IRRN GUIDELINESThe International Rice Reserach Newsletter objective is: "To expedite communication among scientists concerned with the development of improved technology for rice and for ricebased cropping systems. This publication will report what scientists are doing to increase the production of rice, inasmuch as this crop feeds the most densely populated and land-scarce nations in the world . . . IRRN is a mechanism to help rice scientists keep each other informed of current research findings." The concise reports contained in IRRN are meant to encourage rice scientists and workers to communicate with one another. In this way, readers can obtain more detailed information on the research reported. Please examine the criteria, guidelines, and research categories that follow. If you have comments or suggestions, please write the editor, IRRN, IRRI, P.O. Box 933, Manila, Philippines. We look forward to your continuing interest in IRRN. Criteria for IRRN research report has international, or pan-national, relevance has rice environment relevance advances rice knowledge uses appropriate research design and data collection methodology reports appropriate, adequate data applies appropriate analysis, using appropriate statistical techniques reaches supportable conclusions Guidelines for contributors The International Rice Research Newsletter is a compilation of brief reports of current research on topics of interest to rice scientists all over the world. Contributions should be reports of recent work and work-inprogress that have broad, pan-national interest and application. Only reports of work conducted during the immediate past three years should be submitted. Research reported in IRRN should be verified. Single season, single trial field experiments are not accepted. All field trials should be repeated across more than one season, in multiple seasons, or in more than one location, as appropriate. All experiments should include replication and a check or control treatment. All work should have pan-national relevance. Reports of routine screening trials of varieties, fertilizer, and cropping methods using standard methodologies to establish local recommendations are not accepted. Normally, no more than one report will be accepted from a single experiment. Two or more items about the same work submitted at the same time will be returned for merging. Submission at different times of multiple reports from the same experiment is highly inappropriate. Detection of such submissions will result in rejection of all. Please observe the following guidelines in preparing submissions: Limit each report to two pages of double-spaced typewritten text and no more than two figures (graphs, tables, or photos). Do not cite references or include a bibliography. Organize the report into a brief statement of research objectives, a brief description of project design, and a brief discussion of results. Relate results to the objectives. Report appropriate statistical analysis. Specify the rice production environment (irrigated, rainfed lowland, upland, deepwater, tidal wetlands). Specify the type of rice culture (transplanted, wet seeded, dry seeded). Specify seasons by characteristic weather (wet season, dry season, monsoon) and by months. Do not use local terms for seasons or, if used, define them. Use standard, internationally recognized terms to describe rice plant parts, growth stages, environments, management practices, etc. Do not use local names. Provide genetic background for new varieties or breeding lines. For soil nutrient studies, be sure to include a standard soil profile description, classification, and relevant soil properties. Provide scientific names for diseases, insects, weeds, and crop plants. Do not use common names or local names alone. Quantify survey data (infection percentage, degree of severity, sampling base, etc.). When evaluating susceptibility, resistance, tolerance, etc., report the actual quantification of damage due to stress that was used to assess level or incidence. Specify the measurements used. Use generic names, not trade names, for all chemicals. Use international measurements. Do not use local units of measure. Express yield data in metric tons per hectare (t/ha) for field studies and in grams per pot (g/pot) or per specified length (in meters) row (g/ row) for small scale studies. Express all economic data in terms of the US$. Do not use local monetary units. Economic information should be presented at the exchange rate US$:local currency at the time data were collected. When using acronyms or abbreviations, write the name in full on first mention, followed by the acronym or abbreviation in parentheses. Thereafter, use the abbreviation. Define any nonstandard abbreviations or symbols used in a table or graph in a footnote or caption/ legend. Categories of research published GERMPLASM IMPROVEMENT genetic resources genetics breeding methods yield potential grain quality pest resistance diseases insects other pests stress tolerance drought excess water adverse temperature adverse soils integrated germplasm improvement irrigated rainfed lowland upland deepwater tidal wetlands seed technology CROP AND RESOURCE MANAGEMENT soils soil microbiology physiology and plant nutrition fertilizer management inorganic sources organic sources crop management integrated pest management diseases insects weeds other pests water management farming systems farm machinery postharvest technology economic analysis ENVIRONMENT SOCIOECONOMIC IMPACT EDUCATION AND COMMUNICATION RESEARCH METHODOLOGY

CONTENTSGERMPLASM IMPROVEMENTGenetic resources 5 Oryza minuta is not endemic to the Philippines Breeding methods 5 Identification of promising CMS, maintainer, and restorer lines for developing Philippine rice hybrids 6 Low light-tolerant restorers in hybrid rice breeding 7 Physiological traits of certain restorers in hybrid rice breeding Yield potential 7 Effect of nitrogen level on the relation between sink-source parameters and grain yield 8 Rice varieties direct-seeded in puddled soil during boro season in West Bengal 8 Variation in rice husk-kernel ratio (HKR) 9 Lectins in living organisms interact with silicon Grain quality 9 Grain quality of F1 rice hybrids 10 Relationship among grain shape, size, and head rice recovery (HRR) in indica rice Pest resistancediseases 10 Noncapsid protein (NCP) used for serological assay in indexing rice grassy stunt virus (RGSV)-infected plants 11 Nonspecific reaction in ELISA of viruses in rice roots Pest resistanceinsects 11 Resistance to brown planthopper (BPH) in rice germplasm in Raipur, Madhya Pradesh (MP), India 12 Promising cultivars with resistance to gall midge (GM) in Kerala, India 12 Virulence of brown planthopper (BPH) in Raipur, India 13 Evaluating rice cultivars for yellow stem borer (YSB) resistance 13 Field reaction of rice breeding lines to brown planthopper (BPH) in Pondicherry, India 14 Sources of resistance to brown planthopper (BPH) in rice 14 Virulence of a new biotype of brown planthopper (BPH) in Mekong Delta 15 Yield losses due to stalk-eyed fly (SEF) in Nigeria Stress tolerance 15 A simple technique for mass screening of rice germplasm tolerant of photo-oxidation Stress tolerantexcess water 16 Effect of submergence on rice yield Stress to1eranceadverse soils 17 Promising salt-tolerant F 1 anther culture derivatives (ACDs) Integrated germplasm improvementirrigated 17 Performance of Basmati rices in Rajasthan 18 Ptb 45 (Matta Triveni), a promising rice variety for dry season in Kerala, India Integrated germplasm improvementrainfed lowland 18 BR319-1-HR38 and IR74 released as gogorancah varieties in Indonesia 19 CSR10, a newly released dwarf rice for salt-affected soils 19 Five lowland rice cultivars released in Turkey

