Biplot and Heterosis Analysis in Half-Diallel Crosses from Second Selfing Generation of Alfalfa

Heterotic groups distinguished among breeding populations provide basic information to help plant breeders to control heterosis consciously. Development of alfalfa free hybrids can provide heterosis through parents' selection with crossing between partially inbred lines from two or three generations of selfing. In order to study of combining ability for forage dry matter, height and regrowth rate, selected partially inbred lines from the second generation of eight ecotypes of alfalfa were evaluated in a half-diallel cross design. Field experiments were performed in a randomized complete block design with three replications, including eight parents and 28 hybrids (F1) at Karaj and Arak during 2014-2015. Graphical GGE biplot method was applied to analyze the data. Based on the results of analysis of variance, mean square of GCA and SCA, and their interaction with environment were significant(p<0.01). GGE biplot graphical method showed the highest positive GCA for Nikshahri and the highest amount of negative GCA for Kowzareh and Rahnani as parents of crosses for all traits. SCA was maximum for two specific parents, Nikshahri × Ghahavand and Nikshahri × Silvana crosses. Results also indicated that crossing between the Iranian partially inbreds (S2) of alfalfa to produce free hybrids can provide opportunities to exploit heterosis potential and improve forage yields.