Adaptation of green manure legumes to adverse conditions in rice lowlands

摘要: Poor adoption of sustainable pre-rice green manure technology by lowland farmers is frequently associated with unreliable legume performance under adverse environmental conditions such as marginal soils, short photoperiod, and unfavorable hydrology. A series field microplot experiments were conducted at the International Rice Research Institute (IRRI) in 1991 1992 to screen evaluate 12 promising flood-tolerant legumes for adaptation (N accumulation biological N2 fixation) a range stresses, encountered rice lowlands. Legumes belonging genera Sesbania Aeschynomene grown 8 weeks 10×10 cm spacing: (1) fertile control soil four marginally productive irrigated soils (sandy Entisol, P-deficient Inceptisol, acid Ultisol, saline Mollisol); (2) during short- (11.7h) long-day (12.3 h) seasons favorable soil; (3) an aerobic (drought-prone rain-fed lowland) deep-flood-prone (1 week seedling submergence). large variability N was obsersed among species across different environments, ranging from less than 1 over 70 mg plant-1. The nitrogen derived atmosphere (Ndfa) accounted on average 82% total accumulation. virgata least affected but its Ndfa lowest tested (less 60%). Stem nodule formation did not convey significant advantage conditions. However, flooding reduced fixation stem-nodulating solely root-nodulating species. Most drastically short-day afraspera S. speciosa photoperiod. considerable genetic germplasm screened allows selection potentially appropriate most studied, thus increasing manures.