international rice research newsletter vol12 no.1

Contents GENETIC EVALUATION AND UTILIZATION

Overall progress 3 A high-yielding, early-maturing variety for the rainfed uplands of Orissa 3 TPS1, a short-duration red rice in Tamil Nadu 4 Rice variety resistant to gall midge (GM) and bacterial blight (BB)

released in Madhya Pradesh (MP), India

Agronomic characteristics 4 Influence of vegetative growth duration on grain grade 5 Dormancy in some early and medium duration varieties 5 Ratoon tillering in short-duration rice varieties

Grain quality 6 Grain grades in relation to seedling growth and productivity

Disease resistance 6 Susceptibility of rice hybrids to blast (Bl) 7 Tolerance of Sitopas crosses for ragged stunt virus (RSV) 7 Sources of resistance to sheath rot (ShR) 8 Resistance of elite rice strains and varieties to bacterial blight (BB) 8 Source of ufra-resistant deep water rice 8 Performance of medium-duration IRRI lines at Tamil Nadu

Insect resistance 9 Potential donors for brown planthopper (BPH) resistance 9 Multiple resistance of BG367-3 to major insect pests and diseases

10 Resistance of IR varieties to leafhoppers and planthoppers 11 Reaction of eight rices to gall midge (GM)

Other pests 11 Resistance of some rice varieties to the root-knot nematode (RKN)

Meloidogyne incognita

Temperature tolerance 11 Extent of wind-induced tip drying in popular rice varieties in

Coimbatore

Weather 12 Factors causing winter yield declines in high-yielding varieties

Hybrid rice 13 Isolation of restorers and maintainers for two Chinese male-sterile lines

having wild abortive (WA) cytoplasm 13 Recurrent selection in rice 14 Cytogenic relationship between two cytoplasmic male-sterile lines 14 Survival of some F 1 rice hybrids and their parents in saline soil

Tissue culture 15 Variability in quantitative traits of anther culture-derived progenies

PEST CONTROL AND MANAGEMENT

Diseases 16 Virulence of isolates of Xanthomonas campestris pv. oryzae of Haryana 17 Controlling sheath rot (ShR) in rice 17 Pseudomonas fluorescens suppresses development of bacterial blight

17 Multiplication and movement of bacterial blight (BB) pathogen in the

18 Occurrence of rice ragged stunt virus (RSV) in Sri Lanka

(BB) symptoms

rice plant

Insects 18 Meadow grasshopper Conocephalus longipennis damage to rice

19 Ochthera sauteri Cresson (Diptera:Ephydridae), predator of rice whorl spikelets

maggot (RWM) flies

20 Five granular and 4 sprayable insecticides evaluated for yellow stem

20 Daylength effect on development of 4 green leafhopper Nephotettix spp. 21 An earwig predator of Asian pink stem borer (PSB) in upland rice 21 Ovicidal activity of eight insecticides against the rice whorl maggot

22 Leafhopper and planthopper populations and rice tungro virus (RTV)

borer (YSB) control

(RWM) Hydrellia philippina Ferino

incidence at the tail end of an irrigation system

Weeds 23 A survey of weeds in transplanted and wet-seeded rice under rainfed and

23 Control of Eragrostis japonica (Thunb.) Trin. in upland rice 24 Weeds in shifting cultivation in Quezon Province, Philippines

irrigated conditions

Other pests 24 Golden apple snail: a pest of rice

IRRIGATION WATER MANAGEMENT

25 The effect of supplementary irrigation on rice yield in Bangladesh 26 Irrigation management for lowland rice under water constraint

SOIL AND CROP MANAGEMENT

27 Response of rice to N split application on a saline soil 27 Efficiency of urea-based fertilizers in coastal rice 28 Crop establishment with inverted-T seeder 28 Effect of green manure on yield 29 Effect of neem leaf application on nitrogen efficiency in lowland rice 29 Effect of sunlight and temperature on azolla nitrogen requirements 30 Response of rice to Azospirillum inoculation 31 Pulse crop residue as N source in rice-based cropping system 31 Fertilizer efficiency with dry placement 32 Response of rainfed rice to nitrogen level and postplanting soil

32 Integrated nitrogen management for lowland rice 32 Slow-release urea fertilizers in sodic soils 33 Influence of organic amendments and oils on ammonia volatilization in

34 Effect of sowing time and planting method on rice yield per day 34 Efficacy of Azospirillum brasilense in increasing rice yield 34 Phosphate sources for lowland rice

management practices

flooded rice

RICE-BASED CROPPING SYSTEMS

35 Irrigated rice-based cropping strategies in coastal Maharashtra

ANNOUNCEMENTS

35 An inside look at the Green Revolution 36 HY varieties spread 36 T.T. Chang honored 36 M.S. Swaminathan receives Albert Einstein World Award 36 R.F. Chandler honored by U.S. President

Guidelines and Style for

IRRN Contributors Genetic Evaluation and Utilization OVERALL PROGRESS

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

Guidelines • Contributions should not exceed two pages of

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

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

• Appropriate statistical analyses should be involving rice.

done. • Announcements of the release of new rice

• Pest survey data should be quantified. Give varieties are encouraged.

infection percentage, degree of severity, etc.

Style • For measurements, use the International

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

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

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

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

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

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

• Place the name or denotation of chemicals or other measured materials near the unit of

kg/ ha N; 200 kg seed/ ha, not 200 kg/ ha seed. measure. For example: 60 kg N/ ha, not 60

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

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

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

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

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

bibliography.

• Abbreviate names of standard units of

(g/pot) or g/row.

• Do not cite references or include a

A high-yielding, early-maturing variety for the rainfed uplands of Orissa

D. Satpathy, U.N. Dikshit, B. Misro. and D. Parida, Orissa University of Agriculture and Technology, Bhubaneswar 751003, India

Subhadra (DR92), a pedigree selection from TNl/SR26R from the Bhubaneswar Dry land Agriculture Research Centre, has been released by the Orissa State Variety Release Committee for general cultivation in rainfed uplands throughout the state.

The short-statured variety has an average plant height of 70 cm, moderate tillering ability, coarse (medium bold) grains, about 40,000 grains/ kg, and good cooking quality. Maturity is about 90 d. The variety is

drought tolerant and responds well to fertilizers. Yields are stable, with little insect and disease problems.

As a direct seeded kharif crop, Subhadra yielded consistently higher than Bala, Annapurna, and other standard high-yielding varieties in multilocational trials in rainfed uplands (Table 1).

In 1976–78 tests at 4 dryland research centers outside Orissa, Subhadra was the highest yielder at Dehradun (4.1 t/ha) and Rewa (3.2 t/ ha); its performance was commendable at Ranchi (2.5 t/ha) and Varanasi (2.1 t/ ha). In the northeastern hill states — Meghalaya, Manipur, and Sikkim (500-1,000 m altitude) — it was found suitable for direct seeding and transplanting (Table 2). It was tolerant of blast disease and matured in about 140–145 d.

Table 1. Grain yield of Subhadra in kharif multilocational tests (1973–79), Orissa, India.

Location Yield (t/ha)

Years (no.) Subhadra Bala (check) Increase (%)

Bhubaneswar 5 2.0 Chiplima 3 2.0 Joshipur 3 2.4 Berhampur 1 3.5

Overall average 2.4

1.6 1.2 2 .0 3.2 2.0

25 61 20

9 20

Table 2. Grain yield of Subhadra in the northeastern hill regions, India.

Location Yield (t/ha)

Subhadra Local check Increase (%)

Meghalaya 2.6 2.3 14 Manipur 5.0 3.2 55 Sikkim 2.8 1.6 70

TPS1a short-duration red rice in Tamil Nadu A promising short-duration red rice

culture TP1334-1 to replace the local S. Kalaimani, O. Ramanathapillai, S. Palanisamy, G. Radhakumar, and A. Idhyarajan, Paddy Experiment Substation (PES), Thirupathisaram 629901, Tamil Nadu, India

variety Kattisamba in Kanyakumari District performed well in 1980-84 yield trials and in the 1983-84 Adaptive Research Trials in farmers’ fields. It was released by the state

IRRN 12:1 (February 1987) 3

varietal release committee in 1985 as TPS1. This is the first variety released from the Thirupathisaram PES, Tamil Nadu.

IR8/ Kattisamba, is semitall (110 cm), matures in 110-115 d, and has higher

TPS1, a derivative of

yield potential than local Kattisamba. It is medium tillering with light green foliage and good panicle exsertion. Panicles are long and compact.

Average grain yields of 5.0 t/ha, 17.8% more than those of Kattisamba, have been recorded. Production

potential is 7.8 t/ha. Average straw yield is 9.2 t/ha. The grain is short bold with a red kernel closely resembling that of Kattisamba. It possesses good cooking quality.

borer. TPS1 has field tolerance for stem

Rice variety resistant to gall midge (GM) and bacterial blight (BB) released in Madhya Pradesh (MP), India

R.K. Sahu, Plant Breeding Department, IRRI

Usha, a semidwarf high yielding rice variety with resistance to GM and BB, has been released for general cultivation in MP. Usha is derived from IR22/W1263. It resembles IR22 in plant type. IR22 is susceptible to GM and BB but Usha and W1263 are

Table 1. Reaction to BB (PXO 61) of F 1 and F 2 progenies from crosses of TN1 with Usha and W1263. MP, India.

Disease reaction Cross F 2

Resist ant (no.) Susceptible (no.) x 2 3:l TN1/Usha TN1/W1263

Resistant Resistant

671 287

245 113

1:40 2.08

resistant at Raipur, MP. A single dominant gene GM1 conferred Usha’s resistance to the GM biotype.

conferred resistance to BB (Table 1). Usha and W1263 have the same allelic gene Xa -4 as IR22 has (Table 2).

A single dominant gene also

Table 2. Reaction to BB (PXO 61) of F 1 and F 2 progenies from crosses of IR22 with Usha and W1263. MP, India.

Disease reaction Cross F 1 F 2

Resistant Susceptible (no.) (no.)

IR22/Usha IR22/W1263

Resistant Resistant

856 406

0 0

Genetic Evaluation and Utilization AGRONOMIC CHARACTERISTICS

Influence of vegetative growth duration on grain grade

B. Venkateswarlu, B.S. Vergara, and R.M. Visperas, Plant Physiology Department, IRRI

The vegetative growth (VG) period of BPI-76, a photoperiod-sensitive cultivar, was altered to 45, 65, 85, and 105 d by manipulating photoperiod. Plants were grown in 4-liter plastic pots in the glasshouse. Each pot contained 3.5 kg soil fertilized with 4 g ammonium sulfate, 2 g solophos, and 2 g muriate of potash. Five plants per pot were grown under 24-h photoperiod. Sowings were staggered.

Plants were transferred to 10-h photoperiod so that climatic conditions during reproductive and

ripening phases were similar. Grain grade was determined by the specific gravity method.

Grain yield was higher with 45 and 65 d VG (see table) and gradually

4 IRRN 12:l (February 1987)

Influence of vegetative growth duration on number of different grades of grain per hill. a IRRI, 1986.

Parameter Vegetative growth duration

45 d 65 d 85 d 105 d

Grain yield/hill (g) Panicles/hill Total spikelets Empty spikelets

Poor grains b

Average b

Good b

High density grains b

Total grains

6.8 a 3.8 a

459 a 54 a

(11) 46 a (8)

157 a (28) 200 a (49)

1.5 a (4)

405 a (89)

6.2 a 3.1 b

429 ab 72 a

(16) 44 a

(10) 115 a (32) 198 a (41)

1.0 a (.2)

358 b (84)

5.4 b 2.7 c

381 bc 70 a

(18) 34 a (9) 42 b

(10) 233 a (66)

2.2 a (.5)

311 c (83)

4.4 c 3.1 d

336 c 74 a

(22) 24 a (7) 38 b

(11) 193 a (59)

0.7 a (.3)

262 d (78)

a Figures in parentheses are percent of respective grades of total spikelets. In a row, means followed by a common letter are not significantly different at 5% level by DMRT. b Poor grains = collected

specific gravity; and high density grains, 1.20 specific gravity. from 1.0-1.06 specific gravity; average grains, 1.08-1.12 specific gravity; good grains, 1.14 to 1.10

decreased with increased growth duration. The higher grain yield at 45 and 65 d was due mainly to high panicle numbers, fertility percentage, and total grain numbers per hill.

High density (HD) grain yield (grains which submerge at 1.20 sp gr) was not related to VG duration. BPI- 76 produced hardly any HD grains; production of HD grain did not differ

F1

significantly among growth durations. For maximum spikelet formation,

45 to 65 d VG duration appears to be advantageous; for HD grains, longer VG duration is not a disadvantage. All durations studied produced almost similar percentages of good grade grain. Longer VG was associated with

Dormancy in some early and medium duration varieties

Y.S. Veeraraja Urs, NationaI Agricultural Research Project, The University of Agricultural Sciences, Brahmavar 576213, Kannada, India

The dormancy of some early and medium duration high-yielding varieties (HYVs) grown under upland, midland, and lowland conditions in Dakshina Kannada region with heavy rainfall conditions was assessed in 1984 and 1985.

after flowering and sun-dried to 13- 14% moisture. Germination and dormancy (80% germination) were calculated on 25 seeds/ petri dish at

The seed samples were collected 30 d

lower total grain numbers, resulting in character of high numbers of HD lower yields. VG up to 65 d (total grain with any VG duration. For growth duration of 110 d) was higher potential yields, a VG duration associated with moderately high of 45 d (total growth duration of 91 d) numbers of good grade grain and is not limiting. It is possible to fairly high numbers of other grain combine the character of HD grain grades. with very short growth duration.

It should be possible to combine the

Germination and dormancy of some early and medium duration rice varieties. Brahmavar (DK), India, 1985.

Germination a (%)

Variety Duration (d)

5 DH b 10 DH 20 DH Dormancy b

1984 1985 1984 1985 1984 1985

Rasi 110 87 87 99 100 100 100 Jyothi 123 91 95 100 100 – Annapoorna 106 45 75 91 97 99 100 10 KKP2 110 53 79 90 92 100 97 10 IET7303 129 70 76 85 88 97 100 10 Shakthi 135 33 56 98 84 98 96 10 Jaya 139 35 56 99 95 – 100 10 Phalguna 149 15 18 30 46 88 88 20 a DH = days after harvest. b 80% germination.

– – –

10-d intervals, starting 5 d after Shakthi, Jaya, and IET7303 recorded harvest, with 4 replications. 10-d dormancy. Phalguna recorded

(see table). Annapoorna, KKP2, Rasi and Jyothi were nondormant 20d dormancy.

Ratoon tillering in short-duration rice varieties

P. K. Chakraborty and S. K. Bardhan Roy, State Agricultural Experimental Farm, Malda 732101, West Bengal, India

A set of the 1985 International Rice Yield Nursery-Early was grown during 1985-86 dry season at Malda. The main crop was sown on 24 Nov 1985 and transplanted 16 Jan 1986. Cool temperature during Nov-Mar usually extends crop duration.

After harvest, irrigation water and 20-10-10 kg NPK/ ha were applied. Varieties with higher hill regeneration

Ratoon tillering in shortduration rice varieties. Maida, West Bengal, India, 1985-86.

Regenerated Entries Ratoon tillers (no./hill) Main crop hills (no.) days to (%) Range Average 50% flowering

0-60 7 1-2 1 133-146 61-70 1 3 3 133 71-80 5 2-5 4 133-146 81-90 3 5-7 6 130-143 91-100 11 5-13 8 133-146

also showed more ratoon tillers/ hill 3-3-3, IR35546-52-3-3-2, SI-P1681032, (see table). and SI-PI692033 had higher ratoon

BW295-5, C662083, IR18348-36-3-3 tillering ability. Flowering duration of (IR64), IR25621-135-1-1, IR29658-69- the main crop did not affect ratoon 2-1, IR29725-45-1-1-3, IR31868-64-2- tillering ability.

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


Genetic Evaluation and Utilization GRAIN QUALITY

Grain grades in relation to seedling Table 1. Germination and seedling growth in relation to grain grade. a Andhra Pradesh, India.

growth and productivity Germination (%) Seedling growth (cm)

S. P. Rao, Directorate of Research, Grain grade IET7573 IET7574 IET7575 IET7573 IET7574 IET7575

Rajendranagar, Hyderabad 500030, 10 20 10 20 10 20 10 22 10 22 10 22 Andhra Pradesh, India DAS DAS DAS DAS DAS DAS DAS DAS DAS DAS- DAS DAS

This study was designed to determine Average Partially filled 36 91 15 84 17 89 8.0 17.4 8.6 14.8 9.7 19.7

59 93 21 85 31 89 8.5 17.4 8.7 14.8 10.2 19.7 the relationship of 1,000-grain weight Good 68 94 30 86 45 89 9.6 17.5 8.9 14.7 10.8 19.4 to seedling growth and productivity. Very good 95 95 48 88 57 90 9.8 17.4 9.2 14.8 11.3 19.5

IET7575 were sorted by immersing Spikelets of IET75737, IET7574, and a Av of 3 replications. DAS = days after sowing.

them in 1 .0, 1.06, and 1.18 specific gravity solutions using 0, 90, and 270 g common salt/liter of water. Floating grains were categorized as partially filled, average, good, and very good. The graded grains were tested for germination and seedling growth in the nursery and for yield potential in the field.

Germination and seedling growth, influenced by seed size up to 10 d, compensated at 20-22 d after sowing (Table 1). As a result, crop productivity was not affected (Table 2).

Table 2. Yield in relation to grain grade. Andhra Pradesh, India.

Grain grade Yield (t/ha)

IET7573 IET7574 IET7575

Partially filled 3.6 3.8 Average 3.4

3.8

Good 4.0

3.7 3.8

4.4 Very good

4.0 3.7 4.1 4.0

CD (0.05) V = NS V = 11.7% T = NS T = 10.6%

V in T = NS T in V = NS

Because consumer preference is for consumption, rather than for mainly for size and shape of the whole seed. kernel, fully filled grain may be used

Genetic Evaluation and Utilization DISEASE RESISTANCE

Susceptibility of rice hybrids to blast (BI) Susceptibility of rice hybrids to Bl. Tamil Nadu, India.

