SOME GENETIC FACTORS AFFECTING SEEDLING EMERGENCE IN RASPBERRIES

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Summary

The emergence of raspberry seedlings derived from two diallel crosses was studied, and also the effects on emergence of applying auxin to fruits 7 days after pollination. In one diallel, emergence was poor and the variations present were largely determined by maternal effects. In the other it was better and the largest variations were determined by inbreeding depression effects. In most cases maternal effects on emergence were negatively correlated with maternal effects on endosperm size, while inbreeding effects were associated with reductions in embryo size. Maternal interaction effects were of minor importance and were probably correlated with effects on the endocarp. The auxin treatments had variable consequences according to their effects on the seed tissues. It is concluded that the factors which determined seedling emergence would tend to maintain heterozygosity and should therefore be regarded as part of the breeding system.

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