international rice research newsletter vol.13 no.1

IRRN Guidelines The International Rice Research Newsletter objective is:

“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.” 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.

guidelines, and research categories that follow.

It you have comments or suggestions, please write the editor, IRRN, IRRI, P.O. Box 933, Manila, Philippines. We look forward to your continuing interest in IRRN.

Criteria for IRRN research reports

Please examine the criteria,

• 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

Guidelines for contributors 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 Do not cite references or include a bibliography.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 he 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.

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

• Include a brief statement of

• 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.

• When reporting soil nutrient

• Provide scientific names for

• Survey data should be quantified (infection percentage, degree of

• When evaluating susceptibility, severity, sampling base, etc.).

resistance, tolerance, etc., report the

actual quantification of damage due to stress used to assess level or incidence. Specify the measurement used.

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 international measurements.

• 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.

Categories of research reported GERMPLASM IMPROVEMENT

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

IRTP modeling

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

fertilizer

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

modeling

SOCIOECONOMIC AND ENVIRONMENTAL IMPACT

environment production livelihood

EDUCATION AND COMMUNICATION

training and technology transfer

communication research research

information storage and retrieval

CONTENTS

GERMPLASM IMPROVEMENT

Genetic resources 5 Some restorers and maintainers of WA cytosterile lines

Breeding methods 5 Rice dwarf mutant of Seratus Malam variety 5 Effects of antimitotics on growth and differentiation of rice tissues

grown in vitro

Yield potential 6 Performance of japonica/indica cross derivatives under rainfed

7 Japonica and indica differences in large vascular bundles in culm

7 Correlation between rice grain and straw protein content and yield

upland conditions

Grain quality and nutritional value

Disease resistance 8 Tungro (RTV) transmission and mode of green leafhopper (GLH)

feeding 10 Tungro (RTV) development in rice 10 Stability of bacterial blight (BB) resistance in IR varieties 11 Reaction of rice varieties with xa-5 to four Philippine races of

12 Reaction of IR varieties to tungro (RTV) in the Philippines 12 Ketoacids in healthy and bacterial blight (BB)-affected leaves of

13 Resistance to bacterial blight (BB) in rice germplasm material 14 Disease selection in rice in Colombia and Central America 15 Rice cultures with early plant resistance to bacterial blight (BB)

15 Gall midge (GM) resistance in traditional rice varieties in Bihar

16 Growth recovery from salt stress during initial seedling stage 17 Effect of salinity on net assimilation and rice grain yield

bacterial blight (BB)

susceptible and tolerant rice varieties

Insect resistance

Adverse soils tolerance

Integrated germplasm improvement 17 Improved rice varieties released in Nigeria 18 High-yielding, medium-duration variety for Tamil Nadu 18 Promising, long-duration rice variety for Kanyakumari District,

19 BG380-2, a high-yielding, short- to medium-duration rice 19 Performance of selected photoperiod-sensitive breeding lines in

Tamil Nadu

Bangladesh


Soil microbiology and biological N fertilizer 20 Effect of blue-green algae (BGA) inoculation and urea super-

granule (USG) on rice yields in sodic soils

Physiology and plant nutrition

Soil fertility and fertilizer management 20 Influence of iron on nutrient uptake by rice

21 Effect of integrated nitrogen management in rice on soil organic carbon and on succeeding wheat crop yield

Disease management 22 Overwintering of Xanthomonas campestris pv. oryzae 23 Response of rice bacterial blight (BB) pathogen in vitro to

23 Soil incorporation of fungicides to control sheath blight (ShB) 24 Diseases of dry summer rice in eastern Uttar Pradesh, India 24 Virulent strain of rice grassy stunt virus (GSV) identified in

antibiotics and fungitoxicants

Indonesia

Insect management 25 Influence of carbofuran dose and time of application on control of

25 Effect of neem seed bitters (NSB) on green leafhopper (GLH)

26 Compatible insecticides and fungicides to control leaffolder (LF)

26 Brown planthopper (BPH) outbreak in Thanjavur District, Tamil

27 Effect of neem seed bitters (NSB) on green leafhopper (GLH)

27 Effect of neem seed treatment on rice seedling vigor and survival of

28 Effect of plant derivatives on green leafhopper (GLH) and rice

rice water weevil (RWW)

survival and rice tungro virus (RTV) transmission

and sheath rot (ShR) in rice

Nadu

feeding

brown planthopper (BPH) and green leafhopper (GLH)

tungro (RTV) transmission

Weed management 29 Chemical weed control in transplanted rice

30 Nitrogen fertilization and Meloidogyne incognita incidence in rice

30 Economizing irrigation through rice fallow cropping strategies

Managing other pests

Water management

Farming systems 30 Effect of tillage on stem borer (SB) larvae carry-over in a rice -

31 Intercropping upland rice and Lamtoro in acid Red Yellow

32 Performance of transplanted aman rice varieties in cropping

wheat rotation

Podzolic soils

pattern trials

SOCIOECONOMIC AND ENVIRONMENTAL IMPACT

Production 32 Economics of rice gall midge (GM) management in resistant and

susceptible cultures

ANNOUNCEMENTS

33 Deepwater rice workshop examines innovative cropping 33 1987 International Rice Research Conference 33 Gene banks and the world’s food 34 Environmental impact of pesticides 34 Crop loss assessment to improve pest management 34 New IRRI publications

ERRATA

with gamma rays at 0.1, 0.2, 0.3, 0.4 and 0.5 kGy in 1983. Plants were selected in the M 2 generation for dwarf and semidwarf stature.

From 50,000 M 2 plants, 130 semidwarf mutants and 1 dwarf mutant were selected. Dwarf mutant M-362 was isolated from the 0.1 kGy gamma ray treatment. It has significantly shorter plants, shorter culms, lower number of productive tillers, shorter panicles, and lower 1,000-grain weight than Seratus Malam (see table).

In the allelic test, dwarf mutant M- 362 was crossed with Acc. 123 (carrying DGWG gene). Dwarf mutant M-362 was not allelic with Acc. 123.

Performance of dwarf mutant M-362 is shown in the figure.

Agronomic characters of dwarf mutant M-362 and the mother variety Seratus Malam.

Characteristic

Plant height (cm) Productive tillers (no.) Panicle length (cm) Culm length (cm) 41.33 92.00 1,000-grain weight (g) Yield per plant (g)

Mutant Seratus M-362 Malam

58.50 119.00 4.50 10.00

17.17 27.00

12.75 10.55

22.24 18.41

Seeds of Seratus Malam, a local upland rice variety (tall with long panicles and high yielding potential) were irradiated

P.S. Mugiono and A.M.R. Soemanggono, National Atomic Energy Agency, Jakarta, Indonesia

Rice dwarf mutant of Seratus Malam variety

Using Chinese CMS line V20A as a common female parent, eight crosses with standard rice cultivars were made during 1984 wet season. To identify restorers and maintainers, 20 plants from each hybrid and the male parents

S. Saran and R.K. Mandal, Botany Department, Patna University, Patna 800005, India

GERMPLASM IMPROVEMENT Genetic resources Some restorers and maintainers of WA cytosterile lines

grown in the test cross nursery in 1985 were examined for pollen fertility and spikelet seed-setting percentage. Male parents of the F 1 that showed 70-80% pollen fertility and above 80% spikelet fertility were designated restorers. Male parents of the F 1 showing 5-7% pollen

Male parents showing intermediate pollen and spikelet fertility were designated partial restorers.

IR54, BIET8549, BIET1009, and Radha were identified as restorers, Br. 9 and Cuttack Basmati as partial

fertility were designated maintainers.

Spikelet and pollen fertility percentages in F 1 hybrids and their male parents.

Spikelet Pollen Cross and male parent fertility fertility

(%) (%)

V20A/IR54 85.8 76 IR54 86.9 80 V20A/Br. 34 12.2 7 Br. 34 89.1 79 V20A/Br. 9 29.0 16 Br. 9 83.0 76 V20A/Cuttack Basmati 39.0 23 Cuttack Basmati 91.2 88 V20A/BIET8549 82.5 71 BIET8549 89.1 74 V20A/BIET1009 86.8 81 BIET1009 89.2 81 V20A/Radha 84.9 76 Radha 91.0 89 V20A/BIET8550 10.5 6 BIET8550 85.5 76

restorers, and Br. 34 and BIET8550 as maintainers (see table).

Breeding methods

Stature of M-362 dwarf mutant and the mother variety Seratus Malam. Jiakarta, Indonesia.

Effects of antimitotics on growth and differentiation of rice tissues grown in vitro

A.N. Sharma and U. Sinha, Botany Department, Patna University, Patna 800005, India

We studied the effects of three antimitotic agents — chloral hydrate,

IRRN 13:1 (February 1988) 5

Seratus Malam Dwarf mutant

p-fluorophenylalanine (FPA), and ethionine — on growth and differentiation of cultured explants (root, shoot, endosperm, and embryo) of indica rice varieties Sita and Rajendra Dhan 201. All the chemicals decreased the rate of elongation of roots and shoots differentiated from treated embryos and fresh and dry weights of root, shoot, and endosperm calli. The extent of growth inhibition depended on the chemical and its concentration. Of the three, ethionine was most effective.

The morphological changes induced by the chemicals were manifested at the macromolecular levels as well. They lowered the levels of DNA, protein, and carbohydrates of the plantlets differentiated from chemically treated embryos, thereby indicating an overall disturbance in general metabolism (see table).

The decrease in the amount of total DNA gives indirect evidence for the changes induced in the levels of ploidy

Effects of antimitotics on DNA, protein, and carbohydrate contents of 10-day-old plantlets differentiated from excised embryos.

Amount in µg/g fresh weight of plantlets

DNA Protein Carbohydrate Chemical Concentration

(mg/liter)

Control

Chloral hydrate

FPA

Ethionine

0.0

82.7

165.4

827.0

25.0

50.0

100.0

5.0

10.0

15.0

1060.0 ±44.9 534.2

237.4 ±31.4

±31.1 204.6 ±52.6 973.0 ±25.9 789.7 ±57.1 463.2

735.6 ±55.8

295.7 ±69.4

±32.3 253.0 ±8.8

417.6 ±28.4 198.0 ±28.3 130.3 ±2.8 113.2 ±14.2 273.9 ±17.8 176.2 ±28.1 141.7 ±20.4 311.9 ±16.5 163.7 ±40.2 129.4 ±16.2

544.3 ±21.1 259.6 ±21.8 150.7 ±10.8 141.5 ±3.0

228.6 ±13.1 187.2 ±3.8

149.7 ±6.7

345.6 ±25.2 317.8 ±15.8 296.6 ±2.3

of the treated tissues. Cytological studies of the treated tissues are needed to reveal the nature of permanent heritable

changes brought about by these antimitotics.

Yield potential Performance of japonica/indica cross derivatives under rainfed upland conditions

S. K. B. Roy, State Agricultural Experimental Farm, Malda, West Bengal; and M. Arraudeau, International Rice Research Institute, Manila, Philippines

Pre-wet season rainfed rice is grown in about 336.4 thousand ha in northern West Bengal. Rainfall varies from 4,000 mm at Cooch-behar to 1,430 mm at Malda; 80% falls between May and Sep. Drought is not common in Cooch- behar, Jalpaiguri, and Darjeeling districts, but happens occasionally in West Dinajpur and Malda. Germination and initial growth of the crop direct seeded early Mar in the terai region of Jalpaiguri and Cooch-behar is affected by low temperature (17-20 °C). Growth of the crop seeded late Apr and

May in West Dinajpur and Malda is affected by high temperature (around 40 °C).

The problems associated with prekharif yields include unevenly occurring drought spells; soil deficiencies, mostly N and P; diseases,

mostly blast, sheath rot, and brown spot; insects, termites, stem borers, mealybug, and leaffolders; and root- knot nematodes. Weeds also are an important problem.

We screened 37 F 4 bulk population crosses including japonicas and indicas from IRRI and local cultivars at Malda in prekharif 1986. Seeds were sown in

Table 1. Screening F 4 bulk crosses under rainfed upland conditions. Malda, India, 1986.

Designation Cross Varietal Panicle Duration Fertile Grain Selections group a length grains fertility made

(cm) (d) (no./panicle) (%) (no.)

IR47724-14 IR47730-4 IR47705-6 IR47697-2 IR47688-35 IR47687-10 IR47699-28 IR4768-33 IR47721-21 IR47701-20 IR47699-22 Dular Panke Soni

Moroberekan/IRAT177 IRAT112/Apura Moroberekan/Palawan ITA235/IR9669 sel. IRAT112/Sein Talay IRAT104/Salumpikit IRAT104/Palawan IRAT104/Salumpikit IRAT177/H.T. Boewani ITA235/UPLRi 7 ITA235/Palawan Local check Local check Local check

VI/VI VI/I VI/VI VI/I VI/I VI/I VI/VI VI/I VI/I VI/I VI/VI

16-25 15-23 15-20 15-20 15-22 16-19 15-17 13-18 15-22 17-21 19-24 20 23 19

90 81-92 88-90 90-92 90-9 1 91-94

89

89 80

91-93

81-93 85

100 82

50-140 42-92 52-100 54-85 79-102 80-135 80-1 15 46-68 70-113 78-94 65-140

81 123 65

12-47 0-60

10-7 1 32-70 45-50

0-7 2 39-55 37-38 1 2-5 5 63-65 39-67

32 9

43

5 23 10 8 3 5 2 2 8 2 5

a I = indica, VI = japonica.

6 IRRN 13:1 (February 1988)

early May. Individual plant selection Table 2. Cold tolerance of selected advanced lines of rainfed upland crosses. Malda, India, 1986-87.

was based on maturity, panicle length, grains per panicle, grain fertility, and grain acceptability (Table 1). The bulk population materials were as early as local cultivars. Some of them showed better seed fertility and grain numbers per panicle than local cultivars. Duration was about 90 d. The most promising materials are japonica/japonica crosses — Moroberekan/IRAT177 and ITA235/ Palawan. Lack of rain (108 mm) during Aug 1986 affected the reproductive and maturing stages.

to test cold tolerance at the vegetative stage. The transplanted crop was

Selected plants were sown 3 Oct 1986

Lines Average Range of

group (no.) (0-9 scale) tolerance

Designation Cross Varietal tested cold score cold

IR47687-10 IR47698-32 IR47688-78 IR47697-2 IR47699-22 IR47699-28 IR47701-20 IR47705-6 IR47721-21 IR47724-14 IR47730-4 Soni Dular

IRAT104/Salumpikit IRATl12/Sein Talay IRATl12/Sein Talay ITA235/IR9669 sel. ITA235/Palawan ITA235/Palawan ITA235/UPLRi-7 Moroberekan/Palawan IRAT177/H.T. Boewani Moroberekan/IRAT177 IRATl12/Apura Local check Local check

VI/I 3 VI/I 1 VI/I 6 VI/I 6 VI/VI 3 VI/VI 2 VI/I 3 VI/VI 8 VI/I 6 VI/VI 3 VI/I 5

12.5 7.0 87.5 4.0 45.8 7.0 62.5 5.8 12.5 6.0 56.3 5.5 43.8 8.0 64.5 6.7 52.5 4.7 33.8 6.6 12.5 6.5 25.0 9.0 12.5 9.0

7-7 3-5 5 -9 3-9 4-9 5 -6 7 -9 5 -9 1-9 6-7 6-7 8-9 9-9

screened 3 Jan 1987. Average minimum 13 °C in Dec. Table 2 shows crosses temperatures were 18 °C in Nov and promising for survival percentage.

Japonica and indica differences in large vascular bundles in culm

Huang Huang, Agronomy Department, Hunan Agricultural College, Changsha, Hunan, China

We studied the number of large vascular bundles in the first internode from the

top (NLVBFI) and the number of primary branches of panicle (NPBP) at heading, in 45 indica (hsien) and japonica (keng) type varieties during 1981-82. NLVBFI was 20.9 ± 6.3 for indica type and 10.1 ± 1.9 for japonica type (see table). NPBP showed almost no differences between the two types. The ratio for NLVBFI/NPBP for 10 indicas averaged 1.97 and ranged from

NLVBFI and NPB a in selected indica and japonica varieties. Hunan, China.