CROP AND RESOURCE MANAGEMENTFertilizer managementinorganic sources 20 Effect of P fertilizer on sulfur loss in flooded soil Fertilizer managementorganic sources 20 Green manure (GM) management and its effect on lowland rice yield Crop management 21 Managing rice ratoons 21 Effect of plant growth enhancer on lowland rice yield 22 Effect of nitrogen levels and soil moisture conservation practices on rainfed rice 22 Technical inefficiency of rice production in Chiang Mai, Thailand Integrated pest managementdiseases 23 Seed sprout extracts for control of rice tungro disease (RTD) 23 Survey of Pakistans rice crop for bakanae disease 24 Effect of N fertilization on false smut of rice 24 Serological classification of Indian strains of the rice bacterial blight (BB) pathogen Xanthomonas oryzae pv. oryzae (Xoo) with monoclonal antibodies 25 Identification of bacterial blight (BB) pathotype of Xanthomonas campestris pv. oryzae in Batalagoda, Sri Lanka 25 Evaluation of chitinase production as a criterion for selecting bacterial antagonists for biological control of rice sheath blight (ShB) Integrated pest managementinsects 26 Influence of lunar phase on yellow stem borer (YSB) attraction to light trap 26 Effect of foliar insecticide sprays on rice leaffolder (LF) Cnaphalocrocis medinalis Guene and rice yield 27 Influence of weather factors on light trap catches of yellow stem borer (YSB) Integrated pest managementother pests 27 Use of ducks to control golden apple snail Ampullarius ( Pomacea ) canaliculata in irrigated rice 27 Plant parasitic nematodes associated with upland rice in Sitiung, West Sumatra, Indonesia Farming systems 28 Rice - fish farming system for Hunan, China 29 Productivity of rainfed rice-based cropping systems in West Bengal Farm machinery 29 Development of spinning brush VLV pesticide applicator

EDUCATION AND COMMUNICATION30 Impact of extension contact on technology adoption

ANNOUNCEMENTS31 31 31 31 31 31 International Rice Research Institute Conference 1992 Short training courses Course on lowland development Symposium proceedings Deployment of Bacillus thuringiensis discussed at meeting New IRRI publications

GERMPLASM IMPROVEMENTGenetic resourcesOryza minuta is not endemic to the PhilippinesD. A. Vaughan, International Rice Germplasm Center, IRRI; and G. Gorogo, Department of Primary Industry, Port Moresby, Papua New Guinea

The diploid species Oryza officinalis and tetraploid species O. minuta have been confused in the literature. The two species, however, can be clearly distinguished on the basis of spikelet dimension, panicle structure, and habit. Herbarium studies show O. minuta had previously been found only in the Philippines. O. officinalis is widely distributed from India to Papua New Guinea. On the islands of the Malay archipelago, it has been collected in Sabah, Sarawak, Kalimantan, Sulawesi, Sumatra, Java, Halmahera, Bacan Island, and Western Province of Papua New Guinea. We report finding several populations of O. minuta (see figure) around Wasua village (08:20S latitude, 142:50E longitude) in Western Province, Papua New Guinea. The stoloniferous species was growing, either in shade or partial sunlight, beside a small creek in sago swamps. We did not find O. officinalis in the area, but did collect it along the south coast of Western Province. Spikelets of O. minuta populations in the Philippines are thicker than those of populations collected in Papua New Guinea (see table).

Distribution of Oryza minuta (

).

Spikelet dimensions of Oryza minuta. Collection no. Site Philippines Luzon Samar Leyte Southern Leyte Papua New Guinea Western Province Western Province Western Province Western Province Spikelet dimensiona (mm) Length 4.7 4.5 4.8 4.7 4.5 4.2 4.5 4.7 Width 1.8 1.8 1.9 1.8 1.9 1.9 2.0 2.0 Thickness 1.4 1.3 1.2 1.4 0.9 0.9 1.0 1.0

P90-1 P90-6 P90-17 P90-19 91PNG-17 91PNG-18 91PNG-19 91PNG-20

a Mean of 10 measurements per population.

Breeding methodsIdentification of promising CMS, maintainer, and restorer lines for developing Philippine rice hybridsR. J. Lara, I. A. dela Cruz, and M. S. F. Ablaza, Philippine Rice Research Institute (PhilRice), Maligaya, Muoz, Nueva Ecija; and S. S. Virmani, IRRI

Five cytoplasmic male sterile (CMS) lines obtained from IRRI were evaluated at three locations in the Philippines for pollen sterility, spikelet fertility of bagged panicles, field reaction to rice tungro virus, and days to 50% flowering. Stable CMS lines were V20 A and IR46830 A (both with CMS-WA cytoplasm), and IR54755 A (CMS-ARC cytoplasm). CMS lines IR58025 A and

IR62829 A were nearly stable for male sterility (Table 1). IR54755 A, IR58025 A, and IR62829 A showed slight to no infection with tungro viruses. Outcrossing potential of IR62829 A, IR58025 A, and V20 A was acceptable. CMS lines flowered at 81102 d at IRRI, but at 102-116 d at Banaue (high altitude, lower temperature). IR58025 A and IR62829 A

IRRN 17:1 (February 1992)

5

Table 1. Behavior of some CMS lines at 3 locations in the Philippines. Pollen a sterility CS CS CS CS CS CS CS CS CS CS CS S CS PS S Seed setting (%) of bagged panicles 0 0 0 0 0 0 0 0 0 0 0 0.33 0 2.20 0.05 Reaction to RTV b Outcrossing potentialc Days to 50% flowering 83 102 81 86 108 89 81 108 88 102 116 90 85 105 84

