Cross prediction in a potato breeding programme by evaluation of parental material.

It is shown that it is possible to obtain an indication of the parental value of heterozygous cultivars of potatoes for the characters breeders' preference, total tuber weight, mean tuber weight and number of tubers. Three methods of predicting the characteristics of progeny produced from particular parental cultivars were examined, namely: univariate cross prediction (based on mean and variance), mid-parent values and mid-self values. All provided some indication of which crosses would give superior progeny, but univariate cross prediction gave rankings which correlated most highly with observed performance in the second clonal year for the characters breeders' preference and total tuber weight. Interestingly, mid-self values gave the best predictions in the case of mean tuber weight and number of tubers. It is suggested that such predictions of 'parental value', especially when based on univariate cross prediction at the seedling stage, are worth carrying out in practical breeding programmes.