Influence of season on growth and productive efficiency of high yielding rice cultures

The relative influence of the wet and dry seasons on various yield and growth components was tested with 8 early high yielding rice cultures. The yield was reduced by 35 per cent during the wet season when compared with the dry season mostly due to high sterility of spikelets. Post flowering dry matter accumulation and harvest index were also reduced and N accumulation in different plant parts increased during the wet season. Among the cultures, IET 2233 (B. Patna X IR. 8) gave significantly higher yield during the wet season and the characters associated with its productive efficiency are higher grain number/panicle and harvest index and greater dry matter production and N uptake during the post-flowering period.