Abstract :
The objective of this study was stability parameters estimation of orchardgrass ecotypes in order to identify stable ecotype for seed yield in Erzurum ecological condition in Turkey during 2006 and 2007 growing seasons. The experiment was conducted in terms of randomized complete block design with three replications. Plant materials were seeds collected from 16 promising lines obtained from different local orchardgrass ecotype populations (Oltu and Ulubag) along with a standard local variety (control) for seed yield. In order toestimate stability parameters, different methods have been used including mean yield, environmental variance (S_i^2), genotypic coefficient of variation (?CV?_i), ecovalence (W_i^2), stability variance (?_i^2), regression coefficient (b_i), mean of regression deviation (S_di^2), mean variance (? ?_i), superiority index (P_i), rank analysis (L_i)and(R_i). Cluster analysis based on all stability parameters was applied as well. There were significant effects for year, genotype and their interactions for seed yield trait. According to stability parameters, biplot diagram of mean yield and ?CV?_ialong with cluster analysis, ecotype U7 with a good combination of yield and stability can be recommended.
