Implications of Genotype‐Environmental Interactions in Applied Plant Breeding 1

THERE is rather general agreement amongst plant breeders that interactions between genotype and environment have an important bearing on the breeding of better varieties. However, it is much more difficult to find agreement as to what we ought to know about genotype-environment interactions and what we should do about them. Some breeders emphasize the camouflaging effect of such interactions on the "value" of genotypes. Consequent ly they attempt to estimate the magnitude of variances attributable to interactions and to ultilize such estimates in developing ever more precise methods of selection. Other breeders feel that improvements in efficiency are unlikely so long as only "final" characters such as yield and quality are considered. They believe that real progress will be possible only as we clarify the pathways by which final characters are reached. Still others maintain that what is needed is a direct and pragmatic approach which will tell us what types of genetic systems are most likely to give high and stable performance. The literature on genotype-environmental interactions is very large. It varies from reports of variety trials in the field to consideration of the mechanisms which allow cells containing the same genes to become as different as a pollen