CMS line

Location

V20 A

IR46830 A

IR54755 A

IR58025 A

IR62829 A

IRRI Banaue San Mateo IRRI Banaue San Mateo IRRI Banaue San Mateo IRRI Banaue San Mateo IRRI Banaue San Mateo

S R I I I R R R I R R I R R

3

9

9

3

1

a CS = completely sterile (0% fertility), S = sterile (1.10% fertility), PS = partially sterile (11.30% fertility), b RTV = rice tungro

viruses. R = no infection, I = slight infection, S = severe infection. cOutcrossing potential on 19 scale: 1 = high and 9 = low.

were selected to develop heterotic rice hybrids. We made 251 testcrosses using elite lines, IR62829 A, and IR58025 A to identify maintainers and restorers. Pollen sterility was 98100% in testcross F 1 s. This indicates that the male parent is a maintainer that can be converted into a CMS line by recurrent backcrossing. Testcross F1 s showed normal seed setting (more than 75%), indicating that the elite line is a restorer and can be used as a male parent in developing heterotic rice hybrids. We identified 14 maintainer and 18 restorer lines (Table 2). Maintainer lines have been backcrossed 13 times to convert them into CMS lines. Restorers are being purified by re-test crossing single plants before use in developing experimental rice hybrids for yield testing.

Table 2. Maintainer and restorer lines identified at Philippine Rice Research Institute, 1990-91 dry seasons.

Low light-tolerant restorers in hybrid rice breedingK. S. Murty and S. K. Dey, Central Rice Research Institute, Cuttack 753006, India

Cultivar Maintainers BPI 30-2 MRC22387-859 BPI 121-407 IR5537-32-D IR55548-05 IR57893-26 IR60076-04 IR60080-45 IR57934-02 IR60077-09 IR60080-35 IR60080-41 IR55543-51-B Cavitena Restorers BPI Ri 10 MRCl1055-432-23 MRCl8186-611 MRC18624-1466 MRC22367-807 Mantika Banguin PR21209-389-5 RP1057-393-1 OR141-99 IR66 IR3380-60-1-2-2 IR31432-9-3-2 BR11-461-1 BR425-189-1-6-2-1-2 BR316-15-4-4-1 BR11 IR60080-27 PR23342-5

Tester CMS line IR62829 A V20 A IR62829 A IR62829 A IR62829 A IR62829 A IR58025 A IR62829 A IR62829 A IR54755 A IR54755 A IR54755 A IR54755 A IR58025 A IR58025 A IR62829 A IR62829 A IR62829 A IR62829 A IR62829 A IR62829 A IR62829 A IR62829 A IR62829 A IR62829 A IR62829 A IR62829 A IR62829 A IR62829 A IR62829 A IR62829 A IR62829 A IR62829 A

Backcrosses (no.) 3 3 2 1 1 1 1 1 1 1 1 1 1 1

Low light during reproductive and ripening phases can critically constrain rice productivity during wet season.TDM (g/m 2 ) Light872 866 775 983 1190 896 654 888 974 625 993 713 930 937 1029 856 1013 719 854 759 978 88 1 79 94 133 22 1

We studied the low-light adaptability of 19 IRRI purified restorers during dry season. Wooden screens artificially shaded plants (50% normal light) from 35 d after planting to harvest. Controls were maintained under normal sunlight. The experiment was laid out in a splitplot design with three replications. The

Effect of 50% shade from 35 d to harvest on total dry matter (TDM) and yield of restorers. 1990 dry season.

RestorerIR36 IR46 IR50 IR54 IR58 IR64 Milyang 54 ARC1 1353 IR4422-480-2-3-3 IR9761-19-1 IR13419-113-1 IR13524-21-2-3-3-2-2 IR19058-107-1 IR19392-211-1 IR21916-128-2-2-3 IR25912-63-2-2 IR27315-145-1-3 IR28178-70-2-3 IR29723-143-3-2-1 Annapurna (check) Jaya (check) Mean LSD (0.05) Treatments (T) Variety (V) V at same T T for same V

Reduction (%)51.3 58.4 35.5 46.3 70.6 46.5 27.7 39.0 38.5 33.8 58.3 57.2 38.0 54.6 57.6 45.6 54.6 25.3 48.9 48.5 46.4 46.8

Yield (g/m 2) Light405 440 399 406 450 446 302 373 338 305 483 365 413 466 493 435 318 291 424 326 40 1 394 21 55 77 89

Reduction (%)58.0 78.2 49.9 52.5 73.8 54.3 38.4 53.6 38.2 46.0 69.6 67.7 43.8 61.2 69.0 68.5 58.2 38.5 70.0 61.3 42.6 56.8

Shade433 360 500 528 350 479 473 542 599 414 414 305 577 425 436 466 460 537 436 39 1 524 459

Shade170 96 200 193 118 204 186 173 209 165 147 118 232 181 153 137 133 179 127 126 230 165

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IRRN 17:1 (February 1992)

two light treatments were in the main plots and the restorers in the subplots. Total dry matter (TDM) and yield were recorded at harvest. Low light reduced mean TDM 47% and yield 57%. Reductions ranged between 25-71% for TDM and 38-78%

for yield (see table). TDM and yield were higher in IR54, IR58, IR134 19- 1 13- 1, and IR21916-128-2-2-3 under light. IR19058-107-1, Milyang 54, IR4422480-2-3-3, and IR28178-70-2-3 all showed little reduction in TDM and yield percentages under low light. This

indicates their high yield capability under low-light stress. Physiologically effective restorers, especially IR 19058-107-1, may be useful in developing superior rice hybrids for low-light monsoon areas.

Physiological traits of certain restorers in hybrid rice breedingK. S. Murty, S. K. Dey, and P. J. Jachuck, Central Rice Research Institute (CRRI), Cuttack 753006, India

Physiological traits of selected restorers from IRRI. Cuttack, India, 1989 wet season.

