AN ANALYSIS OF GENETIC-VARIATION IN SUGAR-BEET (BETA-VULGARIS L) USING AN AUGMENTED BIPARENTAL (ABIP) MATING DESIGN

An augmented biparental (ABIP) mating design was used to investigate the quantitative variation, particularly the dominance variation, for morphological and chemical characters in sugar beet. Diploid O‐type plants were both crossed and selfed and the progeny were grown in a single‐plant randomised field trial. A comparison of the two kinds of family provided tests for both dominance variation and directional dominance effects. Estimates of the narrow heritability were also obtained for each character. Germination problems reduced the size of the final analysis but evidence was obtained of dominance variation and positive directional dominance effects for leaf length, root weight and potassium concentration and, to a lesser extent, sugar concentration. Genetic control of sodium and alpha‐amino nitrogen concentrations appeared to be mostly additive. Hybrid varieties of sugar beet should exploit these directional dominance effects and the more closely varieties approach true F, hybrids the more they will capitalise on these advantages. It is possible that other factors such as epistasis, contamination, competition and seed effects may cause us to under‐ or overestimate the importance of dominance. Copyright © 1990, Wiley Blackwell. All rights reserved