SUMMARY
Drought is a major constraint for rainfed lowland and upland rice productivity throughout world. A backcross inbred population derived from ‘Swarna’ and ‘WAB450-I-B-P-157-2-1’ (Oryza sativa L. x O. glaberrima) was evaluated under both irrigated and lowland drought stresses for yield and yield related traits across three different seasons. Significant differences were found among all the analyzed traits. Coefficients of variation were recorded relatively high for filled grains per panicle, spikelet fertility, test weight, harvest index and grain yield and low for panicle length under both conditions during the study interval. Broad sense heritability varied from 0.28 (panicle number) to 0.83 (plant height) under stress and 0.31 (test weight) to 0.86 (plant height) under control. However, heritability estimates for grain yield and harvest index were found to be similar under both conditions. Traits such as filled grains per panicle, spikelet fertility, harvest index and grain yield recorded higher values of both heritability, as well as genetic advance under both conditions, indicating the suitability of these traits as selection criteria to derive high yielding genotypes for drought prone regions. Harvest index exhibited maximum positive direct effect on grain yield under both the conditions; in addition, filled grains per panicle, spikelet fertility and biomass had positive direct effect on grain yield under both irrigated and lowland drought stresses state. Hence, for improving the rice yield under lowland drought ecology, a genotype should posses a large number of panicles per plant, filled grains per panicle, high spikelet fertility and maintains higher biomass and harvest index.