Heterosis under aerobic condition in hybrid rice.

An experiment was undertaken to identify heterotic rice hybrids for aerobic condition based on physiological and root characters associated with water stress tolerance in rice. Panicle harvest index, a substitute for spikelet fertility is used as a secondary trait in the selection of drought tolerant genotypes. Deep roots are required to explore the soil profile for effectively absorbing water at deeper layers. A cultivar which partitions more of its dry weight in root can explore more soil volume for extracting water and thus can effectively sustain drought. Four hybrids viz., IR 68885A/IR 73718-3-1-3-3, IR 67684A/CT-6510-24-1- 2, IR 70369A/IR 73718-3-1-3-3 and IR 70372A/PSBRC 80 exhibited heterotic vigour for yield and maximum number of yield components and showed better adaptability to aerobic conditions. These hybrids can be commercially exploited under aerobic condition.