DIALLEL ANALYSIS IN WHITE LUPIN - CONSEQUENCES FOR BREEDING

A complete diallel analysis for several characters was conducted in spring type white lupins (Lupinus albus L). Each of the 7 parents represented a group of the genetic variability available in the Mediterranean area. An analysis of the genetic parameters for the different characters should be of help in the definition of optimum lupin breeding criteria. Both vegetative and reproductive characters were studied. Diallel analysis was carried out via 2 methods, ie those of Griffing and Hayman. As for most of the autogamous species, vegetative characters and seed size showed a mainly additive heredity with a limited amount of specific combining ability (SCA). Both broad and narrow sense heritabilities proved to be high. The correlations between general combining ability (GCA) and phenotypic values were high, which suggested that judgement of the phenotype could give a good estimate of behaviour in the cross. For pod setting characters, both heritabilities were lower likely because of a higher susceptibility to the environment and to larger dominance. A heterotic effect was observed for yield; this could be explained by the low cropping densities and the homeostatis ability of the hybrids. This kind of genetic structure appears to be a means of improving yield stability. Unfortunately, it is not possible at the present time because no male sterility is available. For pure line breeding, the general combining ability (GCA) values showed that Lublanc and LA123 appeared to be first-choice parents for improvement of earliness in flowering with a good pod setting, while Lucky was an interesting candidate for pod setting and seed size characters.