrolyzable organic N up to 45 d after transplanting (DT) and N uptake of the rice crop at different growth stages (except N uptake at 15 DT) showed significant positive correlation (see table). The trend was reversed tor nonhydrolyzable organic N except at 30 DT.

Correlations between N uptake and organic N fractions (hydrolyzable and nonhydrolyzable N). a

Pantnagar, India, 1983-84 wet season.

Hydrolyzable N

15 DT 30 DT 45 DT 60 DT 15 DT 30 DT 45 DT 60 DT

Nonhydrolyzable N Plant N uptake

15 DT –0.331 – – – –0.116 – – – 30 DT 45 DT 60 DT 0.870** 0.805** 0.659* 0.436 –0.051 0.339 –0.387 –0.640* (50% flowering) At harvest 0.862** 0.829** 0.667** 0.468 –0.118 0.338 –0.424 –0.641*

0.702** 0.500 – – –0.115 0.331 – 0.853** 0.743** 0.594* – –0.175 0.321 –0.405

– –

a Significance at the 5% (*) and 1% (**) levels. DT = days after transplanting.

Effect of nitrogen on rice in an alkali soil

K.N. Singh and D.K. Sharma, Central Soil Salinity Research Institute, Karnal 132001, India

We studied the effect of N on rice variety Damodar (CSR1) in a highly barren alkali soil without amendment during 1981-1982 wet seasons. Soil was

Table 2. Influence of N level on N content of grain and straw of Darnodar grown in an alkali soil. Karnal, India, 1981–82.

Nitrogen content (kg/ha)

N level 1981 1982 (kg/ha)

Grain Straw Grain Straw

0 1.12 0.39 1.17 0.32

120 1.37 0.49 1.37 0.44 60 1.30 0.46 1.25 0.39

180 1.45 0.49 1.40 0.46 sandy-loam with pH 10.4, 91% exchangeable Na, 0.32 meq exchangeable Ca + Mg/ 100 g, 40 kg affected by N level, but decreased with available N/ha, 18 kg Olsen’s extractable cultivation.

Table 1. Effect of nitrogen in an alkali soil on yield attributes and yield of Damodar (CSR1). Karnal, India, 1981–82.

1981 1982

N (kg/ha) Height Productive Panicle Yield (t/ha) Height Productive Panicle Yield (t/ha) Soil pH

after rice (cm) tillers/hill length (cm) tillers/hill length 1982

(cm) Grain Straw (cm) Grain Straw

0 81.1 7.1 15.4 1.1 2.1 88.8 60 94.8 10.6 17.1

6.3 14.8 1.2 1.9 9.9 2.2 3.8 105.1

120 104.0 12.2 10.8 16.5

17.9 2.7 2.5

4.6 4.3

112.6 9.8

180 108.7 13.7 18.3 3.2 5.2 12.0 16.9 3.2 5.4

116.1 9.8

13.3 17.7 3.6 6.0 9.8 CD (0.05) 4.4 1.1 0.6 0.5 0.8 3.3 0.8 0.5 0.2 0.6 –

Consequences

Energy management production

in rice

A.S. Saini, Regional Research Station, Dhaulakuan 173001, District Sirmur (H.P.); and R.K. Patel and R.V. Singh, NDRI, Karnal 132001 (Haryana), India

We estimated total energy input and energy-use balance and efficiency in rice

marginal (up to 1.0 ha), 26 small (1. 1–2.0 ha), 29 lower medium (2.1–4.0 ha), 20 upper medium (4.1–6.0 ha), and 13 large (more than 6.0 ha).

In general, farmyard manure (FYM) and chemical fertilizers (stock resources), followed by labor and machinery (flow resources), were the most important energy inputs to rice production (Table 1). FYM and

IRRN 12:4 (August 1987) 61

chemical fertilizers alone accounted for about 60% of the total energy input. Energy inputs (3828 thousand kcal) were highest on the marginal farms and lowest (2287 thousand kcal) on the small farms. Grain and straw yields were highest on the large farms and lowest on the small farms.