NLVBFI NPBP A/B

Average (A) CV (%) Average (B) CV (%)

Indica Guang-lu-ai 4 14.6 8.7 7.2 12.8 2.08 Yu-chi 231-8 15.5 8.7 8.0 8.8 1.94 Xiang-ai-zhao 9 18.1 6.1 8.2 15.0 2.21 Ke-zhen 145 27.5 9.1 16.0 5.6 1.69 Wei-you 6 24.1 16.0 12.0 5.6 2.01 Zhen-zhu-ai 22.7 13.6 11.4 9.4 1.99 Qui-chao 2 22.9 9.5 11.6 7.3 Qiang-yan 1811 18.7 8.7 9.6 11.1 1.95

1.97

Mi-yan 23 23.2 10.7 10.2 11.1 2.27 IR26 18.7 14.9 11.2 5.6 1.64

Japonica Tian-jin-yong 12.0 9.6 10.8 8.5 1.11 Long-hu 6 11.7 7.0 10.2 12.0 1.14 58 fu-nuo 8.3 9.9 7.0 19.0 1.18 177 fu-lei 10.7 15.7 10.5 14.3 1.02 6107 11.0 14.8 10.3 17.8 1.07

1.64 to 2.27. The ratio for 10 japonicas averaged 1.13 and ranged from 1.02 to 1.19.

considered a new character to distinguish the two types. The difference in NLVBFI between the two types may relate to evolution and to nutrient transport.

It seems that the ratio can be

Grain quality and nutritional value Correlation between rice grain and straw protein content and yield

M. M. Ullah and N. A. Khondaker, Regional Agricultural Research Station, Hathazari, Chittagong 4330, Bangladesh

78-14 9.5 12.9 8.0 13.4 1.19 4001 Hai203 9.5 8.8 8.0 11.8 1.19 Agricultural University Farm, Yi-chang 105 11.6 10.8 10.6 15.4 1.09 Mymensingh, May-Oct 1982 with 4 a Means of 10 plants, including 5 main culms and 5 tillers. NLVBFI = large vascular bundles in first treatments of ZnO (0, 2, 5, and 8 kg internode, NPBP = primary branches of panicle. Zn/ha) and gypsum (0, 20,30, and 40

10.3 20.9 9.2 25.2 1.12 BR3 rice was grown at the Bangladesh


Survival (%)

Tungro (RTV) transmission and mode of green leafhopper (GLH) feeding

G. Dahal and H. Hibino, Plant Pathology Department; and R. C. Saxena, Entomology Department, IRRI

feeding behavior of GLH Nephotettix virescens and transmission of RTV- associated viruses in seedlings of nine rice cultivars. Newly emerged adults from a GLH colony reared on rice

We studied the relationship between

kg S/ ha). Normal cultural operations were done.

The experiment was in randomized block design with four replications. Seedlings (25 d old) were transplanted 22 May at 25- × 15-cm spacing and harvested at 134 d.

Rough grain and straw yields were recorded. Samples of rough grain and straw were analyzed for protein content by the improved Kjeldahl method (N × 6.25).

There was a significant positive correlation between grain protein content and yield ( r = 0.84**) and straw protein content and yield ( r = 0.79**) (Fig. 1, 2).

1. Correlation between rice grain yield and protein content. Chittagong, Bangladesh.

Disease resistance

2. Correlation between rice straw yield and protein 1. Transmission of RTBV or RTSV or both by GLH and insect mode during inoculation access feeding content. Chittagong, Bangladesh. on 9 selected rice cultivars. IRRI, 1987.


2. Scatter diagram of acidic and basic honeydew spots excreted by individual virus transmitter and nontransmitter GLH on 9 selected rice cultivars during 22 h inoculation feeding. IRRI, 1987.

cultivar TN1 were given a 4-d acquisition feeding on plants infected with rice tungro bacilliform virus (RTBV) and rice tungro spherical virus (RTSV), then a 1-d inoculation feeding on individual seedlings.

Feeding behavior during inoculation access was monitored by the color reaction of honeydew spots on bromocresol-treated filter paper disks. Blue spots (basic reaction) indicated phloem feeding and brown spots (acidic reaction) indicated xylem feeding. Inoculated seedlings were individually

indexed for the presence of viruses by enzyme-linked immunosorbent assay (ELISA).

Greater xylem feeding occurred in GLH-resistant cultivars ASD7, Gam Pai 30-12-15, Palasithari 601, and ARCl1554 (Fig. 1). Greater phloem + xylem feeding occurred in GLH- susceptible cultivars Utri Rajapan, Habiganj DW8, IR22, and TN1. Except for ARC11554, GLH-resistant cultivars were predominantly infected with RTBV alone. On Gam Pai 30-12-15 and Palasithari 601, GLH that transmitted

viruses fed more on phloem + xylem than on xylem; on GLH-susceptible Utri Rajapan and Habiganj DW8, all GLH fed on phloem + xylem, and most failed to transmit either virus.

honeydew spots excreted by individual GLH on each cultivar varied (Fig. 2), indicating heterogeneity of GLH in the colony used, although the colony has been maintained on TN1 for many years. Virus transmission did not correlate with feeding sites in the scatter diagram.

The areas of basic and acidic


Tungro (RTV) We studied the development of RTV 28 DT, coincidental with detection of development in rice infection in rice varieties with different RTBV + RTSV. RTSV infection rate

E. R. Tiongco, R. C. Cabunagan, Z. M. leafhopper (GLH). In a wet season trial transplanting, and decreased thereafter, Flores, and H. Hibino, Plant Pathology Aug-Oct 1985, high infection by rice whereas infection with RTBV + RTSV Department, IRRI

levels of resistance to the vector green was highest about a month after

tungro spherical virus (RTSV) was increased remarkably 1 mo after

1. Percentage of RTBV and RTSV infection assessed by latex test in 6 rice varieties at different times after transplanting, IRRI. WS = wet season, DS = dry season.

found 30 d after transplanting (DT) in all varieties except IR54 and IR58, which have GLH resistance. RTSV infection remained high to the end of the test period, except in susceptible TN1 and IR22. Infection with both RTSV and rice tungro bacilliform virus (RTBV) was high in TN1 and IR22.

In a similar trial Jan-Mar (dry season) 1986, RTSV infection at 30 DT was low even in TN1 and IR22. Infection increased slowly with both viruses in all varieties. RTV development was more rapid in susceptible TN1 and IR22 than in moderately resistant IR36 and IR42. IR54 and IR58 had low infection, regardless of cropping season (Fig. 1).

2. Percentage of RTBV and RTSV infection In the Jan-Mar 1987 trial using TN1 assessed by latex test, and RTV incidence based on symptoms in variety TN1 at different times after plants, RTSV infection occurred as early transplanting. IRRI, 1987 DS. as 14 DT. RTV symptoms appeared at

transplanting (Fig. 2). The rate of RTV development varied

among varieties and cropping seasons. RTSV infection could occur soon after transplanting, about a month before appearance of RTV symptoms. RTSV incidence also varied with cropping season.

Stability of bacterial blight (BB) resistance in IR varieties

Wei Zi Sheng and Li Yu Rong, Hunan Agricultural Science Academy, Rice Research Institute, Changsha, China

Eleven IR varieties were evaluated for BB resistance at AanRen, Hunan, 1975-


87. Seedlings were transplanted in 1 row at 18- × 18-cm spacing. Plants were artificially inoculated (clipping method) with a virulent local isolate at maximum tillering. Disease reaction was recorded 20 d after inoculation.

IR22, IR26, IR32, IR36, IR38, and IR42 showed stable resistance, with a narrow reaction range. IR20, IR28, IR29, IR30, and IR34 had a wider reaction range (see table).

Stability of BB resistance in IR varieties. Hunan, China.

Test BB reaction a

Range Average Variety duration

IR20 1975-47 1-5 3.15 IR22 1975-87 1-3 2.85 IR26 1975-87 1-3 2.38 IR28 1975-87 1-5 3.30 IR29 1975-47 1-5 3.00 IR30 1975-87 1-5 3.46 IR32 1976-87 1-3 2.67 IR34 1976-47 1-5 3.16 IR36 1976-87 1-3 2.67 IR38 1976-87 1-3 2.67 IR42 1976-87 1-3 2.67

a Standard evaluation system for rice.

Reaction of rice varieties with xa-5 to four Philippine races of bacterial blight (BB)

A.K. Saha, Plant Breeding Division, Bangladesh Rice Research Institute, Joydebpur, Bangladesh; and G.S. Khush, IRRI

More than 100 varieties having recessive gene xa-5 for BB resistance have been identified (genetic analysis using BB race 1). The xa-5 gene conveys resistance to BB races 1,2, and 3. We have found that varieties with xa-5 give widely variable reaction to race 4.

We reinoculated (clipping method) 6 plants each of 74 varieties with 4 races at maximum tillering. All varieties were resistant to races 1, 2, and 3 (see table). However, 52 were susceptible or moderately susceptible and 22 were resistant or moderately resistant to race 4.

We are analyzing some varieties resistant to race 4 to determine if they

Reaction of rice varieties with xa-5 to 4 Philippine races of BB.

IRRI Country of Reaction a to races Variety acc. no. origin

1 (PXO 61) 2 (PXO 86) 3 (PXO 79) 4 (PXO 71)

Hashikalmi 3397 Bangladesh R R R MR Kele 25881 Bangladesh R R R MR Aus 25 1 29043 Bangladesh R R R MS Aus 449 29206 Bangladesh R R R MS Bageri 16193 Bangladesh R R R MS Dharial 3396 Bangladesh R R R MS DV29 8816 Bangladesh R R R MR DV319 8880 Bangladesh R R R R DD100 8649 Bangladesh MR MR MR MS DNJ 142 8426 Bangladesh R R R MS DV32 8818 Bangladesh R R R MR DV52 8828 Bangladesh R R R MR DV85 8839 Bangladesh R R R R DV86 8840 Bangladesh R R R R DZ78 8555 Bangladesh R R R MS Pankhiraj 24139 Bangladesh R R R MS Dharial 34034 Bangladesh R R R MR UCP 28 8728 Bangladesh R R R MS Laksmijota 31595 Bangladesh R R R MS Lahargura 25886 Bangladesh R R R MS Loroi 27567 Bangladesh R R R R Chinsurah Boro II 11484 India R R R R Koalarata 28598 India R R R MR ARC6231 12260 India R R R MS ARC6565 20400 India R R R S ARC7001 20436 India MR R R S ARC7013 20437 India R R R MS ARC7043 20458 India R R R MS ARC7045 20460 India R R R S ARC7046 20461 India R R R S ARC7055 20468 India R R R S ARC7060 20471 India R R R MS ARC7090 20490 India R R R S ARC7098 20498 India R R R MR ARC7102 20501 India R R R MS ARC7128 20524 India R R R MS ARC7207 20545 India R R R S ARC7260 12346 India R R R S ARC7291 12356 India R R R MS ARC7323 20602 India R R R MS ARC7336 20606 India R R R MS ARC7406 20617 India R R R MS ARC7416 20625 India R R R MS ARC7423 20627 India R R R MS ARC10027 20655 India R R R MS ARC10376 20887 India R R R MR ARC10520 20967 India R R R MR ARC10952 12682 India R R R MS ARC11067 42623 India R R R MR ARC11071 21184 India R R R MR ARC11072 21186 India R R R MS ARC11075 21188 India R R R S ARC11083 21189 India R R R MR ARC11092 21192 India R R R MS ARC11109 21199 India R R R MR ARC11121 21207 India R R R MR ARC11204 21223 India R R R MR ARC11219 21236 India R R R MR BJ1 3711 Nepal R R R R Banglaluwa 16268 Nepal R R R MS Devarasi 16173 Nepal R R R MS Dudhi 16 25 6 Nepal R R R MS Lal Ahu 16 12 1 Nepal R R R MS Lalaka Gadur 16255 Nepal R R R S Lal Sar 16185 Nepal R R R MS Matury 16190 Nepal R R R S Nakhi 16254 Nepal R R R S Ram Bilash 16273 Nepal R R R MS

Continued on next page


was observed in the surrounding fields, only RTSV infection occurred in all varieties. In Leyte, where RTV incidence was moderately low, high levels of RTSV infection and low levels of RTBV infection occurred in all varieties. In South Cotabato, where RTV incidence was high, many varieties were infected with both viruses.

Even under high disease pressure in South Cotabato, IR56, IR60, and IR62 had relatively low infection rates. IR50, IR54, and IR64, which have Gam Pai 30-12-15 as a donor for vector resistance in their parentage, showed low infection rates with either virus in Nueva Ecija but high infection rates in Leyte and South Cotabato. IR26 and IR30 were mostly infected with RTBV alone in South Cotabato.

These results indicate field resistance to RTV in IR50, IR54, and IR64 in Nueva Ecija but not in Leyte and South Cotabato.

have an additional gene for resistance. A vast majority of the varieties came

from gene center 1, comprising Bangladesh, Nepal, and northeast India. One variety is from Indonesia and one from Pakistan.

Table continued

Reaction a to races

1 (PXO 61) 2 (PXO 86) 3 (PXO 79) 4 (Pxo 71) Variety IRRI Country of

acc. no. origin

Sajani 16177 Nepal R R R S Sokan Dhan 16250 Nepal R R R MS Tally 16146 Nepal R R R MR Gokhue Sair 16195 Nepal R R R MS Mujaer 18296 Indonesia R R R DL 5

MS

a R = resistant, MR = moderately resistant, MS = moderately susceptible, S = susceptible.

8593 Pakistan R R R MS Individuals, organizations, and media are invited to quote or reprint articles or excerpts from articles in the IRRN.

Reaction of IR varieties to tungro (RTV) in the Philippines

E.R. Tiongco, R.C. Cabunagan, Z.M. Flores, and H. Hibino, Plant Pathology Department; and O. Garcia, R. Necesario, and G. L. Denning, Training and Technology Transfer Department, IRRI

IR varieties were tested for reaction to RTV during the 1986 dry season in Koronadal, South Cotobato; Baybay, Leyte; and Guimba, Nueva Ecija. Disease incidence was based on symptoms; rice tungro bacilliform virus (RTBV) and rice tungro spherical virus (RTSV) in rice plants were indexed by the latex test 60 d after transplanting. Symptoms of RTV incidence in fields surrounding the test sites were assessed visually.

RTV incidence varied among varieties and locations (see table). In Nueva Ecija, where virtually no RTV incidence

RTV incidence based on symptoms, and RTBV and RTSV infection based on the latex test in IR varieties 60 d after transplanting in fields in Nueva Ecija, Leyte, and South Cotabato, Philippines.

Nueva Ecija a Leyte RTSV

South Cotabato

Variety infection RTV Infection (%) RTV Infection (%) (%) incidence incidence

(%) RTBV+ RTBV RTSV (%) RTBV+ RTBV RTSV RTSV RTSV

IR22 11 61 20 13 11 99 50 8 29 IR26 12 0 0 2 0 89 0 34 0 IR30 10 0 0 1 0 49 2 37 1 IR36 29 5 4 3 22 92 19 12 19 IR42 26 25 17 4 64 98 25 14 20 IR50 9 1 2 2 28 100 39 10 19 IR54 4 3 4 2 48 100 65 5 21 IR56 5 0 0 1 2 5 1 IR60

2 10 26 0 0 1 4 29 1 3 11

IR62 13 0 0 0 4 7 4 IR64

2 25 6 3 2 2 28 100 31 15 22

a No visual scoring made. No RTBV+RTSV or RTBV infection observed.

The latex test on test plants and plants from surrounding fields in South Cotabato revealed 12% infection with rice grassy stunt virus (GSV). It seemed that GSV strain 2, which caused RTV- like symptoms, was prevalent in South Cotabato. GSV-infected plants might have been scored RTV-infected.

These results confirm that RTV incidence varies with disease severity and the vector population prevailing in the area. Unsuspected RTSV occurs widely in fields perceived to be disease-free.