P. Vivekanandan, Agricultural College and Research Institute, Madurai; T. B. Ranganathan, Rice Research Station, Tirurkuppam; and M. Kadambavanasundaram, Tamil Nadu Agricultural University, Coimbatore, India

We studied the susceptibility of six F 1 hybrids to Bl caused by Pyricularia oryzae Cavara during navarai (Dec– Jan to Mar-Apr 1983-84). TKM9 was the base parent, crossed with Co 29 (resistant), IR36 (moderately resistant), and IR50 (highly susceptible). The Uniform Blast

Cross

Disease intensity a

Heterosis b

Ovule Pollen hybrid

(%)

(av) parent

(av) parent

(av)

Bl F 1

TKM9/Co 29 Leaf Neck

Co 29/TKM9 Leaf Neck

TKM9/IR36 Leaf

IR36/TKM9 Neck Leaf Neck

TKM9/IR50 Leaf

IR50/TKM9 Neck Leaf Neck

5.4 2.5 4.2 2.5 4.4 2.3 3.8 2.1 4.6 1.3 3.4 0.3

4.8 3.3 2.6 1.2 4.8 3.3 3.6 1.5 4.8 3.3 6.6 5.2

2.6 1.2 4.8 3.4 3.6 1.5 4.8 3.3 6.6 5.2 4.8 3.3

45.95** 11.11 13.51

8.70 4.76

–4.17 –9.5 2 –12.50 –19.30* –69.41** –40.35** –92.94**

a By SES. b Significant at 5% (*) and 1% (**) levels.

6 IRRN 12:1 (February 1987)

Nursery (UBN) screening technique was used and disease rated by the Standard evaluation system for rice (SES).

Scores indicated the dominance of

Tolerance of Sitopas crosses for ragged stunt virus (RSV)

N.L. Manigbas and D. HilleRisLambers, Plant Breeding Department; and G. Z. Salamat, Jr. and H. Hibino, Plant Pathology Department, IRRI

Sitopas, an Indonesian variety, has been reported as susceptible to but tolerant of RSV. Crosses were made to transfer its resistance to IR varieties and lines.

We evaluated 523 F 3 lines from 5 crosses of Sitopas and 3 IR varieties and lines: IR20, susceptible to brown planthopper (BPH) and intolerant of RSV; IR8234-OT-9-2, resistant to BPH biotype 1 but intolerant of RSV; and sitopas, tolerant of RSV but susceptible to BPH biotype 1.

five batches mid-Jun to late Aug. Germinating seeds were transplanted in clay pots. Seedlings were artificially inoculated with RSV at 11 d by the standard mass screening method in the greenhouse. Seedlings infected with RSV were transplanted in the field at 45 d from early Aug to early Oct.

Seeds were soaked in petri dishes in

Sources of resistance to sheath rot (ShR)

H. D. Lewin and P. Vidhyasekaran. Tamil Nadu Rice Research Institute. Aduthurai 612101, Tamil Nadu, India

During 1985-86 thaladi season, 59 rice cultures were screened for resistance to ShR caused by Sarocladium oryzae (Saw.) Gams. under field conditions where disease pressure was very high. Nine cultures showed high resistance (see table).

susceptibility over resistance (see genes although they are individually table). The high heterosis for leaf and susceptible. TKM9/Co 29 and its neck Bl resistance in TKM9/IR50 and reciprocal were susceptible to both leaf its reciprocal shows that these two and neck Bl. parents may have complementary

Reaction of rice varieties and Sitopas progenies to RSV. IRRI, 1985.

Designation Plots (%)

with > 50% fertility

Mean fertility a

Sitopas (check) IR43301 (Sitopas//IR26702-52-3)

IR46641 (Sitopas/IR26702-52-3//IR8234-OT-9-2) IR46630 (IR20/Sitopas//BR118-3B-17)

IR46733 (IR20/Sitopas//BR51-91-7) IR46734 (IR20/Sitopas//New Sabarmati)

(check)

IR20

IR8234-OT-9-2

61.2

12.2

15.3

7 .6

4.2

4.1

2.8

0.6

39.1 a

15.8 b

13.3 b

8.1 c

2.8 d

3.1 d

2.8 d

1.3 d (check) a Means followed by a common letter are not significantly different at the 5% level by DMRT.

Spacing was 30 cm between rows with 25 cm between plants, in a randomized complete block design with 2 replications. N at 100 kg/ ha was applied in 2 splits. Spikelet fertility was used to evaluate level of tolerance for RSV.

Sitopas confirmed its tolerance.

IR20 and IR8234-OT-9-2 were intolerant. Crosses with IR43301 and IR46641 showed significant numbers of fertile plants (see table). They also had more plots with at least 50% fertility, showing that Sitopas was able to transmit its tolerance for RSV into some of its progeny.

Resistance of rice cultures to ShR, 1985-86. Aduthurai, India.

Culture Cross Disease Disease index a reaction a

Manoharasali RB2069-2-6-1 RP2071-18-1-1 CR331-1-1-3 IR9202-21-1 RP1057-35-1-1 VRS286-4-1

ARC14529 IET85 84 TN1 IET7575 IET4 14 1

VRS163-2-2-2-3

Donor 1 Swarnadhan/Andrewsali 1 Swarnadhan/NLR9674 1 Jagannath/Mashuri 1 IR2053-521-1-1-K 116/KN-lB-361-1-8-6-9 1 KN-1B-361-1-8-6-9 RP 5-32/Pankaj 1

1 1 1

IET4141/CR98-7216 1

– – –

– 7 Sona/Manoharsali 9 RP29 1 /IR22 9

HR HR HR HR HR HR HR HR HR HR HS HS HS

a Standard evaluation system for rice 1-9 scale. b HR = highly resistant, HS = highly susceptible.

IRRN 12:l (February 1987) 7

Resistance of elite rice strains and varieties to bacterial blight (BB)

S.S. Malik, Haryana Agricultural University (HAU), Rice Research Station, Kaul (Kurukshetra), India

One hundred thirty-two strains of rice were evaluated for resistance to BB caused by Xanthomonas campestris pv. oryzae at HAU Regional Research Station, Ucha hi Karnal, during the 1983 and 1984 wet seasons (Jul-Oct). Rice plants were inoculated at maximum tillering stage by cutting 5 cm of the upper leaf portion with a sickle dipped in a single-isolate inoculum. The inoculum was prepared by soaking small pieces of naturally infected leaves in water for 20 min.

Disease reactions were scored 15 d after inoculation ( Standard evaluation system for rice ). Strains showing reaction 1-3 were rated resistant (R); 5, moderately resistant (MR); and 7-9, susceptible (S).

Among 30 short-duration strains tested, 7 were R, 13 MR, and 10 S (see table). Among 50 medium-duration strains, 15 were R, 15 MR, and 20 S. Among 52 scented strains, 11 were R, 12 MR, and 29 S.

TKM6, BJI, IET4141, UPRB31, and DV85 have been used as BB resistance donors. In the scented group, resistance to BB has not been developed.

Short- and medium-duration

Elite rice strains showing resistance and moderate resistance to BB in 1983-84. Kurukshetra, India.

Resistant (1-3)

Moderately resistant (5)

Short duration HAUK6-88-1 HKR4 HAUK8-75-1-3 HAUK8-145-1 HAU28-3643-1 HAUK9-176-1 PAU154-453-3 HKR2l IR9763-11-2-2-3 HAU47-3888-3 MRC630-303 HAU118-278 325/UNN-5-1 HAU6-63-1

IR36 IR9828-91-2-3 IR313429-196-1 C1322-28 PR103 Pal 579

HKR109 Medium duration

HKR108 HAUK6-0-2-1 HKR110 HAUK6-0-3-2 HAUK8-45-3-2 HAUK7-176-3-2 HAUK7-217-1

HAUK10-0-19 HAUK10-189-1

HAUK8-0-23-3 HAUK10-221-1 HAUK8-204-1 HAUK102 HAUK9-98-2-2-1 HAUK23A-10 HAUK10-37-2 HAUK23A-67 HAUK10-189-2 HAUK27-10-2 HAUK10-221-2 HAUK28-22-1 HAUK10-228-2 HAUK30-0-1 HAUK8-10-15-2 HAU118-154 IRON81-169 RP5121-173-1-8 IRON81-171 RP2136-43-2

Scented HKR222 HKR221 HAUKlO-0-3-12 T3 dw. mutant HAUK10-0-37-5 HAUK23c-95 HAUK10-221-1-7-1 HAUK10-0-25 HAUK10-184-1-5-1 HAUK10-37-3 HAUK10-211-1-5 HAUK12-72-1-3-1 HAUK12-20-4-2 HAUK33-4-2 HAUK12-52-4-2 HAUK34-9-2 HAUK12-64-4-1-1 HAUK35-11-5 HAUK23B-39 HAU36A-67-1 HAUK12-88-1 HAUK3613-1-1

HAUK36F-14-1

Source of ufra-resistant deep water rice

M.L. Rahman, DWR Project, Bangladesh Rice Research Institute, Joydebpur, Gazipur, Bangladesh

In a series of trials during the 1981-85 growing seasons, 1,358 deep water rice entries were screened in pots or deep water tanks (DWT) for ufra nematode Ditylenchus angustus resistance. In the

pot trials, 3- and 4-wk-old entries were inoculated artificially by releasing 100 active nematodes per seedling in 8-10 cm water. On the basis of infestation percentage and number of nematodes per plant, 18 entries were found resistant or moderately resistant to ufra.

Those entries were retested in deep water tanks. Each entry was sown in three 1- × 1-m plots and inoculated.

as diseased or healthy. Yield at 14% At harvest, panicles were evaluated


moisture content was estimated from healthy panicles. Entries with 0% infestation = highly resistant (HR), 1- 20% = resistant (R), 21-40% = moderately resistant (MR), 41-60% = moderately susceptible (MS), 61-80% = susceptible (S), and 81-100% = highly susceptible (HS).

resistance and high yield potential (see table).

All Rayada entries showed

Ufra infestation and yield of selected deep water rice entries, DWR Project, Joydebpur, Bangladesh.

Entry Ufra

(%) infestation Reaction Yield

(t/ha)

Rayada 16-06 1 Rayada 16-08 1 Rayada 16-09 1 Rayada 16-02 2 Rayada 16-03 2 Rayada 16-013 2 Rayada 16-07 4 Rayada 16-011 4 Rayada 16-05 11 CNL-319 23 BR306-B-3-2 31 BR308-B-2-2 37 Bazail65 35 Dalkatra 40 Choruamotor 44 Gowai 50/9 44 Karkati 161 44

Hassi Amon (check) 95 Habiganj Amon I 93

BR308-B-2-9/A 54

(check)

R 4.5 R 4.0 R 4.0 R 5.0 R 4.7 R 4.1 R 4.1 R 4.4 R 4.3

MR 3.6 MR 3.6 MR 2.6 MR 1.9 MR 2.8 MR 2.9 MR 2.4 MR 1.6 MR 2.4 HS 0.9 HS 0.6

Performance of medium-duration IRRI lines at Tamil Nadu

M. Subramanian, V. Sivasubramanian, Tamil Nadu Rice Research Institute, Aduthurai, Tamil Nadu; and G.S. Khush, IRRI

Forty-five IRRI lines were evaluated during 1984 thaladi season (Sep-Oct to Jan-Feb) with medium-duration check CO 43.

Entries were raised in trial plots. At 32 d, they were planted 2-3 to a hill, spaced 20 cm between rows and 10 cm

between plants. The recommended 100- 50-50 kg NPK/ha was applied.

IR32358-54-2-3-3 and IR32419-28-3- 1-3 flowered the earliest, at 87 d after seeding (DAS) (see table). All other entries flowered 90-107 DAS; check CO 43 flowered 101 DAS. Ten lines yielded more than 6 t/ha.

Leaf yellowing due to RTV and soil problems caused very heavy damage to samba and thaladi crops in 1984. All

the test entries were exposed under field conditions and scored for leaf yellowing reaction. All IRRI lines were free from leaf yellowing and two lines showed resistance.

Entries IR32358-54-2-3-3 and IR28228-112-2-3-3-3 were susceptible to neck blast and IR31809-67-2-3 and IR32823-88-2-3 were susceptible to helminthosporiose.

Genetic Evaluation and Utilization INSECT RESISTANCE

Potential donors for brown planthopper (BPH) resistance

R.K. Sahu, Plant Breeding Department, IRRI

Yield performance of IRRI lines and their reactions to diseases.

Breeding line Days to Yield Helmin- Bacterial Sheath Grain

flowering (t/ha) thosporiose blight rot discoloration 50%

IR13525-43-2-3-1-3-2 (IR62) 94 7.4 3 3 3 1 IR32358-32-2-3-3 96 3.0 1 3 0 1 IR32358-54-2-3-3 a 86 3.2 1 3 3 1 IR32419-28-3-1-3 87 6.5 1 3 3 0 IR25604-99-1-3-2-2 94 3.7 3 0 3 3 IR25619-75-2-3-2-3 100 6.9 3 0 3 3 IR27313-67-1-2 98 8.6 5 1 3 1 IR27325-53-2 98 5.6 3 3 3 3 IR28222-9-2-2-2-2 97 4.1 5 3 3 5 IR328224-3-2-3-2 97 4.1 3 5 3 3 IR28226-24-1-2-3-2 96 4.0 5 3 0 0 IR28228-96-3-2-1-3 99 4.2 5 3 3 3 IR28228-106-1-2-3-2 90 6.2 3 1 1 3 IR28228-112-2-3-3-3 a 95 4.2 5 3 1 3 IR28228-119-2-3-1-1 97 3.7 3 3 3 3 IR29519-116-2-2-2 91 5.4 3 3 1 1 IR29519-135-3-3-2 101 6.0 3 1 0 3 IR29519-157-1-2-1 91 3.0 5 5 3 3 IR29522-4-2-3 92 7.1 5 1 3 5 IR29668-34-1-1-2 103 3.8 3 1 3 3 IR29723-7-1-1-2 104 4.2 3 3 3 3 IR29723-143-3-2-1 107 4.0 5 5 1 3 IR29723-163-3-2-2 91 5.8 3 3 1 1 IR331805-20-1-3-3 91 6.1 3 5 3 1 IR31811-35-3-3-2 102 6.3 3 5 3 1 IR31827-80-3-3-2 102 2.1 3 3 3 3 IR31836-10-1-2-2 98 2.8 3 5 3 3 IR31836-42-1-3-2 101 5.2 5 3 3 3 IR31838-63-2-2-2 99 1.4 3 1 5 5 IR31855-69-1-2-3 91 4.4 3 3 3 3 IR31867-1-2-3-3 100 3.0 3 1 5 1 IR31867-4-3-3-3 101 4.9 5 3 3 3 IR31892-46-3-2 b 93 1.9 3 5 5 3 IR31901-17-1-2-2 b 103 1.8 3 3 5 3 IR31917-31-3-2-3 94 8.1 3 5 3 1 IR31917-96-3-3-1 105 5.4 5 3 3 3 IR31809-67-2-3 98 4.0 7 3 3 IR32822-36-1-3 98 3.1 5 3 3 1

5

IR32823-1-1-3 100 1.2 5 3 3 3 IR32823-22-1-3 104 2.2 3 3 3 3 IR32823-88-2-2 104 6.3 7 0 3 3 IR32830-23-2-2 101 2.1 3 3 5 IR32848-36-2-2 102 2.0 3 1 1 1

5

IR33059-120-2-1 103 2.0 5 5 3 IR34583-38-3

3 102 3.8 3 1 3 3

CO 43 a 101 4.8 3 3 5 3

a All entries scored 0 for blast except IR32358-54-2-3-3 and IR28228-112-2-3-3.3, which scored 7. b All entries had a leaf yellowing score of 0 except IR31892-46-3-2 and IR31901-17-1-2-2, which scored 3. The check CO 43 scored 7.

Of 185 rice accessions from the Madhya Pradesh (India) germplasm collection screened at IRRI for resistance to BPH (standard seedbox screening technique), 18 were resistant.

Each seedling was infested with 7-10 second- to third-instar BPH biotype 1 nymphs at 7 d after seeding. Damage was scored on the Standard evaluation system for rice 1-9 scale.

resistant. Akkalpom, Bhondu parewa, Cross 116, Dubraj, Dudga, Garrakath, Gathwan, Gobindbhog, Haruna dubraj, Hiranakhi, Jawphool, Aagyasal, Aagyasar, Assamchudi, and Makarkam were moderately resistant. Susceptible cultivars died 8-9 d after infestation.

dubraj, Jhili, Aagyasal, and Aagyasar also are resistant to bacterial blight.

Aolesar, Jhili, and Banda were

Aolesar, Cross 116, Dudga, Haruma

Multiple resistance of BG367-3 to major insect pests and diseases

R. Saroja, M. Suriachandraselvan, N. Raju, and T. B. Ranganathan, Rice Research Station, Tirur 602025, Tamil Nadu, India

In the 1981 IRTP, BG367-3 (BG280-1- 2/Ptb 33), a short-duration culture from Sri Lanka, was moderately resistant to rice leaffolder (LF) at IRRI and Tirur. From 1982 to 1986, BG367-3 was evaluated against other insect pests and diseases at Tirur.

BG367-3 was resistant to blast (Bl) and moderately resistant to tungro (RTV), brown spot, gall midge, hispa,


Reaction of BG367-3 to major insect pests and diseases. Tirur, India, 1982-86.