Fertilization and manuring were the

major energy-consuming operations, followed by irrigation, plowing, and planking (Table 2). These operations collectively accounted for about 90% of the total energy input. Energy use by fertilization and manuring was about 1.6 times higher on marginal farms than on other farms. Energy use as irrigation was about double that on marginal

farms on all farm sizes except small farms.

net energy output increased progressively with farm size.

The highest energy input for rice production was on marginal farms. They applied more fertilizers, but had the lowest energy output-input ratio.

Except for marginal farms, total and

Table 1. Source of energy inputs and rice production. Haryana, India.

Energy input a (thousand kcal/ha) Average Rice production b

Farm size farm size Labor Farmyard Chemical Machinery (t/ha) (ha) Seed manure fertilizers Total

Human Bullock Diesel engine Tractor (5 hp) (35 hp)

Grain Straw

0.1-1.0 0.5 8 276 669 64 (7) (17) (2)

1.1-2.0 1.68 244 443 53 (11) (20) (2)

2.1-4.0 3.00 266 529 65 (9) (17) (2)

4.1-6.0 5.25 273 497 87 (8) (16) (3)

6.1 & above 8.50 277 356 88 (10) (12) (3)

Overall 1.46 269 468 76 (9) (16) (3)

1675 (44) 325

8 24

926 (29) 846

(14)

(27)

(29) 848 (28)

969 (25) 91 7

998 (32) 919 (29) 822 (29) 914 (30)

(40)

175 (5)

305 (13) 392 (12) 417 (13) 397 (14) 376 (13)

– 3828 a 2.6 bc 4.4 bc – – 2287 c 2.4 c 4.2 c – 12 3086 b 2.9 b 4.7 b (1) 49 3168 b 3.0 b 4.7 b (2) 95 2881 b 3.6 a 6.1 a (3) 44 2995 b 3.0 b 5.0 b (1)

a Figures in parentheses indicate % of total energy input. b In a column, values followed by the same letter do not differ significantly (P = 0.05) by DMRT.

Table 2. Energy use balance by operation in rice production. a Haryana, India.

Energy use (thousand kcal/ha)

Farm size Plowing Seed, Fertilization Total Total Net Energy

(ha) planking and transplanting manuring input output output ratio groups and nursery raising, and Irrigation Harvesting Threshing energy energy energy output-input

0.1-1.0 4.64 (12)

1.1-2.0 371 (16)

2.1-4.0 432

4.1-6.0 442 (14)

(14) 6.1 & above 392

(14) Overall 417

(14)

167 (4)

141 (6)

157 (5)

187 (6)

172 (6)

(6) 168

2844 (74)

1295 (57)

1924 (62)

1930 (61)

1730 (60)

1848 (62)

228 (6)

357 (15) 448 (15)

478 (15) 452 (16)

432 (14)

63 (2) 62 (3) 63 (2)

67 (2) 68 (2) 66 (2)

62 3282 a 13,175 bc 10,347 b 3.4 c (2) 61 2287 c 12,573 c 10,286 b (3)

5.5 ab

62 3086 b 14,531 b 11,445 b 4.8 b (2) 64 3168 b 15,105 b 11,937 b 4.8 b (2) 67 2881 b 18,373 a 15,492 a 6.4 a (2) 64 2995 b 15,462 b 12,467 b 5.2 ab (2)

a Figures in parentheses are % of total energy input. In a column values followed by the same letter do not differ significantly (P = 0.05) by DMRT.

The International Rice Research Newsletter (IRRN) invites all scientists to contribute concise summaries of significant rice research for publication. Contributions should be limited to one or two pages and no more than two short tables, figures, or photographs. Contributions are subject to editing and abridgment to meet space limitations. Authors will be identified by name, title, and research organization.