Ketoacids in healthy and bacterial blight (BB)-affected leaves of susceptible and tolerant rice varieties

Ch. Ramanamma and A. Sreeramulu, Botany Department, S. V. University, Tirupati 517502, A. P., India

Ketoacids act as precursors of amino acids. Their alteration may affect the composition of amino acids during disease development in rice leaves.

Three ketoacids — pyruvic acid, – ketoglutaric acid, and an unknown ketoacid — were detected in healthy and inoculated plants of susceptible TN1 and tolerant IET4141 rice varieties. Their content during disease development in inoculated leaves of both varieties was greater than in healthy leaves. Disease stages 1 to 5 were monitored at 2, 5, 10 15, and 20 d after inoculation of 55-d- old rice plants with a virulent isolate of Xanthomonas campestris pv. oryzae.


Ketoacid content of 2 healthy and infected varieties. Tirupati, India.

Lesser amounts of ketoacids were found in IET4141 than in TN1. The three ketoacids were present in all stages of healthy and inoculated leaves of TN1. But the unknown ketoacid was absent at stage 1 of healthy plants and stages 1 and 2 of inoculated IET4141.

-ketoglutaric acid was present in higher quantities than the two other ketoacids in both varieties (see figure).

Accumulation of ketoacids in susceptible TN1 shows that the tricarboxylic acid cycle of the plant is affected during disease development.

Pyruvic acid at 500 ppm was phytotoxic to both varieties. ketoglutaric acid was not phytotoxic, but that and the unknown ketoacid may contribute indirectly to symptom development.

For information on ordering IRRI publications, write Communication and Publications Dept., Div. R, IRRI, P.O. Box 933, Manila, Philippines.

Resistance to bacterial blight (BB) in rice germplasm material

R. N. Singh, A. T. Khan, and B. N. Mahto, N. D. University of Agriculture and Technology, P.O. Dabha Semar, Faizabad, U.P., India

We evaluated part of the rice germplasm collection at the Crop Research Station, Dabha Semar, for reaction to BB pathogen Xanthomonas campestris pv. oryzae (Ishiyama) Dye during the 1985 and 1986 wet seasons (1 Jun-30 Nov). Each test entry was planted in two 2-m- long rows at 20- × 15-cm spacing. Plants were clip-inoculated with the suspension of a local isolate at maximum tillering and disease was rated ( Standard evaluation system for rice ) 15 d and 30 d after inoculation. Final scores were used to classify the germplasm.

be free from infection, and only IET6155 had a disease score of 2 (see table).

None of the genotypes was found to


a

a -

Reaction of rice germplasm material to the local isolate of BB pathogen, Faizabad, U. P. India, 1985 and 1986.

Germplasm material Reaction Varieties (no.) score a with similar score

IET6155 2 1 IET4555, NP085, RP419, Pant Dhan 4, NDU7, NDU22, 3 T63, M23, H62, IET4141

10

IET8675, Restonoorin 21-9, T43, W1278, RR51-1, NDR88 4 6 NDR80, NDR84, NDR97, Saket 4, Type 3, CH45, CH1059, 5 20

SRA41, IET6238, Basmati 370, Pankaj, Ranikazal, Chainphool, Kalakand Narendra 1, Narendra 2, NDR308, China 4, Champa coarse, 6 20 Rohini 1708, K333, CH1039, IET9782, FS18, CR1416, T6, Joginia, FR9, K39, RP79-9, Sorhi, Anandi, CBF, Ramaniya

IR28, NDRl19, Indrasan, Ratna, IR24, Improved Sona, 7 46 Sarjoo 52, Dehula, Lalsar, Satha Opening, Anjani I, Padhini, T113, T132, Dulhiniya, T102, Agwar, Karhani (B), Garer, Bazarbhog, JBS1241, T128, T124, Bagari, Banshawa, Bilaspur, Carreon, Champa (F), Delha, Dadhaha, Dudiha, FRG4, FRG10, Jaisuria, Jalhar (C) 11, Kanga (Turahwa), KPW6B, Motibadam, Motipandey, MT4, NDR82, Pahuna, Soron, Sonachoor, Sumokhan, Tudat Govind, NDR118, Kachni, Karanga, Tinpakhiyal, Dalkachari, 8 39 Gajraj, Lakand, Bakaiya, Rohan 2662, Rambhog, Velluthacheera, Chinigurdi 11, Sapna, Sawani bhadai, Selection-8, Lalki bhadai, Lalkawa, Katki I, Katki II, Hari Nibbu, Culture 4, T136, Neebbu, Bagari (B), Karhani (R), Bhadai (R), Babu Ram, NDR501, Pusa 33-18, T42, IR30, Ashahaniya, T-86, Kashi, T116, Kulsha, Motafarm, IR8 Rasi, Pusa 33, Cauvery, Saket 1, Saket 2, Saket 3, Jhona 349, 9 92 N22, Madhuri, T21, Prasad, Kodaya, Kodya Improved, Culture 4 (RE), Karhan, Aktahwa (Red), Aktahwa (Black), Nootan, Dudhi, Champa fine, Ram Bilas, Bakain, Mungera, Sahdeyia, Rodola, Rohani, Reshma, Rajbhog, IET6663, Harikesh, Bhadai (B), Bhadai (W), Bala, Bakki, Singul, Satha Band (B), Satha Band (W), Parsom, Usha, T1242, T2, T46, KSR142, Bhunali, IET7301, Kota Basmati, T129, Gajgaur (B), Kapoorchini, Sarjoo 49, Anjana, Champa (C), Kalamdan, Mutra, Sukhawan, Talman, Tinpakhiya II, Akatahwa (FD), Gheebhat, Sath fine, Karnya, Kashi P. D., Katri III, Madhukar, NDR-49, Ramkajara, Rohan, Sawani, Akatahwa (T. D.), Anand, Basmati, Bindibali, Bindi kali, FH-109, Gajgaur, Gajgaur II (W), Jaya, Karanji, L. C. Pratapgarh, Madanchand, Mangova, Motifarm, Muskan, Nutex, Pasarhi, Safedawa, Sajna, Shyamghata, Sona, Turhawa, Lalka, T(N) 1.

a Standard evaluation system for rice (1980).

HDLL 39, NDU21, NDU37, NDU39, NDU48, SLO-17,

data reported from CIAT Rice Program evaluation plots in Villavicencio and from IRTP collaborators in Central America who reported moderate to severe disease levels in 1982-86 for Bl and in 1985-86 for LSc and BS. Data for 1984 were not used because no disease evaluations from Colombia were available that year.

Each line was classified as selected for a given disease when it received a score lower than that of the nearest susceptible check in the field ( Standard evaluation system for rice ). The coincidence in selection between Colombia and Central America was estimated for each disease as the mean probability for a line to be selected in both locations.

The probability of coincidence in selection for Bl was 0.7 for 1982-83, when selection in Colombia was based on data from the uniform Bl bed in Palmira. It increased to 0.92 during 1985-86, when selection was based on field evaluations in Villavicencio. The predictability of selections done in Colombia for Central America for LSc and BS was calculated as 0.80 for 1985-86.

This indicates high similarity of the race distribution of Bl and the disease environment between Villavicencio, Colombia, and testing sites in Central America.

To estimate the consistency across time of disease evaluations done in Colombia, we calculated the probability of coincidence using 1985-86 data from observational nurseries planted in consecutive years in Colombia. Probabilities of coincidence were 0.83

Disease selection in rice in Colombia and Central America

F. Cuevas-Perez and J. S. Gaona, IRTP Latin America, Centro Internacional de Agricultura Tropical (CIAT), Apartado Aereo No. 6713, Cali, Colombia

Materials are tested by CIAT for disease reaction prior to dispatch to national programs in Central America. Evaluations are done in Villavicencio, Colombia, a highly favorable disease

environment where blast (Bl) caused by Pyricularia oryzae, leaf scald (LSc) by Gerlachia oryzae, and brown spot (BS) by Helminthosporium oryzae are endemic.

We studied whether selecting under the high-disease environment prevalent in Villavicencio would predict disease performance in Central America, and compared the efficiency of this testing with selecting entries based only on Bl bed readings.

The analysis was based on disease

for Bl and 0.93 for LSc (see table). Coincidence for BS could not be estimated because incidence was low in 1986. No significant differences were observed between coincidence values of leaf Bl and LSc within years in Colombia and between Colombia and Central America for the period and genotypes considered.

We estimate that Bl and LSc evaluation in Villavicencio can predict reaction in Central America at least 80% of the time. Consistent BS evaluations might be very difficult to obtain.


The International Azolla Newsletter is published for researchers in the development and application of azolla in rice production. Its content focuses on discussions of current issues; it does not publish research reports. For more information, write Dr. I. Watanabe. Azolla Newsletter editor, IRRI, P. O. Box 933, Manila, Philippines.

Rice cultures with early plant resistance to bacterial blight (BB)

R. N. Singh and A. T. Khan, N. D. University of Agriculture and Technology, P.O. Dabha Semar, District Faizabad 224133, U. P., India

BB caused by Xanthomonas campestris pv. oryzae (Ishiyama) Dye, a serious disease of wet season (1 Jun-30 Nov) rice in eastern Uttar Pradesh, is more damaging during the early crop season when temperature and atmospheric humidity are very high. Only the prebooting stage of long-duration varieties coincides with this period.

We tested a number of cultures for prebooting stage resistance to BB during 1986-87 wet season. Each entry was sown in two 2-m-long rows at 20- × 15-cm spacing. Plants were clip- inoculated with a suspension of a local BB isolate at tillering and rated at 15 d and 30 d after inoculation. TN1 at maximum tillering was the susceptible check.

Eight test cultures had disease scores of 2, 15 had scores of 3 (see table).

Probability of coincidence in disease selection for consecutive years in Colombia and between Colombia and Central America, 1985-86. a

Disease Colombia b Central America

Leaf blast 0.83 0.88 1.54

Leaf scald 0.93 0.85 2.75

Brown spot – 0.79

a Probability of coincidence: probability for a line to be selected in those locations in Central

was too low in 1986; thus no selection was made. America with moderate to severe disease levels, given that it was selected in Colombia. b BS pressure

(0.1 < P < 0.9)

(0.05 < P < 0.1) –

Rice cultures showing early (prebooting stage) plant resistance to local BB pathogen isolate. Faiza- bad, U. P., India, 1986.

Variety or culture Cross Disease a score

The lnternational IPM Newsletter is published for researchers in the development and transfer of integrated pest management (IPM) technology in rice production. Its content focuses on discussions of current issues; it does not publish research reports. For more information, write Dr. B. M. Shepard, IPM Newsletter, IRRI, P. O. Box 933, Manila, Philippines.

RP1860-102-23-4-3 IET5656/Salamat 2 MTU7633 VasistalMahsuri 2 CR210-1018 Pankaj/Jagannath 2 CR98-7269 L. Z. Nira/TN1 2 CR260-131-5 CR151/CR1014 2 OR142-29 Pankaj/Sigadis 2 OR142-93 Pankaj/Sigadis 2 OR151-17 Hema/CR51-1523//Vikram 2 CR149-7171-271 MNP36/CR12//Pankaj 3 CR149-206 CR63-5218-1/Pankaj 3 CR98-8081 L. Z. Nira/TNl 3 MTU5182 MTU4569/ARC6650 3 CN836-3-6 – 3 CN836-3-8 – 3 CR376-KR-1 – 3 CR376-KR-2 – 3 CR376-KR-3 – 3 RAU83-8-4 BR-51-46-5l/Mahsuri 3 RP1859-206-6-4-2-1 Swarnadhan/Benong III 3 RP1860-249-3-1-1 Swarnadhan/Salamat 3 RP1641-11-5-1-B Vikram/Bulu Benong III 3 RP1641-44-7 – 3 RP1641-144-11-B – 3 TN1 (check) – 3

a Based on Standard evaluation system for rice (1980).

Insect resistance Gall midge (GM) resistance in traditional rice varieties in Bihar

P. Chand, Entomology Department, Birsa Agricultural University, Kanke, Ranchi 834006, India

Seven local rice varieties collected from endemic GM areas of Chhotanagpur plateau, Bihar, were evaluated for resistance in 1984-86 wet seasons. Two resistant and one susceptible high- yielding varieties were included for

comparison. One-month-old seedlings were planted in 3- × 4-m plots with 3 replications. Silvershoot percentage was recorded at peak infestation (45 d after transplanting).

showed resistant reactions comparable to those of resistant checks RD202 and Shakti (Table 1). When 3-yr data were pooled, all varieties except Dhusri were better than Jaya. Baghpanjar matched the resistant checks. However, susceptible Jaya recorded the highest yield (Table 2).

Local variety Baghpanjar consistently


c 2

Table 1. Silvershoots in GM resistance trials. Bihar, India, 1984-86.

Silvershoots a (%) Variety

1984 1985 1986 Mean b

Kalamdani 2.13 (4.54) 1.00 (1.00) 3.23 (10.43) 2.13 ( 4.54) c Baghpanjar 1.83 (3.35) 1.60 (2.56) 0.60 (0.36) 1.34 ( 1.80) ab Bhojni 2.73 (7.45) 1.20 (1.44) 2.63 (6.92) 2.20 ( 4.08) c Saraikela 0.87 (0.76) 1.77 (3.13) 2.63 (6.92) 1.76 ( 3.10) bc Dhusri 3.13 (9.80) 1.73 (3.00) 3.63 (13.18) 2.83 ( 8.00) d Karnusal 2.97 (8.82) 2.13 (4.54) 4.50 (20.25) 3.30 ( 9.18) de Bheri-rice 3.03 (9.18) 1.37 (1.88) 3.13 (9.80) 2.51 ( 6.30) cd Jaya (susceptible check) 4.37 (19.10) 3.20 (10.24) 4.63 (21.44) 4.07 ( 16.60) e RD202 (resistant check) 1.10 (1.21) 1.40 (1.96) 0.60 (0.36) 1.03 ( 1.06) a Shakti (resistant check) 2.10 (4.41) 0.63 (0.40) 1.50 (2.25) 1.4l ( 2.00) ab

CD (0.05) 0.89 1.15 0.86 0.93

a Figures in parentheses = original values. b Values followed by a common letter are not significantly different at the 5% level.

Adverse soils tolerance

Table 2. Yield in GM resistance trial. Bihar, India, 1984-86.

Yield (t/ha)

1984 1985 1986 Mean a Variety

Kalamdani 4.3 1.2 2.1 2.5 Baghpanjar 2.4 1.5 3.3 2.4 Bhojni Saraikela

3.7 0.7 2.8 2.4 2.6 1.5 2.8 2.3

Dhusri 3.7 1.4 2.9 2.7 Karnusal 3.3 0.6 2.8 2.2 Bheri-rice 3.0 0.8 2.4 2.1 Jaya RD202

4.0 1.2 2.9 2.7

Shakti 3.6 1.2 2.5 2.5 2.6 0.8 3.8 2.4

Growth recovery from salt stress during initial seedling stage

K.S. Gill and O.S. Singh, Botany Department, Punjab Agricultural University, Ludhiana, India

In the southern and eastern part of India near the sea, the rice crop is affected by tides at the early seedling stage. We studied the effect of salinity on seedling growth after removal of salt stress.

The experiment was conducted in petri dishes at electrical conductivity (EC) of 1.5 and 13.6 dS/m. Forty seeds each of Jaya (tolerant) and Basmati 370 (sensitive) varieties were placed in petri dishes lined with filter paper Whatman No. 1, with 30 replications. Seeds were surface-sterilized by 0.1% mercuric chloride solution.

Salinity stress was removed 4.6, and 8 d after sowing (DAS) by washing 10 replications/treatment with water at EC 1.5 dS/m. Two replications were removed at each sampling to measure Carryover effect of salinity at seedling stage on root and shoot length after stress removal, Ludhiana, India.

length of root, shoot, dry weight of root and shoot, endosperm part, and recovery rate. growth. On removal of salt stress, Initial recovery in root and shoot

Salinity retarded root and shoot seedlings began to recover. length was better when stress was

Arrows indicate days when stress was removed.

