Orissa University of Agriculture and Technology, Bhubaneswar
Online published on 25 January, 2012.
A 4 × 4 diallel cross was analysed by Method II and Model I of Griffing to obtain information on the nature of gene action for yield and five of its components-number of panicles per plant, panicle length, number of grains per panicle, weight per panicle and 1000 grain weight. The four parents used in the diallel mating system were the reputed rice cultivars, Adt 27, Ptb 10, T(N) 1 and IR 8.
The highly significant general and specific combining ability variances indicated that genes having additive and nonadditive effects were influencing yield and yield components. The exception was panicle number which showed highly significant s.c.a. effect but nonsignificant g.c.a. effect. The relative importance of general and specific combining ability effects varied from character to character. The additive genetic effects were more important for number of grains per panicle and 1000 grain weight. For yield and the remaining three components nonadditive, genetic effects were of greater importance than additive effects. On the basis of the combining ability effects the short × tall cross, Adt 27 × IR 8 appeared to be more promising; this cross exhibited high degree of heterosis for all the characters except 1000 grain weight.