Restorer IR36 IR46 IR50 IR54 IR58 IR64 Milyang 54 ARC11353 IR4422-480-2-3-3 IR9761-19-1 IR13419-113-1 IR13524-21-2-3-3-2-2 IR19058-107-1 IR19392-211-1 IR21916-128-2-2-3 IR25912-63-2-2 IR27315-145-1-3 IR28178-70-2-3 IR29512-81-2-1 IR29723-143-3-2-1 Annapurna (check) Jaya (check) Mean LSD (0.05)

Pn (mg CO 2/ dm2 per h) 36.3 28.9 34.3 30.4 40.4 35.5 35.2 25.2 26.2 39.3 24.3 35.5 27.3 33.3 29.6 35.3 24.4 28.9 31.9 26.7 31.6 38.4 31.7 3.4

LAI F 2.48 3.78 2.46 3.80 2.05 2.88 2.34 4.47 4.15 2.28 4.49 2.60 4.94 2.47 3.09 6.39 4.85 4.17 3.71 5.13 2.09 2.71 3.51 0.95

Pn LAI (g/m2 per h) 8.9 10.9 8.4 11.5 8.3 10.2 8.2 11.3 11.1 9.0 10.9 9.2 13.5 8.2 9.1 22.5 11.8 12.0 11.8 13.7 6.6 10.4 10.8 3.5

Total DM (g/m2 ) 30 d 99 86 88 109 121 123 96 129 140 105 103 118 150 130 90 110 112 109 83 137 109 86 110 ns Flowering 619 617 394 691 420 600 498 1124 886 550 818 534 1213 564 564 1010 886 869 955 953 429 582 717 I62 Harvest 887 901 537 789 569 758 606 1326 1074 714 964 707 1547 751 701 1365 1161 1192 1227 1194 590 798 925 179

Yield (g/m2 ) 339 262 207 289 234 256 188 478 347 198 233 228 458 238 196 456 389 482 476 490 279 318 320 85

Restorers have been selected for cytoplasmic genetic male sterile lines based on fertility restoration and general combining ability for yield. We tested the photosynthetic potential, growth, and yield efficiency of 20 purified IRRI restorers against controls Annapurna (early) and Jaya (medium) under field conditions during the 1989 wet season. We periodically drew samples to assess leaf area index (LAI) and dry matter (DM) production. The photosynthetic rate (Pn) of the top three leaves at flowering was measured with the LI-6000 Portable Photosynthesis System at near saturated light (above 900 E/m2 per s). The high Pn entries IR58 and IR9761 19-1 had low LAI (see table), resulting in low canopy photosynthesis (Pn LAI). IR25912-63-2-2, with moderate Pn and

high LAI, recorded high canopy Pn, DM, and yield. IR19058-107-1 was especially efficient in LAI at flowering, DM production, and yield. To develop stable,

superior F 1 hybrids with high yield potential, IR25912-63-2-2 and IR19058107- 1 may be useful for heterotic combination of physiological traits.

Yield potentialEffect of nitrogen level on the relation between sinksource parameters and grain yieldP. S. Deshmukh and N. M. Chau, Plant Physiology Division; and F. U. Zaman, Genetics Division, Indian Agricultural Research Institute (IARI), New Delhi 110012, India

We studied correlation coefficients between sink-source parameters and grain yield in lowland rice. In a field

experiment at IARI during the 1988 kharif (monsoon), seedlings of C-1907, Pusa 169, and Pusa 312 were transplanted at 20- 10-cm spacing. The experiment was laid out in a splitplot design with three replications. Various growth and biochemical parameters were recorded at different stages and then correlated with grain yield. Nitrogen levels were in the main plots and cultivars in the subplots. Grain yield correlated better with source than sink parameters particularly LAI and total chlorophyll content at flowering stage (Table 1). An increased

Table 1. Correlation values between different sink and source parameters and grain yield. IARI, 1988 kharif.

r value aSink components Panicles (no./m 2) 1000-grain weight (g) Spikelets (no./m 2) Sink size 0.46* 0.49 * 0.46* 0.42*

Source components LAI 0.70** Total chlorophyll content at flowering stage 0.60** Leaf N content at flowering stage 0.43*a Significant at 5% (*) and 1 % (**) levels.

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7

Table 2. Effect of N level on LAI, unfilled grain percentage, and grain yield. IARI, 1988 kharif. N level (kg/ha) 0 50 100 LSD (0.05) LAI 3.06 3.80 4.10 0.67 Unfilled spikelets (%) 11.92 13.75 16.60 2.08 Grain yield (t/ha) 4.64 5.20 5.87 0.39

Yield and growth duration of some rice varieties under 3 systems of crop establishment. Chinsurah, India, 198586 boro. Variety Dular CR126-42-1 IET1444 IET5851 HPU741 IR36 IR50 IR56 IR60 IET4786 IET4094 Mean Durationa (d) NSD 120 144 144 142 136 136 150 150 136 151 156 142 SD 123 144 150 144 140 155 151 151 140 156 157 146 SST 132 158 158 158 162 163 162 162 163 163 162 158 (NSD-SST) 12 14 14 16 26 27 12 12 27 12 6 16 NSD 2.0 5.2 4.3 5.2 4.8 5.3 5.6 5.3 4.8 4.7 4.3 4.7 Grain yield (t/ha) SD 2.2 4.3 5.6 4.5 4.0 5.2 5.3 5.7 5.6 5.4 5.5 4.8 SST 2.9 4.3 4.3 4.6 4.0 4.7 4.9 4.5 4.7 5.6 6.1 4.6 Mean 2.4 4.6 4.7 4.7 4.3 5.0 5.2 5.2 5.0 5.2 5.3 5.3

LAI (source) due to applied N, however, led to a larger gap between grain number/m2 and spikelet number/m2. This resulted in a higher sterility percentage (Table 2).

a Seeding dates were 9 Dec, 13 Dec, and 13 Dec; transplanting date was 13 Jan.

