Additive and non-additive genetic control for sucrose content among unselected South African regional sugarcane progeny populations

Abstract

Knowledge of trait genetic control in sugarcane breeding is limited but is required to develop breeding strategies that optimise trait breeding. The objective of this study was to determine additive and non-additive genetic variance for sucrose content, and to evaluate genetic control and its implications on breeding strategy. Data for Brix% (a proxy for sucrose content) were collected from unselected progeny plots nested within replicated family plots in six irrigated and six rainfed trials and analysed using linear mixed models. Female variance was significant (p < 0.05) in eight trials, while male variance was significant in three trials, suggesting dominant maternal effects. Female × male interaction variance was significant (p < 0.05) in six trials from older breeding programs, suggesting presence of non-additive genetic effects. The proportion of parents (6.2%) producing significant additive and breeding values was higher than crosses (2.4%) producing significant non-additive values. Female and male variances were larger than female × male interaction variance in nine out of twelve trials, further suggesting predominance of additive genetic control. Young breeding programs produced higher additive variance while older programs produced higher non-additive variance. Selecting parents producing high breeding values and optimising cross-combinations will develop progenies that produce higher sucrose content.