16 IRRN 13:l (February 1988)

removed 4 DAS. Jaya gained more than Basmati 370 (see figure).

Root and shoot weight decreased with salinity and the recovery gap widened with days under stress. Salinity caused less decrease in endosperm weight due to decreased metabolic mobilization. Seed weight decreased more in Jaya than in Basmati 370 (see table).

Salinity appeared to retard root and shoot growth more on Basmati 370 than on Jaya. Recovery also was better in Jaya. High initial recovery rate in Jaya was accompanied by less dry weight decrease of endosperm, showing more hydrolysis and translocation of metabolite from endosperm. This indicated that longer stress might cause irreversible effects on metabolism. Jaya’s faster recovery may be due to higher metabolic utilization from the endosperm.

Effect of salinity on net assimilation and rice grain yield

S.K. Dutt and A.R. Bal, Central Soil Salinity Research Institute, Regional Research Station, P.O. Canning Town, 24 Parganas (S), Pin 743329, India

We studied the critical limits of salt tolerance and the effects of salinity on net assimilation rate (NAR) of M1-48, Jaya, CST-202-2, CST-438-1, CST-14-2, CST-100-1, and CSR-1 rice varieties. M1-48 and CSR-1 were the salt-sensitive and salt-tolerant checks. Jaya and the CST genotypes have been found promising in coastal saline soils.

Three salinity levels — ECe 4.0, 8.0, and 12.0 dS/m — were created artificially by adding saline river water. At 25 °C, average composition of river water at 35 dS/m was 7571.3 Na, 269.2 K, 403.8 Ca, 778.0 Mg, 1314.3 Cl, 969.1 ppm SO 4 , and pH 7.8.

transplanted in 20-kg capacity porcelain pots, 4 plants/pot, with 4 replications. Fertilizer was applied at 120 kg N, 26.4 kg P, 49.8 kg K/ ha as urea, single superphasphate, and muriate of potash.

Thirty-day-old seedlings were

Effect of salinity on endosperm utilization rate (% seed weight decrease/5 seeds) on recovery from salt stress. a Ludhiana, India.

Day of Endosperm utilization rate at given time (d) after germination Salinity stress Variety (dS/m) removal 4 d 6 d 8 d 10 d 12 d 14 d 16 d

Seed weight (%) 1.5 Jaya 0.0 30.5 41.2

Basmati 370 0.0 9.7 36.7

(30.5) (15.3)

(9.7) (29.9)

Recovery from stress 13.6 4 Jaya 0.0 7.5 24.3

(7.5) (18.2) Basmati 370 0.0 2.5 22.1

(2.5) (20.1)

6 Jaya – 0.0 11.3 (11.3)

Basmati 370 – 0.0 13.0 (13.0)

8 Jaya – – 0.0

Basmati 370 – – 0.0

62.5 (36.5)

48.9 (19.1)

51.6 (35.9) 38.7

(21.3) 25.4

(15.8) 25.1

(13.9) 19.5

(19.5) 8.3

(8.3)

65.6 (7.8) 57.5

(16.8)

59.6 (16.6) 51.1

(20.1) 48.3

(30.6) 38.9

(18.9) 29.8

(12.8)

20.1 (12.9)

66.0 66.6 (2.3) (0.6) 64.1 63.7

(15.5) (1.2)

– –

– –

(27.2)

(14.4) 47.7 –

62.2 –

39.0 59.7 (13.1) (33.9) 34.2 45.3

(17.6) (16.9)

a Values in parentheses indicate increase over time interval.

Effect of salinity levels (3, 8, 12 dS/m) on grain yield and NAR of 7 varieties. Parganas, India.

Grain yield (g/plant) NAR at peak tillering (g/plant per wk)

3.0 8 .0 12.0 3.0 8.0 12.0

M1-48 17.1 10.3 Nil 3.24 0.51 0.06 Jaya 14.4 12.3 11.7 3.08 1.55 1.08

Variety

CST-202-2 32.6 21.8 10.7 1.47 1.01 0.16 CST-438-1 22.1 20.7 8.7 3.04 0.60 0.08 CST-14-2 28.5 23.3 15.2 3.24 2.10 1.80 CST-100-1 21.6 21.6 9.6 1.81 1.36 0.76 CSR-1 31.8 29.5 13.0 1.81 2.00 1.09

CD at P = 0.05 Varieties: 2.67 Salinity: 1.74 Var. × Sal: 4.62

0.13 0.08 0.22

CST-14-2 had the highest grain yield with increase in soil salinity. This at ECe 12 dS/m, followed by CSR-1 reduction was least in CST-14-2. CST- (see table). At peak tillering, NAR was 14-2 and CSR-1 are the more tolerant of significantly reduced in all genotypes the genotypes tested.

Integrated germplasm - -

improvement Improved rice varieties Five NCRI breeding lines belonging to released in Nigeria S.O. Fagade, P.G. Pillai, and J.K. Kehinde, released as FARO 30 to 34. Three National Cereals Research Institute (NCRI), medium-duration ITA lines were Badeggi, Ibadan, Nigeria released as FARO 35 to 37. The

three crosses (Table 1) were recently


Table 1. Pedigree, parentage, and agronomic characters of 8 lowland rice varieties newly released in Nigeria.

Variety Pedigree Parentage Ht Maturity Panicles Reaction a to (cm) (d) (no./m 2 ) Bl Fe toxicity RYMV

Early duration FARO 30 FARO 31 FARO 32 FARO 33 FARO 34 FARO 27 (check) Medium duration FARO 35 FARO 36 FARO 37

FARO 29 (check)

FAROX 228-2-1-1 FAROX 228-3-1-1 FAROX 228-4-1-1 FAROX 233-1-1-1 FAROX 239-2-1-1 TOx 103

ITA 212 ITA 222 ITA 306

BG90-2

FARO 15/IR28 105 FARO 15/IR28 104 FARO 15/IR28 91 FARO 12/IR28 100 lR28/FARO 12 90

– 91

BG90-2 4 /Tetep 97 Mahsuri/IET1444 91

TOx 711//BG6812 TOX 494-3696/ 105

– 97

115 118 117 115 115 119

132 127 124

130

194 258 221 25 9 209 25 3

210 227 203

216

R R

MR R R

MR

R R R

S

MR MR MR

S MR MR

S MR MR

MR

MR MR MR MR MR MR

MR MR MR

MR

a S = susceptible, R = resistant, MR = moderately resistant.

varieties were tested in zonal and multilocation trials.

All the varieties exhibit high yield potential. They are resistant to blast (Bl) and moderately resistant to rice yellow mottle virus (RYMV) (diseases common in the irrigated lowland ecology). In the early-duration group, FARO 30 had the highest yield (6.5 t/ ha), with very good cooking quality (Table 2). FARO 34 combines long slender grains, a character highly preferred by Nigerian consumers, with very good milling and cooking qualities.

The medium-duration FARO 37 possesses high yield and long slender grains.

FARO 33 and 35 are susceptible to Fe

Table 2. Grain yields and grain qualities of 8 lowland rice varieties newly released in Nigeria.

Variety Grain yield a

(t/ha) Grain type Cooking quality Amylose group b

Early duration FARO 30 FARO 31 FARO 32 FARO 33 FARO 34 FARO 27 (check) Medium duration FARO 35 FARO 36 FARO 37 FARO 29 (check)

6.5 5.0 5.3 5.8 5 .0 4.9

5.6 6.3 5.8 5.6

Medium bold Medium bold Medium bold Long slender Long slender Medium bold

Medium bold Medium bold Long slender Medium bold

Very good Good Good Good Very good Good

Good Good Good Good

Intermediate Intermediate Intermediate Intermediate Intermediate High

High High High High

a AV of 3 yr (1984-86) multilocation trials. b Intermediate = 20-25%, high = above 25%.

toxicity, the others are moderately intermediate amylose; the medium- resistant. maturing have high amylose.

All early-maturing varieties have

High-yielding, medium- ACM31, a high-yielding, medium- duration variety for duration (132 d) variety, is a cross Tamil Nadu derivative of CO 13 and IR26. The

culture is semidwarf and nonlodging S. Sevugaperumal, G. Soundrapandian, and with medium slender white grains. Its A. Amirthadevarathnam, Agricultural Botany Department, Agricultural College

performance was evaluated for 3 yr

and Research Institute (ACRI), Madurai 1984-85 to 1986-87 (see table). Mean

625104, Tamil Nadu, India grain yield was 6.2 t/ ha, 31.9% more

Performance of ACM31, a promising, medium-duration culture at ACRI, Madurai, Tamil Nadu, India, 1984-85 to 1986-87.

Mean Days to Plant Panicle Variety yield a 50% height length

(t/ha) flowering (cm) (cm)

Panicles (no./hill)

ACM31 6.2 92 95.6 20.6 10.4 IR20 4.7 96 101.8 22.8 13.6

a For 3 yr.

than IR20. This variety could replace IR20 in the Periyar-Vaigai River ayacut area.

Promising, long- duration rice variety for Kanyakumari District, Tamil Nadu

T. Sundaram, O.R. Pillai, S. Sevugaperumal, J. G. Robinson, and A. S. Mathar, Agricultural Research Station (ARS), Thirupathisaram 629901, Tamil Nadu, India

Traditional rice varieties are grown in about 40% (9,200 ha) of the rice area in


Kanyakumari District during the second season (pishanam). They have long duration and low yield potential. Farmers prefer them because of their high straw yield, the only local feed for cattle.

The performance of TP4121 (CO 25 / CO 40), 163-d duration, was evaluated for 3 yr, 1983-84 to 1985-86 (see table). It had the highest grain yield (5.3 t/ha) in 1984-85; mean grain yield was 4.8 t/ha, 40 and 61% more than Vallarakkan and Valsiramundan,

BG380-2, a high- yielding, short- to medium-duration rice

S. Sevugaperumal, G. Soundrapandian, and A. Amirthadevarathnam, Agricultural Botany Department, Agricultural College and Research Institute, Madurai 625104, Tamil Nadu, India

An experiment in the 1986-87 dry season tested 22 International Rice Yield Nursery entries in a random block design with 3 replications. BG380-2

Performance of selected photoperiod- sensitive breeding lines in Bangladesh

M.A. Kabir, L. Ali, and N. M. Miah, Bangladesh Rice Research Institute, Gazipur, Bangladesh

Bangladesh farmers grow transplant aman (T. aman) rice after aus rice or jute, in a delayed planting. Photoperiod- insensitive varieties are subjected to cold stress at flowering, resulting in drastic yield loss.

Eleven photoperiod-sensitive advanced breeding lines, one local photoperiod-sensitive check, and one long-duration, high-yielding check were evaluated during the 1986 T. aman season at Joydebpur, Comilla, and Barisal. Test entries were evaluated in normal and late plantings. The normal planting was 8 Aug using 30-d-old seedlings, the late planting was in Sep,

Performance of TP4121 at ARS Thirupathisaram, Tamil Nadu, India, 1983-84 to 1985-86.

Grain yield (t/ha) Duration Plant Panicles Panicle Variety Parents 1983- 1984- 1985- Mean (d) height (no./hill) wt (g)

84 85 86 (cm)

TP4121 CO 25/CO 40 4.2 5.3 5.0 4.8 163 123.6 9 2.13 CO 25 CO 4/ADT10 2.6 4.2 3.8 3.5 162 122.4 7 2.00 Vallarakkan Traditional 1.9 4.3 4.0 3.4 180 126.7 7 1.85 Valsiramundan Traditional 1.7 3.4 3.8 3.0 170 122.9 7 1.98

respectively. due mainly to higher panicle weight and

white grains. Its higher yield potential is tillers. TP4121 is 123 cm tall with short bold increased number of productive

Yield performance of promising entries. Madurai, Tamil Nadu, India, 1986-87.

Entry Grain % of Days to Plant Panicle Panicles

Parentage yield IR20 50% height length (no./m 2 ) (t/ha) flowering (cm) (cm)

BG380-2 BG90-2*/OB677 9.4 149.2 90 93.7 23.1 520 BR316-15-4-4-1 IR5 (P)/Biplab 9.3 147.6 86 106.8 21.4 457

C1333-4 IR42/C4-63(G) 7.7 122.2 92 65.9 18.2 477 IR20 IR262/TKM6 6.3 – 95 83.9 19.5 493

S512 B-199 – 7.9 125.4 97 82.4 19.8 540

CD (0.05) 1.9

yielded 9.4 t/ha in 120 d, compared with showed reduction in yield — for 6.3 t/ha in 125 d for IR20 (see table). cultivation in the Periyar-Vaigai River BG380-2 can replace IR20 — which Project.

Ancillary characteristics of the selected photoperiod-sensitive lines. Bangladesh, 1986 T. aman.

Plant height (cm) Yield (t/ha)

1st 2d 1st 2d Designation Parentage

BR716-7-2-1-1 DA29/BR4 115 105 4.2 3.5 BR545-5-1-2-1 BR52-87-1/Tilakkachari 106 95 4.0 3.3 BR1141-2B-37 BR4/Jhingasail 128 112 4.0 3.1 Nizersail (local check) – 126 110 2.8 2.3 BR11 (check) 110 90 3.8 1.0 IR20/IR5-47-2

using 45-d-old seedlings. Entries were grown in 5.4 m long × 12 row wide plots at 25- × 15-cm spacing with 2 seedlings/ hill, in a randomized complete block design with 3 replications. The whole plot was harvested for yield data, which were statistically analyzed separately for location, planting date, and the combination of locations.

No entry gave high yields at all locations (see table). Combined yield analysis of both plantings showed an interaction between location and variety.

BR716-7-2-1-1, BR545-5-1-2-1, and BRl141-2B-37 were selected for future breeding of photoperiod-sensitive varieties.

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


P. Pandiyarajan and A. Rajamannar, Soil Salinity Research Centre, Trichy 620009, India

We studied the effect of BGA inoculation in a sodic soil (pH 9.01, EC 0.33 dS/m, and exchangeable sodium percentage 32) at 4 levels of N (0, 75, 100, and 125% of recommended) applied as USG.

Influence of iron on nutrient uptake by rice

N. K. Fageria, National Rice and Bean Research Center, EMBRAPA, Goiania- Goias, Brazil

Brazil has about 30 million ha of lowland areas suitable for rice. But after 1 or 2 yr cultivation, Fe toxicity builds up in flooded rice because of a decrease in soil fertility. Nutrient imbalance may be the main cause.

A solution culture experiment with increasing Fe concentrations was conducted to understand the nutrient uptake behavior of lowland rice cultivars. With slight modifications, the nutrient solutions were those developed


by IRRI. The macronutrient composition in mM follows: 2.85 NH 4 NO 3 , 0.13 NaH 2 PO 4 , 1.03

Soil microbiology and biological ~

N fertilizer showed the need for 127.5-80-87.5 kg NPK/ ha. All the plots were treated basally with superphosphate (16% P 2 O 5 ), muriate of potash (60% K 2 O), and 25 kg ZnSO 4 /ha.

Inoculation of BGA significantly Effect of blue-green The field experiment was conducted increased grain and straw yield over the algae (BGA) inoculation Sep-Jan 1985-86. Plots were 3 × 1.75 m control and in the treatment with 100% and urea supergranule with 3 replications of 8 treatments, in a fertilizer N (see table). (USG) on rice yields in randomized block design. Soil test sodic soils

Effect of BGA inoculation on rice grain and straw yie1d. a Trichy, India.

Grain yield (t/ha) Straw yield (t/ha) N level (%) % increase % increase

Without BGA With BGA Without BGA With BGA

0 2.0 2.3 15* 4.6 5.4 17*

2.9 3.6 12* 7.0 7.9 12* 75 2.6 2.7 ns 6.1 6.8

100 ns

125 3.3 3.4 ns 7.5 7.7 ns CD (0.05) 0.2 0.8

a * = significant difference, ns = not significant.