Rice varieties direct-seeded in puddled soil during boro season in West BengalA. K. Mitra, A. Roy, and S. K. B. Roy, Rice Research Station, Chinsurah, West Bengal, India Boro season rice in West Bengal grows with supplemental irrigation during NovMay after the wet season rice harvest in lowland and deepwater ecosystems. The area under boro rice has increased from 0.3 million ha in 1980 to 0.7 million ha in 1990. Average grain yield is 4.5 t/ha. We direct-seeded 11 modern semidwarf rices in puddled soil at Chinsurah to decrease irrigation costs during boro 198586. Three methods were used: direct seeding of nonsprouted seed (NSD), direct seeding of sprouted seed (SD), and seedbed with sprouted seed and subsequent transplanting (SST). We sowed the nonsprouted seed 4 d before the sprouted seed. Crop duration was slightly less under NSD (142 d) than under SD (146 d); plants in SST matured at 158 d (see table). Growth duration for HPU741, IR36, and IR60 differed more (26-27 d) than that for IET4786, IR56, and CR12642-1 (12-14 d). Grain yield was approximately the same, but some varietiesIR36, IR50, CR126-42-1, and IET5851yielded higher (5.2-5.6 t/ha) under NSD. IR56, IR60, and IET1444 yielded higher under SD, while IET4094 and IET4786 yielded higher under SST. Results indicate that early harvest of direct seeded rice is possible without

sacrificing grain yield. Compared with transplanting, direct seeding shortens the growth duration an average of 16 d, and

saves four to five irrigations during the reproductive phase.

Variation in rice husk-kernel ratio (HKR)R. K. Das and N. M. Miah, Plant Breeding Division, Bangladesh Rice Research Institute (BRRI), Gazipur 1701, Bangladesh Increasing the ratio of grain to biomass (harvest index [HI]) is a way to improve rice yields in the tropics. Reduced partitioning of dry weight to the husk could improve HI. We examined seasonal variations in HKR in modem rice varieties BR1, BR3,

BR9, BR12, and BR16 grown at the BRRI farm during the 198586 transplanted aus, transplanted aman, and boro seasons. Plots had four 5.4-m rows each with 25- 20-cm spacing and were laid out in randomized complete block design with five replications. Fertilizer was 80-26-33 kg NPK/ha, 23 kg Zn/ha, and 100 kg gypsum/ha. Filled spikelets (specific gravity = 1.10) of each harvest were separated with salt solution and dried at 80 C for 5 d. Husk and kernel weights were determined for 100 g seed/season per

Table 1. Varietal difference in HKR in 3 seasons. BRRI, Gazipur, 1985-86.

Variety BR1 BR3 BR9 BR12 BR16 Av

HKR Transplanted aus 0.256 0.269 0.290 0.267 0.267 0.270 0.002 0.003 0.002 0.003 0.002 Transplanted aman 0.232 0.261 0.261 0.253 0.259 0.253a

Boro 0.229 0.263 0.260 0.250 0.258 0.252 0.004 0.004 0.00l 0.003 0.001

0.004 0.001 0.003 0.002 0.002

Table 2. Genetic parameters for HKR in 3 seasons. BRRI, Gazipur, 198586.

Season

Range

Mean

Variance ratio b 36.53** 24.96** 31.21**

PCV

GCV

ECV

Mean Heritability genetic (%) advance (%) 87.66 82.74 85.79 9.71 9.00 10.49

Transplanted aus Transplanted aman Boro

0.2500.298 0.2270.273 0.2220.276

0.270 0.253 0.252

5.377 5.280 5.937

5.035 4.803 5.500

1.888 2.194 2.237

a PCV = phenotypic coefficient of variability, GCV = genotypic coefficient of variability, ECV = environmental coefficient of variability. b** = significant at 1% level.

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replication. A rubber dehusker was used to dehull the grain. The HKRs (husk weight divided by kernel weight) of a variety in transplanted aman and boro seasons were similar but numerically higher than those in

transplanted aus, which had comparatively lower spikelet fills. Clear HKR differences occurred in the five varieties. HKR variation was wide and environmental coefficient of variability was low in all seasons, indicating that HKR

is less responsive to environmental factors. Heritability for HKR was high; genetic advance was more or less similar in the three seasons. HKR may be a nearly stable indicator in screening for cultivars with lower husk content.

Lectins in living organisms interact with siliconN. E. Alyoshin, E. R. Avakyan, E. M. Sorochinskaya, N. G. Turnanyan, and E. P. Alyoshin, Krasnodar Agricultural Biotechnological Centre, P.O. Belozernoe, Krasnodar 353204, USSR

An unspecified interaction of lectins with silicon compounds exists in the tissues of silicophiles, both in living organisms and in histological preparations. Scientists need to consider this phenomenon when they use lectins, immunochemicals, and their dyes in silicophile studies. Lectin preparations (including stains) were previously considered to interact specifically with sugars or their residues.

Silica structures of the rice husk of Krasnodarsky 424. Microspodography 20

We have shown that during rice husk microspodography the lectins interact actively with silicon compounds that are present in large amounts in silicophile tissues (see figure). Silica can comprise up to 20% of some rice tissue dry matter.

Attention to this may prevent erroneous conclusions that interactions were with sugars rather than with silicon compounds.

Grain qualityGrain quality of F 1 rice hybridsY. P. Khanna, J. S. Bijral, T. R. Sharma, B. B. Gupta, C. L. Raina, and K. S. Kanwal, SKUAST, Regional Agriculture Research Station (RARS), R. S. Pura (Jammu) 181102, India

Nine rice hybrids developed at RARS and check cultivar Jaya were evaluated for physicochemical and cooked rice characteristics. Standard methods were used to analyze dried grain with about 12% moisture content. Recovery varied from 78 to 80% for hulling and from 72.5 to 75.5% for milling. Five of the hybrids

showed significantly higher head rice recovery than Jaya (RHR1, RHR4, RHR6, RHR7, and RHR9). The rest (except RHR5) were statistically at par with Jaya (see table). Head rice recovery was very high, which suggests undermilling of rice by a Kett Polisher (model TP 20).

