Growth and yield in relation to maturity duration in rice

Physiological analysis of different maturity duration groups in rice indicated high photosynthetic rate, stomatal conductance, chlorophyll and nitrogen per unit area at flowering in early varieties as compared to medium and late duration varieties. However, Leaf area index (LAI), total dry weight and grain yield were highest in late varieties. Medium group recorded the lowest yield because of high spikelet sterility. In general, major yield constraints were low grain number/panicle in early, high spikelet sterility in medium and low panicle number/m² in late duration groups. Swarnaprabha, CR 157-190 and Savitri from early, medium and late groups, respectively showed highest yield through high CGR at reproductive stage, dry matter at flowering and harvest with high harvest index (HI).