Role of secondary traits in improving the drought tolerance during flowering stage in rice

Studies were conducted to examine the role of different secondary traits in improving the flowering stage drought tolerance in rice. Six varieties were exposed to drought for three weeks during flowering stage. The tolerant varieties maintained leaf temperature lower than air temperature under drought. The maintenance oflower leaf temperature was related with higher transpiration rates with the help of higher root to shoot ratio. It was found that maintenance of higher plant water status under drought plays a central role in stabilizing the various plant processes and yield. A strong relationship between leaf water potential with delay in flowering and membrane stability was observed under drought. Drought delay flowering in all varieties, and a larger delay in flowering was related with higher spikelet sterility and lower gain yield. It is concluded that flowering delay due to drought is an strong indicator of drought susceptibility. The less delay in flowering, high leaf water status, higher root to shoot ratio, low leaf temperature and higher membrane stability under drought contributes significantly to flowering stage drought tolerance in rice.