Investigation of Relationships between Yield and Yield Components in Bread Wheat Using Causality Analysis under Salinity Stress Conditions

Abiotic stresses, such as salinity, affect plant growth and reduce grain yield. The objective of this study was to identify the agronomic traits related to changes in grain yield of bread wheat under normal conditions and salinity stress. In this study, 111 pure bread wheat lines were examined as an Augmented experiment (When the number of lines is high or the grain density is low, it is not possible to perform duplicate tests, so the design is used without Augmented duplication.) in two research fields of Yazd province, Iran, in the 2020 crop year. After planting 20 genotypes, three wheat cultivars named Narin, Barzegar, and Sistan were planted as the control. During the growth period, yield traits and yield components were evaluated considering morphological traits and compared with the control cultivars. The experimental results showed great diversity in the studied genotypes in terms of most quantitative and qualitative traits. Also, correlation showed that in both normal and stress conditions, the grain number, 1000-kernel weight, and spike weight had a positive and significant correlation with grain yield. In stepwise regression, the grain number, 1000-kernel weight, days to heading, plant height, and spike length were included in the model, and even in path analysis, 1000-kernel weight and the grain number per spike had a direct effect on grain yield. Therefore, selection can be done based on 1000-kernel weight and the grain number per spike and reduction of days to heading, in order to achieve salinity-tolerant lines.