Hybrid prediction based on SSR-genetic distance, heterosis and combining ability on agronomic traits and yields in sweet and waxy corn

Abstract

Limited labor, cost, and time regarding hybrid formation and yield trials encourages corn breeders to identify potential F1 hybrids without crossing all possible combinations by line screening based SSR-genetic distance. Therefore, this study aimed to (i) determine combining ability and heterosis of 24 hybrids, (ii) group 11 parental lines employing both phenotypic and SSR markers, and (iii) study the association between SSR based-genetic distance and hybrid performance on agronomic traits and yields. 11 parental lines, 3 waxy and 8 sweet corns, were crossed following North Carolina Design II and were genotyped applying 30 SSR markers. 24 hybrids, 11 parents, and 3 check varieties were evaluated in two seasons (2017/2018) at Khon Kaen University, Thailand. Among eleven lines, 101 L/TSC-10, KV/mon, and KV/3473 were good combiners for developing early maturity (46 DAP,-1.43**; 49 DAP,-2.51**; 52 DAP,-0.73**, respectively) and lodging resistance (102.3 cm,-16.34**; 140.5 cm,-5.89*; 125.1 cm,-11.10**, respectively) hybrids meanwhile 101 LBW (6.8 ton ha−1; 1.10**) and Y.18 (6.9 ton ha−1; 1.08**) were suitable parents for high-yielding hybrids. High heterosis estimates with lack of SCA effects for certain traits revealed an essential role of parental adaptation. SSR based-genetic distance between sweet and waxy lines was wide enough ranging from 0.67 to 0.92. Contrasting dendogram pattern and insignificantly poor correlation between SSR and phenotypic based-genetic distances indicated that agreement between SSR and phenotypic markers was lacking. SSR based-genetic distance failed to predict hybrid performance, heterosis, and SCA as poor correlation was revealed. Absence of dominance effects and relatively high genetic distance among parental lines were possible explanations for the poor predictions.