Nature of combining abilities and genetic interpretation for some quantitative traits in Egyptian cotton
2011
Dewdar, M.D.H.
This investigation was conducted with the objective of approaching an efficient parental choice of cotton cultivars in the breeding program for developing superior cultivars for high yielding and .good fiber quality. Five Egyptian cotton genotypes were crossed in a diallel pattern i.e. in all possible combinations excluding reciprocals in season 2009. In the summer 2010 field evaluation experiment of 15 entries (5 parents and 10 F1 s) was undertaken. The data revealed that there were noticeable differences between the parental genotypes for their positive significant general combining ability (GCA) effects for most studied traits. In generall the magnitude of GCA mean squares was mostly greater than SCA mean squares expressed as GCA/SCA ratio indicated that the magnitude of additive and additive x additive genetic effects were considerable in the inheritance of all characters rather than non-additive effects except for boll number where the effects were mainly non-additive. The parental genotype Giza 83 (P4) superseded all other parents for GCA effect and showed the highest GCA effects for lint yield and was also in the 2nd rank for seed cotton yield. Giza 81 (P3) had maximum GCA effects for seed cotton yield followed by Giza 85 (P2) for boll number. Furthermore, Giza 75 (P,) was in the ls` rank by having maximum GCA effects for fiber strength and showed desirable negative GCA, effects for fiber fineness revealing that these parental genotypes could be considered as good combiners in breeding program for developing high yielding genotypes. Out of 10 hybrids, five hybrid combinations, i..e. Pl x P2 Pl x P3 Pr x P4 P4 X P5 and P4 X P5 showed desirable specific combining ability And heterotic effects for most of the studied traits
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