Heterotic Response from a Diallel Analysis between Alfalfa Cultivars of Different Geographic Origin

Abstract

A semihybrid variety development strategy could capitalize on natural hybrid vigor that exists between alfalfa (Medicago sativa L.) germplasms, populations and cultivars. Successful semihybrid model is the identification of improved germplasm with superior agronomic traits as well as good combining ability between designated heterotic groups. Identification of heterotic groups and patterns among breeding populations provides fundamental information to help alfalfa breeders more knowledgeably manipulate heterosis. In this experiment, hybrids among several germplasm sources were evaluated. The significant variation among crosses was attributed primarily to general combining ability (GCA) effects, while specific combining ability effects were also significant. Both mid-parent heterosis (MPH), ranging from 2.6 to 25.4 %, and high-parent heterosis (HPH), ranging from 4.2 to 15%, was detected. The hybrids between French and Spanish, as well as between Iranian and Spanish cultivars, demonstrated the highest cross mean performance in diallel crosses. The results indicate that these crosses should be recognized as a heterotic groups. MPH results suggest that we may have capitalized heterotic response between divergence alfalfa cultivars (different geographic origin) to improve alfalfa forage yield.