Maturity Damage a

Entry (d) RTV B1 Brown Sheath Grain Gall Hispa Green Stem borer Yield spot rot discoloration midge leafhopper LF (t/ha)

Deadheart Whiteheads

BG367-3 115 3 1 4 5 5 3 3 3 3 IR36 120 5 3 7 5

3 5

3 5.1

IR50 7 3

115 7 9 5 5 7 9 5 9 5.5

TKM9 5 5 3 9 7 9 6.3

115 8 9 5 5

5 ADT36

5 5 3 9 9 7 9 5.6 115 8 2 5 5

PY 3 5

115 4 3 5 7 5

7 7 7 9 7

5 9 4.4

5 3 9 9

9 5 TN1 (susceptible check) 125 8 5 5 7 5 9 9 9 9 4.2

9 4.5

a By the Standard evaluation system for rice. 1-9 scale.

green leafhopper (GLH), and stem navarai (Dec-Apr). TKM9, samba (Jul-Nov). borers (SB) (see table). It has good recommended for sornavari (Apr- BG367-3 is now under multilocation yield potential. Aug), also was heavily damaged by trials in Tamil Nadu and is being used

are severely damaged by Bl during susceptible to LF and SB in early resistance at Tirur. The highly popular IR50 and TKM9 RTV in 1984-85. IR50 is highly in breeding for insect and disease

Resistance of IR varieties to leafhoppers and planthoppers

R. Velusamy, R. Rajendran, and P.C. Sundara Babu, Tamil Nadu Agricultural University, Coimbatore, India; and G.S. Khush, Plant Breeding Department, IRRI

We evaluated 25 IR varieties for resistance to rice green leafhopper (GLH) Nephotettix virescens, brown planthopper (BPH) Nilaparvata lugens, and whitebacked planthopper (WBPH) Sogatella furcifera. Pregerminated seeds were sown in rows in 60- × 40- × 10-cm seedboxes with Ptb 33 as the resistant check and TN1 the susceptible check. Each variety had five replications. At 7 d after sowing, seedlings were thinned to 20 per variety and infested with 7-8 1st-instar nymphs of BPH and WBPH and 5 2d-instar GLH nymphs per seedling. When the susceptible check died, test varieties were rated for damage by the Standard evaluation system for rice (SES).

Levels of resistance to GLH, BPH, and WBPH differed significantly. IR62 and IR64 exhibited high resistance to all three hopper species (see table). IR28, IR52, IR54, IR56, IR58, IR62,


Reactions of IR varieties to leafhoppers and planthoppers.

Damage rating a

GLH BPH WBPH Variety

IR5 6.6 e 5.4 d 5.4 d IR8 IR20

9.0 f 9.0 f 9.0 f

9.0 f 9.0 f

IR22 9.0 f

9.0 f 9.0 f IR24 5.4 d 9.0 f IR26 9.0 f IR28

9.0 f 9.0 f

IR29 1.0 a 5.4 d 5.4 d 6.2 e 9.0 f 9.0 f

IR30 5.4 d 9.0 f 6.2 d IR32 IR34

3.4 c 9.0 f 5.4 d 3.0 bc 9.0 f

IR36 5.4 d

2.6 b 6.6 e 5.0 c IR38 IR40

5.4 d 9.0 f 6.6 e 6.6 e

IR42 6.6 e

2.6 b 5.2 d 6.6 e

IR46 5.0 c

6.6 e 4.6 c 5.4 d IR48 2.6 b 3.4 b IR50

3.0 b 3.4 c

IR52 9.0 f 9.0 f

IR54 1.0 a 2.6 b 1.4 a 1.0 a

IR56 6.6 e 2.6 b

1.4 a 3.4 b 2.6 b IR58 IR60

1.0 a 5.4 d 3.4 b 3.4 c 5.4 d

IR62 1.0 a IR64

1.4 a 1.4 a

Ptb 33 (resistant check) 1.0 a 1.0 a 1.0 a 1.0 a 1.0 a

TN1 (susceptible check) 9.0 f 9.0 f 1.0 a 9.0 f

a Mean of 5 replications. In a column, means followed by a common letter are not significantly different at the 5% level by Duncan’s multiple range test. Damage rating is based on the SES 0-9 scale.

5.4 d

and IR64 were highly resistant to IR60 were moderately resistant to all GLH; IR5, IR36, IR42, IR46, and three species.

9.0 f 9.0 f

Reaction of eight rices to gall midge (GM)

C. Durairaj, M. Gopalan, and M.S. Venugopal, Entomology Department, Agricultural College and Research Institute, Tamil Nadu Agricultural University, Madurai 625104, India

CO 37 (Vaigai), IR50, ACM2, ACM8, ACM9, ACM10, ARC10550, and TN1 were field tested for resistance to GM during the first growing season. Seedlings were transplanted at 30 d in 2- × 1.5-m plots in a randomized block design with 3 replications. Silvershoot damage on 5 randomly selected hills was recorded at 30 and 50 days after

Response of 8 rice varieties to GM in Tamil Nadu, India.

Variety Source Silvershoot damage a (%) Yield

(d) 30 DT 50 DT (t/ha) Maturity

ACM8 IR8/W1263 120 3.6 a 2.8 a 4.8 ARC10550 Selection from Vellutha Cheera 125 5.1 a 7.0 b 2.4 TN1 DGWG/Tsai-Yan-Chung 135 17.2 b 17.8 cd 3.6 IR50 IR2153-14-1-62/IR28//IR2070-625-1 105 21.9 bc 21.2 cd 5.4

(Vaigai) CO 37 TN1/CO 29 120 21.9 bc 33.2 e 5.1

ACM9 IET7281 110 22.3 bc 17.1 c 4.8 ACMl0 IRCTN 09546 115 24.6 c 24.4 d 6.3 ACM2 Kannagi/IR28 105 27.3 c 27.5 e 4.2 a Mean of 15 plants. In a column, means followed by a common letter are not significantly different at 5% level.

planting (DT). (see table). At 50 DT, the range was GM damage at 30 DT ranged from from 2.8% on ACM8 to 33.2% on

3.6% on ACM8 to 27.3% on ACM2 CO 37.

Genetic Evaluation and Utilization OTHER PESTS

Resistance of some rice varieties to Resistance to RKN at Ibadan, Nigeria. the root-knot nematode (RKN) Meloidogyne incognita

Chlorosis Gall Nematodes R factor b Resistance c

Variety index index a (no.) (Pf/Pi)

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

Fifty-six rice varieties were screened for resistance to root-knot nematode Meloidogyne incognita (Kofoid & White) at Moor Plantation, Ibadan. Plants grown in 10-liter plastic buckets were inoculated with suspensions of RKN eggs and juveniles (5,000/bucket) with 3 replications. Root-galling and nematode recovery were scored 52 d after inoculation.

Faro 21 displayed an exceptionally high resistance (no root galls were recorded) (see table).

Faro 1 Faro 2 Faro 11 Faro 19 Faro 21 Faro 27 ITA252 M666-301 IR22082-41-2 IRRNR29692 IR31917-3-1-3-2 IR4744-295-2-3 IR18349-22-1-2-1-1 IR19672-140-2-3-2-2 IR42 (international check)

2 2 1 4 1 1 1 3 2 1 1 2 3 3 2

4 4 4 4 3 0 3 4 1 3 2 3 3 3 3

15,424 11,188 13,606 10,820 5,199 5,631 7,548 8,388 6,476 9,945 6,658 3,454

10,668 10,448 6,076

3.08 2.24 2.72 2.16 1.04 1.13 1.51 1.58 1.30 1.99 1.34 0.69 2.14 2.09 1.22

S S S S

R HS HS HS S HS T S S HS

R/S

a Gall index scale: 0 = 0 galls, 1 = 1-2 galls, 2 = 3-10 galls, 5 = 100 + galls. b R factor = average final egg count ÷ 500 (inocula level). c R = resistant, T = tolerant, S = susceptible, HS = highly susceptible.

Genetic Evaluation and Utilization TEMPERATURE TOLERANCE

Extent of wind-induced tip drying Tip drying due to high wind is in popular rice varieties in common in May-Jun nursery and

Individuals, organizations, and media are Coimbatore transplanted crops. Average wind invited to quote or reprint articles or excerpts from articles in the IRRN. K. Natarajamoorthy, G.A. Palanisamy,

velocities of 30 km/h lead to up to 2 cm drying. Leaves formed without

and S. Palanisamy, School of Genetics, high winds are normal. Tamil Nadu Agricultural University We assessed tip drying in prerelease (TNAU), Coimbatore 641003, India. and popular short-duration rice



Factors causing winter yield declines in high-yielding varieties

K. Viswambharan. K. P. Rajaram, D. Alexander, and N. Rajappan Nair, Kerala Agricultural University, Regional Agricultural Research Station, Pattambi, Kerala 679306, India

We studied the factors responsible for low productivity of high-yielding varieties grown Sep-Jun 1983-86. Treatments consisted of seven planting dates between 22 Aug and 12 Nov, of IR8, Jaya, IR20, and Bharathi. The layout was a split-plot design with three replications. Cultural practices and fertilizer applications were optimum. Weather variations were recorded.

Preliminary analysis for IR8 and Jaya are presented here. Yields varied from 1.0 to 4.6 t/ha for Jaya and 0.7 to 4.4 t/ha for IR8. This wide variation could not be attributed primarily to spikelet sterility (see table).

Correlation analysis between

varieties sown 15 May 1986. Tip random for each entry (25-m 2 plots). drying was measured at 40 d after Leaves and dried tips were counted seeding. Ten plants were selected at (see table).

Rice entries showing extent of tip drying. TNAU, India.

Rice entries with indicated % of leaf tip drying

Up to 10% 11-20% 21-30% 31-40% 41-50%

TNAU801793 TNAU801790 TNAU831520 Rasi TNAU831521 PY 3

TNAU83077 PY 2 TNAU842805 ET1722 TNAU842806 ET4786 TNAU83133 Co 37 TNAU801803 TNAU830641 AD85001 TNAU801804

IR56 TNAU801103 Co 41 TNAU83069/1 IR64 TPS 1 ADT31 TKM9 ASD16 IR50 MDUl TNAU83134 AD85003 TM8089 ADT36 IR36 IR60

Complete slide sets of photos printed in Field problems of tropical rice, revised 1983, are available for purchase at $30 (less developed county price) or $60 (developed country price), including, airmail postage and handling, from the Communication and Publications Department, Division R, IRRI, P. O. Box 933, Manila, Philippines. No orders for surface mail handling will be accepted.

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

Genetic Evaluation and Utilization WEATHER

Performance of two high-yielding varieties under different planting dates during three winter seasons in Kerala, India.

Planting date Height Thousand Thousand Grain Height Thousand Thousand Grain (cm) spikelets filled yield (cm) spikelets filed yield

per m 2 grains (t/ha) per m 2 grains (t/ha) per m 2 per m 2

Jaya IR8

1 983- 84 22 Aug 5 Sep 18 Sep 3 Oct 17 Oct 30 Oct 12 Nov

1984-85 22 Aug 5 Sep 18 Sep 3 Oct 16 Oct 30 Oct 12 Nov

1985-86 22 Aug 5 Sep 18 Sep 3 Oct 16 Oct 30 Oct 12 Nov

82 91 87 75 81 77 73

84 81 85 78 78 73 74

82 81 84 80 80 77 83

26.8 18.4 4.6 83 27.7 24.0 11.5 3.2 88 27.0 28.8 8.8 2.2 83 23.8 22.7 3.2 1.0 74 23.2 29.3 6.5 1.6 71 24.2 29.3 10.8 3.1 76 30.2 31.8 6.8 1.8 69 24.0

25.4 16.3 4.3 80 24.5 25.8 13.4 3.4 77 25.2 28.8 13.6 3.4 81 26.9 32.1 13.4 3.4 76 33.9 25.2 10.9 2.9 76 28.7 26.5 13.8 3.4 69 26.0 28.2 14.6 3.9 75 27.7

22.8 7.7 2.3 80 24.3 25.8 13.9 4.0 80 26.9 30.2 12.4 3.6 84 25.0 27.7 14.5 4.1 80 23.6 28.9 13.2 3.3 80 28.5 29.0 14.2 4.0 79 26.4 30.3 13.7 3.8 71 27.9

18.5 4.4 10.2 2.4 6.9 2.4 3.2 0.7

10.9 2.1 13.8 3.2

5.3 1.6

13.9 3.6 12.0 3.1 13.9 3.6 10.6 2.8 12.3 3.2 12.3 3.1 13.2 3.6

7.6 2.2 14.0 3.9 12.3 3.6 13.1 3.6 13.5 3.4 14.2 4.0 13.9 3.7

weather parameters and yield showed a positive relationship between total solar radiation during 5-1 5 d before 50% heading and a negative relationship between number of rainy days 15-30 d before 50% heading. Yield was predicted by these equations:

Jaya: Y = 11.74** X 1 – 308.02* X 2 – 2175 (3.91) (2.16)

R = 0.73

IR8: Y = 10.36**X 1 – 238.80 X 2 – 1720 (3.42) (1.65)

R = 0.68

**Significant at 1% level *Significant at 5% level

Where, Y = grain yield (kg/ha), X 1 = mean solar radiation 5–

15 d before 50% heading in mWh/cm 2 per d, and

X 2 = number of rainy days 15– 30 d before 50% heading.

Figures in parentheses are the “t” values of the regression coefficients.

predominant for crops planted 18 Sep, 3 Oct, and 17 Oct, but yield reductions occurred under adverse weather parameters regardless of planting date.

Yield declines were more

Genetic Evaluation and Utilization HYBRID RICE

Isolation of restorers and Pollen parents classified according to spikelet fertility percentage. TNAU, India.

maintainers for two Chinese male- Effective Weak restorers Weak maintainers Effective sterile lines having wild abortive Cytosterile restorers maintainers (WA) cytoplasm >80% 60-80% 40-60% 20-40% 15-20% 10-15% 5-10% <5%

M. Rangaswamy, K. Natarajamoorthy, Zhen Shan – – IR36 IR54 IR40 IR9752 ADT31 – 97A IR56 IR50 TKM9 PY2

G.A. Palanisamy, and S.R. Sree IR58 IR52 BAS370 Co 13 Rangaswamy, School of Genetics, Tamil Nadu Agricultural University (TNAU), Coimbatore 641003, India

IET1722 IET4786 PTB10 Kanchi ASD8 A09246 TNAU4372 TNAU658 Co 41 Co 33 K. Samba Co 37

Co 39 Pollen from 26 early- and medium- duration rice varieties (8 from IRRI and 18 from India) were crossed with cytosterile Zhen Shan 97A and 12 varieties (6 from IRRI and 6 from India) were crossed with cytosterile Er- jiu Nan 1A to identify restorers and maintainers of pollen fertility. The two cytosteriles are of Chinese origin with wild abortive (WA) cytoplasm.

The F 1 hybrids were raised during 1985 rabi in a test cross nursery at Paddy Breeding Station, TNAU. The

Er-jiu- – IET6208 IR9698 IR19053 IR18599 IR2307 BPHR5 – Nan 1A IET5103 IR19058 AS19789

IR9715 IET3630 IET13267

main panicle of each hybrid plant was weak maintainers (5-20%) and effective bagged and spikelet fertility was maintainers (<5%) (see table). estimated at harvest. On the basis of Stable male-sterile lines MS47A, spikelet fertility, pollen parents were MS37A, and MS31A are being classified as effective restorers (>80% developed utilizing weak maintainers spikelet fertility); partial or weak Co 33, Co 37, and ADT31. A program restorers (20 to 80% fertility), which is to identify effective restorers and again subdivided into three groups; maintainers is in progress.

Recurrent selection in rice

T. James, E.P. Guimaraes, Brazilian National Research Center for Rice and Beans, CNPAF/EMBRAPA CP179 74000, Goiania GO, Brazil

To complement conventional breeding systems and to facilitate hybrid breeding programs, CNPAF and IRAT are synthesizing populations with broad genetic bases. The ability

of these populations to produce good varieties through conventional breeding or to provide good female parents with high prospects for cross pollination for the hybrid program will gradually increase through cyclic application of intermating and selection.

male sterile gene [from IR36 male sterile (MS)] was introduced. Control of recombination and conservation of

To facilitate intermating, a recessive

the MS gene are assured by harvesting only open-pollinated seeds from male sterile segregants.

Two populations, one for irrigated rice and one for upland rice, are now ready to be used in conventional breeding systems. The rate of natural outcrossing on male sterile plants is sufficient to guarantee renovation of the populations. An average 165 seeds from male sterile plants of irrigated rice and 26 seeds from upland rice


(0.5 × 0.5 m interplant space) were collected.

For the hybrid program, we are

Cytogenic relationship between two cytoplasmic male-sterile lines

S.S. Virmani and R. C, Dolores Dalmacio, Plant Breeding Department, IRRI

Cytoplasmic-genetic male sterility (CMS), conditioned by the interaction of nuclear and cytoplasmic factors, is used extensively in hybrid breeding programs for self-pollinated crops. Hybrid varieties grown commercially in China are derived mostly from cytoplasmic sources of wild rice Oryza sativa f. spontanea, designated as WA (wild rice with aborted anthers). Alternative sources of cytosterility are needed to protect F 1 hybrids against potential genetic vulnerability to 0

diseases and insects. We have developed a new CMS (A)

line, IR54755A, which has the cytoplasm of land race ARC13829-16 introduced from Assam, India, and the nuclear genotype of elite breeding line IR10179-2-3-1. Another CMS line, IR46828A, was developed in the same nuclear genotype with the WA cytoplasm from Chinese CMS line Zhen Shan 97A. We studied the cytogenic relationship between the two cytosterile lines developed from the two different cytoplasmic sources.

Each CMS line was crossed with its maintainer and single plant selections of a number of other maintainers,

Survival of some F 1 rice hybrids and their parents in saline soil

D. Senadhira and S. S. Virmani, Plant Breeding Department, IRRI

Increased vegetative and root vigor are useful traits to use in adapting rice plants to soil and climatic stresses. Usually, F 1 hybrids express these traits. We evaluated 12 F 1 rice hybrids


synthesizing one population for allogamous species Oryza irrigated rice and one for upland rice. longistaminata is being introduced in The long stigma of the wild these populations.

Pollen fertility behavior of F 1 progenies between CMS, maintainer, and restorer lines. IRRI, 1986 dry season.

