Graphic analysis of genotype, environment and genotype × environment interaction of seed yield trait in bread wheat (Triticum aestivum L.) under dryland conditions

Wheat bread is one of the most important food products in the world. In terms of area under cultivation and production it ranks second among different products. Therefore, Genetic advances in sustainable wheat production can play a large role in global food security. The average wheat production in the world is reported Nearly 3.425 and its average production in Iran is 2.164 tons per hectare. Given the importance of wheat, Production of this product should be increased by cultivating modified genotypes with high grain yield. Wheat grain yield is affected by environmental conditions, genetic potential and its interaction. Identifying genotypes that have good performance and stability in different environmental conditions seems to be complex due to the strong interaction of genotype and environment. The change that occurs in the relative performance of genotypes in different environments is called genotype × environment interaction.Genotype × environment interaction is one of the most important issues in plant breeding which is of great importance in introducing and releasing modified varieties. Cultivation of genotypes in test environments during different years and places it has determined the stability of performance. And genotypes with less genotype × environment interaction are selected. Usually in breeding programs, Genotypes are known as compatible that the variance of their interaction with the environment is small. Among the multivariate methods, GGE biplot method is one of the most important methods for investigating the interaction of genotype × environment and determining stable genotypes.Water scarcity is the most essential limiting element of agricultural production, particulary in arid and semi-arid areas throughout the world. Evaluation of the bread wheat genotypes under different environmental conditions would be useful to identify stable and high yield potential genotypes.

15 new bread wheat lines along with Aftab cultivar were evaluated in a randomized complete block design with three replications in four experimental field stations (Gachsaran Khoramabad, Moghan and Gonbad) during three crop seasons (2017-2020). GGE biplot statistical method (genotype effect + genotype × environment interaction) was used to study stability of genotypes in the studied environments.

Results of combined analysis of variance indicated that the effects of environments, genotypes and genotype × environment interaction were significant. The results indicated that 91.49, 1.54 and 5.03 percent of total variation were related to the environment, genotype and genotype × environment interaction effects, respectively. The polygon-view of GGE biplot recognized five superior genotypes and four mega-environments so that the best genotypes within each environment were determined. Based on the hypothetical ideal genotype biplot, the line G7 with 3818 Kg ha-1 grain yield was the better genotype than other genotypes. Also this genotype showed the most stability and had the high general adaptation to all environments. Biplot of correlation among environments revealed that environmental vectors of Gachsaran and Gonbad were near to 90◦ so, these locations were different environments. The results showed that all environments had high discriminating ability so that could able to show differences between genotypes.

Generally, the results indicated that the line G7 with suitable mean seed yield and high broad adaptability was selected as superior line for further investigation to introduce the new commercial wheat cultivar under dryland conditions. Also, the Moghan environment was the nearest environment to ideal environment that had the highest discriminating ability and representativeness.