Evaluation of Seed Yield Stability of Winter Rapeseed (Brassica napus L.) Genotypes Using Non-Parametric Methods

Evaluating of the rapeseed genotypes under different environmental conditions would be useful to identify genotypes with stable and high yield potential. In order to study yield stability of winter rapeseed genotypes, 9 new advanced lines along with four cultivars Okapi, Ahmadi, Nima and Nafis were evaluated in a randomized complete block design in six experimental field stations including Esfahan, Hamedan, Karaj, Kermanshah, Khoy and Zarghan during 2015–2017 growing seasons. Results of combined analysis of variance indicated that the effects of environments, genotypes and genotype × environment interaction were significant, suggesting that the genotypes responded differently in the studied environment conditions. So, there was the possibility of stability analysis. Cluster analysis based on the mean yield and nonparametric stability statistics showed that there were three main clusters. According to mean rank of nonparametric stability parameters, the genotypes G1, G2, G5 and G13 with the lowest value for mean rank were stable, whereas genotypes G4, G11, G7 and G9 with highest values were unstable. Also, the results indicated that the nonparametric statistics Si(3), Si(6), NPi(2), NPi(3), NPi(4) and KR were associated with mean seed yield and the dynamic concept of stability. Therefore, these methods were suitable for selecting stable and high yielding genotypes in winter rapeseed. Based on these parameters, the genotypes G13 and G2 with mean seed yield 4086 and 3829 kg h-1 respectively, were identified as high yield stable genotypes. So, these genotypes could be used for cultivation in cold and mild cold regions of the country.