if Parents A & B show significant positive G.C.A and A x B shows significant positive S.C.A effects but the heterosis estimate for this cross is significant negative for flowering attributes in maize, what does this infer? is it a must for g.c.a and s.c.a to be negative to indicate potential to develop early maturing hybrid combination?? negative heterosis mean hybrid matured early than parent.
Dear Tauseef Taj Kiani, Generally maize shows a high degree of heterosis or hybrid vigor particularly in relation to yield. Seed size and number being the biggest yield components with outstanding heterosis. In terms of heterosis in maturity this shows up as an earlier date for flowering and half flowering dates. These effects are much less than the grain yield traits. It is usually quite a bit easier to increase yield from the heterosis than to greatly lower the flowering dates. Earliness is very important for short seasons and is generally preferred to get yield with mature seed rather than have a prolonged maturity with needs more resources and in temperate areas frosting is quite a potential issue. In maize breeding the races of maize are testing for their combining abilities. Breeders keep these separate and develop inbred lines with a test cross grow out to identify the specific outstanding combinations. Inbred lines start being pure inbred which are largely stable are 3 or more self pollinations and better heterosis is available in more inbred parents. Maize hybrids and inbreds are classified based on heat units to maturity.
Thank you Paul for a nice elaborate reply, helped me understand well. Thanks again
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