Use of canonical correlation analysis to improve grain yield of wheat genotypes through indirect selection under rainfed conditions

In order to investigate the relationship between agronomic and physiological characteristics of wheat genotypes, a research was conducted with 24 genotypes based on randomized complete blocks design with four replications in the 2018-19 and 2019-20 crop seasons under dryland conditions. Photosynthesis rate, transpiration rate, stomatal conductance, intercellular CO2 concentration, mesophyll conductance, days to heading, days to physiological maturity, plant height, 1000-kernel weight and grain yield were measured during the growing season. Simple correlation analysis showed significant relationship between yield and physiological traits during the two years of the experiment, Also, canonical correlation analysis between physiological traits and agronomic traits showed a significant canonical correlation in the first year (r = 0.64) and the second year (r = 0.64). Correlation of traits with their canonical variables and the opposite canonical variables during two years of experiment showed that all physiological traits have a positive and significant relationship with each other and their canonical variables. The relationship between days to heading with the agronomic and physiological traits was negative and significant over the two years of experiment, but the results showed a positive and significant relationship between grain yield with the agronomic and physiological traits during the two years of the experiment. Also, in the second year of the experiment, the relationship between plant height and the agronomic and physiological traits was assessed as positive and significant. Therefore, genotypes with a shorter growth period and a longer grain-filling period can be recommended for obtaining maximum grain yield under dryland conditions.