Stability analysis of grain yield of promising bread wheat genotypes in the cold climate zone under non-stress and late season drought-stress conditions

Introduction
Bread wheat (Triticum aestivum L.) is the most important field crop and is related directly to human food across the world. Wheat is also the first important crop in Iran based on area under its cultivation as well as its production. Increase of wheat production in Iran has an essential importance for improvement of economy and supply of people’s basic food. In recent years, deficit of water has become a major problem all over the world (Mathur et al. 2019). Drought is one of the most important growth limiting factors in cereals especially in wheat (Mahdavikia et al. 2019) Drought stress has a negative impact in growth of wheat plants at the seedling stage and also development of wheat plants at the adult plant stage (Bardehji et al. 2020). Recommendation of a new variety for an environment should not be only based on its yield potential and it is better to select a verity in the environment based on its adaptability and yield stability. Different methods have been suggested by scientist to evaluate yield stability and to analyze genotype environment interactions. Additive main effects and multiplicative interaction (AMMI) is a method that combines analysis of variance and principal component analysis (PCA) to predict adaptability of the genotypes to different environments.
Materials and Methods
To evaluate grain yield stability and late season drought-stress tolerance of 14 bread wheat promising lines and four check cultivars of the cold regions including Mihan, Haidari, Zarine and Zare cultivars, these genotypes were tested in a randomized complete block design with three replications under normal irrigation and late season drought-stress conditions in 2019-2021 cropping seasons in Seed and Plant Crop Improvement Institute and Khairabad-Zanjan research station. Combined analysis of variance under both normal irrigation and late season drought-stress conditions was carried out. Since the year × location and genotype × year interaction effects were significant under both normal irrigation and late season drought-stress conditions, Stability analysis using AMMI method (Additive Mean effect and Multiplicative Interaction model) was employed to examine the effects of genotype × environment interaction and to determine adaptation of the genotype under different conditions.
Results & Discussion
Combined analysis of variance under normal irrigation and late season drought-stress conditions showed significant differences of the grain yield among year × location interaction effect for both conditions at 1% probability level and among genotype × year interaction effect for both conditions at 5% probability level. AMMI analysis showed that genotypes No. 8, 5, 6 and 12 had the highest yields among genotypes tested. Genotype 12 with high grain yield and low amounts of first and second principal components had the highest adaptability but genotype 5 despite high grain yield had high amounts of first and second principal components and therefore did not show good adaptability in different environments.
Conclusion
In total, results showed that genotype 12 had good adaptability yield stability among studied genotypes.