Interpretation of genotype x year interaction in rainfed durum wheat under moderate cold conditions of Iran

A multi-year trial was conducted to compare the effects of genotype, year and genotype x year (GxY) interactions for grain yield and several drought-adaptive traits of 25 wheat genotypes during five seasons (2005-2010). Four conventional stability statistics, covering a wide range of stability concepts (Types 1-4), and the additive main effect and multiplicative interaction (AMMI) model were applied to analyse GxY interaction and to investigate the causes of GxY interaction in rainfed durum wheat. For all the traits, the largest sum of squares (SS) was accounted for by the year, followed by GxY interaction and genotype effects. Most of the GxY interaction (73.4%-90.6% of total GxY interaction) was of crossover type, which would complicate the development of genotypes with stable performance. Partitioning SS due to GxY interaction for genotypes indicated that the breeding lines were the smallest contributors to crossover GxY interactions. The results indicated that the freezing days and earliness were among the climatic and genotypic co-variables, respectively, that contributed most to the GxY interaction in rainfed durum wheat.