62 IRRN 12:4 (August 1987)

Rice - fish cultivation in the hilly region of Karnataka, India

K. Manjappa, S.J. Patil, M. Rajashekar, and K. V. Devraj, Regional Research Station, Mudigere 577132. Karnataka, India

We evaluated rearing of different species of fish to the fingerling stage in ricefields. A trench 1.5 m wide and 0.9 m deep was dug in the center of each of three 360-m 2 plots. Corrugations 0.3 m wide and 0.15 m deep were made on either side every 6 m to help the fish to move along the trench. Plot bunds were raised to 45 cm high. The trenches covered 14% of the total plot area.

Fertilizer was applied at transplanting of 30-d-old Intan rice seedlings. Topdressing with 50% recommended N

Rice-based Cropping Systems

Effect of soil amendments on rice and wheat yields in salt-affected soils

S. K. Mathur, O.P. Mathur, and N.R. Talati, Krishi Bhawan, Bikaner (Raj.), India

More than 0.17 million ha in the Indira Gandhi Canal Command is affected by moderate to severe salinity and sodicity. We studied the effect of organic manure and gypsum on rice and wheat yields in Typic Salorthid, fine-textured, salt- affected soils in a split-plot design (Table I). Farmyard manure (FYM) was the main plot treatment (0, 5, 10, 20, and 40 t/ ha) and gypsum was the subplot treatment (0, 5, 10, 15, and 20 t/ha).

transplanted in the wet season and wheat variety C591 was sown as the dry season crop. N at 100 kg/ha and P at 18 kg/ ha were applied after adjusting for N supplied by FYM.

FYM significantly increased rice and wheat yields (Table 2).

Gypsum did not significantly affect

Rice variety Jhona 349 was

Table 1. Characteristics of experimental soil profile, Typic Salorthid. Bikaner (Raj.), India.

Depth pH

ECe ESP a Silt Clay CaCo 3 (cm) (mmho/cm) (%) (%) (%)

0-1 8 8.7 6.0 39.6 36.7 25.5 11.2 18-72 9.2 7.5 62.5 45.1 43.8 11.6 72-99 9.5 10.4 58.5 34.4 15.8 11.0 99-140 9.0 22.7 56.4 50.4 28.4 12.6

140-172 9.0 26.3 66.0 27.9 23.0 9.4

a Exchangeable sodium percentage.

Table 2. Yield of rice and wheat with farmyard manure and gypsum application. Bikaner, India.

Yield (t/ha) with indicated amount of gypsum Mean FYM (t/ha) yield

0 gypsum 5 t/ha 10 t/ha 15 t/ha 20 t/ha (t/ha)

0 5

10 20 40

Mean

0 5

10 20 40

Mean

1.3 1.5 2.0 2.2 2.3 1.9

1.1 1 .0 1.9 1.3 2.2

1.5

1.4 1.6 1.8 1.5 2.5 2.0

1.0 1.3 1.5 1.6 2.1

1.5

Rice a

1.8 1.7 2.1 2.4 2.7 2.1

Wheat b

1.3 1.5 1.4 1.9 1.6

1.5

1.8 1.9 1.7 2.1 2.3 2.0

1.2 1.2 1.7 1.6 2.1 1.6

1.7 1.8 1.8 2.1 1.8 1.9

1.8 1.8 1.2 1.5 1.8 1.6

1.6 1.7 1.9 2.1 2.3 1.9

1.3 1.4 1.5 1.6 2.0

1.6

yields. a CD = 5.57 with FYM, ns with gypsum. b CD = 2.68 with FYM and ns with gypsum.

Fish harvest in a rice - fish system for the hilly region of Karnataka, India.

Length Weight

Fish Initial At harvest Times Initial At harvest Times (mm) (mm) increase over (g) (g) increase over

initial initial

Survival (%)

Catla 23 51 2.22 Rohu 24 54 2.25 Mrigal 22 57 2.59 Common carp 26 61 2.35

Mean 24 56 2.35

was done 30 d after transplanting (DT). Carbofuran granules were applied at transplanting to protect the crop against pests. For plankton production, plots were manured with cow dung before fish were stocked. Fish at the fry stage were released in the ratio of 4 catla:2 rohu: 1 mriga1:and 3 common carp 20 DT at

1.81 12.31 6.8 69.3 1.93 9.48 4.9 48.1 1.87 10.68 5.7 65.7 1.95 25.49 13.1 71.4 1.90 14.49 7.6 63.6

50,000/ ha (each plot received 1.800 fish fry). The plot was manured once a month and the fish fed regularly. After 100 d in the field, fingerlings were harvested and survival, length, and weight of each species recorded. Rice was harvested 6 d after fish.