Physiology and plant nutrition

Table 1. Uptake of nutrients in the roots and shoots of rice cu1tivars. a

Fe 0.09 mM Fe 0.89 mM Fe 1.78 mM

Concn % or Content (mg or Concn % or Content (mg Concn % or Content (mg Nutrient

ppm µg/4 plants) ppm or µg/4 plants) ppm or µg/4 plants)

Roots N 2.82 a 23 a 2.76 a 11 b 2.53 b 6 b P K

0.33 ab 2.66 a 0.27 b 1 a 0.39 a 0.96 b 2.95 a 25 a 1.73 b 6 b 1.46 b 4 b

Ca 0.08 a 0.65 a 0.10 a 0.38 b 0.11 a 0.26 c Mg 0.12 a l a 0.11 b 0.42 b 0.11 a 0.26 b

Zn 44 a 37 a 26 c 10 b 38 b 10 b Cu 19 b 15 a 22 a 8 b 23 a 6 c Mn 22 c 18 a 27 b 10 b 38 a 9 b

N 4.09 b 186 a 3.38 c 51 b 4.18 a 50 b P 0.48 a 21 a 0.18 c 3 b 0.26 b 3 b

Fe 2258 c 1806 c 12717 b 4658 b 37458 a 9202 a Shoots

K 2.95 a 133 a 1.94 c 26 b 2.17 b 25 b Ca 0.17 b 8 a 0.24 a 3 b 0.22 a 3 b Mg 0.43 a 19 a 0.39 b 5 b 0.22 c 5 b

Zn 24 a 109 a 18 c 24 b 21 b 25 b cu 14 b 62 a 16 ab 22 b 17 a 20 b Mn 199 a 874 a 139 c 183 b 152 b 184 b Fe 350 c 1578 c 2008 b 2627 b 4233 a 4988 b a Values are mean of 12 cultivars. Concentrations of macronutrients are in % and micronutrients in

values for each nutrient followed by a common letter are not significantly different at the 0.05 level ppm. Similarly, macronutrient contents are in mg and micronutrients in µg. Under each Fe level,

by Duncan's multiple range test.

K 2 SO 4 , 1 CaCl 2 , 1.64 MgSO 4 ·7H 2 O. (NH 4 ) 6 · Mo 7 O 24 · 4H 2 O, 18.48 B as Micronutrient composition in µM is 9.1 H 3 BO 3 , 0.15 Zn as ZnSO 4 ·7H 2 O, and Mn as MnCl 2 · 4 H 2 O, 0.52 Mo as 0.16 Cu as CuSO 4 ·5H 2 O. Fe was


cpsadmin

Line

cpsadmin

Line

cpsadmin

Line

cpsadmin

Line

cpsadmin

Line

supplied as Fe EDTA in amounts required for Fe concentrations of 0.09, 0.89, and 1.78 mM. Nutrient solutions were changed weekly. Solution pH was adjusted to 4 ± 0.2 initially, then once every 2 d with 0.1 N NaOH or 0.1 N HC1.

Seeds of rice cultivars were germinated in nutrient solution using 2- liter plastic pots. At 17 d, uniform seedlings were transplanted to acrylic discs with holes in the center and held in place with cotton. Discs were transferred to plastic pots containing about 8 liters nutrient solution with different Fe treatments. Each treatment was replicated twice.

After 35 d growth in Fe-treated solutions, plant shoots and roots were harvested separately and washed in distilled water. Plant material was dried at about 80 °C to a constant weight. Dry matter was ground and digested with a 2:1 mixture of nitric and perchloric acids. Composite samples of 12 rice cultivars per treatment were analyzed chemically for N, P, K, Ca, Mg, Zn, Cu, Mn, and Fe. The P concentration in the digest was determined colorimetrically; other elements were determined by atomic absorption spectroscopy. Total N in the tissue was determined using a Tecator 1016 digester and 1004 distilling unit.

reduced with increasing Fe concentration in the growth medium (Table 1). Among macronutrients, P uptake was most highly affected, followed by K and N. Among micronutrients, absorption of Mn and Zn was most affected. Nutrient inhibition by Fe can be put in the following order (Table 2): macronutrients — P>K>N>Mg>Ca micronutrients — Mn>Zn>Cu. Among macronutrients, P uptake was highly inhibited and Ca uptake was least affected. Among micronutrients, Mn was most inhibited and Cu least affected. The results suggest that with higher Fe concentrations in lowland rice, P, K, and Zn deficiencies will be the first to appear. Fe toxicity problem in lowland rice could be alleviated by increased P, K, and Zn fertilization.

In general, uptake of all nutrients was

Table 2. Inhibition of nutrient uptake by higher concentrations of Fe in rice cultivars shoots

Cultivars (no.) under each group

Nutrient Fe 0.89 mM Fe 1.78 mM

Low Medium High Low Medium High

N P K Ca Mg Zn Cu Mn

– – – 2 – – 1 –

6

1 10 8 5

10 1

– 6

12 11

4 7 1

11

–

– – – 2

1 1

–

–

7 5 – 12 1 11

10 – 8 4 3 8 8 3 4 8

nutrient content at – nutrient content at

nutrient content at optimum Fe level Inhibition = optimum Fe level high Fe levels

× 100

Optimum Fe level was 0.09 mM.

Soil fertility and fertilizer management Effect of integrated We studied the residual effect of applied nitrogen management N (organic + inorganic) in lowland rice in rice on soil organic on soil organic C content and grain carbon and on yield of the succeeding wheat crop succeeding wheat crop grown without fertilizer on a Mollisol of yield the Tarai region of Uttar Pradesh.

The silty clay loam soil had pH 7.2, B.S. Mahapatra and G.L. Sharma, Agronomy Department, G. B. Pant 1.20% organic C, 0.116% total N, 42.5

University of Agriculture and Technology, kg available P/ ha, 214 kg available Pantnagar, Nainital 263145, U. P., India K/ha, and bulk density 1.33 g/cc. Soil

Soil organic C after wet season rice harvest and wheat yield after integrated N management in rice. a

Pantnagar, India, 1984-85 and 1985-86.

Treatment b Soil organic C (%) after Wheat grain yield

N wet season rice harvest (t/ha) (kg/ha)

1984-85 1985-86 1984-85 1985-86

No N USG 58 1.17 1.17 a 1.2 b 1.9 b USG + fresh wheat straw (29+29) 58 1.17 1.21 ab 1.2 b 2.2 b PU + azolla (58+29) 87 1.20 1.20 ab 1.3 ab 1.9 b PU + fresh wheat straw (58+29) 87 1.19 1.24 abc 1.3 ab 2.1 b USG + azolla (58+29) 87 1.24 1.25 abc 1.4 a 2.0 b USG + fresh wheat straw (58+29) 87 1.19 1.29 bc 1.3 ab PU

3.3 a 120 1.17 1.20 ab 1.3 ab 1.9 b

USG + azolla c (60+60) 120 1.26 1.31 c 1.6 a 3.5 a – 0.09 0.11 0.45

0 1.16 1.16 a 1.0 c 1.3 c

CD (0.05)

a In a column, values followed by the same letter do not differ significantly. b Figures in parentheses

was best split. USG placed 10-12 cm deep 7 d after planting rice. Fresh wheat straw incorporated at are kg N/ha. Treatment of rice crop only in both years. Azolla was incorporated. Prilled urea (PU)

puddling. In the first year, azolla with PU or USG showed more increase in organic C content. Azolla left on the surface at incorporation multiplied and added organic matter throughout rice growth. In other treatments, variations were 0.01-0.03%. c Half the azolla N incorporated at planting and half inoculated 7 d after planting rice.


organic C (by modified Walkley and Black method) after harvesting the wet season rice crop and wheat grain yield were observed 1984-85 and 1985-86.

Integrated use of organic and inorganic fertilizer in rice had a significant residual effect on the succeeding wheat crop grain yield (see

table). The residual effect was more pronounced the second year. In both years, urea supergranule (USG) (60 kg N) + azolla (60 kg N) applied to the rice crop showed the maximum residual effect on wheat yield (0.6 t/ha in 1984- 85, 2.2 t/ha in 1985-86). Fresh wheat straw combined with chemical N in rice

showed a higher residual effect the second year. Chemical N alone had very low residual effect. The increase in grain yield of wheat after organic-inorganic N fertilization in rice is explained by the significant modification of organic C, which in turn gives more hydrolyzable organic N.

Disease management Ovewintering of Xanthomonas campestris pv. oryzae

K. Raj and V. Pal, Plant Pathology Department, Haryana Agricultural University, Hisar, India

We studied the overwintering of Xanthomonas campestris pv. oryzae — the causal pathogen of bacterial blight (BB) — in soil, seeds, and infected leaves collected from a rice crop artificially inoculated during the 1985-86 crop season.

Samples of seeds and leaves were collected in cloth bags and stored in a refrigerator (8+1 °C), incubator (28±1°C), and at room temperature (5-42°C) in the laboratory. Bacterium in the samples was measured at 1-mo intervals from Nov 1985 to Aug 1986. Methods were direct plating (DP), dilution streak plating (DSP), ooze test (OT), pathological test (PT) with

Recovery a of X. c. pv. oryzae from soil, seed, and leaves collected from diseased fields showing heavy infection with BB during the 1984-85 crop season, Hisar, India.

Source of Storage Detection infection conditions methods Nov 1985 Dec 1985 Jan 1986 Feb 1986 Mar 1986 Apr 1986 May 1986 Jun 1986 Jul 1986 Aug 1986

Recovery

Soil

Seed

Leaf

Refrigerator (8±l°C)

Incubator (28±1°C)

Room

(5-42°C) temperature

Refrigerator (8±1°)

Incubator (28±1°C)

Room temperature (5-42° C)

–

+ –

– –

ND ND

–

– – – ND ND – –

ND ND

–

+ + + + ND + + + + ND + + + + ND

– – – – – – ND ND – – – ND ND – – – ND ND + + + + ND + + + + ND + + + + ND

– – – – –

ND ND

–

– –

ND ND

–

– –

ND ND

–

+ + + + ND + + + + ND + + + + ND

– –

– –

– –

– – – – –

– –

– –

– ND ND

– ND ND

– ND ND

– – – – – ND ND

–

ND ND

– – – ND ND

– –

– –

– –

ND ND

–

+ + + + ND

– ND ND + + + + ND

– ND ND + + + + ND

+ + + + ND + + + + ND

+ + + + ND + + + + ND

+ + + + ND + + + + ND

– – – – – – ND ND – – –

ND –

– – – – ND + + + + ND + + + + ND + + + + ND

– – – – – – – ND – – – – – – – – – –

+ + + + + + + + + + + + + + +

– – – – – – – ND – – – – – – – – – –

+ + + + + + + + + + + + + + +

DP – DSP IF-S +

–

DP – DSP –

GOB ND PT ND DP – DSP – IF-S – GOB ND PT ND DP – DSP – IF-S GOB ND PT ND OT + DP + DSP +

PT ND

OT + DP + DSP + IF-S + PT ND OT + DP + D SP + IF-S + PT ND

IF-S –

–

IF-S +

a + = X. c. pv. oryzae present, – = bacterium absent, ND = test not performed.


extracts of seed and leaf, growing on bioassay (GOB), and immunofluorescence staining (IF-S) using antiserum raised against X. c. pv. oryzae. Watanabe’s medium was used for DP and DSP methods.

of the test bacterium in soil up to 1 mo after harvest (4 Nov 1985); negative results were recorded by DP and DSP test methods (see table).

IF-S technique indicated the presence

X. c. pv. oryzae could not be detected

in stored seed lots by any of the methods. However, saprophytic yellow bacteria were found associated with the seeds. The seed did not produce diseased seedlings by GOB test and their extract (inoculation by tip clipping) did not initiate BB in 2.5-mo-old seedlings of rice TN1 in the next crop season, when conditions were congenial for disease development.

The presence of bacterium could be confirmed by all the methods in infected

leaves irrespective of storage conditions. BB could successfully be induced in seedlings of the test cultivar with a bacterial suspension obtained from the leaves.

These findings indicate that X. c. pv. oryzae did not overwinter in soil nor in seed collected from the diseased crop. Infected leaves seem to constitute the primary inoculum for the next crop season.

Response of rice bacterial blight (BB) pathogen in vitro to antibiotics and fungitoxicants

B.N. Mahto, R.N. Singh, and G. P. Singh, N.D. University of Agriculture and Technology, P.O. Dabha Semar, District Faizabad 224133, U.P., India

We tested the effect of 2 antibiotics and

10 fungitoxicants on rice BB pathogen Xanthomonas campestris pv. oryzae using the paper disc assay method. Filter paper discs 12 mm in diameter, impregnated separately in 1,000, 100, and 10 ppm solutions of the chemicals, were placed on the surface of plated solidified and bacterium-seeded nutrient agar. Paper discs immersed in distilled water were the check.

of each chemical and for sterile distilled One paper disc for each concentration

In vitro bacterial inhibition efficiency of antibiotics and fungitoxicants at different concentrations against Xanthomonas campestris pv. oryzae. U. P., India.

Chemical Concentration Mean inhibition zone (mm)

24 h 48 h 72 h (ppm)

Streptocycline

Thiram (75% WP)

Streptomycin

MEMC

Zineb (75% WP)

Copper oxychloride

Foltaf (80% WP)

Carboxin (75% WP)

Deltan (50% WP)

Captan (50% WP)

1000 100

10 1000

100 10

1000 100

10 1000

100 10

1000 100

10 1000

100 10

100 100

10 1000

100 10

1000 100

10

27.8 25.8 23.0

22.0 17.0

0.0 21.0 16.0 0.0

18.0 15.0 0.0

18.0 0.0 0.0

17.0 0.0 0.0

15.0 14.0

0.0 15.0 0.0 0.0

15.0 0.0 0.0

27.8 25.8 23.0

22.0 16.5

0.0 21.0 16.0 0.0

17.8 15.0 0.0

18.0 0.0 0.0

16.6 0.0 0.0

15.0 14.0

0.0 15.0

0.0 0.0

14.0 0.0 0.0

27.8 25.7 22.6

21.0 15.2

0.0 20.5 15.0 0.0

17.3 14.5

0.0 17.8 0.0 0.0

15.5 0.0 0.0

14.5 13.0 0.0

14.0 0.0 0.0

14.0 0.0 0.0

water were placed in a petri dish. The experiment had three replications, three petri dishes serving as one replication. The plates were incubated at room temperature (30 °C ± 2). Zone of inhibition was recorded 24, 48, and 72 h after incubation.

Both antibiotics and seven fungitoxicants inhibited growth of X.c. pv. oryzae (see table); zineb, carbendazim (50% WP), thiophanate- methyl (70% WP), and sterile distilled water did not.

Streptocycline exhibited the widest zone of inhibition (27.83 mm) 24-48 h after incubation. It inhibited bacterial growth at all three concentrations. Thiram, streptomycin, MEMC, and Foltaf inhibited BB at 1,000 and 100 ppm. Four other chemicals showed inhibition only at 1,000 ppm. Higher concentrations invariably increased growth inhibition.

Maximum growth inhibition by Deltan was achieved 24 h after incubation. Other fungitoxicants did not differ with incubation time. In general, the inhibition declined 72 h after incubation, except with streptocycline.

Soil incorporation of fungicides to control sheath blight (ShB) I.F. Telan and D.B. Lapis, Plant Pathology Department, University of the Philippines at Los Baños (UPLB)

Fungicides were evaluated singly and in combination under upland and lowland


a Based on percent leaves (BB, BLS, BS), percent culms (ShB, ShR), and percent plants (khaira) infected/unit area. b Standard evaluation system for rice, 1980.

conditions during the 1983 wet season. Varieties were UPLRi 4 for upland and UPLRi 5 for lowland. Upland treatments (six) and lowland (eight) were in a randomized complete block design with three replications. Upland plots measured 2 × 3 m with 20 cm between rows; lowland plots were 2 × 2 m with 20- × 20-cm spacing. Fungicides were incorporated into the plots, and fields were planted the day after treatment. Plants were inoculated 45 d after fungicide application. Rice grain-hull culture of Rhizoctonia solani 3-4 wk old was inserted between tillers and between plants. Disease readings were taken 2-3 d before harvest on 10

Rice in the eastern part of Uttar Pradesh is mainly grown in the hot wet season 1 Jun-30 Nov. However, some farmers plant a small part of their holdings to rice during the hot dry season 1 Feb-15 Jun. Seedlings are raised while temperatures are still low. Although mainly dependent on irrigation, the crop occasionally receives one or two mild showers. It is harvested before the normal rainy season begins.