Female parent

IR46828A IR54755A Male parent

Plants F 1 plants (no.) in Plants F 1 plants (no.) in (no.) pollen fertility class a

(no.) pollen fertility class

CS S PS PF F CS S PS PF F

IR54755B 19 19 0 0 0 0 48 48 0 0 0 0 IR46828B 49 0 0 0 0 0 15 0 0 0 0 0 IR46829B 9 7 2 0 0 0 10 10 0 0 0 0 IR46830B 8 8 0 0 0 0 10 10 0 0 0 0 IR36R 9 0 0 0 0 9 8 0 0 0 2 6 IR46R 9 0 0 0 0 9 10 0 0 0 0 10 IR64R 6 0 0 0 0 6 10 4 3 1 2 0 IR9761-19-1R 6 0 0 0 0 6 6 0 0 0 1 5 IR28 9 0 0 0 0 9 9 0 2 0 3 4 IR34 5 2 2 1 0 0 10 IR43 10 6 4 0 0 0 10 5 2 0 0

9 1 0 0 0

IR52 8 0 0 0 0 8 10 0 0 0 10

a pollen fertility classes: cs = completely sterile, 0% pollen fertility; s = sterile, 1-10% pollen fertility1 PS = partially sterile, 11-30% pollen fertility; PF = partially fertile, 31-60% pollen fertility; F = fertile 61-100% pollen fertility.

restorers, and partial restorers of the WA cytosterility system. The F 1 population of these crosses was evaluated for pollen fertility using 1% IKI solution.

The maintainers of the two CMS lines (IR54755B and IR46828B) effectively maintained the male sterility in the two cytosterile lines (see table). However, IR64R, IR9761-19-IR, IR28, IR34, and IR43 showed differential fertility in crosses with the two CMS lines.

These results indicate that the cytoplasmic factors inducing male sterility in IR46828A and IR54755A may be different. The maintainers IR46828B and IR54755B, derived from the line IR10179-2-3-1, have genotypes capable of maintaining both cytosterility systems. The cytogenic differences observed here need to be substantiated by analysis of mitochondrial DNA of the two CMS lines.

and their parents for survival in saline adding common salt. Check varieties soil at IRRI in the 1986 dry season. were IR28 (salt sensitive) and IR9884- Although the hybrids’ parents are not 54-3 (salt tolerant). The field salinity known to be tolerant of salinity, our level was maintained throughout the objective was to test the usefulness of experiment. Plant survival was hybrid vigor under such stresses as soil recorded at 6, 12, and 15 wk after salinity. transplanting.

Five-wk-old seedlings grown on wet Salinity prolonged the growth seedbeds were transplanted at 50 duration of all varieties tested. Very hills/entry in a field where salinity to early parents and hybrids flowered an EC of 7 dS/m had been induced by about 100 d after seeding.

3

Six of the 12 hybrids showed strikingly increased survival compared to their parents (see table). In three cases, hybrids and parents were comparable; in two, hybrids were inferior to the better parent. The hybrid 97A/Milyang 54 showed superiority over the parents at early stages but subsequently became comparable to them.

These results indicate that F 1 hybrids could be superior to their parents in adaptability to salinity. Because the parents of the hybrids tested are not known for salinity tolerance, better performance of some hybrids can be attributed to increased root and shoot vigor.

Survival of some parents (female, male) and their hybrids (F 1 ) at 6, 12, and 15 wk after transplanting (WAT) in a saline field (EC = 7 dS/m). IRRI, 1986.

Survival (%)

Hybrid or variety 6 WAT 12 WAT 15 WAT

Female Male F 1 Female Male F 1 Female Male F 1

97A/Milyang 54 26 32 50 16 12 16 16 10 16 IR46830A/IR50 28 58 60 8 46 54 8 40 46 IR46830A/IR9761-19-1 28 26 64 8 14 34 8 8 18 V20A/IR9761-19-1 16 26 28 16 14 18 14 8 12 IR21845/IR29512 28 74 38 18 66 22 14 62 16 IR21845/IR19392 28 48 60 18 44 54 14 44 50 IR21845/IR20933 28 22 44 18 8 40 14 8 34 IR21845/IR14753 28 28 46 18 24 40 14 24 30 IR21845/IR15847 28 22 24 18 16 18 14 12 12 IR21845/IR4422 28 36 32 18 28 24 14 20 12 IR21845/IR13146 28 38 36 18 24 28 14 24 22 IR21845/IR54 R 28 28 46 18 28 46 14 26 40

IR9884-54-3 (resistant check) 93 90 83 IR28 (susceptible check) 42 40 33

Genetic Evaluation and Utilization TISSUE CULTURE

Variability in quantitative traits of anther culture-derived progenies

S. R. Sree Rangasamy, T. B. Ranganathan, and G. Manimekalai Gurunathan, School of Genetics, Tamil Nadu Agricultural University, Coimbatore 641003, India

We studied the pattern of variability in quantitative traits of homozygous lines developed from anther-derived plants of the cross Co 37/Co 40.

Anthers were collected from F 1 plants during 1979 wet season and cultured in the laboratory. Sixteen

plants were established in October 1980. Seven A 1 plants (R1 to R7) resembling the parent (Co 37) in vigor, growth, and seed set were grown individually in A 2 in 1981 wet season (Jun-Sep). They were uniform within each progeny and carried forward as individual lines.

During 1982 wet season, 10 plants were established for each entry, with 3 replications. The F 4 of Co 37/Co 40 and Co 37 alone were included for comparison. Plant height at maturity, number of productive tillers, panicle

length, grains per panicle, and grain yield per plant were measured for each plant.

All the seven lines exhibited variations comparable to that in Co 37. The F 4 population of the cross showed perceptible variation between plants and within lines for all characters. Similar variation was observed in the next generation during 1983 dry season for all the traits except panicle length. Compared to that in the anther-derived lines, variation was high for all traits (see table).

Performance of anther-derived lines at Coimbatore, India, 1983 dry season.

Plant height (cm) Tillers (no.) Panicle length (cm) Grains/panicle Grain weight/plant (g)

Range Mean ± CV Range Mean ± CV Range Mean ± CV Range Mean ± CV Range Mean ± CV Culture

SE SE SE SE SE

433 A R1 433 A R2 433 A R3 433 A R4 433 A R5 433 A R6 433 A R7 Vaigai (Co 37) Vaigai/Co 40 (F5)

84-98 84-92 85-98 83-95 79-95 75-96 82-94 94-1 19 90-138

91.5±3.9 4.9 6-11 89.1±2.6 3.6 5-12 90.8±3.7 4.1 5-12 88.8±3.2 3.7 5-12 85.2±5.5 6.3 7-12 85.0±5.5 6.6 7-12 87.8±3.6 4.3 6-12

103.5±6.4 6.4 5-12 116.2±7.4 7.8 6-12

7.9±1.6 8.7±2.3 8.3±2.2 8.2±1.9 9.7±1.9 8.9±1.8 9.2±1.9 7.9±2.1 9.6±2.1

21.4 27.1 27.4 24.0 20.2 20.8 22.2 27.9 30.2

20.1-27.1 22.6±28.0 82.7 19.5-23.6 21.6±13.1 62.7 19.5-24.3 22.4±11.9 54.7 21.8-24.8 23.5± 9.4 41.6 19.0-23.2 21.8±10.5 49.8 19.7-24.5 21.5±13.3 63.9 18.3-23.5 21.1±14.2 69.8 21.4-24.4 22.7±12.8 38.3 20.1-27.2 23.4±16.2 72.4

143-167 95-165

116-228 105-188

85-191 75-205 97-185

100-160 7 7-1 75

153.5±8.3 130.5±20.2 169.1±28.3 138.1±26.0 131.9±34.9 122.1±39.2 141.4±30.0 129.7±17.3 127.7±27.0

5.6 9.0-10.0 15.9 8.2-9.0 17.3 8.1-8.8 19.5 6.3-7.0 27.4 10.2-11.1 33.2 9.2-10.3 21.9 9.0-9.9 14.2 8.4-9.2 26.8 8.1-13.4

9.6±3.1 3.2 8.6±2.6 3.0 8.5±2.3 2.8 6.7±2.3 3.5

10.7±2.9 2.8 9.7±3.3 3.5 9.5±3.0 3.2 8.8±2.5 2.9

10.6±5.0 5.7


Duration of the anther-derived in anther-derived plants in the A 2 diploidized haploids developed progenies was 135 d; it was 120 d in generation was manifest and through anther culture. These lines are Co 37. stabilization in the immediate being tested for yield performance.

Homozygosity for quantitative traits generation was exhibited in the

Pest Control and Management DISEASES

Virulence of isolates of Xanthomonas campestris pv. oryzae of Haryana

P.R. Ray, Plant Pathology Department, Haryana Agricultural University (HAU), Hisar; S.S. Malik, HAU Rice Research Station, Kaul (Kurukshetra); and J. N. Chand, HAU, Hisar, India

Twenty-four isolates of the bacterial blight (BB) pathogen Xanthomonas campestris pv. oryzae collected from rice growing areas of Haryana State (12 from Karnal, 4 from Kurukshetra, and 8 from Ambala District) were

Reaction of isolates of Xanthomonas campestris pv. oryzae on rice differential hosts. Haryana, India, 1985.

Reaction a

TN1 TKM6 Sigadis IR36 IET4141 BJ1 DV85 Zenith Isolate no.

1 MS MR R MR Karnal

2 S MR R R

MR MR MS MS MS R

3 MS

HS HS MR

4 MS S

S HS

HS R HS

MS S MR

MS 5 HS MS MR MR R MS

MR MR R

S

6 HS MR R S R HS S MR

7 MS

HS R MR MS MR R 8 S R R R R R

S MR MR

9 MR

MS R R R MR R R 10 HS R R R

R

11 MS R R R R

R R R R R 12

R MS R

R MR R R R R R

tested Jul-Aug 1985 in the screenhouse Kurukshetra on 8 differential hosts. Inoculations 13 MS R MR R R R R

14 MS MR

were made at maximum tillering stage R R R R R R 15 MS

R R MR R R R R R

by the clipping technique using a 16 MS R R R R R R R single-colony culture of bacterial Ambala suspension (10 D at 600 nm) isolated 17 S R MS R MR

18 MS R R R

from samples taken from different R 19 MS

R R MR R MR R

locations. R R R R R

20 R

S MS MR MR MR R MR MS R

Disease reaction was assessed by 21 HS MR MR MS MR R MS MR

lesion length: 0.0-3.0 cm = resistant, 22 S MR R R 23 HS

R R R MR MS

3.1-6.0 cm = moderately resistant, 6.1- R S MS

24 S R MR MR R R R R R MS MR

9.0 cm = moderately susceptible, 9.1- 12.0 cm = susceptible, and 12.1 cm or longer = highly susceptible. Lesion development on 9 randomly collected inoculated leaves was high 15 d after inoculation (see table).

considerably. TN1, with no known major resistance gene, had a susceptible reaction to all the isolates. BJ1 displayed the broadest resistance. One isolate was virulent on BJ1, three on Zenith, four on TKM6 and Sigadis, five on IET4141, and seven each on IR36 and DV85.

to divide differential isolate-variety interaction into 9 groups (I has isolates 1, 8-16, 18, 19, 22, and 24; II has

Virulence of isolates varied

A difference of one grade was used

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

isolate 2; III, 3; IV, 4; V, 5, 7, and 21; isolates, which cannot be expected to VI, 6; VII, 17; VIII, 20; and IX, 23). show identical reactions with isolates Group I is weakly virulent; groups II, of another country. The major genes V, VII, VIII, and IX are moderately in the rice differential genotypes were virulent; and groups III, IV, and VI from different genetic backgrounds are highly virulent. These results show and could vary in their expression. An that more than one pathotype of X. isogenic set of differentials is the only campestris pv. oryzae has developed in way to rule out this variation. Rice Haryana. varieties could have horizontal

The variation in rice differentials- resistance governed by polygenes. The bacterium interaction might have variation in lesion length in these several explanations. All the major differentials could be explained by the genes in the rice differentials from existence of such horizontal Japan or from the Philippines were resistance. identified by using domestic bacterial


Controlling sheath rot (ShR) in rice

H.D. Lewin and P. Vidhyasekaran, Tamil Nadu Rice Research Institute, Aduthurai 612101, India

All the high yielding cultivars in Tamil Nadu are susceptible to ShR caused by Sarocladium oryzae Sawada. The disease is severe during samba and thaladi seasons (Aug-Feb).

Pseudomonas fluorescens suppresses development of bacterial blight (BB) symptoms

C.S. Anuratha and S.S. Gnanamanickam, Centre for Advanced Studies in Botany, Guindy, University of Madras, Madras 600025, India

Xanthomonas campestris pv. oryzae, the BB pathogen, was isolated from naturally infected IR20 and ADT36 plants collected from Coimbatore and Tirurkuppam fields. We also isolated native strains of P. fluorescens (biotype III) from roots of rice, pearl millet, and citrus.

strains restricted the growth of X. c. pv. oryzae. The strain isolated from rice inhibited growth the most. The diameter of inhibition zones varied

In in vitro assays, all P. fluorescens

Multiplication and movement of bacterial blight (BB) pathogen in the rice plant

P.R. Ray and J.N. Chand, Plant Pathology Department, HAU, Hisar, India; and S. S. Malik, HAU, Rice Research Station, Kaul 132021, India

Multiplication of the BB pathogen in host tissue would be reflected in the total inoculum generated and scope for further disease buildup and spread.

Seed of resistant IET4141 and susceptible TN1 were sown separately in earthen pots during Jul-Aug 1985. Seedlings were thinned to five uniformly spaced plants per pot.

Several fungicides inhibited mycelial growth of the fungus in vitro. Their efficacy in the field was tested with cultivar Co 43 in four annual trials 1982-86. Plot size was 24 m 2 in a randomized block design with 4 replications. The fungicides were sprayed at panicle initiation and 15 d later. Disease intensity was assessed 10 d before harvest.

from 1.1 to 5.1 cm. The citrus strain was used in greenhouse experiments. Bacteria-coated rice seeds and nontreated seeds were planted in pots.

P. fluorescens (10 8 cfu/ ml) was mixed with a 1% solution of sterile carboxy methyl cellulose and powdered vermiculite, and dried overnight at room temperature (28ºC). Control seeds were coated with a mixture that did not contain the bacteria. Bacterized seedlings received a spray with P. fluorescens (l0 8

cfu/ml) 20 d after seeding. Four hours later, bacterized and nonbacterized seedlings were inoculated with X. c. pv. oryzae (l0 6 cfu/ml) by the standard clipping technique. The seedlings were maintained on greenhouse benches (24-25 °C). Severity of BB was recorded 7 d after inoculation.

Plants were inoculated at 6 wk with bacterial suspension (OD 1 at 600 nm) using the clipping technique. Lesion lengths were measured in 10 leaves of each variety at 3, 6, 9, 12, and 15 d after inoculation.

One-square-centimeter sample leaf areas from the tip of inoculated leaves collected at intervals up to 12 d were assessed for in vivo multiplication. Each leaf piece was macerated aseptically in a mortar and pestle and a tenfold dilution was plated on NDA in triplicated petri plates. The petri plates were incubated at 27-30°C and colonies were counted after 48 h. Two leaf pieces were used for each variety at each interval.

All fungicides tested — carbendazim (0.l%), edifenphos (0.l%), mancozeb (0.25%), thiophanate methyl (0.l%), captafol (0.125%), carboxin (0.2%), glycophene (0.2%), validamycin (0.1%), IBP (0.l%), iprodione (0.1%), tridemorph (0.1%), and copper oxychloride (0.25%) — were ineffective.

Bacterized rice plants showed substantial reduction (40-60%) in BB severity (see table).

Effect of Pseudomonas fluorescens treatment on BB incidence in rice, Madras, India. a

BB index b in 3 experiments

I II III Cultivar Treatment

TN1 Untreated 3.6 5.6 6.3 Treated 1.9 3.0 3.8 Difference 1.7** 2.6** 2.5**

IR8 Untreated 3.4 7.2 – Treated 2.0 3.3

TKM9 Untreated 1.6 – –

Difference 1.4* 3.9**

Treated 3.0 Difference 4.6**

a Av of 60-187 observations each. b ‘t’ value significant at P = 0.05 (*) and P = 0.01 (**).

The in vivo multiplication of the bacterium and population buildup per unit area of inoculated leaves at different intervals were faster in the susceptible variety than in the resistant variety (see table). Lesions developed in the susceptible variety when the population level reached 10 3 at 3 d and expanded rapidly to a maximum of 15 cm at 15 d. In the resistant variety, lesions developed at 9 d after inoculation when the population level reached about 10 6 and expanded gradually to a maximum of 3.5 cm at 15 d. The bacterium population declined faster in the lesions of the susceptible variety than in the resistant variety. Most of the lesion area in both


Mutiplication and development of lesions caused by Xanthomonas campestris pv. oryzae in diseased rice plants, India.

Days Bacterial cells/cm 2 leaf area Nature and range of lesion length (cm) after

inoculation TN1 ET4141 TN1 IET4141

3 2.83 × 10 3

6 2.65 × 10 5

9 2.16 × 10 3

12 2.65 × 10 6

15 Necrotic lesion Necrotic lesion 7.0-15.0, straw color 1.5-3.5, brownish

1.0 × 10 3 0.2-0.5, grey green No lesion 1.5 × 10 4 0.5-1.5, yellow 1.5 × 10 6

1.33 × 10 5 5.0-10.0, brownish 2.0-5.0, yellow

No lesion 0.5-0.8, light yellow 1.0-1.5, yellow

varieties became necrotic after 12 d. The rate of multiplication was

consistently higher in the susceptible than in the resistant variety. It appeared that lesion size was not necessarily determined by the population of the pathogen but particular host-pathogen relationship.

~~

by a

Occurrence of rice ragged stunt virus (RSV) in Sri Lanka

K. W. Jayasena, Regional Research Station. Angunukolapalana, Sri Lanka; and H. Hibino, IRRI, Philippines

Plants showing symptoms similar to those of rice RSV were first observed in Hambantota district in 1984. Varieties BG276-5, BG34-8, BG94-1,

BG34-6, and BG380 were affected. Disease incidence ranged from 20 to 70% in farmers' fields in Weeraketiya and Ranna.

Plants with typical symptoms collected from Weeraketiya, Walasmulla, Belliatta, Ranna, and Jandura were tested for virus recovery. Virus-free Nilaparvata lugens and Nephotettix sp. reared on TN1 plants in insect-proof cages were allowed to

feed on infected plants for 4 d, then confined with 7-d-old TN1 seedlings for 4 d.

The first symptoms similar to those reported for RSV were observed 21 d after inoculation. N. lugens but not Nephotettix sp. transmitted the disease to TN1 seedlings. Dried infected TN1 leaves were serologically tested at IRRI. ELISA test confirmed RSV in extracts of the leaves.

