Glasshouse-based selection to identify agronomically adapted, uniform true potato seed (TPS) progenies

Twenty-five true potato seed progenies and five clonally maintained cultivars were grown in a glasshouse. Tubers of each clone of each progeny were grown in a field experiment. At harvest, one seed tuber was taken from each plant and field grown for a second year. After each experiment, the tubers from every plant were weighed and counted and their colour, shape, form (regularity) and skin finish assessed. Progeny means and variances for each character were calculated. There were significant differences between means for each character in all experiments, except mean yield in the glasshouse, variances for each character in both field experiments and tuber number variances and colour variances in the glasshouse. In general, Pearson's product-moment correlations between glasshouse and field assessments were moderate or poor (r ≤ 0.6) and inconsistent between experiments. Spearman's rank correlations between glasshouse and field assessments for progeny means were similar to the linear correlations, while those for variances were somewhat better. Rank correlation gave more consistent results between experiments. Ranking glasshouse means will allow some worthwhile progeny selection for tuber colour, shape and skin finish. It can be a useful screen for progenies with the highest levels of uniformity for all characters.