Average fish survival was 63.6%; it

IRRN 12:4 (August 1987) 63

was highest with common carp (71.4%), 14%, there was little difference in grain 10% of the cost of trench preparation is and lowest with rohu (48.1%) (see table). yield from plots with fish (4.6 t/ha) and taken to calculate cost of one season). Weight increase of common carp was control plots (4.7 t/ha). The additional The total return from fish yield was 13.07 times initial weight. Weights of cost incurred in raising fingerlings $751/ha per 100 d. Net return was other species increased 4.91-6.80 times. (preparation of trench, fish stock, feed, $266/ ha per 100 d.

Although the rice area was reduced labor) was $485/ha per 100 d. (Only

Rice-based crop rotations for upland fields

P. K. Mahapatra, B. B. Bhol, and R. N. Patnaik, Orissa University of Agriculture and Technology, Bhubaneswar, India

Upland crop rotations were tried 1980- 81 under partially irrigated conditions at the Regional Research Station, Semiliguda, Koraput (884 m, 18º20’ N, 82°30’ E) in a randomized block design with 4 replications. Short-duration rice was direct sown during the wet season under rainfed conditions, followed by wheat cultivar Utkalika, gardenpea Bonneville, chickpea JG62, mustard M- 27, and potato Kufri Chandramukhi in the dry season (DS). Rice varieties used were OR 165-24- 12 in 1980 and Culture-I in 1981, both with 90 d duration.

The rice received 60-13-25 kg NPK/ha in 1980 and 40-9-17 kg in 1981. DS crops received the recommended package of practices. The soil was red clay loam with 5.1 pH, EC 0.168 dS/m, 0.68% organic C, 0.06% total N, 5 kg available P, and 320 kg available K/ha.

- potato (see table). Rice - potato also was most efficient. Single crop rice was the most inefficient. Highest net profit was with rice - potato (see figure).

Highest yield (20.9 t/ha) was with rice

Efficiency of crop rotations under partially irrigated conditions. Semiliguda, India, 1980-81.

Crop rotation Yield (t/ha)

Wet season Dry season

Protein a Carbohydrate a Energy a

(t/ha) (t/ha) (MJ × 10 3 /ha)

Rice - fallow 1.9 – 0.1 1.0 18.2 Rice - wheat 1.7 3.0 0.4 3.0 59.0 Rice - gardenpea (green pod) 1.7 2.5 0.2 1.1 21.4 Rice - chickpea 1.7 0.7 0.2 1.3 26.8 Rice - mustard 1.7 0.8 0.1 1.1 34.4 Rice - potato 2.0 18.9 0.4 4.7 84.3 a Protein, carbohydrate, and energy components were calculated for edible portions only, per stan- dards fixed by the National Institute of Nutrition (ICMR), Hyderabad, India.

Efficiency of crop rotations in terms of net profit. Semili- guda, India, 1980-81.

Zinc required for a rice - wheat sequence in alkali soils

T. N. Singh, H. P. Singh, and G. Singh, Crop Physiology Department, N. D. University of Agriculture and Technology, Faizabad (U. P.), India

We evaluated Zn levels needed for a rice - wheat crop rotation in field experiments in the alkali soils of

Kumarganj. Experimental fields had pH 10.2-10.4, ESP 70-90 and EC 2-2.5 mmho/cm in 1:2 soil-water suspension. Gypsum (14% S) at 12 t or pyrite (30% S) at 4.5 t/ha had been added to improve soil conditions before the first rice crop in 1976. Plot size was 6 × 3.5 m in a randomized block design with 4 replications.