Pest Control and Management INSECTS

Meadow grasshopper Conocephalus longipennis damage to rice spikelets

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

Tettigoniids as foliage feeders occur on rice worldwide. The nocturnal C. longipennis (de Haan) is more abundant in crops past the vegetative stage.

It shows dual food habits - as a pest feeding on rice foliage and as a predator of rice bug and stem borer eggs and nymphs of leafhoppers and planthoppers. Conocephalus also eats the highly nutritive rice anthers by cutting through the lemma or palea. In the process, it damages rice spikelets.

Whitish cut holes on damaged 1-d- old spikelets become noticeable when they turn brown on the third day (see figure). We found that caged adults (right). can destroy 10-28 spikelets daily.

Conocephalus damage can be distinguished from bird, rat, or rice are eaten in each spikelet. Feeding Bugs feeding on seeds do not make bug damage because only small holes birds and rats strip off many spikelets. noticeable holes in spikelets.

Conocephalus damage to rice spikelets: undamaged (left), 1-d-old damage (middle), and 3-d-old damage


Ochthera sauteri Cresson (Diptera: Ephydridae), predator of rice whorl maggot (RWM) flies

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

RWM Hydrellia philippina Ferino has few recorded natural enemies. Recently, we found an ephydrid fly preying on RWM flies.

The predator Ochthera sauteri Cresson (identified by P.J. Clausen, University of Minnesota, USA) is in

the subfamily Parydrinae previously recorded only in Taiwan. The 5- to 7- mm-long adult can be identified by its black and silvery body, 0.16 mm head index value, 3 aristal hairs on the antenna, pointed frons, mantis-like forelegs with 4 long spines, and tibial spur as long as the basal segment of the tarsus, forecoxa and tarsus subequal in length, wings hyaline with tips of vein R 4 + 5 and M 1 + 2 close to each other (see figure).

different from that of its relatives in this mainly phytophagous group. It

The behavior of O. sauteri is

walks on the rice foliage or water surface, or dives from the plant to the water to grab sighted prey. The prey is held transversely in its mantis-like forelegs and rapidly pricked by the tibial spur 3-10 times prior to feeding.

The predatory fly laps up the body fluids that ooze from the prey’s body. Cage studies showed Ochthera live 4-7 d. They prey on species of Hydrellia, Brachydeutera, Psilopa, and Paralimna, consuming 4-18 flies/d. They also feed on Notiphila spp. at 1-3 flies/d.

Female of O. sauteri (a), frontal view of head (b), side view of face with 3 aristal hairs (c), clypeus (d), mantis-like foreleg stretched to show spur (e) and held at rest (f), hind leg (g), tarsal segments (h-i), and tip of male’s abdomen (j). Scale = 1 mm except d, h, and i.


Five granular and 4 sprayable insecticides evaluated for yellow stem borer (YSB) control

M.S. Purohit, A.H. Shah, and S. Raman, National Agricultural Research Project, Gujarat Agricultural University, Navsari Campus, Navsari, India

In 1982 and 1983, five granular and four spray insecticide formulations were tested against YSB Scirpophaga incertulas.

GR-11 seedlings were transplanted in 6-m 2 plots in a randomized block design with 6 replications. Granular insecticides were applied at 15 and 45 d after transplanting (DT); spray formulations were applied at 15, 45, and 60 DT. Deadhearts at 75 DT and whiteheads at harvest were counted; unhulled grain yield was recorded.

Of five granule and four spray formulations tested in three seasons,

cypermethrin spray was most effective (Table 1). Next was monocrotophos, followed by fenitrothion. Among

effective; carbaryl + gamma BMC was least effective. Chlorpyrifos, phorate, and quinalphos were ineffective. None of the granule formulations were

granules, carbofuran was most

effective during rainy season 1982. Although cypermethrin spray

resulted in the highest yield (3.43 t/ha), broadcasting carbofuran and spraying monocrotophos and fenitrothion significantly increased yield (2.94-3.01 t/ha) over the untreated control (Table 2).

Table 2. Effect of granular and sprayable insecticide application on yield, Navsari, Gujarat, India, 1982 and 1983.

Insecticide Dosage Grain yield a (t/ha)

(kg ai/ha) 1982 rainy season 1983 summer 1983 rainy season

Carbofuran 3G 1.00 2.5 a 3.0 ab 3.4 b Chlorpyrifos 10G Phorate 10G

1.00 2.5 a 2.0 c 2.8 c 1.00

Quinalphos 5G 1.00 1.8 a 1.7 c 2.9 c 2.5 a

Carbaryl + gamma BHC 2+2G 1.00 2.0 c 2.9 c

Fenitrothion 50 EC 2.6 a 2.1 bc 3.2 bc

Monocrotophos 36 EC 0.50 2.4 a 3.0 ab 3.4 b 0.36

Carbaryl 50 WP 2.5 a 3.1 ab 3.4 b

1.00 2.2 a 2.1 bc 3.1 bc Cypermethrin 25 EC 0.15 3.0 a 3.3 a 4.0 a Untreated control – 2.2 a 1.8 c 2.8 c

a In a column, figures followed by the same letter are not significantly different at the 5% level.

Table 1. Control of yellow stem borer by 5 granular and 4 sprayable insecticides. Navsari, Gujarat, India, 1982 and 1983. a

Insecticide

1982 rainy season 1983 summer 1983 rainy season

Deadhearts Whiteheads Deadhearts Whiteheads Deadhearts Whiteheads (no.) (no.) (no.) (no.) (no.) (no.)

Dosage (kg ai/ha)

Carbofuran 3G 1.00 8.7 cd 394.2 a 14.5 ab 139.8 a Chlorpyrifos 10G 1.00

18.5 ab 7.8 cd 304.8 a

Phorate 10G 1.00 384.3 a 22.5 c 195.2 c 23.7 bcde 21.5 c

10.0 d 187.7 c 26.5 de

Quinalphos 5G 1.00 9.7 d 340.7 a 18.5 c Carbaryl + gamma BHC 2 + 2G

185.8 c 23.5 bcde 1.00 9.5 d 348.0 a 14.5 ab

Fenitrothion 50 EC 174.8 bc 19.7 abcd

0.50 3.8 a 353.2 a 14.7 ab Monocrotophos 36 EC

148.0 ab 19.5 abc 0.36

Carbaryl 50 WP 6.3 bc 408.2 a 14.5 ab 124.7 a 19.0 abc

1.00 4.0 ab 337.5 a 17.8 c 186.3 c 21.8 bcd Cypermethrin 25 EC 0.15 1.5 a 260.7 a 10.7 a 114.2 a Untreated control

15.7 a – 7.8 cd 370.8 a 23.0 c 199.0 c 29.0 e

a No. of deadhearts or whiteheads/6 m 2 . In a column, figures followed by the same letter are not significantly different at the 5% level.

18.5 ab 40.8 cde 42.8 cde 41.5 cde 36.7 bcd 24.8 abc 15.2 a 44.3 de 13.0 a 58.9 e

Daylength effect on development of 4 green leafhopper Nephotettix spp.

R.R. Valle, Entomological Laboratory, Faculty of Agriculture, Kyoto University, Sakyo-ku, Kyoto 606, Japan

Although diapause in the temperate species of rice green leafhopper (GLH) N. cincticeps (NC) has been well studied, not much is known about diapause in the tropical species N. virescens (NV), N. nigropictus (NN), and N. malayanus (NM). The three


tropical GLH species were subjected to the daylength and temperature conditions that induce diapause in NC.

Sixty newly hatched 1st instars of each species in individual test tubes (20 mm diameter and 170 mm long) were fed 5-d-old seedlings of the susceptible japonica variety Nipponbare. The insects were reared at 20°C under 8, 10, 12, 14, and 16 light hours (LH). The nymphs were fed fresh seedlings every 3 d and nymphal duration measured daily.

Short daylengths — 8, 10, and 12 LH — did not induce diapause in the

tropical species, although development was slightly prolonged as daylength shortened from 16 LH to 8 LH (see table). Nymphal development of both males and females of NN was significantly different in daylengths shorter than 10 LH and longer than 12 LH, except that for males under 8 LH development was about 1 d longer.

The development of NV males did not significantly differ between photoperiods, but that of females was significantly prolonged under photoperiods shorter than 12 LH. The 5-d difference between 8 LH and 16

Adult of E. staIi (a) and its feeding behavior on PSB larva inside the plant stem (b). Scale = 1 mm.

Developmental period of Nephotettix spp. exposed to different photoperiods at 20 °C. Japan.

Species

N. virescens Male 44.0 a 44.3 a 42.4 a 41.2 a 42.3 a

N. malayanus Male

a In a row,means followed by the same letter are not significantly different at the 5% level by DMRT.

Female

Female N. cincticeps Male

Female

Female

8 LH 10 LH 12 LH 14 LH 16 LH

46.3 a

45.6 a

74.2 a 77.9 a 44.1 a 46.7 a

46.4 a

45.2 a

55.2 b 58.6 b 43.8 a 46.1 a

Developmental period a (d)

44.2 a 44.0 c 43.7 c

43.6 a 45.3 a

44.1 b 44.4 b

42.7 b 39.6 d 42.8 c 42.7 a 45.3 a

44.0 b

40.8 c 40.4 d 42.9 c 40.3 b 43.4 b

N. nigropictus Male 43.8 a 44.3 a 42.0 c 42.8 bc 42.3 c photoperiods.

LH was the largest among the tropical

Among the four species, only the

species of GLH. Under 16 LH, the

temperate NC showed a clear

development of both sexes of NM was

lengthening of nymphal development

significantly shorter than under other

under 10 LH. Under 8 LH, both the 4th- and the 5th-instar nymphs of NC exhibited arrested development; total development was prolonged to 74.2 d for males and 77.9 d for females.

An earwig predator of Asian pink stem borer (PSB) in upland rice

A. T. Barrion, E. M. Libetario, and J. A. Litsinger, Entomology Department, IRRI

Asian PSB Sesamia inferens (Walker) can be particularly abundant in upland rice grown near sugarcane or related grasses. We found the earwig Euborellia stali (Dohrn) preying on PSB larva in stem borer-damaged tillers in upland ricefields in Claveria, northern Mindanao, Philippines. The predatory earwig bites the anal portion as the larva attempts to escape. There is a similar record of this earwig preying on the Oriental maize borer Ostrinia furnacalis (Guenée).

E. stali (see figure) has a shiny black body, light yellow brown legs with a black band on midfemora, and 17- segmented antennae with segments 14- 15 colored white. It is common in dryland habitats and can be collected by digging in the soil at the base of rice hills.

The female earwig drags its prey out of the stem to her nest at the base of the plant to feed the newly hatched nymphs. A female shows maternal care to the 200-350 pale yellow and globular eggs it lays.

The nocturnal earwigs live 3-5 mo. Cage studies show that this earwig can consume 20-30 young PSB larvae a day.

Ovicidal activity of eight insecticides against the rice whorl maggot (RWM) Hydrellia philippina Ferino

P. C. Pantua and J. A. Litsinger, Entomology Department, IRRI

Two-wk-old potted rice plants were caged in nylon mesh. Field-collected male and female RWM adults were introduced into the cage and allowed to oviposit. Eggs on each potted plant were counted at 1 d. Plants with at least 10 eggs were used in the experiment.

Four potted plants laden with 2-d- old RWM eggs were placed in a mylar cage and sprayed with 25 ml (equivalent to spray water volume of

Ovicidal activity of 8 insecticides applied as foliar spray on plants with 2-d-old eggs of RWM. IRRI, 1986.

Insecticide Rate

Formulation (kg ai/ha) Egg.

mortality a

(%)

Deltamethrin 2.5 EC 0.012 98 a Triazophos 40 EC 0.4 97 a Azinphos-ethyl 40 EC BPMC

0.4 94 a 50 EC 0.4 50 b

Carbaryl 85 WP 0.4 42 b Carbosulfan 20 EC 0.4 39 b Buprofezin 25 WP 0.125 32 b Malathion 51 EC 0.4 25 b

level by DMRT. Abbott’s formula was applied for corrected percent egg mortality. a Av of replications. All means followed by a common letter are not significantly different at the 5%

1,000 liters/ ha ) of each test (see table). Some ovicidal activity insecticide using a 1-liter plastic hand occurred with BPMC, carbaryl, sprayer. carbosulfan, buprofezin, and

azinphos-ethyl were highly ovicidal Deltamethrin, triazophos, and malathion.


Leafhopper and planthopper populations and rice tungro virus (RTV) incidence at the tail end of an irrigation system

A.L. Alviola III and J.A. Litsinger, Entomology Department, IRRI

The tail end of the 100,000 ha Upper Pampanga River Integrated Irrigation System (UPRIIS) in Central Luzon, Philippines, is an endemic area for RTV. Irrigation canals block natural drainageways, converting the west side of Batitang near the tail end of one lateral from a first class rainfed rice area to an uncultivated fallow. In dry season, irrigation water reaches only the east side of Batitang. In wet season, the laterals drain runoff water into Batitang, causing floods. Ricefields east of Batitang near the fallow are planted asynchronously because irrigation releases are undependable. Many farmers have their own pumps.

To measure differences in insect populations in the 1981 wet (WS) and 1982 dry seasons (DS), pairs of kerosene light traps were installed and

monitored daily in six villages from the head to the tail end of the canal system. RTV symptoms were determined visually and confirmed by the iodine test. They correlated highly ( r = 0.73**) with increasing distance from the head end of the system (Table 1). Staggered planting, measured as the variance in planting date, increased significantly ( r = 0.87*) from the head to the tail end.

Three green leafhopper (GLH) species were collected in the light traps. Their numbers also increased from the head to the tail end of the system. Nephotettix malayanus was the most abundant species at the tail end, but only N. virescens ( r = 0.59*) and N. nigropictus ( r = 0.68*) numbers correlated with RTV incidence. In sweep net samples taken twice a week from 25 ricefields in 1982 DS, less than 3% of the GLH catches were N. malayanus; 75-86% were N. nigropictus and N. virescens (Table 2).

The most abundant planthoppers Sogatella panicicola and Sogatodes pusanus feed on Echinochloa sp. and Leersia sp. weed. Echinochloa glabrescens (52%) and Leersia

Table 1. GLH and RTV incidence in ricefields of 6 villages from head to tail end of UPRIIS, Central Luzon, Philippines, 1981 WS-82 DS.

Distance a Variance RTV- Light trap collection d (no./season per trap) Village from head end of planting infested

(km) date b hills c N. virescens N. nigropictus N. malayanus (%)

Ibabaw Bana 0 49 0 128 16 16 Rajal Centro 9 90 0.4 1191 321 215 Marawa 15 217 4.5 486 136 156 Santa Rita 16 241 8.0 1001 238 511 Manaol 17 314 4.0 619 143 507 Batitang 18 429 10.5 2324 931 2788

a Measured along length of canal system. b Based on a sample of all fields within a 0.5-km radius of the center of a pair of kerosene light traps in each village, 1981 WS. c Sample of 125 hills in each of 5 randomly selected fields planted to IR36 or IR42. RTV incidence at reproductive stage was averaged from 1981 WS and 1982 DS. Diagnosis was confirmed by iodine test. d A pair of kerosene light traps placed 100 m apart in open ricefields in each village. Values are an average of 1981 WS and 1982 DS catches. Season = 6 mo.

hexandra (38%) dominated the fallow in weed biomass. Weeds in ricefields east of Batitang were mainIy Echinochloa crus-galli, Cyperus difformis, and Monochoria vaginalis.

FARMCOP suction samples from three fields of IR42 on nine sampling dates during 1982 WS in east Batitang revealed no N. malayanus nymphs. Less than 1% of the total GLH adult catch was N. malayanus. The GLH nymphal population was split evenly between N. virescens and N. nigropictus.

Because N. malayanus was reared from E. glabrescens and L. hexandra but not from rice, its role as a vector of RTV is questionable. We conclude that increased RTV incidence is associated more with the increasing incidence of staggered planting than with the nearness of ricefields to uncultivated weedy fallow. However, weedy fallow areas can harbor low numbers of rice leafhoppers and planthoppers.

Table 2. Leafhoppers and planthoppers collected by sweep net from abandoned ricefields. Zaragoza, Nueva Ecija, Philippines, Jan-Mar 1982 DS. a

Species Collected (X)

Cicadellidae Nephotettix malayanus 21 N. nigropictus 12 N. virescens 3 Recilia dorsalis 1

Sogatella panicicola 43 Sogatodes pusanus 16 Sogatella kolophon 2 Sogatella furcifera 1 Sogatella longifurcifera 1 Nilaparvata lugens 1 N. bakeri 1

a 100 sweeps in each of 3 fields every 10 d for 5 mo. Rice plants were not encountered in 10-m 2

samples in each of 3 fields nor seen in any fields. Weeds, representing 3% dry weight each, were Paspalum paspalodes, Echinochloa picta, Ipomoea aquatica, and Ludwigia adscendens

Delphacidae

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


Pest Control and Management WEEDS

A survey of weeds in transplanted Percentage weed cover associated with transplanted and wet seeded rice in Pili, Camarines Sur,

and wet-seeded rice under rainfed Philippines.

and irrigated conditions Cover percentage

P. P. Pablico and K. Moody, IRRI

A survey was carried out in Sep 1985 in barangays Sagrada, San Isidro, Alternanthera sessilis (L.) DC. Amaranthaceae – 11

Pawili, and Takbong of Pili, Commelina diffusa Burm. f. Commelinaceae <1 – – –

Camarines Sur, Philippines. Ten wet Cyperus difformis L. Cyperaceae <1 <1 <1 <1 Cyperus iria L. Cyperaceae 4 – 9 <1

Weed species Family Transplanted rice Wet seeded rice

Rainfed Irrigated Rainfed Irrigated

– –

seeded (pregerminated seed sown on puddled soil) ricefields (six rainfed and four irrigated) and seven transplanted ricefields (three rainfed and four irrigated) were assessed 60–70 d after planting. Percentage weed cover was determined visually.

