Family versus individual plant selection for stem borer (<i>Eldana saccharina</i>) resistance in early stages of sugarcane breeding in South Africa

Abstract

Eldana saccharina is an indigenous lepidopteran insect pest and the most damaging stem borer of sugarcane in southern Africa. Breeding for E. saccharina resistance in South Africa started in 1980 by crossing resistant parents (expected to possess resistance genes) and selecting for resistance. The objectives of this study were to compare family to individual plant selection, identify superior families and parents using best linear unbiased predictors (BLUP) and determine the optimum sample size for data collection. Data on number of bored stalks were collected from a randomised block design trial with 12 families and three replications. The larger broad-sense heritability and percent predicted selection gains of families indicated superiority compared with individual plant selection. BLUP estimates identified superior families (VV0061 and VV0564) and parents (80M0971 and 87M0965), indicating that breeding for E. saccharina would be enhanced using family selection. Parents selected from breeding programmes where E. saccharina is endemic consistently produced less damaged progenies than those from low E. saccharina infestation, indicating the occurrence of natural and recurrent selection. The results suggested presence of additive and non-additive genetic effects as well as significant maternal effects for resistance. The optimal sample size for data collection would be four replications and 10 individuals per family plot to adequately discriminate families.

Keywords: best linear unbiased prediction, Eldana saccharina resistance, stem borer, sugarcane