Investigating grain yield and yield stability of wheat cultivars introduced in Iran over the last half century

Breeding for yield and yield stability has always been the main goal for breeders. In the current research, yield and yield stability of 51 wheat cultivars introduced over the last half century were evaluated in a randomized complete block design with two replications during five years. Analysis of variance revealed that genotype × environment interaction was significant. Therefore, the pattern of genotype × environment variation was analyzed using graphical method. According to the results of GGE biplot analysis, the first and second components as genotype and genotype × environment interaction components, explained 41.98% and 20.28% of the total variation, respectively. Simultaneous pattern of yield and yield stability divided the studied cultivars into three groups including desirable, moderate and undesirable. Among the studied cultivars, Mahdavi, Maroon and Sistan showed high yield and yield stability, while Shahpassand and Zagros had a low yield and yield stability. The results of this study showed that breeders have successfully introduced the genotypes with high yield and good stability over time, however due to the complexity of yield and yield stability traits, 10% of genotypes with low yield and 30% with poor stability have been introduced during 1986-2006, which confirms the need for more accurate tests in the future. Winter genotypes showed lower yield and yield stability compared to spring and facultative cultivars. Since, spring cultivars showed high yield in autumn cultivation, it is therefore recommended to cultivate spring cultivars in autumn as well.