Physicochemical characters of F1 rice hybrids a at RARS, R. S. Pura, India. Hybrid or variety RHRI RHR2 RHR3 RHR4 RHR5 RHR6 RHR7 RHR8 RHR9 Jaya Cross combination Zhen Shan 97 A/IR3 1868 V20 A/IR31802 Zhen Shan 97 A/IR8585 Zhen Shan 97 A/IR31802 Zhen Shan 97 A/IET1410 Zhen Shan 97 A/VL 15 VA20 A/IR3 1851 IR48483 A/IR83619 IR46830 A/IR36 Check LSD (0.05) Hulling (%) 80.0 78.0 78.0 78.5 78.0 79.5 79.5 78.0 79.0 79.0 0.5 Milling (%) 75.0 73.0 72.5 75.5 73.5 74.5 74.0 73.0 74.0 74.5 0.7 Head rice (%) 73.5 68.5 70.0 72.0 68.0 70.5 71.0 69.5 71.0 69.0 1.2 Length (mm) 5.60 6.65 5.84 5.67 6.98 5.66 6.59 6.14 6.62 6.37 0.36 Width (mm) 2.27 2.26 2.41 2.36 1.99 2.71 2.34 2.39 2.09 2.57 0.14 L/W Abdominal ratio 2.47 2.94 2.42 2.40 3.51 2.09 2.82 2.57 3.17 2.48 white b Alkali spreading value 2.0 2.0 4.0 2.0 6.0 3.0 3.0 3.0 2.0 7.0 1.3 Water uptake (%) 165 160 170 150 350 200 140 150 140 350 59 Volume expansion ratio 3.7 4.0 3.7 3.7 3.7 3.7 3.7 3.7 3.7 4.0 0.7 Elongation ratio 1.7 1.5 1.6 1.7 1.5 1.4 1.5 1.6 1.5 1.7 0.1 Amylose (%) 19.2 17.0 17.0 17.0 20.3 20.9 17.5 16.0 19.2 29.6 2.70

OP Present Present Absent Absent Present Present OP Absent Present

aAv of 2 replications. bOP = occasionally present.

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Length/width ratio of the milled grain ranged from 2.09 to 3.51. All hybrids except RHR5 and RHR9 displayed some degree of abdominal white. Volume

expansion ratio and elongation ratio after cooking of hybrids were statistically at par with or significantly inferior to Jaya. Water uptake values of all hybrids,

except RHR5 (alkali spreading value 6), were significantly lower than that of Jaya. Amylose content was 1620.9% for hybrids and 29.6% for Jaya.

Relationship among grain shape, size, and head rice recovery (HRR) in indica riceYan Wenchao, Qiu Bieqin, Jin Qingsheng, and Luo Rubi, Crop Institute, Zhejiang Academy of Agricultural Sciences, Hangzhou 310021, China

We grew 19 conventional indica rice cultivars in a randomized block design with three replications. Seedlings (32-dold) were transplanted 2 May 1990 at 16.7- 13.3-cm spacing. Five plants from each plot were randomly selected at harvest to measure 1,000-grain weight (GW), rough rice length, breadth, length/breadth (L/B) ratio, and HRR.

1. Relationship between grain length and head rice recovery in 19 indica rice cultivars. Hangzhou. China, 1990.

2. Relationship between L/B and HRR in 19 indica rice cultivars. Hangzhou, China, 1990.

The negative correlation between grain length and HRR was highly significant (Fig. l), as was the correlation between L/B ratio and HRR (Fig. 2).

HRR was inversely associated with length and L/B ratio, but seems not to be associated with GW and breadth. The correlation varied more in grain length and L/B ratio than in GW or breadth.

Pest resistance diseasesNoncapsid protein (NCP) used for serological assay in indexing rice grassy stunt virus (RGSV)-infected plantsG. J. Miranda and H. Koganezawa, IRRI

but not with purified RGSV and healthy plants in DAS-ELISA. Using indirect ELISA greatly increased sensitivity. NCP was detected

RGSV-infected plants were found to produce 24 kDa NCP which is common to all tenuivimses. We prepared antisera against NCP produced by RGSV. Antiserum from NCP purified by differential pH precipitation and single ultra centrifugation reacted strongly with purified RGSV and infected plants, but not with healthy plants in double antibody sandwich enzyme-linked immunosorbent assay (DAS-ELISA). This indicates a slight contamination of viral coat protein in NCP preparation. NCP was further purified by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). The antiserum produced reacted positively with purified NCP and infected plants,

in purified NCP preparation at a concentration less than 10 ng/ml and in sap from infected plants diluted to 10 -5. Sap from healthy rice plants never positively reacted (see figure). Antiserum produced from a purified NCP obtained from differential pH precipitation can be used to routinely index RGSV-infected plants instead of using RGSV antibody, which is laborious to prepare. Antiserum produced from SDS-PAGE can be used to specifically detect NCP in infected plants. RGSV-NCP antisera reacted with NCP of rice stripe virus in a double diffusion test, indicating a close relationship between the viruses.

Absorbance (405 nm) values for indirect and DASELISA tests during the 24 kDa antiserum purified by SDS-PAGE. The purified NCP, RGSV, and plant sap were adjusted to an initial concentration of 1 mg/ml, A 260= 3.0, 1 g tissue/ml, respectively.

Surveys of disease or insect incidence severity in one environment are useful only if the information is related to other variables (e.g., climatic factors, crop intensification, cultivars, management practices, etc.). By itself, information an incidence in one environment does not increase scientific knowledge.

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Nonspecific reaction in ELISA of viruses in rice rootsE. L. Coloquio and H. Koganezawa, IRRI

Number of healthy plants showing positive reaction a in ELISA using 4 virus antisera.

