Coheritable Variation in Rice

Intra-group coheritability of different pairs of characters involv'ng days taken to flower, plant height, flag leaf area, panicle length, spikelets per panicle, ear-bearing tillers, 100-grain weight, grain-straw ratio and yield per plant in 120 varieties of rice classified into early short, early tall, late short and late tall groups was determined. None of the characters was found to have higher coheritability value with yield per plant than the heritability of yield per plant and the coheritability values depended upon the material chosen. Nevertheless, selection criteria on the basis of high coheritability value exhibited by a few character pairs involving yield was formed. Incorporation of bold seed size, more number of spikelets per panicle and high grain-straw ratio in early short and grain-straw ratio in late tall types for yield improvement was suggested whereas for early tall types, simultaneous selection for plant height, days taken to flower, flag leaf area, panicles per plant and spikelets per panicle could lead to gains in yield.