Evaluation of combining abilities and heterosis effect for a better selection of hybrid barley

Abstract

Heterosis effect and the combining ability are two main indices of hybrids performance. Predicting hybrid performance and heterosis effect is an important approach in the breeding of hybrid barley. In order to i) combine the local and introduced genetic material; ii) study the combining abilities of parents and hybrids; and iii) analyze the relationships between the heterosis effect, the combining ability and the performance of hybrids, the present research has been initiated. In this study, five cultivars of barley (Hordeum vulgare L.) were crossed according to a full diallel plan comprising P² combinations. The twenty hybrids F2 were assessed by the general combining ability analysis (GCA); by the specific combining ability (SCA) as well as by the calculation of the heterosis effect of six agronomic characters, namely, the weight of the spike (WE), the number of grains per spike (NGE), the weight of a thousand grains (WTG), plant earliness at flowering (PRF), plant harvest index (IR) and plant productivity (P P). The results indicate that GCA for all parameters was significant except for the WE trait while SCA was significant for three of the six traits studied: WTG, IR and PRO. The GCA/SCA ratio revealed that non-additive effects were the main effect on traits assessed in the hybrids F2. Heterosis was significantly correlated with SCA for all traits tested, indicating that non-additive effects were the main effect of heterosis. Hybrids from two parents with a high GCA have consistently shown better SCA and better hybrid performance. Indeed, the selection of parents should be mainly based on their GCA.