The influence of composite traits on genotype by environment relations.

In breeding for multiple trait value functions, the existence of genotype-by-environment interaction effects can vastly complicate the designation of optimum sets of genotype-environment pairings into Target Populations of Environments. In this paper it is shown that even in the absence of any changes in genotypic ranking over environments on a trait-by-trait basis, it is possible to generate changes in genotypic ranking in value in different environments. This is shown to be true even for linear value functions in a case example in pine breeding.