3.4 Discussion
3.4.6 Conclusions and implications to maize breeding
1) The proportions of additive to non-additive genetic effects for LCC character differed between the two crosses and between HN and LN. Generally the trend was that the fixable gene effects were predominant under HN, whereas the non-fixable effects prevailed under LN, although the magnitude of these effects varied with genotypes.
2) Generally, the additive genetic effects predominated for LCC at mid-silking and milk grain-filling stages, whereas dominance effects were highest at dent and maturity stages. Mid-parent heterosis increased with growth stage and this was expressed better under low N than under high N, pointing to the possibility of taking advantage of heterosis for LCC under low N conditions. The best stage for selection for LCC to develop breeding populations (e.g. inbred lines) would be at the early grain-filling stages.
3) The frequencydistributions that considered the relative positionsof recurrent parents to their segregating generations demonstrated observation of transgressive segregants under both HN and LN. These curves also tended to normal and continuous distribution, which implied that many genes were involved in the inheritance of LCC character. The positive segregants can be exploited in a breeding programme.
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