Canonical variate analysis of genotype × environment interactions

The additive main effects and multiplicative interaction (AMMI) model is used to investigate genotype × environment interactions often encountered in variety trials. Interaction effects are accounted for by several multiplicative terms in the model, with each consisting of a genotypic and an environmental parameter. These effects are estimated using principal-component analysis. An alternative method is presented to estimate the genotypic and environmental parameters in the multiplicative terms of the AMMI model by canonical variate analysis. The number of significant interactive terms can be easily determined using the χ2 test. Each of the multiplicative terms include a unitless coefficient measuring genotypic response and an environmental effect in terms of the physical unit of the concerned trait. Biplots can be used with the scores of both genotypes and environments for graphic examination of analytic results. Total tuber-yield data from potato genotypes tested in a series of international trials are ...