Multivariate combining ability for tuber characters in potato early generation selection

The diallel analysis provides estimates of useful parameters to parent selection and to the understanding of the genetic effects involved in a trait control. This research was aimed at estimating multivariate combining ability of potato parents in the initial generations of selection. Twenty potato clonal families (5*4) of nine genotypes in a partial diallel design were evaluated for two successive generations. The experiments were conducted at the Embrapa Clima Temperado, in Pelotas, RS (31 degrees S, 52 degrees W), in the spring of 2005 and autumn of 2006. Fourteen morphological tuber traits were evaluated and the six more stable, or those that were best repeated in the generations were selected for further analysis. The analysis of variance revealed significant differences for all traits. The diallel multivariate analysis, using principal components, showed '2CRI-1149-1-78', 'Eliza', 'C-1786-6-96' and 'White Lady' genotypes with higher general combining ability for tuber appearance, smoothness, eye brown, pointing, curving and flatness, contributing with additive effects for crossings. The 'C-1750-15-95'/'Agria', 'C-1786-6-96'/'Asterix' and 'Eliza'/'Asterix' cross combinations were outstanding for specific combing ability for tuber eye brown, pointing, curving and flatness, and '2CRI-1149-1-78'/'Vivaldi', 'Eliza'/'BPI' and 'Eliza'/'Agria' for tuber appearance, smoothness and eye brown.