Analysis of genotype, environment and genotype × environment interaction in bread wheat in warm rainfed areas of Iran

Stable performance of new improved bread wheat (Triticum aestivum L.) genotypes in multi-environment trials is important in crop improvement programs. In such trials, genotype evaluation and mega-environment identification are the most important objectives. The yield stability of 18 bread wheat genotypes was investigated through genotype (G) and genotype × environment (GE) interaction using the GGE biplot technique. Field experiments were conducted in 12 warm rainfed environments in Iran to characterize G × E interactions for grain yield of bread wheat genotypes. A combined analysis of variance across locations showed that both main effects (environment and genotype) and GE interactions were highly significant. Principal component analysis was performed, and the first two principal components (PC1 and PC2) explained 45% and 26% of the total sum of squares, respectively; they were used to create GGE biplot diagrams. The polygon tool of the biplot suggested two bread wheat growing environments in warm dryland regions of Iran: a small one (Moghan) and a large one (Gachsaran, Gonbad and Khoramabad). Visualizing the mean and stability parameters of the genotypes in the biplot indicated that genotypes HAMAM-4 (G1) and CHEN/AEGILOPS SQUARROSA (TAUS)//BCN/3/VEE#7/4/PASTOR (G4) are adapted to warm rainfed areas of Iran. The vector view of the biplot showed that Gonbad, Khoramabad and Gachsaran were correlated, but had no association with Moghan. Finally, it was concluded that G1 and G4 showed high yield stability across environments and are, therefore, recommended for release in warm rainfed areas of Iran.