Yield response of rice genotypes to reproductive stage drought adapted to drought prone rainfed lowland

Drought is one of the most severe constraints in rainfed lowland ecosystem of rice and genetic improvement for drought tolerance focuses on both moderate and severe drought stress at reproductive stress stage. Field screening of a large number of entries [78 genotypes of 100–120 days duration, 29 with more than 120 days duration and 18 high yielding varieties of Bihar were conducted to identify drought tolerant genotypes using drought tolerance parameters viz., drought susceptibility index and drought tolerance efficiency for grain yield and component characters under severe reproductive stage drought stress. The results suggested the existence of genetic variation for grain yield and yield contributing characters in the population and showed differential reaction of cultivars in their relative adaptation to drought stress environment. Sterility (%) was observed to be governed by additive gene action in both non stress and drought environments. Grain yield had positive correlation with tiller number plant⁻¹ under both the conditions while, sterility (%) had negative association. Most of the genotypes expressed low DSI value (<1) and high DTE for yield and yield contributing characters. Thus, genotypes IR84899-B-183-CRA-19-1, R-RF-65, IR80461-B-7-1, IR82870-11, IR80463-B-39-1, NDR 118 and NDR 97 with the lowest DSI and the highest DTE values were accepted drought resistant genotypes.