Plant ageb (wk) 5 6 7 8 9

Plants (no.) Culms RTBV 0 0 0 2 1 RTSV 0 0 0 1 7 RRSV 0 0 0 1 RGSV 0 0 0 0 RTBV 7 1 0 2 8 7 0 0 3 17 Roots RTSV RRSV 2 0 1 8 RGSV 3 0 0 4

Enzyme-linked immunosorbent assay (ELISA) has been routinely used to detect rice viruses. An initial test of rice roots indicated that many apparently healthy plants collected from IRRI fields reacted positively for rice ragged stunt virus (RRSV). We examined whether a nonspecific reaction or false positive reaction occurs in ELISA of different rice plant parts. We tested 18 healthy 3- to 9-wk-old TN1 plants. Seedlings were kept in a screen cage and sprayed with cypermethrin 5 wettable powder at 2 and 6 wk to prevent rice virus infections. Plant samples were collected weekly and subdivided into leaf blades, leaf sheaths, culms, and roots. Samples were weighed, homogenized in 10X volume of 0.02 M phosphate buffer solution Tween, and assayed by double antibody sandwich (DAS)-ELISA

a Positive reaction defined as >0.05 of ELlSA value and >3 the negative mean of healthy leaf blades at 10-d-old seedling stage. No virus was detected in leaf blades and sheath. bNo virus was detected in any plant parts at 3 and 4 wk.

using four virus antisera: rice tungro bacilliform virus (RTBV), rice tungro spherical virus (RTSV), RRSV, and rice grassy stunt virus (RGSV). Four plants, each infected with a virus, served as controls. Rice viruses were not detected in leaf blades and leaf sheaths throughout the experiment, indicating that all plants were healthy. But some root samples of the 5and 9-wk-old plants tested positive for al four virus antisera (see table). Mean ELISA absorbance values of positive reactions for root samples obtained during weeks 5 and 9 were 0.17 for RTBV, 0.36 for RTSV, 0.36 fo

RRSV, and 0.18 for RGSV; values for samples from infected plants were 0.45 for RTBV, 0.64 for RTSV, 1.06 for RRSV, and 0.33 for RGSV. Only a few root samples at 6, 7, and 8 wk and a few culm samples at 8 and 9 wk showed positive reactions. The obtained ELISA values were low compared with those from infected roots. Results suggest that nonspecific reactions in ELISAnot caused by the virus occurred when rice roots were tested. ELISA data from leaves and healthy roots should accompany data for virusinfected roots to accurately interpret results.

Pest resistanceinsectsResistance to brown planthopper (BPH) in rice germplasm in Raipur, Madhya Pradesh (MP), IndiaD. J. Pophaly and D. K. Rana, Entomology Department, I.G.K.V.V., Raipur (MP), India

Five hundred germplasm accessions from Madhya Pradesh Rice Research Institute (MPRRI) were screened for resistance to BPH Nilaparvata lugens. Susceptible TN1 and resistant Ptb 33 were used as check varieties. We sowed seed in wooden seedboxes in the greenhouse during 198990. Ten-dold seedlings were uniformly infested with second- to third-instar BPH nymphs. Damage for all entries was scored using the Standard evaluation system for rice when TN1 died. Entries scoring 41 30% of surveyed fields. Nematodes are considered crop parasites when 200 individuals are recovered per dm3 of soil (abundance = 2.3) or an average of more than 20 individuals are recovered from 1 g of root (abundance = 1.3). Hoplolaimus, Rotylenchulus, and Trychodorus were detected in only 1, 1, and 3 samples, respectively, indicating they are not important upland rice parasites in Sitiung. Population densities of Helicotylenchus were low in 13% of the samples. High population densities of the four most important nematodes were observed in the rhizosphere and roots of upland rice, indicating they are parasites. The prevalent genus of plant parasitic nematode (Pratylenchus) in Sitiung was found in 66% of the samples. Duration of rice cultivation affected its occurrence, with detection in 39% of NF and 100% of OF. Criconemella was detected in 43% of OF. High population densities of Meloidogyne were in a few locations

Frequency and abundance per dm3 of soil and g of root of the major plant parasitic nematodes associated with upland rice in Sitiung, Sumatra, Indonesia. Vertical line = when nematode genera are considered frequent (>30%). Horizontal line = when abundance index >2.3 in soil and 1.3 in roots.

(16%). Xiphinema was frequently detected in NF (31%), but nor in OF (7%). Population with the highest frequency appears to shift from Xiphinema to Pratylenchus with increased years of cultivation.

Pratylenchus seems to be the main concern, but methods used to control it must not favor buildup of Meloidogyne and Criconemella populations.

Farming systemsRice - fish farming system for Hunan, ChinaShen Huashan, Chen Shujun, and Yang Guangli, Institute of Soil and Fertilizer Research, Hunan Academy of Agricultural Sciences, Changsha 410125, China

About 87,000 ha were devoted to rice fish farming in Hunan Province in 1990. We evaluated the suitability and economics of the rice - fish system in 199091. Soil was Quaternary period red earth with pH 6.1, 0.8% organic C, and 140.2, 38, and 127 ppm available N, P, and K, respectively.

The multiple system experiment consisted of the three dominant patterns in Hunan and was laid out in a randomized block design with three replications. Varieties used were early rice Wei You 35, late rice Wei You 64, and rape variety Xiang 11. Rice - azolla - rape had the highest rice yield (Table 1), but the lowest

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Table 1. Yield and income from rice - fish farming system. Hunan, China, 199091. Farming system Rice - rape (control) Rice - azolla - rape Rice - azolla - fish - rape Yield (t/ha) Rice 13.8 14.2 12.9 Rape 1.2 1.2 1.2 Fish Gross return ($/ha) 2068.9 2119.2 2490.8 Net return ($/ha) 1145.0 1167.9 1501.1 Benefitcost ratio 1.24 1.21 1.52

0.5

Table 2. Energy transformation of rice - fish farming system. Hunan, China, 199091. Rice - rape (control) Total Organic Inorganic Commodity Total Product Secondary product By-product Output:input Product:inorganic Product:commodity Inorganic:input Light use efficiency (%) Energy input (10 8J/ha) 2274 1594 268 413 Energy output (10 8 J/ha) 3774.1 2119.9 1654.2 Energy efficiency 1.66 7.92 5.14 0.12 1.03 Rice - azolla rape 2647.0 1984 260 404 4647 2182.4 2465 1.76 8.40 5.41 0.10 1.23 Rice - azolla fish - rape 2739 2082 252 404 4626 2092 69 2465 1.69 8.29 5.17 0.09 1.21

benefit-cost ratio. Gross return, net return, and benefit-cost ratio were highest in the rice - azolla - fish - rape farming system. Rice - azolla - rape gave the highest energy output, output-input energy ratio, product energy-inorganic energy ratio, product energy-commodity energy ratio, and light use efficiency (Table 2). Inorganic energy-input energy ratio was lowest in rice - azolla - fish - rape system.

