Manifestation of heterosis in rice (Oryza sativa L.) in a saline environment.
1988
Sajjad M.S.
The expression and magnitude of heterosis in rice were studied in a saline environment. Five varieties and strains were crossed during 1982: NIAB RICE (NR-I)/C23-3-1; NR-I/IR6; NR-I/Jhona 349; Jhona 349/IR6; IR6/Basmati 370. The F1 and the parents were grown in NIAB National Inst. for Agriculture and Biology, Pakistan fields in Jun 1983. Six-week-old seedling were transplanted into drainable concrete field basins (6 x 6 x 1 m). For artificial salinization, four commercial salts - MgCl2, NaCl, CaCl2, Na2SO4 - were mixed with soils at ratios of 1:4:5:10. Desired salinity was further achieved by infrequent irrigation with tubewell water (saline sodic). In the randomized complete block design with four replications, seedling were transplanted at 1/hill and 20-cm spacing. At least 20 plants/replication were observed. Yield and 1,000-grain weight were recorded after drying grains to 14.0% moisture. To test the performance of F1 hybrids, heterosis was calculated over that of the better parent. Heterosis was variable and inconsistent not only for plant attribute but also for crosses. No heterosis was observed for number of primary branches per panicle and panicle fertility percentage in the saline environment. The greatest heterosis for yield per plant was 154.4% for Jhona 349/IR6. This was based on simultaneous heterosis in plant height, number of productive tillers per plant, panicle length, total florets per panicle, and 1,000-grain weight. Heterosis for yield for the best four crosses varied greatly from 13.9 to 154.4%. Results indicate the potential for harnessing hybrid vigor in the development of relatively salt-tolerant strains of rice.
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