The influences of genotype, environment, and genotype x environment interaction on wheat quality

Knowledge of the relative contributions of genotype (G), environment (E), and genotype and environment interaction (G x E) effects on wheat (Triticum aestivum L.) quality leads to more effective selection in breeding programs and segregation of more uniform parcels of grain better suited to the needs of customers. Their effects on wheat quality were reviewed using papers obtained from 4 major international databases. The literature is dominated by research from North America, with lesser contributions from Europe, Australia, and the rest of the world. Use of analysis of variance to partition sources of variation due to G, E, and G x E was the most common approach but, more recently, residual maximum likelihood methods that can accommodate large, but unbalanced, datasets have been used. In North America and Europe, the relative contributions of G, E, and G x E varied across studies, but traits associated with protein content were more influenced by E and G x E than those associated with protein quality, dough rheology and starch characteristics, where G effects were more important. Variation in the relative contributions of G, E, and G x E was highly dependent on the G and E sampled. The Australian studies were characterised by a relative lack of G x E, with G and E rankings being similar across the country for the protein quality, dough rheology, and starch quality traits examined in detail. This suggests that, in Australia, more efficient testing of potential cultivars will be possible for these traits, especially when the underlying variation at the gene level is known, and that efficiencies in the design and conduct of trial systems and quality evaluations could be achieved by testing samples from targetted environments without affecting genetic gain and overall crop quality.