Grain yield responses to varied level of moisture stress at reproductive stage in an interspecific population derived from Swarna/O. glaberrima introgression line

Understanding response of plants to drought stress is critical for developing drought tolerant genotypes with stable performance under water limiting conditions. A backcross inbred population derived in the background of a popular variety Swarna, was evaluated for yield and yield attributing traits under reproductive stage and shoot morphological traits at seedling stage under drought stress over a period of two years during 2011-2013. Selection intensity varied across seasons and years with varied level of moisture stress. Traits such as flowering (DTF), plant height (PH), spikelet fertility (SF), biomass (BM), harvest index (HI) and grain yield (GY) are drastically affected by drought across seasons. Yield reduction varied from 48.5% to 92.4% over control trials. Chlorophyll content (CC) and canopy temperature (CT) recorded higher under drought rather than control. Yield was highly associated with DTF (−0.29* to −0.76**), SF (0.32** to 0.77**), HI (0.82** to 0.97**) and CT (−0.38**). Heritability is found to be similar for grain yield under both conditions. Genotypes displaying higher SF and HI, lower CT, reduction in flowering delay and low DSI are able to produce better grain yield under drought. High yielding genotypes at reproductive stage stress also showed superior performance under stress at seedling stage. Hence, selection intensity for high yield potential under favorable conditions, drought tolerance to varied level of stress (across seasons) and screening under target population environment had the advantage of identifying stable high yielding genotypes with wider adaption suitable for drought-prone regions, which can significantly benefits the poor farmers relying on rainfed lowland rice.