We surveyed farmers' fields in different districts and university experimental rice plots at Faizabad for incidence and severity of diseases in 1986 and 1987.

We identified bacterial blight (BB) caused by Xanthomonas campestris pv. oryzae (Ishiyama) Dye, bacterial leaf streak (BLS) caused by Xanthomonas

Diseases of dry summer rice in eastern Uttar Pradesh, India a Mean of 10 plants/treatment in 3 replications.

b Sampling area for yield was 1 m 2 . Means followed by the same letter are not significantly different at the 5% level. c Ethyl 3-(3-5 dichlo- rophenyl)-5-methy1-2-4 deoxo-5-oxazoldine carboxylate (Serinal 50% WP).

random plants/plot and severity computed:

plots treated with iprodione and benomyl-EMDOC had significantly less disease than the control (Table 2). In both situations, PCNB had the highest disease rating and disease severity. Iprodione and benomyl, singly or in combination, seem to control disease, although yields did not show significant differences.

Under lowland conditions, all treatments except PCNB had significantly less disease than the control (Table 1). Under upland conditions,

Table 1. Soil incorporation of fungicides to control ShB on UPLRi 4 under lowland conditions. a UPLB, Philippines.

Fungicide Rate Disease Yield b

(kg/ha) severity (t/ha) (%)

Iprodione 50% WP 1 71.0 4.6 a Benomyl 50% WP Benomyl-EMDOC c 1 77.7 4.1 a Benomyl-iprodione 1 72.9 4.1 a Triphenyltin acetate 1 71.8 3.6 a

74.9 4.5 a

60% WP-triphenyltin hydroxide 50% WP

iprodione Triphenyltin acetate 1 74.8 4.1 a

PCNB 50 87.3 4.3 a No fungicide (control) - 90.0 3.7 a

R.N. Singh, R.N. Vishwakarma, and A. T. Khan, N.D. University of Agriculture and Technology, P. O. Dabha Semar, District Faizabad 224133, U. P., India

Table 2. Soil incorporation of controlling ShB on UPLRi 5 under upland conditions. a UPLB, Philippines.

ate Disease Fungicide (kg/ha)

Yield b

(t/ha)

Iprodione 50% WP 1 47.0 3.4 a Benomyl 50% WP 1 50.7 3.1 a Benomyl-EMDOC c 1 44.4 2.1 a Triphenyltin acetate 1 48.8 2.9 a

60% WP-triphenyltin hydroxide 50% WP

PCNB 50 51.1 2.9 a No fungicide (control) - 57.7 2.4 a a Mean of 10 plants/treatment in 3 replications. b Means followed by the same letter are not significantly different at the 1% level. Sampling area for yield was 1 m 2 . c Ethyl 3-(3-5 di-

carboxylate (Serinal 50% WP). chlorophenyl)-5-methyl-2-4 deoxo-5-oxazoldine

Incidence and severity of major diseases in hot season rice in eastern U.P., India, 1986-87.

Disease Disease score b

BB BLS 0-20 1-5 BS 0-20 1-3 Khaira 0-15 2-5 ShB 0-10 1-3 ShR 10-60 5-7

Disease incidence a

(%)

10-80 3-9


campestris pv. oryzicola (Fang et al) Dye, brown spot (BS) caused by Helminthosporium oryzae Breda de Haan, khaira induced by Zn deficiency, sheath blight (ShB) caused by Rhizoctonia solani Kuhn, and sheath rot (ShR) caused by Sarocladium oryzae (Saw.) Gams (see table). Incidence and severity of the diseases varied from cultivar to cultivar and field to field in both years. BB and ShR occurred consistently and, depending on conditions, severely.

Virulent strain of rice grassy stunt virus (GSV) identified in Indonesia

Y. Suzuki, N. Widiarta, N. Raga, and S. Nasu, Directorate of Food Crop Protection, Indonesia: and H. Hibino, Plant Pathology Department, IRRI

An unidentified rice disease showing tungro (RTV)-like symptoms was noticed in Java in 198 1. We used a serological assay and transmission test to confirm its causal agent, a virulent strain of GSV.

Latex suspensions sensitized with antisera to GSV, rice tungro bacilliform virus, and rice tungro spherical virus were obtained from IRRI. GSV was detected by the latex test only in leaf samples collected from plants showing RTV-like symptoms at Cianjur, West Java. None of the samples reacted positively to antisera against the RTV- associated viruses.

planthopper (BPH) Nilaparvata lugens Laboratory colonies of brown

cpsadmin

Text Box

Rate (kg/ha)

cpsadmin

Text Box

Disease severity (%)

cpsadmin

Text Box

sum of disease rating total no. of rating ´ 9

cpsadmin

Text Box

´ 100

cpsadmin

Text Box

disease severity =

cpsadmin

Line

and green leafhopper (GLH) Nephotettix virescens were given 1-2 d access feeding on diseased plants collected at Cianjur. The test insects were transferred to healthy Cisadane seedlings for 1-d inoculation feeding immediately after acquisition feeding and after a 9-d incubation. Only BPH that had 9-d incubation transmitted the disease (see table). Transmission by BPH also was confirmed using artificially inoculated source plants,

Seedlings inoculated at 7 d developed stunting and pale-green to pale-yellow discoloration 6-14 d after inoculation. Later symptoms consisted of striping or mottling on the second and third leaves from the youngest, rusty spots on lower leaves, and narrowing and shortening of leaf blades. Drying started from the tips of leaves before chlorosis spread over a whole leaf. Additional N failed to retrieve infected plants.

Most infected plants died 19-75 d after inoculation. Tiller numbers in

Transmission of a virulent strain of GSV by BPH and GLH. a

Insects/ Incubation Plants Plants

Inoculation

Source plant Insect seedlings period (d) inoculated infected after feeding (no.) (%)

on source

Field collected GLH (2d instar) 30/10 0 30 0 BPH (2d instar) 30/10 0 30 0 BPH (2d instar) 9 60 23.3

Greenhouse infected BPH (2d instar) 30/10 9 40 Greenhouse infected GLH (adult) 1/1 0 30

7.5

1/1 0

GLH (adult) 9 30 0 BPH (2d instyb) 10/1 9 9 22.2

1/1

a Insects were allowed an acquisition access feeding of 1 or 2 d and then were given a l-d inoculation access to 7-d-old seedlings after no or 9-d incubation period. b Seedlings inoculated at 30 d.

diseased plants were not significantly stages of infection. Neither stunting nor different from check until 30 d after narrowing of leaves was conspicuous in inoculation. Plants that did not die 20 d after inoculation. However, later produced numerous small tillers. Leaves symptoms were not markedly different with symptoms responded positively, from those in 7-d-old seedlings. but not consistently, to iodine. These results show that the infectious

Seedlings inoculated at 30 d exhibited agent is a virulent strain of GSV. A uniform RTV-like orange-yellow recent field survey found the strain discoloration on the third leaves at early occurring widely in Central Java.

Insect management Effect of neem seed bitters (NSB) on green leafhopper (GLH)

Influence of carbofuran Effect of different levels of carbofuran 5% G virus (RTV) survival and rice tungro

transmission dose and time of on RWW. a Sancti-Spiritus, Cuba. application on control of rice water weevil (RWW)

Adult mortality Dosage (%) Larvae R. C. Saxena and M. E. M. Boncodin,

(kg ai/ha) 2 DAI 14 DAI 10 DAI

morta1ity (%) Entomology Department, IRRI

R. Meneses-Carbonell, Rice Experiment Station “Sur del Jibaro”, Sancti-Spiritus, Cuba

The RWW Lissorhoptrus brevirostris affects 10-28% of the land planted to rice in Cuba, and it is the most difficult insect pest to control.

Different levels of carbofuran 5% G (0.6-1.9 kg ai/ha) were broadcast before sowing (test 1) and 25 d after germination (DAG) (test 2).

Three plants of variety J-104 were sown in 12-cm-diameter clay pots. In test 1, they were inoculated with 20 RWW adults/pot 20 DAG. In test 2, 20 first-instar larvae/pot were inoculated the day after insecticide application.

All levels of carbofuran controlled RWW adults and larvae. Control was

0.6 72 82 98 0.8 70 88 98 0.9 68 84 98 1.1 68 86 96 1.5 70 88 100 1.9 74 88 100 Check 2 2 0

a Av of 4 replications. DAI = days after inoculation.

greater when carbofuran was applied 25 DAG than when it was broadcast before sowing (see table).

In the field, the insect shows similar behavior in respect to the time of invasion.

Application must be done when larvae are leaving the leaf sheath after hatching; that is the stage most susceptible to insecticides.

A reduction in phloem feeding by GLH Nephotettix virescens, the vector of RTV disease, is observed in plants with foliar or systemic application of NSB. RTV is phloem-specific. We evaluated RTV transmission efficiency of GLH feeding on NSB-treated plants.

Two-week-old TN1 seedlings were treated by 24-h root immersion or sprayed with 2,500 ppm NSB. Untreated seedlings were used as check. Each seedling was placed in a 15- × 1.5-cm test tube covered with nylon mesh and arranged by treatment.

Newly emerged GLH females reared on virus-free TN1 plants were allowed a 3-d acquisition feeding on source plants. One viruliferous GLH was transferred to each tube. One day after infestation


(DAI), surviving insects were transferred to freshly treated seedlings. Inoculated seedlings were transplanted in seedboxes for disease development. Successive inoculation feeding continued up to 5 d. RTV symptoms were observed at 20 DAI.

GLH survival decreased significantly after 2-d exposure to systemically treated plants. Although survival of GLH exposed to foliar NSB-treated seedlings was not significantly different from check, ability to transmit RTV was significantly lower than that of untreated seedlings (see table).

Systemic NSB application was best against RTV transmission. RTV transmission efficiency of the vector

became negligible after 2d inoculation feeding in check as well as in treated plants.

Compatible insecticides and fungicides to control leaffolder (LF) and sheath rot (ShR) in rice N. Raju, R. Saroja, and M. Suriachandraselvan, Rice Research Station, Tirur 602025, India

We studied the compatibility of commonly used insecticides phosphamidon, monocrotophos, and chlorpyrifos with popular fungicides edifenphos, mancozeb, and carbendazim

during 1985-86 and 1986-87. Field trials consisted of 10 treatments replicated 3 times. In both years, 25-d-old Co 43 seedlings were planted in 10-m 2 plots at 20- × 10-cm spacing. Combined sprays were applied at 20, 40, and 60 d after transplanting.

Only rice LF and ShR occurred during the study. In both years, combined spraying of monocrotophos with any one of the three fungicides was the most effective treatment, keeping LF infestation well below economic injury level (<5%). In 1986-87, combined

spraying of monocrotophos with carbendazim resulted in the lowest incidence of ShR (see table).

In both years, combined spraying of monocrotophos with the three fungicides resulted in the highest yields.

Brown planthopper (BPH) outbreak in Thanjavur District, Tamil Nadu

K. Natarajan, M.S. Venugopal, and S. Chelliah, Tamil Nadu Rice Research Institute, Aduthurai 612101, Tamil Nadu, India

During the Jun-Sep 1987 drought due to failure of the monsoon, a BPH out break in Sivapurani, Kondasamudram, and Kurichi villages of Kumbakonam division, Thanjavur District, caused typical hopperburn symptoms on IR50. Approximately 100 ha were affected. Farmers applied double the recommended N as basal fertilizer. Because the insecticides used were not directed toward the base of the plants, control was inadequate. Furthermore, the farmers sprayed quinalphos, a resurgence causing insecticide, which aggravated the pest population.

Unsprayed fields recorded 56 hoppers/hill; phosphamidon-sprayed fields had 8 hoppers/hill. Where quinalphos was sprayed, populations

Survival of GLH females and RTV transmission after 5 d exposure to TN1 rice seedlings treated with 2,500 ppm NSB. a IRRI, 1987.

GLH survival (%) RTV infection (%)

1d 2d 3d 5d 1d 2d

Foliar 95 a 91 b 84 b 69 b 38 b 8 a Systemic 90 a 74 a 69 a 51 a 17 a Check

4 a 95 a 89 b 84 b 74 b 65 c 22 a

a Av of 5 replications, 30 GLH and 30 TN1 seedlings/replication. In a column, means followed by a common letter are not significantly different at the 5% level by DMRT.

Treatment

Efficacy and compatibility of insecticides and fungicides in the control of rice pests and diseases. Rice Research Station, Tirur, India, 1985-86 and 1986-87.

1985-86 1986-87

Treatment LF-damaged Grain LF-damaged ShR Grain

leaves yield leaves infected yield (%) (t/ha) (%) tillers (%) (t/ha)

Phosphamidon 250 ml/ha + 29 3.1 15 7.0 4.2



Monocrotophos 500 ml/ha + 4 3.4 2 6.0 4.5

Monocrotophos 500 ml/ha + 3 3.6 3 6.0 4.2

edifenphos 500 ml/ha

mancozeb 1000 g/ha

carbendazim 250 g/ha

edifenphos 500 ml/ha

mancozeb 1000 g/ha Monocrotophos 500 ml/ha +

carbendazim 250 g/ha Chlorpyrifos 500 ml/ha +

edifenphos 500 ml/ha Chlorpyrifos 500 ml/ha +

mancozeb 1000 g/ha Chlorpyrifos 500 ml/ha +

carbendazim 250 g/ha Control

CD (P=0.05)

3 3.2 2 4.9 4.2

15 2.8 9 6.2 3.9

17 2.9 25 5.6 4.0

63 2.7 77 13.5 3.1 5.0 1.5 15.4 5.5 0.4

11 3.1 7 7.0 4.2


exceeded 250 hoppers/hill. Populations of natural enemies like mirid bug, wolf spider, and coccinellid beetles were higher in unsprayed fields.

Effect of neem seed bitters (NSB) on green leafhopper (GLH) feeding

R. C. Saxena and M. E. M. Boncodin, Entomology Department, IRRI

A simple process has been developed at IRRI to extract the “bitters” (limonoids) from neem seed kernel. Using an electronic device, we monitored the feeding behavior of newly emerged GLH Nephotettix virescens females on 21-d- old TN1 rice seedlings that had been treated systemically by overnight root immersion or by dipping the foliage in a 2,500 ppm NSB aqueous solution for 25 s.

During a 3-h observation, waveform

patterns (see figure) showed that duration of phloem feeding was significantly reduced in neem-treated seedlings (see table). The decrease in phloem feeding was accompanied by a corresponding significant increase in frequency of probing, salivation period, and xylem feeding. If GLH feeds less in the phloem, it has less probability of acquiring or transmitting tungro viruses.

Waveforms electronically recorded during N. virescens feeding on TNI rice plants, IRRI, 1987. a = control, b = 2500 ppm NSB-systemic, c = 2500 ppm NSB-foliar. P = probe, S = salivation, Pi = phloem ingestion, R = rest, Xi = xylem ingestion.

Events in 3-h feeding by N. virescens females on TN1 rice seedlings treated with 2,500 ppm NSB solution. a IRRI, 1987.

Probes Salivation (no .) (min)

Phloem Xylem Total ingestion ingestion ingestion

(min) (min) Treatment

(min)

Systemic 25 a 20.7 a 27 b 23 a Foliar 24 a 15.2 ab 33 b 27 a 60 a

50 a

13 b Control 9.6 b 77 a 1 b 78 a

a Av of 10 replications. In a column, means followed by a common letter are not significantly different at the 5% level by DMRT.

Effect of neem seed treatment on rice seedling vigor and survival of brown planthopper (BPH) and green leafhopper (GLH)

A.A. Kareem, R.C. Saxena, M.E.M. Boncodin, Entomology Department; and V. Krishnasamy and D.V. Seshu, IRTP, IRRI

The principal bitters of neem, particularly azadirachtin, are known to be systemically translocated through the roots. We evaluated seed treatment with crude neem seed kernel extract (NSKE) or neem cake (NC) as a BPH or GLH control measure for young seedlings. We also measured the effect of neem treatment on seed germination and seedling vigor.

