ABSTRACT
Five wheat cultivars, representing variability in dormancy, grain coat colour, and germinative alpha-amylase, were used as parents in a combining-ability diallel analysis. Two ripening environments were provided by repeating the experiment at a later sowing-date. Regression fits of harvest-ripeness (HR), HR germinative maturity, HR dormancy and HR germination provided data for the diallel analysis.
Dormancy and germination had specific combining-ability (sea) as their main source of variance. In contrast, the main variance for maturity was sca-environment interaction, with general combining-ability (gca) as the only non-trivial genetic component. Bunker-germination was influenced most by environmental variance, with notable-contributions also from gca and sea. The environmental variance was substantial as well for sprouting-index (for which gca also was non-trivial), alpha-amylase (where gca-environment interaction was substantial too), and test-weight (for which sca variance also was significant). Grain coat colour had large gca and sea variances, with a small non-trivial environmental variance. The flavanol pigment precursors were affected substantially by environmental variance, with a smaller notable genetic effect from sca only.
These results revealed substantial heterosis for dormancy and suggested that hybrid-cultivars may be a viable method of obtaining non-sprouting wheats, rather than purelines. However, selection against alpha-amylase production was not indicated as useful in this experiment. Selection using bunker-germination relied on different genetic variability to that for dormancy. Sprout-index was not indicated as a useful selection criterion.