Severity of weed cover was greater in wet seeded rice and under rainfed conditions. Of the 27 weed species found (see table), 10 were grasses and 6 were sedges. Of the 22 species found in wet seeded rice and 18 found in transplanted rice, 11 were common to. both types of culture. More weed species were found under rainfed conditions than irrigated conditions.

Echinochloa glabrescens, Fimbristylis miliacea, and Ludwigia octovalvis were observed in all growing conditions. Pseudoraphis spinescens, which has never been reported as a weed of rice in the Philippines, and F. miliacea were the major weeds under rainfed conditions. In irrigated transplanted rice, Monochoria vaginalis dominated. In irrigated wet seeded rice, the important species were

Only Cyperus difformis,

Cyperus rotundus L. Cyperaceae Echinochloa colona (L.) Link Poaceae Echinochloa crus–galli (L.) Beauv. Poaceae

Echinochloa glabrescens Munro Poaceae

Eclipta prostrata (L.) L. Asteraceae Eclipta prostrata (L.) L. Hassk. var. Asteraceae

Fimbristylis miliacea (L.) Vahl Cyperaceae Isachne globosa (Thunb.) 0. K. Poaceae Ischaemum polystachyum Presl Poaceae Ischaemum rugosum Salisb. Poaceae Leersia hexandra Sw. Poaceae Lindernia antipoda (L.) Alston Scrophulariaceae Ludwigia octovalvis (Jacq.) Raven Onagraceae Macroptilium lathyroides (L.) Urb. Papilionaceae Marsilea minuta L. Marsileaceae Monochoria vaginalis (Burm.f.) Presl Pontederiaceae Panicum repens L. Poaceae Pseudoraphis spinescens (R. Br.) Poaceae

Scirpus grossus L. f. Cyperaceae Scirpus supinus L. Sphaeranthus africanus L.

Cyperaceae Asteraceae

Sphenoclea zeylanica Gaertn. Sphenocleaceae Sporobolus diander (Retz.) Beauv. Poaceae

ssp. hispidula (Retz.) Honda

ex Hook. f.

zippeliana (B1.) Koster

J. Vickery

– 2

<1

<1

<1 1

29 <1 <1

– –

<1 <1 <1 <1

25

–

–

– 9 – – –

– –

<1

<1

– –

<1 <1 <1

– – –

<1 – – 4 – –

– –

<1 –

–

<1 8 –

3

<1 <1

15 – – 1

<1 <1 <1 <1 – –

<1 55

<1

<1

<1

–

–

– 5 –

13

<1 <1

15 –

10

<1 <1

<1 9

5

–

–

–

–

–

<1 <1

–

–

Total no. of species 17 9 18 16 Species in common (no.) 8 12 Total cover (%) 72 6 98 70

Alternanthera sessilis, E. glabrescens, Irrigation and transplanting reduced F. miliacea, Ischaemum rugosum, and weed cover. M. vaginalis.

Control of Eragrostis japonica and thiobencarb (1.0 and 1.5 kg/ ha) with a population of 252/m 2 , (Thunb.) Trin. in upland rice followed by postemergence application constituted 90% of the total weed

of 2,4-D EE and hand weeding were A. Mohamed Ali and K. Ramamoorthy,

population and caused 86% yield

Agricultural College, Tamil Nadu compared with the manually operated, reduction. With pendimethalin at 1.25

Agricultural University, Tirunelveli 627003, long-handled rotary weeder, 3 hand kg/ha, it numbered 12 m 2 ; with India weedings, and unweeded check in a thiobencarb at 1.50 kg/ ha, it was 16

field experiment in Vertisols of m 2 . Total weed dry matter production Preemergence herbicides Paramakudi, South India, in 1984–85. at 80 DAS with these treatments was pendimethalin (0.75 and 1.25 kg/ ha) Eragrostis japonica, the major weed low compared to that with 2 hand


Weeds gowing in association with rice, citrus, and sweet potato in Real, Quezon, Philippines, Jul-Sep 1984.

Rice Weed species Citrus Sweet potato

Sloping land Flat land

Ageratum conyzoides Axonopus compressus BIumea sinuata Crassocephalum crepidioides Cyperus halpan Emilia sonchifolia Imperata cylindrica Paspalum conjugatum Pseudoelephantopus spicatus Solanum eumingii

Golden apple snail: a pest of rice

R. C. Saxena, International Centre for Insect Physiology and Ecology, Nairobi, Kenya, and IRRI; A. V. de Lara, Department of Invertebrate Zoology, College of Arts and Sciences, University of the Philippines at Los Baños; and H. D. Justo, Jr., IRRI

weedings and in the unweeded check. Pendimethalin at 1.25 kg/ ha and

thiobencarb at 1.50 kg/ha followed by hand weeding gave highest grain yields (see table).

Weeding cost was highest with the peg-type weeder. The marginal benefit- cost ratio was highest with the combination of thiobencarb at 1.00 kg/ha followed by 2,4-D EE.

Weeds in shifting cultivation in Quezon Province, Philippines

In Real, Quezon Province, farmers plant rice at the start of the rainy season immediately after clearing secondary forests by dibbling into fields that have had no land

preparation. After the rice is harvested, citrus or sweet potato is planted, depending on the availability of citrus seedlings.

In 1984, we surveyed 4 recently cleared fields 19, 69, and 76 d after seeding (DAS) rice. At the same time, we surveyed adjacent areas planted to citrus and sweet potato which had been cleared the previous year. Percentage of weed cover and weed

Pest Control and Management OTHER PESTS

Effect of weed control treatments on major weed, total weed dry matter, and grain yield in upland bunded rice. Tirunelveli, India, 1984-85.

Eragrostis Total weed Grain Rate japonica dry matter yield

80 DAS 80 DAS

Weeding Benefit: cost cost Treatment a

(kg/ha) (no. m 2 ) (kg/ha) (t/ha) ($/ha) ratio

Pendimethalin fb HW 30 DAS 1.25 12.6 61.5 3.1 48.6 6.03 Thiobencarb fb HW 30 DAS 1.5 15.8 69.5 3.0 31.4 7.50 Hand weeding at 20, 35, – 19.8 75.9 2.8 63.8 3.65

Working peg-type weeder at – 25.7 185.4 2.6 82.2 2.16

Thiobencarb fb post-em 1.0

Pendimethalin fb HW 30 DAS 0.75 33.6 277.5 2.5 41.1 4.76 Thiobencarb fb HW at 30 1.0 30.3 227.6 2.5 51.7 3.73

Pendimethalin fb HW at 0.75 31.6 221.3 2.5 56.2 3.41

Thiobencarb fb HW 30 DAS 1.0 36.6 265.6 2.4 37.0 5.28 Pendimethalin fb post-em 0.75

Hand weeding at 20 – 106.3 117.3 2.2 48.0 2.97

Unweeded check – 252.6 1354.5 0.4 – –

CD (P = 0.05) 3.9 65.9 1.5 – – a Pre-em = preemergence, post-em = postemergence, fb = followed by, HW = hand weeding. Men labor at US$0.8/8 h and women at US$0.6/8 h. Pendimethalin cost, US$8.0/liter; thiobencarb, US$7.1/liter; 2,4-D EE, US$4.0/liter.

and 50 DAS

20, 35, and 50 DAS

2,4-D EE 35 DAS 0.5 28.5 206.6 2.6 24.3 9.34

and 50 DAS

30 and 50 DAS

2,4D EE 35 DAS 0.5 26.4 208.7 2.4 30.1 6.86

and 35 DAS

species were recorded. None of the crops were weeded. In

recently cleared areas where the land was sloping, weeds were not a problem. Weed cover was 0-3% at 19 DAS and 0-15% at 69-76 DAS. In one field, 10% was flat land adjacent to a stream. The soil was moist most of the time, which favored weed seed germination and growth. Weed cover in this area ranged from 30% at 19 DAS to 90% at 76 DAS.

Where clearing had been done the previous year, weed infestation was severe, particularly in the area planted to citrus where weed cover was 98%. Paspalum conjugatum, the predominant weed, covered 95% of the area. Sweet potato suppressed weed growth; weed cover in that field was only 30%.

the different crops are listed in the table. P. conjugatum was the predominant weed in all fields. It is expected that P. conjugatum and Imperata cylindrica, which are aggressive species, will provide most of the weed cover in future years in fields currently planted to rice.

To our knowledge, this is the first

Weeds growing in association with

time Axonopus compressus and Solanum cumingii have been reported as weeds of rice in the Philippines.

R. T. Lubigan and K. Moody, IRRI

The golden apple snail Pomacea canaliculata, an aquatic gastropod originating from South America, was introduced recently in the Philippines as a culture material to be farmed in


cement tanks, ponds, or other controlled environments.

In recent surveys, the snail and its egg masses (Fig. 1a) were found in abundance in the Azolla propagation ponds of the U.P. College of Agriculture at Los Baños (Fig. 1b) and in adjoining irrigated ricefields on the IRRI experimental farm. The snail feeds voraciously on Azolla. Adults measuring 22-26 mm can consume up to 15 g of Azolla fronds in 12-24 h.

succulent aquatic vegetation, such as newly transplanted rice. It attacks the base of rice seedlings and then devours aerial parts. A large snail can consume a blade of rice in 3-5 min (Fig. 1c). The snail is most active at dusk, night, and dawn.

Damage is most severe in low-lying portions of newly transplanted ricefields. Severely damaged plots are characterized by missing seedlings and floating, cut leaves (Fig. 1d). Damage can reach 10-20%. In a freshly transplanted 0.1-ha ricefield on the IRRI farm where damage was observed, three 3-gallon pails of golden apple snails were collected.

preferably on substrates protruding above the water surface (rice hills, weeds, rat fence walls, and bamboo stakes). A single gravid female can lay 25-320 bright pink eggs per week. Eggs hatch in 8-15 d, depending upon temperature.

mm in diameter readily disperse

The snail feeds also on other

Females start laying eggs at 75-90 d,

Newly hatched snail larvae about 2

1. Golden apple snail: a) females and their egg masses on rice plants; b) clusters of egg masses on bamboo stakes in an Azolla propagation pond; c) full-grown snail grazing on a rice seedling; d) missing seedlings due to feeding by full-grown snails.

through irrigation water to other ricefields. Young snails feed on algae. Older snails have a horny tongue or radula with rows upon rows of sharp teeth (Fig. 2). The snails are more active and grow faster during warmer months, but mortality is high under hot temperatures.

The golden apple snail can be controlled with organotin molluscicides. However, these chemicals are also toxic to aquatic animals such as fish and tadpoles. Manual collection of snail egg masses can alleviate the problem in ricefields. 2. Radular tooth pattern of the golden apple snail.

Irrigation Water Management

The effect of supplementary irrigation on rice yield in Bangladesh

A. F. M. Saleh, Water Resources cover 89% of the total cropped area mm in the northwest to over 5,000 mm Engineering Department, Bangladesh and yield 84% of the total rice output, in the northeast) occurs during aus and University of Engineering and Technology, they are still grown as rainfed crops. aman. Dhaka, BangIadesh Uncertain rainfall during transplanting We studied the amount of

In Bangladesh, rice is grown in aus and critical growth periods means crop (summer), aman (autumn), and boro losses, even though 80% of the mean (winter). Although aus and aman rice annual rainfall in the country (1,400


supplementary irrigation needed, its effect on yield, and the risks associated with rainfed aus and aman rice cultivation on the farm of the Bangladesh Rice Research Institute, Joydebpur, in 1980-81. The three treatments were I) rainfed, 2) rainfed with supplementary irrigation to keep the plots saturated, and 3) rainfed with supplementary irrigation to keep the plots under 25-50 mm standing water. The water balance method was used to determine the crop water requirement, with provisions for measuring rainfall, evaporation, and seepage and percolation.

Treatment 3 had yields 8-71% higher than in treatment 1 during aus and 71% higher during aman. Rainfall was 842 mm during aus and 783 mm during aman. Supplementary

Supplementary irrigation required (SIR) during aus and aman seasons at rainfall probabilities of 25, 50, and 75%. BRRI, Bangladesh. 1980-81.

irrigation was required because of erratic distribution. For treatment 3, 69 mm supplementary irrigation was were calculated as 643 mm for aus and supplementary irrigation required required in aus and 573 mm in aman. 893 mm for aman. would vary 0-69 mm with rainfall For treatment 2, a 57% higher yield Probability analysis projected that probabilities of 50-75% for aus and 67- over treatment 1 during aman required aus rice would require supplementary 309 mm with rainfall probabilities of only 15 mm supplementary irrigation. irrigation in 1 out of 4 yr and aman 25-75% for aman (see figure). Crop water requirements at field level rice 3 out of 4 yr. The amount of

Irrigation management for lowland Water management effects on yield in Tamil Nadu, 1985-86. a

rice under water constraint Kharif Summer

R. Marimuthu and R. Kulandaivelu, Tamil Treatment Nadu Agricultural University (TNAU), Coimbatore 3, India

Water Yield WUE Water Yield WUE consumed (t/ha) (kg/ha mm) consumed (t/ha) (kg/ha mm)

(mm) (mm)

A trial on irrigation practices used IR50 rice on clay loam soil at TNAU during 1985 kharif and 1986 summer. Kharif treatments were I) continuous 5-cm submergence, 2) saturation to 5- cm submergence, 3) field capacity to 5- cm submergence, 4) a turn system of two 7-cm irrigations at 3- and 4-d intervals in 1 wk, with no irrigation the alternate week, and 5) continuous 5- cm submergence to 30 d after transplanting (DT) and thereafter no irrigation for 4 d, followed by 1 wk continuous submergence. In summer, field capacity submergence was

1 1639 2 97 1

5.30 3.2 5.19

3 723 4.18 5.8 6.4

4 917 5 1463

4.58 6.0 4.98 4.1

CD at 5% – 0.57 –

a WUE = water use efficiency.

replaced by a partial turn system — 4 d no irrigation followed by 1 wk continuous 5-cm submergence up to 30 DT — and then continuous submergence.

Saturation to 5-cm submergence

165 1 1013

5.18 3.1 5.04 5.0

1430 5.48 3.8 960

1387 4.83 5.24

5 .0 3.8

– 0.46 –

saved about 40% of the water needed for continuous submergence without significantly affecting yield (see table). Under the turn system, yields were 14% less in kharif and 7% less in summer.

26 IRRN 12: 1 (February 1987)

Soil and Crop Management

Response of rice to N split application on a saline soil

A.B. Niane, Institut Sénégalais de Recherches Agricoles, Djibélor, B. P. 34, Ziguinchor, Senegal

This study in IRRI’s soil chemistry greenhouse used soil samples taken from Kalawagan, Pangasinan, Philippines. The soil was nonsaline, nonsodic, low in organic matter, and had a pH of 7.4. Sodium chloride was used to obtain soil solution EC, values of 2.8, 4.8, 8.2, 10.0, and 13.4 dS/m at 25 °C. IR56 seedlings were planted.

The soils were fertilized with superphosphate and muriate of potash at 25 mg/ kg. Basal N as urea was applied as 25, 25, 50, and 100 mg N/ kg. The two 25 mg/ kg levels received additional urea at 50 and 100 mg N/kg at panicle initiation. The 4

Effect, of 5 salt and 4 N levels on yield. IRRI greenhouse.

Salt level Shoot av Straw av Grain a (g/pot)

(dS/m) (g/pot) (g/pot) 50 75 b 100 125 b Mean

ECe 2.8 17.6 16.5 17.2 a 22.6 a 17.5 a 25.9 a 20.8 ECe 4.8 13.3 14.1 13.0 b 21.3 a 14.3 b 22.2 b 17.7 ECe 8.2 5.2 8.6 4.4 c 8.5 b 3.5 c 6.5 c 5.7 ECe 10.0 2.2 4.4 2.1 d 3.8 c 0.6 d 1.0 d 1.9 ECe 13.4 0.6 0.0 0.0 d 0.0 d 0.0 d 0.0 d 0.0

Mean 7.8 8.7 7.4 11.2 7.2 11.1 9.2

a In a column figures followed by a common letter are not significantly different at 5% level by DMRT. b Split application: (25 basal + 50 mg/kg topdressed) or (25 basal + 100 mg/kg topdressed).

levels of N finally imposed were 50, 75, the yield-contributing characters. Plant 100, and 125 mg/kg. height, tiller numbers, panicle weight,

Regardless of the amount and and 1,000-grain weight were affected. timing of N, increasing salinity levels N did not significantly affect shoot strongly affected yields from EC, 8.2 weight. However, the straw and grain to 10.0 dS/m (see table). At EC, 13.4 yields differed with basal and split N dS/m, plants died. applications. In saline conditions,

attributed to the effects of salinity on than basal application. The yield reduction may be topdressed nitrogen was more efficient

Efficiency of urea-based fertilizers in Urea-based fertilizers’ effects on grain yield and N uptake. Mangalore, India, 1984. coastal rice

B. N. Patil, A.M. Krishnuppa, Badrinath, (t/ha)

K. Kenchaiah, K. B. Rao, and N.A. Control 3.7 385 7.7 73 Janardhana Gowda, Agricultural Research Urea split (50% basal + 25% 4.7 493 9 .1 92 Station, Kankanady, Mangalore 575002, tillering + 25% panicle initiation) Karnataka, India Urea basal application 4.4 500 9.0 88

Lac-coated urea 5.1 485 10.3 94 Neem cake-blended urea 5.1 458 10.0 91

Grain Productive Grain wt N uptake Treatment a yield tillers/m 2 (g/hill) (kg/ha)

We evaluated the efficiency of urea- based N fertilizers in midland soil of coastal Karnataka. The experimental field was fine, loamy, mixed- isohyperthermic family of Ustoxtropepts with pH 5.1, 1.26% organic C, and 78 kg P and 50 kg available K/ ha. The experiment was laid out in randomized block design with four replications.

seedlings were transplanted on 17 Jul 1984 at 20- × 10-cm spacing, 3 seedlings/hill. Plots were treated with

Medium-duration IET3232 26-d-old

Green manure + urea (1:1) 4.9 458 9.8 90

CD (0.05) 0.7 59 1.4 –

a Urea at the rate of 90 kg N/ha.

