Genetic analysis of variation for grain yield and protein concentration in two wheat crosses

Grain yield and protein concentration are two of the more important criteria for wheat breeding in Queensland. Three aspects of the inheritance of both of these traits can have an impact on achieving genetic progress: (i) the magnitude and form of the genetic correlation between the traits, (ii) the magnitude of genetic variation and genotype x environment interactions, and (iii) the importance of epistasis in genetic variation. These 3 factors were examined for 2 crosses in a multi-environment trial conducted in Queensland in 1989. Negative genetic correlations were found between. grain yield and protein concentration in both crosses. Genetic variation and genotype x environment interactions were found to be important for both traits. There was little evidence for the existence of significant additive x additive epistasis for either trait and the genotype x environment interactions were predominantly additive x environment in nature. From both crosses, progeny combining the high yield and high protein levels of the parents were identified. This suggests that there was a degree of independent segregation of the genes controlling grain yield and protein concentration in both crosses. Therefore, simultaneous genetic progress for yield and protein concentration is possible in Queensland environments.