Productivity of rainfed ricebased cropping systems in West BengalN. R. Das andA. Kashyapi, Agronomy Department, FacultyofAgriculture,Bidhan ChandraKrishiViswavidyalaya,Kalyani 741235, WestBengal,India We studied the relative productivity of summer crops and their effect on weta

season (WS) rice and their residual effect on lentil Lens culinaris L. The rice-based cropping systems were evaluated under rainfed conditions in the subhumid tropics during 1989-91. The soil was clayey loam with pH 6.8, 0.61% organic C, 0.062% total N, 15 kg available P, and 160 kg available K/ha. WS rice fertilized with 0, 50, or 100 kg N/ha was transplanted after the

Effect of crops and N level on wet rice yields and aftereffect on lentil under rainfed condition. West Bengal, India, 198991. Crop yield (t/ha) Treatmentb

1st crop Grain/ fiber Straw/ stock 0.0 8.1 2.7 7.8 9.1 5.5 1.4

2d crop (rice) Grain Straw

3d crop (lentil) Grain Stock

Total Grain/ fiber 3.1 6.6 5.4 5.5 3.9 4.9 Straw/ stock 4.6 14.6 6.8 14.1 13.2 10.7

Net returns (US$ha)

harvest of a fallow check and four upland crops: jute cultivar Basudev, direct seeded rice MW 10, mungbean cultivar Pusa Baisakhi, and sesame cultivar Tilottama. The experiment was laid out in a split-plot design on 8- 2-m plots. All summer crops were sown 2 May and harvested 31 Jul; IR36 rice was transplanted 7 Aug (25 d after seeding) at 25- 25-cm spacing, with 4 seedlings/ hill. K and P (25 kg/ha each) were applied to the rice, which was harvested 14 Nov. Lentil (B77) was broadcast 19 Nov and harvested 28 Feb. No fertilizer was used. Grain and straw yields of rice were maximum after either jute or mungbean (see table). Results were similar for thirdcrop lentil grain and stock yields. Jute rice - lentil showed the maximum crop production and net return among the 3crop systems. The mungbean - rice lentil sequence was second. Grain and straw/stock yields of both rice and lentil increased as the N level increased. Net returns of rice also increased.

Cropping system Fallow - rice - lentil Jute - rice - lentil Rice (d) - rice - lentil Mungbean - rice - lentil Sesame - rice - lentil Mean LSD (0.05) N level in rice (kg/ha) 0 50 100 Mean LSD (0.05)

Farm machinery312 1212 816 980 644

0.0 1.8 2.5 0.8 0.9 1.2 0.2

1.7 3.2 1.6 3.2 1.6 2.3 0.2 2.0 2.3 2.6 2.3 2.0

2.0 3.7 1.8 3.7 1.7 2.6 0.2 2.4 2.5 2.9 2.6 0.1

1.4 1.6 1.3 1.5 1.4 1.4 0.1 1.4 1.4 1.5 1.4 ns

2.6 2.8 2.3 2.6 2.4 2.5 0.1 2.4 2.6 2.6 2.5 ns

Development of spinning brush VLV pesticide applicatorN. K. Awadhwal, G. R. Quick, and E. F. Cabrido, IRRI

3.4 3.7 4.1 3.7

4.8 5.1 5.5 5.1

376 440 528

a Mean of 2 yr. ns = not significant. bRice (d) = direct seeded rice.

The spinning brush very low volume (VLV) pesticide applicator is a new lowcost system that reduces labor. It works on the principle that when the bristles of

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Characteristics of spray delivered from different pesticide applicators,a IRRI. Equipment Brush applicator Micro ULVA (orange nozzle, 6 V) b CP 15 (HC 60) b CP 16 (Blue) Tung Ho (H. cone) VMD (m) 187 105 90 230 200 NMD (m) 90 73 70 125 70 VMD/ NMD 2.07 1.43 1.28 1.84 2.85 Swath width (cm) 100 150 60 50 50 Droplet density Mean (no./cm2 ) 43.1 127.5 32.9 81.2 35.5 CV (%) 30.2 47.0 60.1 48.3 41.0

a Mention of a commercial product is for specific information only and should not be construed as product endorsement by IRRI. b

Nozzle identification in parentheses.

Spinning brush VLV pesticide applicator. A. Brush atomizer. B. Main frame. C. Bevel gear. D. Chemical container. E. Nozzle. F. Deflector.

a wet brush are forcibly deflected and then allowed to bounce back swiftly, a spray of fine droplets is generated. The pesticide applicator consists of a rotary brush atomizer mounted on the end of a shaft that passes through a pipe frame. The structure is rotated manually with a bevel gear (see figure). An air bleed system is built into the lid of a 1liter container mounted on the frame. Chemical flows by gravity at a reasonably constant rate and drips onto the brush bristles. A sheet metal deflector generates a spray when the brush is rotated.

Droplets from the brush applicator have a volume median diameter (VMD) of 187 m, smaller than that of knapsack sprayers CP16 and Tung Ho but bigger than that of CP15 and Micro ULVA droplets (see table). The ratio of VMD to number median diameter (NMD) for the brush applicator was 2.07 compared with 2.85 for Tung Ho, indicating greater uniformity in droplet size from the brush. The brush applicator had a mean droplet density of 43.1 droplets/cm2 (CV 30.2%), which is adequate for pesticide application. The brush applicator applied pre- and post-emergence herbicides as well as other sprayers in replicated field trials. One application of butachlor (1.5 kg ai/ha) reduced weed intensity significantly (P