75 kg superphosphate and 90 kg muriate of potash/ ha and kept flooded from transplanting to harvest. Pests and diseases were controlled. Harvest was on 6 Nov 84.

table). Yield and its attributes differed significantly with N source. Maximum grain yield with neem cake-blended

Five N sources were tested (see

urea and lac-coated urea was statistically significant. Split application of urea was more productive than basal application. Yields with green manure + urea (1:l) at planting were comparable to those with coated urea. N uptake was higher with coated urea than with conventional urea applied basal.


Crop establishment with inverted-T seeder

M.A. Choudhary, M. Aban, T. Santos, B. Mambani, and R.A. Morris, IRRI

We compared the newly developed inverted-T seeder (see figure) with traditional sowing methods. Experimental treatments were conventional tillage and hand sowing (one plowing by carabao, two harrowings, seed furrows made with lithao, seed dibbling and covering by hand) (CTH); conventional tillage and

Inverted-T seeder.

Effect of tillage and sowing methods on upland crop establishment. IRRI.

Tillage and sowing method Plant emergence a (%)

Maize Soybean Mungbean

Conventional tillage and hand sowing 41 b (49) 29 b (39) 15 b (15) Conventional tillage and seeder sowing 67 a (77) 24 b (46) 49 a (65) No-till and seeder sowing 69 a (73) 45 a (58) 46 a (56) a Seed germination = maize 97%, soybean 47%. and mungbean 75%. Values in parentheses indicate

values followed by different letters show significant differences at P 0.05. plant emergence, including subsurface surviving seedlings, at 12 d after sowing. In each column,

inverted-T seeder-sown (CTI); and no- tillage and inverted-T seeder sown (NTI).

Mean soil moisture potential at seeding was -11 kPa for CTH, -14 kPa for CTI, and -19 kPa for NTI. Each tillage treatment area was divided into three 20- × 3.5-m plots with 0.3-m row spacing. They were sown with maize at 5 seeds/m row, soybean at 7 seeds/m row, or mungbean at 18 seeds/m row.

Soil was sandy clay loam in an upland field previously under sorghum. Glyphosate herbicide at 4 liters/ ha was sprayed to control sorghum ratoons and other weeds in no-till plots. Plant establishment counts represented 25% of total planted area.

Plant establishment with the

inverted-T seeder (average of CTI and NTI) was 65% better in maize and 300% better in mungbean than with CTH (see table).

Analysis of the unemerged seed recovered suggested that a large proportion of seed did not germinate in CTH. In-groove soil studies suggested that uneven depth of seed placement and low bulk density in CTH plots resulted in low soil moisture conduction (particularly capillary) from the soil matrix and low availability at the seed interface. More subsurface surviving seedlings were found in both CTI and NTI plots, suggesting further potential plant establishment if more moisture had been available.

Effect of green manure on yield

B. Rabindra, R.A. Setty, B.S. Naidu, S.N. Swamygowda, and B.B. Channappagoudar, University of Agricultural Sciences, Regional Research Station, V.C. Farm, Mandya 571405, Karnataka, India

We studied the effects of azolla and sunhemp incorporation with eight treatments in a randomized block design replicated four times during summer 1986. Soil was red sandy loam (Alfisol) with pH 7.4, 1.2% organic matter, 15 kg available Olsen’s P/ha, and 146 kg available K/ha. Azolla A. pinnata with 4.7% N and 0.3% P, and sunhemp Crotalaria juncea at 2.5% N and 0.2% P were incorporated 3 wk before transplanting.

Effect of green manure on nutrient uptake and rice yield at Karnataka, India.

Treatment a

Uptake (kg/ha) Recovery (%) Grain (grain and straw) (grain and straw) yield

(t/ha) N P N P

Azolla at 100 kg N/ha, basal Azolla at 50 kg N/ha + urea in 2 splits

Sunhemp at 100 kg N/ha, basal Sunhemp at 50 kg N/ha +

urea in 2 splits at 50 kg N/ha Urea in 3 splits at 100 kg N/ha Sunhemp at 25 kg N/ha +

Urea at 75 kg N/ha 70.1 Control, no N 58.3

‘F’ Test CD (0.01) 9.8

at 50 kg N/ha

urea at 50 kg N/ha

**

79.2 96.1

75.4 102.3

77.3 80.2

14.0 20.9 26.8 5.1 16.2 37.8 36.8 5.8

14.1 17.1 27.3 4.9 16.8 44.0 39.5 6.1

14.3 19.0 28.2 5.2 10.2 29.2 9.5 5.0

12.2 15.7 18.6 4.4 8.1 – – 2.6

0.5 CV (%) 3.2 8.7

a All treatments received 22 kg P and 41.5 kg K/ha.

Combined green manure and urea significantly more than urea applied in to supply equal quantities of three splits (see table). recommended N dose yielded


**

Effect of neem leaf application on nitrogen efficiency in lowland rice

S. R. Santhi ond SP. Palaniappan, Tamil Nadu Agricultural University, Coimbatore 84-1003, India

A field experiment on the Coimbatore lowland farm in 1984–85 wet (Jun-Sep) and dry (Oct–Feb) seasons studied the effect of neem Azadirachta indica L. leaf on N efficiency. Short-duration IR50 rice was planted in a clay loam (Typic Haplustalf) with low available N, medium available P, and high available K. We evaluated prilled urea (PU), neem cake-coated urea (20% urea by weight) (NCU), fresh neem leaf (FNL) at 5 t/ha and dry neem leaf (DNL) at 1.25 t/ha, each with 50, 75, and 100 kg N/ha applied basally. Fresh pongam (Pongamia glabra Vent) leaf (PL) at 4 t/ha substituted for FNL in the dry season. All plots received 22 kg P and 42 kg K/ha. The leaves were incorporated in the respective treatment plots 1 wk before planting.

30 d after planting were analyzed for NH +

4 -N and NO – 3 -N. FNL conserved

more N in the form of NH + 4 -N (15

ppm) in wet season (Table 1). Neem cake conserved appreciable N as NH +

4 - N (16 ppm) in dry season. PL had little effect on NH +

4 -N content (11 ppm) and hence on nitrification rate in the soil. In both seasons, leaf or cake neem plots had lower NO –

3 -N than untreated urea plots. Neem products probably inhibited nitrifying organisms.

FNL produced higher grain yields in both seasons, followed closely by DNL in wet season and PL in dry season

Soil samples collected 5, 10, 20, and

Table 1. Effect of neem leaf application on NH + 4 -N and NO –

3 N content of lowland soil. a Coimbatore, India.

NH + 4 -N (ppm) NO –

3 N (ppm) Treatment b

Wet season Dry season Wet season Dry season

PU - N50 PU - N75 PU - N100 NCU - N50 NCU - N75 NCU - N100 FNL - N50 FNL - N75 FNL - N100 DNL - N50 DNL - N75 DNL - N100 PL - N50 PL - N75 PL - N100

CD (P = 0.05)

11 12 9

15 13 13 17 14 14 14 13 15 – – –

2

8 14 17 13 17 18 12 15 16 13 16 15 11 11 12

2

16 12 12 10 11 11 12 11 11 11 14 15 – – –

5

10 12 12 7 7 9 7 8 8

10 7 7 7 6 5 2

a Mean values of 4 soil sample analyses. b PU = prilled urea, NCU = neem cake urea, FNL = fresh neem leaf, DNL = dry neem leaf, PL = pongam leaf. 50, 75, and 100 indicate kilograms N/ha.

Table 2. Neem leaf fertilizer and N recovery, response, and grain yield. Coimbatore, India.

N recovery N response Grain yield Net return percentage ratio (t/ha) ($/ha)

Wet Dry Wet Dry Wet Dry Wet Dry

Treatment a

PU - N50 59 42 PU - N75 44 40 PU - N100 32 32 NCU - N50 65 69 NCU - N75 44 35 NCU - N100 38 30 FNL - N50 67 75 FNL - N75 51 52 FNL - N100 47 48 DNL - N50 61 59 DNL - N75 51 51 DNL - N100 41 38 PL - N50 – 72 PL - N75 – 53

Control PL - N100 – 52

CD (P = 0.05) – – –

–

16 14 14

4.2 11 5 .0

15 10 37

5.5 29 5.5

32 13 31

6.1 13 6.7

53 42 6.3 45 32 7.0 37 22 7.3 48 30 46

6.1 27

29 7.1

14 6.5 – 38 –

19 – – 22 –

– 3.7 1 .0

–

– – –

3.9 218 163 4.0 312 170 4.1 360 177 4.6 374 265 4.1 420 174 4.5 504 202 5.3 478 362 5.6 555 365 5.4 599 340 4.7 607 248 5.2 572 319 4.6 488 236 5.1 – 316 4.6 – 247 5.4 – 353 3.2 161 83 0.8 167 105

a 50, 75, and 100 indicate kilograms N/ha.

(Table 2). In both seasons, FNL response ratio. Neem leaf application recorded higher N recovery and N also resulted in higher net returns.

Effect of sunlight and temperature on azolla nitrogen requirements

Wu Xi-Zhou, Zheng-kou Middle School, Gucheng County, Hebei Province, China

In North China, Azolla (Filicales Lamk) is used as livestock and poultry feed. We have found that Azolla in manure water has different NH 4 -N

requirements in winter. In summer, with high temperature and sunlight, Azolla growing in dense stinking pond water is emerald green. But in the greenhouse in winter and in the propagating tent in spring, temperatures are low and sunlight scarce. If NH 4 -N in the water is over 4 ppm, Azolla gradually dies. This leads

to failure to propagate in spring and failure to survive over winter.

We measured water temperature in the pond at 5–8 cm deep at 1 day hour and 1 night hour to calculate average temperature. A ZF-2 was used to measure sunlight. NH 4 -N ppm density was measured on the 2d and last day of spring and winter periods. Changes


in Azolla color, multiplication, and death rate were calculated.

In summer, when water temperature rose to 28-30 °C with 100,000 lux and NH 4 -N was 4-7 ppm, Azolla grew well. When NH 4 -N was above 8 ppm, Azolla died. Azolla needed less NH 4 -N at low temperatures and sunlight. In the spring propagating tent and winter greenhouse, Azolla died when NH 4 -N was 4-5 ppm. It grew well when NH 4 - N was 0.5-2 ppm in the winter greenhouse and 2-3 ppm in the spring propagating tent.

Growth of azolla at different air temperatures, sunlight hours, and NH 4 -N levels in Hebei, China.

Hours Light force Av temp Place Sunlight

NH 4 -N (Lux) (°C) ppm Azolla condition

WPH a 5 0.05 7 3-4 Slowly died WPH 7 0.5 15 4-5 Slowly died NTH 7 0.5 15 3-4 Retarded growth WPH 7 1 10 SPT b 7 1 15

0.5-1.5 Good growth 0.5-2

SPT Good growth

SPT 8 0.8 15 4-5 Quickly died SPT 10 1 20 5-6 Quickly died SPT 10 2 23 2-3 SGP c 12 10 30 6-7 Good growth

Good growth

SGP 12 10 30 8-12 Died SGP 12 10 28 4-6 Good growth

a Winter-passing house. b Spring propagating tent. c Summer growing pond.

8 0.8 10 5-7 Died

Response of rice to Azospirillum inoculation

D. Purushothaman, S. Gunasekaran, and G. Oblisami, Tamil Nadu Agricultural University, Coimbatore 641003, India

Azospirillum Germination Vigor Increase isolate (%) index (%)

CO 40 Sp. 7 92.0 1140 16.3 IPI 96.0 1680 71.4 S-3 94.0 1480 51.0 Untreated control 86.0 980 –

CD (P=0.05) 4.8 180 IR50

sp. 7 97.0 1380 27.7 IPI 96.0 1440 33.3 S-3 92.0 1260 16.6

We studied the influence of inoculating seed of IR50 and Co 40 rice varieties with three strains of nitrogen-fixing bacterium Azospirillum brasilense: Sp. 7, Brazil; IPI isolated from root tissues of Ipomoea sp., India; and nonnitrogen-fixing A. brasilense mutant S-3, University of Florida, USA.

Seeds of IR50 and Co 40 were surface sterilized by soaking in sterile water for 12 h, separately inoculated with broth cultures of the bacterium strains, and dried in the shade. Each seed surface had an average 2.2 × 10 5

cells of the bacterium. The seeds were germinated at 30°C (paper towel method). Vigor index (shoot length + root length × % germination) was determined at 5 d.

In another experiment, inoculated

seedling weight, root biomass, number of roots, and plant height were recorded.

increased germination and vigor index of both cultivars (Table 1).

Azospirillum enhanced seedling vigor. Shoot and root development, number of primary and secondary roots formed, and seedling weight increased significantly. Response was higher with IPI (Table 2).

Inoculation with S-3 also had positive effects. All three strains produced appreciable amounts of phytohormones in vitro, notably indoleacetic acid and gibberellic acid. This suggests that initial growth responses to inoculation might be due more to the secretion of growth-

Seed inoculation significantly

In general, all three strains of

Untreated control 88.0 1080 – seeds were sown in pots containing wet promoting substances than to field soil. At 30 d after seeding, biological N fixation. CD (P=0.05) 3.2 148

Table 2. Effect of Azospirillum inoculation on growth of 2 rice varieties. a Coimbatore, India.

CO 40 IR50

Treatment Shoot Root Primary Dry wt Shoot Root Primary Dry wt length length roots (mg) of length length roots (mg) of (cm) (cm) (no.) seedling (cm) (cm) (no.) seedling

Azospirillum (Sp. 7) 16.34 a 6.20 a 5.80 a 74.0 ab 14.26 bc 5.80 bc 5.60 b 92.0 b Azospirillum (IPI) 17.26 a 5.80 ab 5.33 a 80.0 a 18.20 a 6.48 c 6.90 a 112.0 a Azospirillum (S-3) 16.20 a 5.20 b 5.20 a 68.0 b 19.20 a 5.40 a 4.20 cd 96.0 b Uninoculated control 11.60 b 4.70 c 4.30 b 60.0 c 12.21 c 5.00 a 3.60 d 86.0 b

CD (P = 0.05) 2.27 0.69 0.81 6.7 2.26 0.76 0.93 10.9

a Figures followed by the same letters are statistically similar.


Table 1. Effect of Azospirillum seed inoculation on seed germination and vigor index. Coim- batore, India.

Pulse crop residue as N source in rice-based cropping system

R. Prasad and SP. Palaniappan, Tamil Nadu Agricultural University, Coimbatore, India

Incorporating green leaf manures to maintain soil fertility and to

Table 1. Effect of incorporating pulse residues on succeeding rice crop yields. Coimbatore, India. a

Treatment Grain Straw yield yield (t/ha) (t/ha)

Green gram stalks incorporated 4.4 7.4 + 100-22-42 kg NPK/ha Green gram stalks incorporated 3.2 4.7 + no fertilizer Green gram stalks cut + 100-22-42 kg NPK/ha

3.8 6.4

Green gram stalks cut + 2.9 4.1 no fertilizer Soybean stalks incorporated + 4.4 8.1 100-22-42 kg NPK/ha Soybean stalks incorporated 3.8 5.9 + no fertilizer Soybean stalks cut + 4.3 6.9 100-22-42 kg NPK/ha Soybean stalks cut + 3.3 4.2 no fertilizer a Data not statistically analyzed.

economize on fertilizer costs has been a farmer practice. But because costs of collecting and transporting have become major hurdles, the practice is being discontinued. An integrated system of pulses grown for both grain and green manure would help reduce costs and maintain soil fertility.

We compared residual N from two pulse crops — green gram Co 4 and soybean Co 1 — grown with normal fertilization in Jun-Aug preceding a Sep-Jan rice crop. Experimental field soil at Tamil Nadu Agricultural University was clay loam with pH 7.9, low available N, medium available P, and high available K. The rice variety

was Co 43 (135 d). Plot size was 130 m 2 . Treatments were pulse crop residues

incorporated after harvest, with and without recommended 100-22-42 kg NPK/ha. The trial was not replicated because it studied residual effects of pulse crop residues on rice yield in large plots.

than green gram did (Table 1). Chemical analysis showed that soybean residue added 52 kg N/ ha and green gram residues, 43 kg N/ha.

Returns were highest when soybean stalks were incorporated without fertilizer application to rice (Table 2).

Soybean stalks added more residue

Table 2. Economic return of pulse crop residue incorporated preceding rice. Coimbatore, India.

Treatment

Green gram stalks incorporated + 100-22-42 kg NPK/ha Green gram stalks incorporated + no fertilizer Green gram stalks cut + 100-22-42 kg NPK/ha Green gram stalks cut + no fertilizer Soybean stalks incorporated + 100-22-42 kg NPK/ha Soybean stalks incorporated + no fertilizer Soybean stalks cut + 100-22-42 kg NPK/ha Soybean stalks cut + no fertilizer

Total Net return return Return/$ ($/ha) ($/ha) invested

780 553 625 510 798 664 760 562

475 316 370 275 493 426 454 328

2.56 2.33 2.21 2.15 2.6 1 2.80 2.49 2.38

Fertilizer efficiency with dry placement

M.S. Zia, M. Ashraf, and M.A. Sagar, National Agricultural Research Centre, Park Road, Islamabad, Pakistan

We studied the relative efficiency of fertilizer incorporated in dry soil and in puddled soil. Experimental soil was heavy-textured clay loam, pH 8.0. In both treatments, 26 kg P/ha was basally applied. IR6 was the test variety.

In dry soil incorporation, the soil was well pulverized and 80 kg N/ha placed in deep furrows. Irrigation water was applied immediately after leveling. Leveling was repeated twice in standing water before transplanting. In puddled soil incorporation, the field was flooded 20 d before transplanting

Productive tillers, weed count, yield and water use under different fertilizer placement methods. a

Sadhoke (Sheikhupura), Pakistan.

Weed count Productive Water Fertilizer Water use Fertilizer placement 30 DT b tillers/plant Yield use c efficiency efficiency

(no./m 2 ) (no.) (t/ha) (mm) (kg yield/kg N) (kg/mm per ha)

Puddled soil (no fertilizer) 4 9 b 4.6 c 1575 – 2.9 Incorporation of fertilizer 5 15 a 8.0 a 1725 34 in dry soil

4.6

Incorporation of fertilizer 4 14 a 7.2 b 1950 26 in puddled soil

3.7

DMRT. b Days after transplanting. c Excluding rainfall. a In a column, means followed by the same letter are not significantly different at the 5% level by

and conventionally puddled with 80 kg between treatments (see table). N/ ha applied before the last plowing However, yield was significantly higher and leveling. At panicle initiation, 20 with fertilizer incorporated in dry soil. kg N/ ha was applied to both Weed count was slightly higher in dry treatments. soil. However, dry soil incorporation

in number of productive tillers There was no significant difference used more water.


