Nonparametric Methods for Evaluating of Winter Wheat Genotypes in Multi-environment Trials

Abstract

2 Abstract: The objective of this study was to compare nonparametric stability procedures and apply different nonparametric tests for genotype×environment interaction (G×E) on grain yield data of 20 winter wheat genotypes selected from Iran/ICARDA joint project grown in 18 rainfed environments during 2003-05 in Iran. Results of nonparametric tests of G×E and a combined ANOVA across environments indicated the presence of both crossover and usual crossover interactions and genotypes varied significantly for grain yield. In this study, low values of sum of ranks of mean yield and Shukla's stability variance (rank-sum) were associated with high mean yield, but the other nonparametric stability methods were not positively correlated with mean yield but they characterized a static concept of stability. The results of Principal Component (PC) analysis and correlation analysis of nonparametric stability statistics and yield indicated that only rank-sum methods would be useful for simultaneous selection for high yield and stability. According to the rank-sum statistic, G18 (Fengkang15/Sefid), G17 (Anza/3/Pi//Nar/Hys/4/Sefid), G1 (Unknown-1), G10 ('Sardari'//Ska/Aurifen) and G4 (Unknown-1) had the minimum value for rank-sum and therefore were stable genotypes with high yield.