Short-duration semidwarf Pusa 2-21 was transplanted at 15 × 15 cm with 4-

Table 1. Zn requirement of transplanted rite Pusa 2-21 in alkali soils of Kumarganj, India.

Grain yield (t/ha) at foliar Zn spray intervals of

(kg/ha) 1 wk 2 wk 3 wk

0 0.6 0.5 0.9 3.4 1.7 1.5 1.1 6.8 2.5 2.2 1.7

10.0 2.1 3.4 2.9

LSD (0.05) 0.3

64 IRRN 12:4 (August 1987)

Eight nonmonetary awards recognized important efforts in using science and technology resources to help improve the lives of people in developing countries. A 2-d symposium on science and technology for development also was held on the occasion of USAID’s 25th anniversary.

New IRRI Publications

World rice statistics 1985

Appendix to the Rice economy of Asia

Training in the CGIAR system

5 seedlings/hill. Elemental N and P were added at 120 and 22 kg/ ha. Zinc sulfate (22% Zn) was applied at 0, 3.4, 6.8, and 10 kg Zn/ha as a soil drench; 1.1 kg Zn was applied as a single foliar spray at 1, 2, or 3 wk after transplanting. Medium-duration IR24 and Jaya responses to a single dose of 9 or 7.9 kg Zn/ ha also were evaluated.

Without Zn and at the lower levels, rice plants developed severe Zn deficiency symptoms – leaf browning and stunted growth with eventual death of many plants. Foliar Zn spray brought a withered crop back within 3-4 d of spraying.

Zn increased grain yield tremendously

(Table 1). The responses of medium- duration varieties were even greater. At 9 kg Zn, IR24 yielded 5.3 t/ha; at 7.9 kg Zn, Jaya yielded 6.4 t/ha in 1977 and up to 6.8 t/ha in 1978, indicating a lower demand for Zn with progressive improvement in soil conditions.

Wheat was grown after rice in 6- × 4- m plots in the field treated with pyrite in a randomized block design with 4 replications. Rows were spaced 25 cm apart and sown with 125 kg seeds/ha. Fertilizer was 100-18-17 kg NPK/ha. ZnSO 4 at 0, 2.3, 4.5, 6.8, and 9.0 kg Zn/ha was applied basally at sowing. Zn deficiency caused stunted growth and poor tillering.

Table 2. Zn requirement of wheat in alkali soils of Kumarganj, India, 1976-79.

Grain yield (t/ha) Zn

(kg/ha) 1976-77 1977-78 1918-79 (HD1982) (HD1553) (HD1553)

0 1.9 2.1 1.9 2.3 2.3 2.5 2.6 4.5 3.0 3.2 3.3 6.8 3.6 3.6 3.5 9.0 3.3 3.5 3.5

LSD (0.05) 0.4 0.3 0.3

Wheat yields increased with Zn application; 6.8 kg Zn pushed yield to 3.6 t/ha (Table 2).

Announcements

World Food Prize to Swaminathan

M.S. Swaminathan, IRRI director general, has been named the first recipient of the General Foods World Food Prize, a new, major international award to recognize, encourage, and reward outstanding individual achievement in improving and increasing the world food supply.

Swaminathan will receive the prize 6 Oct 1987 at the Smithsonian Institution, Washington, D.C., where a colloquium on international food issues will be held in conjunction with the award ceremony.

Norman E. Borlaug, 1970 Nobel Peace Prize laureate, conceived the

World Food Prize, which is sponsored by the General Foods Fund, Inc. The prize consists of a $200,000 cash award and a commemorative sculpture.

IRRI - CIMMYT honored

The National Research Council and the Agency for International Development of the United States have honored IRRI and CIMMYT jointly for significant and sustained contributions in science and technology for international development over 25 yr. The awards were presented in Washington, D.C., 22 Jun 1987.

IRRN 12:4 (August 1987) 65

international rice research newsletter vol12 no.4

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