In one treatment, healthy seeds of TNl, IR36, and IR42 were soaked in 2.5, 5, or 10% aqueous NSKE solution for 24 h, then incubated for 48 h. In

Table 1. Effect of seed treatment with crude NSKE and NC on BPH and GLH survival. a

IRRI, 1987.

Neem Nymphs becoming adults (%)

BPH on GLH on GLH on TN1 TN1 IR42

concentration (%)

NSKE 2.5 46.7 b 57.0 b 6.7 a 5.0 63.3 cd 44.3 b 10.0 a

10.0 30.0 a 6.7 a 10.0 a NC

1.0 50.0 bc 50.0 b 6.7 a 2.0 30.0 a 30.0 b 13.3 a 0 (check) 70.0 d 70.0 b 36.7 a

replication. In a column, means followed by the a Av of 3 replications, 10 first-instar nymphs/

same letter are not significantly different at the 5% level by DMRT.


another treatment, seeds soaked in water for 24 h were dressed with 1 or 2% NC powder and incubated for 48 h. Untreated seeds were used for the check.

At 7 d after sowing, individual TN1 seedlings in 15- × 1.5-cm glass test tubes were infested singly with first-instar BPH nymphs. TN1 or IR42 seedlings were infested with first-instar GLH nymphs. Insect survival was recorded daily until all nymphs became adults or died.

Fewer BPH nymphs reached adulthood on TN1 seedlings treated with NSKE or NC than on check seedlings, but only 10% neem extract treatment was significantly more effective than other treatments (Table 1). Only treatment with 10% NSKE reduced GLH nymph emergence on highly susceptible TN1. GLH nymph emergence on IR42 was not significantly affected by neem derivatives, probably because IR42 is already moderately resistant to GLH.

Seed germination of IR36 and IR42 and seedling root length, shoot length, and chlorophyll content were not affected by neem treatment. In fact,

Effect of plant derivatives on green leafhopper (GLH) and rice tungro (RTV) transmission

V. Narasimhan and V. Mariappan, Agricultural College and Research Institute, Tamil Nadu Agricultural University, Madurai 625104, India

Leaf extracts of nirgunda Vitex negunda L., croton Crotons sparsiflorus Marong, bilwa Aegle marmelos Coor., ocimum or sweet tulsi Ocimum sanctum L., and ikshugandha Tribules terestris L. in water; seed oils of neem Azadirachta indica A. Juss, laural Calophyllium inophyllum L., mahua Madhuca longifolia Koen. Macbr. var. latifolia Roxb. chevai, custard apple Annona squamosa Linn. in water emulsified with 1% teepol; crude seed extract of neem and cake extract of neem in water; and insecticides phosphamidon (dimecron)


Table 2. Effect of treating rice seed with crude NSKE and NC on germination and seedling vigor. a

IRRI, 1987.

Neem Germination Growth index treatment

Length (mm) Dry wt Chlorophyll b

(%) (%) (mg)/10

Root Shoot Root Shoot seedlings (µg/g)

NSKE 2.5 5.0

10.0

NC 1.0 2.0 0 (check)

NSKE 2.5 5.0

10.0 NC

1.0 2.0 0 (check)

IR36

96 a 77.5 a 66.0 a 95 a 79.8 a 71.3 a 94 a 81.5 a 70.5 a

94 a 60.8 b 60.5 b 96 a 55.0 c 63.5 b 94 a 34.8 d 44.3 c

IR42

96 a 43.8 ab 46.8 b 96 a 39.5 b 47.8 b 95 a 48.8 a 52.5 a

95 a 24.8 c 22.5 c 95 a 24.8 c 26.3 c 94 a 16.0 d 17.3 d

250.3 a 249.3 a 250.8 a

249.3 a 250.0 a 249.8 a

218.0 a 220.5 a 219.5 a

220.0 a 220.8 a 219.0 a

105.0 a 91 a 104.0 a 92 a 106.0 a 90 a

106.0 a 90 a 105.8 a 89 ab 105.3 a 85 b

80.0 a 83 ab 80.8 a 85 a 80.0 a 84 ab

80.0 a 80 bc 81.0 a 82 abc 81.0 a 78 c

51 a 50 a 52 a

50 a 51 a 49 a

106 a 106 a 105 a

104 a 106 a 104 a

a Av of 5 replications. In a column, means for each variety followed by a common letter are not sit- nificantly different at the 5% level by DMRT. b Fresh weight basis.

soaking seed in NSKE increased much as NSKE. Dried IR36 and IR42 seedling vigor, with significantly higher seedlings germinated from seeds without seedling root and shoot growth indices neem treatment weighed significantly than control. NC treatment also less than seedlings germinated from improved seedling vigor, but not as neem-treated seeds (Table 2).

GLH survival and RTV infection rates on TKM9 seedlings sprayed with leaf extracts, seed oils, and insecticides.

GLH survival (%) Source Rate a RTV

1 d 5 d 10 d (%)

Leaf extracts Nirgunda 10 100 65 15 14 Crotons 10 100 90 30 64 Bilwa 10 100 40 5 26 Ocimum 10 100 65 5 33 Ikshugandha 10 100 60 10 36

Neem oil 1 15 0 0 25 Custard apple oil 1 60 0 0 33 Laural 1 60 5 0 39 Mahua 1 80 45 5 17 Neem seed extract 2 95 75 0 54 Neem cake extract 5 100 55 5 31

Carbofuran 3 G 1.3 7 0 0 29 Phosphamidon 0.1 15 0 0 50

Control 100 90 15 75

a In percent, except carbofuran in kg/ha.

Seed oil or extracts

Insecticides

and carbofuran were tested for effects The plant derivatives and insecticides on survival of GLH Nephotettix were sprayed on l0-d-old TKM9 virescens Dist. and RTV transmission. seedlings raised in mud pots, using a

baby hand sprayer. Five hours after spraying, the seedlings were removed and the root portion washed.

The seedlings in test tubes with water were exposed for 24 h to GLH that had fed on RTV-infected plants for 4 d, at 2 insects/ seedling. Fifty seedlings were inoculated per treatment.

Inoculated seedlings were

transplanted in pots in insect-proof cages for development of symptoms. A fresh seedling already treated with a plant product or chemical was introduced into each tube containing an insect. Survival of insects was recorded until all insects died.

Seed oils gave higher GLH mortality than leaf extracts (see table). Neem oil

gave the highest mortality. GLH mortality on leaf extract-treated seedlings was not significantly different from that on untreated seedlings. Percentage RTV-infected seedlings was much reduced in all treatments over control. Seedlings treated with leaf extracts of nirgunda and bilwa had low RTV infection rates.

Weed management Chemical weed control in transplanted rice

M.A. Zafar, Adaptive Agricultural Research Farm, Sheikhupura, Pakistan

Two experiments, one in less weedy and one in highly weedy fields, evaluated five herbicides — piperophos + dimethametryn, butachlor, chlornitrofen, thiobencarb, and pendimethalin — at the adaptive research farm and 5 farmers' fields in 1983. Chlornitrofen and piperophos + dimethametryn were

not used in the highly weedy trials. An unweeded check was maintained.

The experiments were laid out in completely randomized blocks with three replications. KS-282 rice variety seedlings were transplanted at 35-40 d in 10- × 6-m plots the last week of Jun. Butachlor mixed with 60 kg sand and other granular herbicides were broadcast; pendimethalin in 400 liters water/ ha was sprayed 2-3 d after transplanting (DT). Water (4-5 cm deep) was retained in the fields for 5 d to allow herbicides to dissolve and make a

Effect of chemical weed control on tillering and yield of transplanted coarse rice and benefit-to-cost ratios of different weeding treatments in less and highly weedy fields.

Herbicide a Dose Weed Tillering b Paddy control b

(no./m 2 ) yield b Benefit:cost c

(t/ha) (kg ai/ha) (no./m 2 )

layer or film on the soil or water surface. Fertilization was 115 kg N, 25 kg P, and 47.3 kg K/ha. All the P and K and half the N were added at puddling, half the N at 30 DT. Weed count at 45 DT and at tillering (75 DT) was taken from 2 randomly selected 1-m 2 quadrats/plot. Yields were averaged.

Benefit-to-cost ratios were calculated by dividing the extra benefits attained from enhanced yield by the extra costs incurred for each treatment. Extra costs and benefits included cost and labor charges for herbicide application and price of enhanced yield.

Tillering was enhanced significantly by weed treatments except at the lower rate of butachlor in highly weedy fields (see table). The presence of grassy and more competitive weeds such as Echinochloa colona (L.) Link, E. crus- galli (L.) Beauv. and Paspalum distichum L., resulted in significant yield losses. Weed control was not necessary

Less weedy fields Check – 25.7 e 299.2 a 5.1 a Piperophos + dimethametryn G 0.910 4.0 bc 328.7 ab 5.5 a Butachlor EC 0.975 11.3 d 309.1 ab 5.1 a Butachlor EC 1.200 2.0 a 340.0 b 5.6 a Chlornitrofen G 3.600 15.5 d 305.5 ab 5.1 a Thiobencarb G 2.000 6.0 c 327.3 ab 5.4 a Thiobencarb G 2.500 3.0 ab 337.9 b 5.5 a Pendimethalin EC 1.237 5.0 bc 334.0 ab 5.5 a

Highly weedy fields Check – 164.3 e 215.6 a 5.3 a Butachlor EC 0.975 72.0 d 226.2 a 5.6 a

when weed infestations were low. Weed control in rice can be economically achieved with chemical herbicides. Underdosing of butachlor is not beneficial.

In order of their prevalence, weeds in the experimental fields were Cyperus iria L., C. difformis L., C. rotundus L.,

– Fimbristylis miliacea (L.) Vahl, 1.82:l Echinochloa crus-galli ssp. hispidula

Butachlor EC 1.200 11.7 a 285.6 c 7.5 d 9.79:1 Thiobencarb G 2.000 35.0 c 252.5 b 6.2 b 2.88:1 Thiobencarb G 2.500 22.3 bc 268.1 bc 7.0 c 4.40:1 Pendimethalin EC 1.237 15.3 ab 270.4 bc 7.0 c 4.33:1

a G = granule, EC = emulsifiable concentrate. b Av of 6 sites and 3 replications at each site in the district. In a column, figures followed by a common letter are not statistically different at 0.05% level of confidence (DMRT). c For economic analysis, the costs included herbicide price (thiobencarb 10 G @ $1.21/kg, and butachlor 60 EC and pendimethalin 33 EC @ $8.62 and $8.05/liter, respectively) and application costs ($2.59 or $1.44/spray or broadcast). Benefits included the price of enhanced yield over that of the check @ $3.33140 kg paddy.

Benefit:cost = extra benefits (for treatments). extra costs

(Retz.) Honda, Sphenoclea zeylanica Gaertn., E. colona, E. glabrescens Munro ex Hook. f., Marsilea minuta L., Cynodon dactylon (L.) Pers., Paspalum distichum, Nymphaea nouchali Burm. f., Eleusine indica (L.) Gaertn., Dactyloctenium aegyptium (L.) Willd., Leptochloa chinensis (L.) Nees, Digitaria ciliaris (Retz.) Koel., and Trianthema portulacastrum L.


Managing other pests Nitrogen fertilization and Meloidogyne incognita incidence in rice

O. A. Fademi, Rice Research Program, National Cereals Research Institute, Badeggi, P.M.B. 8, Bida, Nigeria

We examined the influence of different rates of sulfate of ammonia on M. incognita in a greenhouse experiment. Faro II (OS6) seeds were grown in autoclaved sandy loam soil in microplots (1.5 × 1 × 1 m). Each block was inoculated with 600 eggs and second-stage juveniles of M. incognita obtained from galled roots of Celosia sp.

Sulfate of ammonia treatments at 30 and 45 kg N/ha, and an unfertilized control were in a completely randomized block design with 3 replications. Data on emergence, seedling vigor, and plant height were taken. Roots were examined for galls

and processed for nematode recovery. Plant performance in the fertilized

plots was better (see table). Galling was less in plants that received 45 kg N/ha, and the galls obtained were much smaller. Nematode recovery from infected roots was highest in plants without fertilizer. Although plants were much taller at reduced N, seedling vigor was less.

Effect of ammonium sulfate fertilizer on M. incognita in rice. Badeggi, Nigeria.

Plant Treatment height

(cm)

Seedling Galling vigor a index b

Nematode recovery

(no.)

No N 30 kg N/ha 45 kg N/ha

LSD (5%)

53.5 48.0 42.3

4.7

4 3 1.5

1.71

2.5 0.5 –

23.50 16.10

7.20

15.03

a Standard evaluation system for rice. b 0 = no galls, 5 = maximum galling.

Water management

Economizing irrigation through rice fallow cropping strategies

B. P. Patil, Irrigation Research Scheme, Konkan Krishi Vidyapeeth, Wakawali 415711, Dist. Ratnagiri (M.S.), India

Water needs of alternative crops (peanut, sunflower, and green gram) were evaluated in irrigated rice fallows of coastal Maharashtra in 1986. The area receives essentially monsoon rainfall (2,500-3,500 mm) Jun-Sep, with a characteristic rain-free period Oct-May.

Soil of the experimental plot was medium black, with 0.63% organic C, 12.68 kg P, and 157.7 kg K/ha. Peanut, sunflower, and green gram were sown the first week of Jan; rice was sown in mid-Dec and transplanted in late Jan. Recommended fertilizer, plant density, plant protection, and irrigation were adopted. Water used by different crops was recorded throughout growth. Water use efficiency (WUE) was based on yield and water utilized.


The rice crop needed 1,185 mm of water for a yield of 4.1 t/ha (see table). Peanut, sunflower, and green gram

required 612-775 mm less water than rice, a 53-65% water economy with WUE almost identical (2.92-3.49 kg/ha per mm) to that of rice. The gross return from 1 mm of irrigation was about 2.4 times greater with alternative crops.

Water use by rice, peanut, sunflower, and green gram on the irrigated rice fallows. Ratnagiri, Maha- rashtra, India, 1986.

Gross Water Gross Water use Economy in

(t/ha) ($/ha) (mm) ($/mm irrigation) (kg/ha per mm) water (mm) Crop Yie1d returns a applied returns efficiency irrigation

Rice Peanut Sunflower Green gram

4.1 2.0 1.5 1.2

788 923 692 646

1185 572 430 410

0.66 1.60 1.60 1.58

3.46 3.49 3.49 2.92

– 612 (53) 755 (64) 775 (65)

a From grain or pod.

Farming systems Effect of tillage on stem borer (SB) larvae carryover in a rice - wheat rotation

M.A. Zafar and A. Razzaq, Adaptive Agricultural Research Farm, Sheikhupura, Pakistan

Little time is left after rice harvest to prepare land for sowing wheat. Farmers cultivate twice, broadcast wheat seed, and cover it with a tractor-drawn wooden plank. Zero tillage or direct drilling is being introduced to reduce production costs.

But zero tillage leaves intact the rice stubble that harbors hibernating Scirpophaga incertulas, S. innotata, and Sesamia inferens SB. The larvae carry over to the next rice crop. Sesamia sp. also attacks wheat, spring maize, and sugarcane.

We assessed the extent to which Basmati 370 rice stubble would remain in condition for infestation by hibernating SB larvae in four differently tilled wheat fields in 1984-85 and 1985- 86. A 65-hp tractor and implements (cultivator, plank, rototiller, and seed drill) were used in tillage operations in 30- × 30-m plots at the adaptive research farm and on 3 farmers’ fields. Stubble was collected from 4 randomly selected 3-m 2 areas of each tillage type — zero-tilled/direct-drilled; cultivator run twice followed by one planking; cultivator run three times followed by two plankings; rototiller once, cultivator

Intercropping upland rice and Lamtoro in acid Red Yellow Podzolic soils

D. Djamaan, A. Tahir, A. Yusuf, A. Jugsujinda, and A. K. Syarifuddin, Sukarami Research Institute for Food Crops (SARIF), P. O. Box 103, Padang, West Sumatra, Indonesia

We studied the interactions of four cultivars of Lamtoro Leucaena leucocephala with upland rice Oryza sativa cultivar Sentani in acid Red Yellow Podzolic soil during 1983-84 cropping season. The soil was classified Haplorthox - Paleudult, with a 0-27 cm clayey topsoil, with pH of 4.2, exchangeable Al+H and Ca+Mg 4.0 and 0.7 meq/100 g, and A1 saturation 85%.

