Simple approach to the analysis of GxE interactions in a multilocational spaced plant trial with timothy

Summary Sixty genotypes of timothy, comprising 12 genotypes originating from each of five locations, were grown at the same locations in northern Scandinavia and Iceland, as a part of a joint breeding project in timothy. The trials were observed for two years and various characters were evaluated. Large genotype x environment interactions occurred for most characters and the response of individual genotypes. irrespective of origin contributed most to the variation. A superiority measure (P.), based on the genotype's response and the maximum response, averaged over all locations, was used to rank the genotypes with respect to yield and other morphological attributes. Based on this ranking it is possible to choose genotypes which are high yielding and show good stability over the area.