Response of rainfed rice to nitrogen level and postplanting soil management practices

K. K. Katoch, B. R. Sharma, and V. K. Bhatnagar, Vivekananda Laboratory for Hill Agriculture, Indian Council of Agricultural Research, Almora, Uttar Pradesh 263601, India

We studied the response of rainfed rice to 0, 20, 40, and 60 kg N/ha under uncompacted interrow soil (C 0 :1.36 g/cm 3 bulk density) and compacted interrow soil (C: 1.6 g/cm 3 bulk density). Soil was a loamy sand with 0.44% organic C and saturated hydraulic conductivity of 45 mm/h. VRS163-2-3 was sown at 23-cm row spacing on 28 Jun 1985 with 18 kg P and 33 kg K/ha. Compaction was imposed after complete crop emergence.

Increasing N levels raised yields in general. Compacting soil to a bulk density of 1.6 g/cm 3 raised yields by about 15% (see figure). Straw yields did not differ significantly.

Simple linear regression equations (a) Y = 2.19 + 0.014 X ( r = 0.98**) for uncompacted soil and (b) Y = 2.50

^ ^

+ 0.017 X ( r = 0.93**) for compacted soil, correlating rice grain yield and N application, show a higher response under soil compaction. That can be attributed to more water retention and less leaching losses in compacted than in uncompacted soils.

Integrated nitrogen management for lowland rice

B. S. Mahapatra, K. C. Sharma, and G. L. Sharma, Agronomy Department, G. B. Pant University of Agriculture and Technology, Pantnagar, Nainital, U. P. 263145 , India

An integrated approach or complete substitution of chemical N with bio- organic N sources would help increase lowland rice productivity. We experimented with azolla and Sesbania aculeata alone and in combination with chemical N during the 1982-83 and 1983-84 wet seasons.

The loam soil had pH 7.6, 2% organic C, and 0.21% total N. Each treatment received 17 kg P and 33 kg K/ ha. Zn was sprayed at 60 and 90 d after transplanting.

Yields with Azolla incorporation at 45 kg N/ha + 45 kg chemical N/ha, S. aculeata as green manure at 60 kg N/ ha + Azolla inoculation at 30 kg N/ha in 1982-83 and 1983-84, and Azolla inoculation at 30 kg N/ ha + 30 kg chemical N/ ha in 1983-84 equaled yields with prilled urea at 90 kg N/ ha (see table). N uptake showed a similar trend.

due to low plant population, dry matter production, and panicle numbers. In 1983-84, low dry matter production resulted in low N uptake.

wet season, S. aculeata green manuring + Azolla inoculation or Azolla incorporation or inoculation + chemical N can be substituted for chemical N alone.

The lower grain yield in 1983-84 was

These results suggest that during the

Yield and N uptake with bio-organics alone or in combination with chemical N. a Pantnagar, India, 1982-83 and 1983-84 wet season.

Grain yield (t/ha) N uptake (kg/ha) Treatment b

1982-83 1983-84 1982-83 1983-84

Control 2.7 2.5 47.3 46.3 S 30 kg N + PU 30 kg N 3.4 d 3.0 c 68.2 b 61.9 cd A 30 kg N + PU 30 kg N 3.5 cd 3.6 ab 70.6 b 71.0 bc PU 60 kg N 3.3 d 3.0 c 64.0 b 59.0 d S 45 kg N + PU 45 kg N 4.7 a 3.5 ab 102.5 a 17.8 ab A 45 kg N + PU 45 kg N 4.6 a 3.7 a 104.9 a 78.8 ab PU 90 kg N 4.3 ab 3.6 ab 96.3 a 78.5 ab S 60 kg N + AI 30 kg N 4.7 a 3.6 ab 103.7 a 83.8 a USG 30 kg N + AI 30 kg N 4.0 abc 3.6 ab 82.3 79.9 ab PU 30 kg N + AI 30 kg N 3.5 cd 3.5 ab 69.7 b 72.8 b

CD at 5% 0.5 0.6 7.4 10.6

a Values followed by the same letter do not differ significantly. b S = Sesbania aculeata green manure, PU = prilled urea, A = Azolla incorporation, AI = Azolla inoculation at 7 d after transplanting (DT), USG = urea supergranules placed at 10-cm depth at 7 DT.

Slow-release urea fertilizers in sodic soils

D.L.N. Rao and S. K. Ghai, Central Soil Salinity Research Institute, Karnal 132001, Haryana, India

Volatilization of applied N is high in sodic soils. We are experimenting with timing and N splits to match the plant needs, slow-release fertilizers, deep placement, and urease inhibitors to improve urea efficiency.

Yields under varying N levels with and without soil compaction. Almora, India.

In a field experiment in 1984 wet season, we evaluated the efficiency of prilled urea applied all at once (PUW) prilled urea applied in split doses (PUS), one-half at transplanting, one- fourth at 21 d after transplanting (DT) and one-fourth at 42 DT; sulfur-coated urea (SCU), 37.4% N; lac-coated urea (LCU), 30.4% N; and urea 1-g supergranules (USG). All were applied at 120 kg N/ ha.

Calciorthid Natrustalf, pH 8.4, EC Soil was sodic sandy loam,


0.37 dS/m, 0.6% organic C, 0.06% total N, and 100 kg KMnO 4 oxidizable N/ha. Plots were 4 × 4 m with 3 replications of 6 treatments in a randomized block design. Jaya seedlings were transplanted at 35 d after seeding. Fields were treated with 10 ppm ZnSO 4 and 5.4 ppm P as single superphosphate. All urea sources except USG were surface mixed followed by flooding to 5 cm. USG was placed 10 cm deep between 4 hills.

alkalinity, NH 4 -N concentration) was monitored at 1330 h daily for 1 wk. Ammonia volatilization was studied separately on bare soil in pots. Semi- open can traps were calibrated in a pure ammonia system. Because the semi-open cans allow a fair exchange of air and water between the outside and the inside of the traps, an artificial microclimate does not develop inside the trap.

SCU did not affect grain yields, LCU decreased yield, and USG increased yield significantly (see table). LCU had no effect on dry matter, SCU and USG increased dry matter. USG significantly enhanced N uptake

Floodwater chemistry (pH,

Influence of organic amendments and oils on ammonia volatilization in flooded rice

G. R. Singh and T. A. Singh, Soil Science Department, G. B. Pant University of Agriculture and Technology, Pantnagar, Nainital, U. P. 263145, India

We measured NH 3 volatilization loss from urea with amendments and oils in flooded conditions in a greenhouse study. Soil was Beni silty clay loam, Aquic Hapludoll with 7.2 pH, 1.5% organic C, 24 meq/ 100 g of soil CEC, 24% free CaCO 3 , and percolation rate of 14 mm/d. Pots were filled with 16 kg soil amended with 50 ppm of p- benzoquinone (PBQ) and catechol (Cate) and 50 g plant residue babul Acacia arabica, khair Acacia catechue, and inknut Terminalia chebula.

Effect of slow-release urea fertilizers on yield and N uptake in a sodic soil. Haryana, India.

Yield (t/ha) N uptake (kg/ha) N uptake N source efficiency a

Grain Straw Total Grain Straw Total (%)

No N 5.4 3.6 9.0 52 17 69 Prilled urea 7.4 5.9 13.2 76 29 105 28 Prilled urea split 7.4 6.2 13.6 84 31 115 35 SCU 7.3 7.4 14.6 86 48 134 50 LCU 6.6 6.4 13.1 71 36 107 29 USG b 8.8 8.3 17.1 96 49 145 59

LSD (P = 0.05) 0.5 0.3 0.8 12 11 22 18

–

a Apparent N uptake efficiency = N uptake in treatment – N uptake in control × 100. b 1-g granules. N applied

by grains; both SCU and USG enhanced N uptake by straw. SCU and USG significantly increased total N uptake and improved apparent N uptake efficiency.

These results are consistent with floodwater chemistry and ammonia volatilization analyses. SCU and USG were most effective in maintaining low ammoniacal N concentration and alkalinity; PUW, PUS, and LCU were ineffective (see figure). SCU and USG reduced ammonia volatilization losses from prilled urea. Slow-release urea Dynamics of ammoniacal N in floodwater of a fertilizers like SCU and USG promise sodic soil following 120 kg N/ha applied as PUW

to improve fertilizer N efficiency in or as PUS and slow-release and SCU and LCU.

sodic soils. USG were deep placed at 10 cm.

Jaya rice was transplanted at 23 d twice. A cylindrical frame covered with after seeding at 4 seedlings/ pot. At 5 d a heavy-duty polythene bag was after transplanting, coated or uncoated immediately placed on each pot and urea was broadcast and incorporated sealed. A petri dish filled with and 1-g urea supergranules (USG) standard H 2 SO 4 hung inside the frame. were deep placed 5 cm at the center of The petri dish was emptied every 4 d, 4 hills. Treatments were replicated the contents distilled for NH 3 by

N loss through NH 3 volatilization in flooded rice. Pantnagar (U.P.), India.

N loss (%) Cumulative Treatment a loss (%)

0-4 d 4-8 d 8-12 d 12-16 d 16-20 d 20-24 d 24-28 d in 28 d

Urea 4.2 4.4 4.7 2.9 0.9 0.8 0.6 USG deep placed 0.4 1.5 2.6 0.9 0.9 0.8 0.6 Linseed oil-coated urea 1.3 1.4 1.5 3.0 2.6 1.5 0.8 Neem oil-coated urea 1.3 1.4 1.7 2.9 2.6 1.5 0.8 Urea + p-benzoquinone 0.5 1.0 1.3 1.6 1.8 1.0 0.7 Urea + catechol 0.6 1.3 1.5 1.7 1.9 1.2 0.8 Urea + Acacia arabica 4.9 6.6 7.7 5.0 3.0 1.4 0.8 Urea + Acacia catechol 4.3 4.6 5.2 4.1 2.3 1.1 0.8 Urea + Terminalia chebula 4.4 5.7 6.2 4.8 3.0 1.1 0.8

18 8

12 12

8 9

29 21 26

a Each treatment received 2.0 g urea.


microkjeldahl method, and ammonia first 4 d after fertilizer application were Ammonia volatilization was higher volatilization estimated. highest with Acacia arabica and lowest with plant residues (more than 20%)

Ammonia volatilization losses in the with deep placed USG (see table). than with urea.

Effect of sowing time and planting method on rice yield per day

N. Acikgöz, Ege University, Faculty of Agriculture, Agronomy Department, Bornova, Izmir, Turkey

A 3-yr study (1975-77) evaluated the effect of sowing time and method on rice (Ribe) productivity per day. Main plots were early, normal, and late sowing; subplots were planting methods, transplanting, broadcasting, and drilling. Subplots were 40 m 2 .

In general, yield decreased with

Effect of sowing time and planting method on yield. Izmir, Turkey, 1975-77. a

21 May 4 Jun 20 Jun

Duration Yield Duration Yield Duration Yield (d) (d) (d)

t/ha kg/d t/ha kg/d t/ha kg/d Transplanting

127 5.1 40.2 140 5.6 40.0 130 5.1 39.2

120 Drilling

4.5 37.5 117 4.4 37.6 112 4.4 39.3

124 5.7 46.0 115 5.7 49.6 111 5.1 45.9 Broadcasting

a Duration = day from sowing or transplanting to harvest. LSD at 5%: yield = 0.45, duration = 2.3, yield per day = 6.10.

delayed sowing (see table). Yields were and lower with drilling in all sowing higher with early season broadcasting times.

Efficacy of Azospirillum brasilense in increasing rice yield

G. Gopalaswamy and P. Vidhyasekaran, Tamil Nadu Rice Research Institute, Aduthurai 612101, India

Azospirillum brasilense Tarrand et al. colonizes rice roots and fixes atmospheric N in soil. Its efficacy depends on the pre-inoculum soil N status. We studied the effect of A. brasilense in the field at different N (urea) application levels.

Peat-based A. brasilense inoculum mixed with well-powdered farmyard manure (2 kg inoculum + 15 kg farmyard manure/ ha) was uniformly

Grain and straw yield response to A. brasilense inoculation. Aduthurai, India.

Dose of Grain yield (t/ha) Straw yield (t/ha)

fertilizer Without With Without With (kg N/ha) A. brasilense A. brasilense A. brasilense A. brasilense

nitrogenous % increase a % increase a

0 3.1 3.1 0 ns 4.5 5.9 31* 25 3.5 3.8 9* 6.0 6.5 8 ns 50 4.1 4.4 7* 6.0 1.6 27* 75 3.6 4.4 22* 5.9 8.3 41*

100 4.3 4.1 ns 6.8 7.7 13* CD (0.05) 0.2

a * = significant difference, ns = not significant.

broadcast in the field after urea Inoculation increased grain and application. Roots of ADT36 seedlings straw yield over urea alone, were soaked in 1 kg A. brasilense/ 400 particularly at 75 kg N/ha (see liters water solution for 20 min before table). transplanting.

Phosphate sources for lowland rice

S. K. Sahu, Soil and Agricultural Chemistry Department, College of Agriculture, Orissa University of Agriculture and Technology, Bhubaneswar 75 1003, India

We compared the efficiency of seven phosphate sources in a randomized block design replicated three times

during 1980 and 1981 wet seasons. The soil was clay loam (Typic Aquept) with pH 5.6, 0.65% organic C, and 9 kg Olsen’s P/ ha.

Phosphate sources were single superphosphate (6.9% P), Mussorie rock phosphate (9.5% P), mixture of single superphosphate and Mussorie rock phosphate at 3:1 and 1:1 P, urea ammonium phosphate (28-12-0 NPK), diammonium phosphate (18-20.6-0

NPK), and seedling root dip phosphate slurry prepared with single superphosphate, soil, water, and fresh cow dung at 1:2:3:1. We used 8.6 kg P/ ha for the phosphate slurry and 17.8 kg P/ ha for soil application. Pankaj was planted with 60-17.8-25 kg NPK/ha.

Single superphosphate and Mussorie rock phosphate at 1:1 gave better yields than 5 other treatments


Irrigated rice-based cropping strategies in coastal Maharashtra

B. P. Patil, V. N. Khade, S.A. Khanvilkar, and J. H. Dongale, Central Experiment Station, Irragation Research Scheme Wakawali 415711, Konkan Krishi Vidyapeeth, Maharashtra, India

Most ricefields in coastal Maharashtra remain fallow following one monsoon (Jun-Oct) crop. However, a growing number of medium and small irrigation projects are enabling dry season cropping. Because irrigation water usually is released from mid-Dec to early Jan, we evaluated irrigated crops at 2 planting times, 15 Dec and 5 Jan, in 1983-84 and 1984-85.

Soil was medium black. clayey with 6.3 pH, 0.65% organic C, 28.85 kg available P 2 O 5 /ha, and 190.0 kg available K 2 O/ha. The rice crop (Jaya) transplanted in early Jul and fertilized

with 100-50-50 kg NPK/ha yielded 4 t/ ha. The postrice crops were harvested from mid-Mar to late Apr.

In general, early sowing was more profitable than late sowing (see table).

Cowpea sown on 15 Dec had the highest net return ($717.29/ha). Planting date of wheat. pigeonpea, groundnut, sunflower, and sesamum did not affect net return.

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uptake. Full Mussorie rock phosphate

and equaled 100% single

phosphate at 1:1 and urea ammonium

superphosphate at 3:1 urea ammonium

phosphate were superior for grain P

phosphate (see table). Mussorie rock phosphate and phosphate slurry were inefficient.

Single superphosphate, single superphosphate and Mussorie rock

and phosphate slurry contributed less P to the grain.

Effect of P sources on rice yield and P uptake. Bhubaneswar, India.

Yield P content P uptake (t/ha) (%) (kg/ha)

Treatment 1980 1981 1980 1981 1980 1981

Single superphosphate 100% 3.0 3.7 0.36 0.37 10.8 13.7 Mussorie rock phosphate 100% 2.6 3.2 0.29 0.32 7.5 10.2 Single superphosphate 75% + Mussorie rock phosphate 25% 2.7 3.6 0.31 0.33 8.4 11.9 Single superphosphate 50% + Mussorie rock phosphate 50% 3.0 3.8 0.35 0.39 10.5 14.8 Urea ammonium phosphate 3.0 3.5 0.36 0.37 10.8 12.9 Diammonium phosphate 2.9 3.5 0.33 0.34 9.6 11.9 Phosphate slurry 2.8 3.0 0.29 0.30 8.1 8.7 Control (60, 0, 30 kg NPK/ha) 2.4 2.9 0.24 0.29 5.7 8.4

CD at 5% 0.4 0.2 0.001 0.002 – –

Rice-Based Cropping Systems

Grain yield and net returns of the postrice dry season crops, by sowing date. Maharashtra, India,

1983–85.

Crop a Grain yield (t/ha) Net return ($/ha)

15 Dec 5 Jan 15 Dec 5 Jan

Sorghum (120-60-60) Wheat (100-50-50) Green gram (25-50-0) Cowpea (25-50-0) Black gram (25-50-0) Pigeonpea (25-50-0) Groundnut (25-50-0) Sunflower (50-30-0) Soybean (25-50-0) Niger (25-25-0) Sesamum (25-25-0)

Mean

3.27 1.96 0.76 3.25 0.96 14.8 3.09 1.79 0.56 0.8 1 0.55

2.4 1 2.03 0.42 2.45 0.53 1.56 2.99 1.67 0.37 0.34 0.64

290.18 251.67

64.38 717.29 110.66 243.03 454.82 317.30

60.61 83.57 78.34

231.87

209.87 269.02

26.97 578.59

3.56 266.22 426.84 273.91

92.29 50.37

115.89 178.83

a Figures in parentheses indicate kg NPK/ha.

international rice research newsletter vol12 no.1

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