Three-month-old Lamtoro seedlings were planted in double hedgerows 2 m apart (see figure). Each double hedgerow was 50 cm apart, with 33.3 cm between plants. Triple superphosphate (TSP) at 200 kg/ ha was applied at the bottom of the plant hole at planting. The plants were cut back to 30 cm above the ground 4 mo after planting

Effect of tillage on stubble destruction and rice SB larvae hibernation in wheat following rice. a

Sheikhupura, Pakistan.

Tillage operation Stubble SB-infested Larvae Destruction (%) (no./3 m 2 ) stubble (%) (no./stubble) of stubble

Zero-tilled b /direct-drilled 137 a Cultivator (2) + plank (1) 44 b Cultivator (3) + plank (2) 26 c Rototiller (1) + cultivator 1 e (2) + plank (1)

Zero-tilled b /direct-drilled 138 a Cultivator (2) + plank (1) 37 b Cultivator (3) + plank (2) 14 d Rototiller (1) + cultivator (2) 0 e + plank (1)

1984-85 84 a 46 b

5 d 0 e

1985-86 83 a 37 c

5 de 0 e

3.8 ab 1.8 d 0.7 ef 0.0 f

2.9 be 2.0 cd 1.8 d 0.0 f

0 64 79 99

0 70 88 99

a Figures followed by common letters are not statistically different (95% level of confidence by DMRT). b No land preparation carried out. Wheat seed directly drilled.

twice, and planking once. The stubble Cultivating followed by planking was was dissected in the laboratory for not as effective in stubble destruction, number of SB larvae/ stubble. but its effectiveness increased with

of stubble and no hibernating SB larvae highest in the stubble of zero- in the rototilled fields (see table). tilled/direct-drilled fields.

Data reveal nearly 100% destruction number of runs. Larvae infestation was

Planting arrangement of Lamtoro and upland rice. Sumatra, Indonesia, 1983-84.

and the biomass incorporated into the soil.

incorporating Lamtoro, upland rice was interseeded at 25- × 25-cm spacing into the well-established Lamtoro rows. Then 200 kg TSP, 50 kg KCl, and 40 kg carbofuran/ ha were applied at the bottom of the plant hole with rice seeds. Two additional cuttings of Lamtoro were made at 2-mo intervals after rice seeding.

One month after cutting and

The experiment with Lamtoro cultivars Peru, K-8, K-28, Gung, and control without Lamtoro was laid out in a randomized complete block design with four replications. Plot size was 5 × 5m.

After three cuttings, cumulative dry weight of biomass of Peru was 4.6 t, Gung 4.7 t, K-8 5.2t, K-28 6.3 t/ha (see table). However, the interactions between upland rice and Lamtoro did not appear to favor upland rice growth


and yield. At harvest, rice had a significant plant height reduction of 9- 12% and tiller number reduction of 18- 24%. The pure stand of upland rice yielded 2.8 t/ha; intercropped rice showed significant yield reduction. Reduced plant height, tiller number, and grain yield was correlated positively with

Lamtoro cumulative dry weight. exchangeable Ca+Mg occurred in the

interaction between Lamtoro cultivars rice and Lamtoro and returning and intercropped upland rice with the Lamtoro biomass to the soil over a 2 m row spacing. Row spacing should period of several years may actually be adjusted for optimum rice yield. result in decreased A1 and increased

and Al saturation and an increase in

The results suggest a negative intercropped plots. Intercropping upland

A decrease in exchangeable A1+H plant nutrients in the soil.

Cumulative dry weight of Lamtoro after 3 cuttings, growth and yield of intercropped upland rice, and soil chemical properties after rice harvest. a Sumatra, Indonesia, 1983-84.

Lamtoro dry weight variety Cumulative Upland rice plant height (cm) Upland rice tillers (no./hill) Upland rice Exchangeable Exchangeable A1

grain yield A1+H Ca+Mg saturation (t/ha) 30 DAS 60 DAS Harvest 30 DAS 60 DAS Harvest (t/ha) (meq/100 g) (meq/100 g) (%)

Peru 4.6 a 43 a 73 a 111 c 19 a 34 a 13 b 2.1 b 3.9 ab 0.8 a 82 ab K-8 5.2 a 45 a 74 a 120 ab 20 a 37 a 14 b 2.4 b 3.8 ab 0.8 a 82 ab K-28 6.3 a 47 a 76 a 120 ab 18 a 38 a 14 b 1.7 c 2.8 b 1.5 b 63 b Gung 4.7 a 41 a 69 a 115 bc 17 a 39 a 14 b 2.1 b 3.5 ab 0.9 a 84 a

Control – 42 a 79 a 126 a 21 a 36 a 17 a 2.8 a 4.0 a 0.7 a 85 a

a DAS = days after seeding. Data are means of 4 replications. Mean separation by DMRT at 5%.

Performance of Performance of T. aman varieties in farmers’ cropping patterns at Hathazari, Bangladesh, 1982-83. a

transplanted aman rice varieties in cropping Flowering (DT) Maturity (DT) Grain yield (t/ha)

Variety pattern trials 1982 1983 1982 1983 1982 1983

A. Hashem, Agronomy Department, BR3 68 b 70 ab 109 b 112 b 3.2 a 3.5 ab

Institute of Postgraduate Studies in BR4 65 c 67 bc 106 bc 109 bc 2.6 ab 3.0 b BR10 64 c 66 c 106 bc 108 c 3.2 a 3.4 b

Agriculture; and Md. Jahiruddin, Farm BR11 62 d 64 c 101 c 108 c 3.2 a 4.3 a Division, Bangladesh Agricultural Research Pajam 56 e 59 d 97 d 101 d 2.8 a 2.7 b Institute, Joydebpur, Gazipur, Bangladesh Chakkal (check) 72 a 73 a 114 a 117 a 2.0 b 2.8 b

CV (%) 2.7 4.6 2.9 2.1 19.8 20.0

We evaluated six T. aman rice varieties in cropping pattern trials in the 1982-

a DT = days after transplanting.

1983 late wet seasons. The Hathazari cropping systems site is medium high land. The objective was to identify short-duration varieties with higher SOCIOECONOMIC AND yields at low fertilizer levels in the broadcast aus - T. aman - cowpea cropping pattern under rainfed ENVIRONMENTAL IMPACT conditions.

The experiment was laid out in a randomized complete block design with Production five replications across farms. Each year, 37-d-old seedlings were transplanted 24- 27 Aug at 20- × 15-cm spacing with 60- 17.6-16.6 kg NPK/ha.

The varieties exhibited significant variations in yield, days to flowering, management in a split-plot design with

Economics of rice gall midge (GM) management in resistant and susceptible cultures

We studied the incidence of GM in three resistant and one GM-susceptible cultivars with and without pest

and days to maturity (see table). G. Logiswaran, V. Kr. Sathiyanandam, and three replications during the 1986 wet

shattering, with medium grains. Its Entomology Department, Agricultural GM incidence in the susceptible market value is higher because its grains College and Research Institute, Madurai variety crossed the economic threshold produce quality rice and pop. 625104, India (ETL) 48 d after transplanting (DT)

BR11 is resistant to lodging and P. C. Sundara Babu, Agricultural season.


and again 68 DT. Incidence in the 3 resistant varieties did not cross ETL, but leaffolder incidence crossed ETL at 68 DT.

In the pest management plots, the susceptible variety received two sprayings; the resistant varieties received one. Phosalone 35 EC at 1.5 liters/ ha

was sprayed 48 DT, monocrotophos 36 WSC at 500 ml/ha was sprayed 68 DT. GM incidence was calculated as percentage affected tillers.

GM incidence among the three GM- resistant varieties was significantly lower in IET8649 and higher in IET6315 (see table). The three GM-resistant varieties

that received only one spraying gave higher yield and income than the GM- susceptible variety with two sprayings.

Yield of GM-susceptible variety Sona was on a par with that of GM-resistant varieties IET8649 and 6315. Highest income was from GM-resistant variety IET8655 (1:12.12 cost-benefit ratio).

Economics of the use of GM-resistant and susceptible cultures. a

GM incidence (%) 80 DT Grain yield (t/ha) Added returns Cost Added net Cost-to-

PM No PM Mean PM No PM Mean ($/ha) ($/ha) to PM ($/ha) due to PM of PM returns due benefit ratio Culture

GM-resistant IET8649 1.7 2.0 1.85 a 6.40 5.83 6.12 b 89.7 9.8 79.9

IET8655 3.8 3.2 3.50 b 8.22 7.40 7.81 a 129.1 9.8 119.3

IET6315 4.8 7.1 5.95 c 7.02 6.45 6.74 b 89.7 9.8 79.9

1:8.12

1:12.12

1:8.12

(7.9) (8.4) (8.15)

(11.7) (10.9) (11.30)

(13.2) (15.7) (14.45) GM-susceptible

Sona 11.4 18.6 15.00 d 5.93 5.72 5.83 b 33.1 24.8 8.3 Loss (20.1) (25.5) (22.80)

(13.2) (15.1) Mean b 5.4 7.7 6.89 b 6.35 a

a Figures in parentheses are arc sine values. PM = pest management, no PM = no pest management. Means in a column followed by a common letter are not significantly different at the 5% level. b Means followed by a common letter are not significantly different at the 5% level.

ANNOUNCEMENTS Deepwater rice rice crop; ratooning the deepwater rice; workshop examines use of rice herbage from the deepwater innovative cropping rice crop; methods for screening against

ufra nematode and yellow stem borer; The Deepwater Rice Workshop in and methods for measuring oxygen, Bangkok, Thailand, 26-30 Oct 1987 was carbon dioxide, and ethylene in cosponsored by IRRI and the Thai floodwater. Department of Agriculture and the Rice IRRI will publish the proceedings. Research Institute of the Ministry of Agriculture and Cooperatives. The 79 participants and 36 observers from 16 1987 International Rice countries included trainees in the special Research Conference Genetic Evaluation and Utilization Training Course for Deepwater Rice Nearly 100 participants from 19 and participants in the Deepwater Rice countries met 21-25 Sep 1987 in Monitoring Tour that visited Vietnam, Hangzhou, China. The focus was on India, and Thailand. Discussion groups irrigated rice. Discussions spanned the on research priorities, methodology, global rice situation, physiological breeding strategies, and terminology aspects of yielding ability, disease, insect, made recommendations for future and weed management; nutrient action. management; water management and

The workshop produced a number of farming systems; innovative breeding; innovative ideas, such as additional grain quality; farm machinery and crops (sunflower, early-maturing rice, postharvest management; and etc.) before, with, or after the deepwater collaborative research relationships.

Extensive recommendations for research and related priorities were made in all areas.

dedication of the China National Rice Research Center research facilities and buildings at the experimental farm site. National Minister of Agriculture, Animal Husbandry, and Fishery He Kang addressed the conference during opening ceremonies.

A proceedings including selected key papers and abstracts of the 64 papers presented will be published by IRRI in late 1988.

A highlight of the conference was the

Gene banks and the world’s food

Gene banks and the world’s food by D.L. Plucknett, N.J.H. Smith, J.T. Williams, and N.M. Anishetty provides a history of germplasm preservation and exchange (from botanical gardens to modern cold-storage units) and an assessment of the scientific and political ramifications of gene bank programs. It contributes to the debate on how best to


preserve some of the world’s most valuable raw material, and gives an up- to-date report on the stocks and locations of gene banks. Data for ordering: Princeton University

Press. 1987. Hardcover. 248 p. ISBN 0-691-08438-6. Price includes shipping, US $35; Outside USA: $42.00 via surface mail; $47.00 via airmail.

Payment must accompany order to AGRIBOOKSTORE, Winrock International, 1611 North Kent St., Arlington VA 22209, USA

Environmental impact of pesticides

The Pesticide Impact Section of the London-based Overseas Development Natural Resources Institute has compiled a computer database of books and scientific articles about the environmental side-effects of pesticides (including herbicides and fungicides) in the tropics. ENVIRON is designed to provide a rapid and comprehensive information service to scientists, farmers, and agricultural administrators living in developing countries and working for international development organizations.

information previously widely scattered throughout the scientific literature. Use of such information can help ensure that inefficient and environmentally damaging uses of pesticides are minimized.

Gathered within ENVIRON is

Topics covered include: • Pesticide toxicity to nontargets • Pesticide persistence and residues • Environmental fate of pesticides • Ecological impact of pesticides on

nontarget organisms: evidence of mortalities, population changes, and sublethal effects (e.g., animal behavior)

ENVIRON can handle inquiries about the effect of pesticides on nontarget organisms (including soils). It requires specifying the pesticide or pesticides, the target pests or nontarget organisms, or a combination of these. The output is a list of references, each of


which is followed by an indication of the contents of each paper and, in some cases, a relevant abstract. Depending on the request, an information synthesis is available. At present, there are no plans to provide on-line facility for external users. For information, contact: PESTICIDE

IMPACT SECTION, Overseas Development Natural Resources Institute, College House, Wrights Lane, London W8 5SJ, England.

Crop loss assessment to improve pest management

More than 100 scientists attended this workshop 11-17 Oct 1987 at IRRI. Five working groups and national program leaders of the UN Food and Agriculture Organization (FAO) and the Inter- country Program on Integrated Pest Control (IPC) made recommendations for future work.

The term pest was taken to include insects, disease, pathogens, weeds, and vertebrates that damage the rice crop.

Pest assessment and sampling recommendations focused on standardization of methods and formats for collecting, managing, and exchanging data. Thresholds and intensity/ loss relationship recommendations focused on establishing a network to facilitate exchanges among national programs.

The farm-level decisionmaking group defined the important objective as increasing self-reliance of all workers in the technology transfer system in making correct pest management decisions. Pest and crop loss databases need pan-national information on distribution; effects on farm infestations, yields, and pesticide use; policy decisions and planning; pesticide logistics; modeling and forecasting research; germplasm evaluation; and quarantine.

The concerns of the group working on economics and utilization of pest and loss data were data reliability and extension of research technology deeper into national programs.

National program leaders from the FAO intercountry program on IPC in

rice agreed that IPC goals should be based on local problems and be determined by national priorities, with emphasis on farm and community level pest management.

New IRRI publications Farmer’s primer on growing soybean on

Farmer’s primer on growing cowpea on riceland

riceland

ERRATA 12 (2) (Apr 1987). Minimum isolation distance for hybrid rice production, by H.L. Sharma, H. Singh, and D.P. Joshi p. 24: In the table, the seven columns under percent seed set . . . should bear, respectively, the following headings indicating direction: N, NNE, NE, ENE, E, SE, and S.

12 (3) (Jun 1987). A simple device for mass extraction of rice anthers, by S.K. Raina and S. Hadi. p. 24: In column 1, lines 9-10 should read: “with a 3.5-cm length of steel tubing fitted into the screw cap of the bottle. From ”. . . In the figure, 1) add this sentence to step 4: “Anthers float out of the slits.” 2) Replace the sentence in Step 5 with this “Debris is removed with the bottle, leaving usable anthers floating in the medium.”

12 (4) (Aug 1987). Stem borers (SB) in dryland and wetland rice, by A.T. Barrion and J.A. Litsinger. p. 17: In the figure, 1) the names of 4 varieties should be corrected to read as Beira Campo, Jaguarizhino, Levanta Homem, and Meruim Vermelho; and 2) Seratus Malam is an indica variety.

In column 2, replace sentence 2 of paragraph 2 with this sentence: “Traditional upland japonica varieties were more severely damaged, but two improved upland japonicas (IRAT144 and CNA108-13-42-24-2B) had the lowest numbers of whiteheads and stem borer larvae (see figure).”

international rice research newsletter vol.13 no.1

Documents