Combining ability and heritability in upland rice (Oryza sativa L.)
1981
Oyedokun, J.B., Institute of Agricultural Research and Traing,University of Ife,P.M.B.5029,Moor Plantation,Ibadan, (Nigeria) | Chheda, H.R., Department of Agronomy,University of Ibadan,Ibadan (Nigeria)
A 5 x 5 diallei analysis (excluding reciprocals) of combining ability for five yield characters in upland rice (Oryza sativa L.) was conducted to obtain information on the genetic architecture of the crosses, identify suitable parents for hybridization and estimate heritability values. Although the estimates of both general and specific combining ability variances were highly significant (P:S:0.01) for all five characters studied, the magnitude of the general combining ability (g.c.a.) variances were two to three times higher than the specific combining ability (s.c.a.) variances, with low ratios of additive to total genetic variance for all characters. Tox 7-4-2 was the best general combiner for yield per plant and mature plant height. Juma I and 63-83 were good general combiners for harvest index and earliness respectively. lAC 1391 might likely provide source materials for effective election to improve grain weight. The cross Tox 7-4-2 x IR 154-6I10S.6 significantly outyielded other hybrids except lAC 1391 x Tox 7-4-2. The performance of parents per se indicated their combining ability, and parents associated with negative g.c.a. effect did not necessarily show negative s.c.a. effect and vice versa. The additive genetic variance was more important for earliness to heading than the other traits as shown by its slightly higher narrow sense heritability estimate.
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