Inbreeding depression in cassava for productive traits

Abstract

Understanding inbreeding in cassava can guide breeders to explore its effects. Therefore, the aim of this study was to evaluate the effects of inbreeding depression in cassava, as well as to select transgressive individuals. Five elite cassava varieties were self-pollinated (Cascuda, BRS Formosa, Fecula Branca, Mani-Branca, and BRS Mulatinha), and the S1 families were evaluated in an augmented block design with six repetitions. The traits evaluated were fresh root yield (RoYi), above ground yield (AGYi), starch yield (StYi), harvest index (HI), dry matter content (DMC), and plant height (PlHe). The inbreeding depression varied widely between families; it was high in BRS Formosa, with averages of 19.38 % (RoYi), 1.68 % (AGYi), 18.18 % (HI), 0.47 % (DMC), 17.54 % (StYi) and 3.5 % (PlHe). Except for the S1 family of BRS Formosa, the additive effects (μ + α) were the most important, ranging from 69.95 % (RoYi) to 98.20 % (AGYi). In contrast, the contribution of heterozygous loci (δ) was most relevant to RoYi, HI, and StYi, with averages of 30.05, 23.07, and 27.82 %, respectively, although these effects were more pronounced in S1 derived from BRS Formosa and Mani-Branca. Therefore, the exploitation of inbreeding effects in cassava can contribute to the selection of plants with better agronomic performance in order to obtain cassava inbred with high genetic and agronomic potential for use per se or as parents to produce new hybrids.