Evaluation of Photosynthetic Parameters and Their Relationships with Grain Yield in Red Bean Lines in Field Conditions

The use of physiological traits is one of the best methods for the rapid production of new varieties, therefore, in order to evaluate photosynthetic factors and their relationship with total yield in red beans, an experiment was conducted in a randomized complete block design with three replications at Khairabad Research Station in Zanjan under normal irrigation conditions during two consecutive crop years (2018-2020). The studied genotypes showed significant differences in all traits (except photosynthetically active radiation). The studied genotypes showed significant differences in all traits (except photosynthetically active radiation). These results indicate that there is a high genetic diversity between genotypes in terms of photosynthesis-related traits and, consequently, yield capacity. Genotypes G1, G2, G4, G9 and G12 showed higher photosynthesis, stomatal conductance, water use efficiency and mesophilic conductivity than other genotypes. G6, G7 and G3 genotypes had less mesophilic conductivity, water use efficiency and photosynthesis than other genotypes. There is a significant negative correlation between photosynthesis and sub stomatal CO2 and a significant positive correlation with the stomatal conductance, mesophilic conductance, water use efficiency and yield; therefore, genotypes with more photosynthesis, in addition to high stomatal conductance, have higher mesophilic conductivity and, in other words, are more efficient in using carbon dioxide entering the stomatal. As a result, the concentration of sub stomatal CO2 is reduced, so there is a close relationship between photosynthesis, water use efficiency and mesophilic conductivity. Regression analysis showed that when total yield is considered as a function variable, the photosynthetic active radiation and photosynthesis justify grain yield. However, when the photosynthesis is a function variable, the traits of photosynthetic active radiation, sub stomatal CO2, leaf temperature, and transpiration rate justify changes in photosynthesis. Due to the diversity of photosynthetic indices in genotypes, this experiment can be performed in different stress conditions such as drought and salinity and the results can be used with normal conditions to select efficient genotypes in stress conditions.