Antioxidant Potential and Osmotic Adjustment Modulate Growth and Yield Formation in Kabuli-Type Chickpea Genotypes Under Freezing Stress

Understanding the physiological and biochemical basis of plant tolerance to freezing stress is very critical in in breeding plants tolerant to freezing stress. In this study, consisting of two independent experiments, kabuli type chickpea genotypes (701) were exposed to freezing stress (- 12 degrees C) at the seedling stage under controlled conditions. Thirty days after the stress, alive seedlings were transferred to the field, and at the end of the growing season, yield and yield-related variables were assessed. In general, 42% of the genotypes survived after the freezing stress, among which 38 had a survival rate above 75%. A significant and positive correlation was observed between survival percentage and maximum photochemical efficiency of photosystem II in the light (F-v '/F-m '), water soluble carbohydrates and ascorbate peroxidase (APX) activity after freezing stress. However, the survival percentage negatively correlated with electrolyte leakage. Principal component analysis showed that in the PC3 survival percentage, F-v '/F-m ' after freezing stress, water soluble carbohydrates after freezing stress, and APX activity after freezing stress had a high negative coefficient, while EL had a high positive coefficient. Stepwise regression analysis revealed that F-v '/F-m ' after freezing stress and APX activity after freezing stress described the most changes in survival percentage. In the field experiment, seed weight had the highest correlation coefficient with biomass and harvest index. In the principal component analysis, the coefficients of the PC1 for seed weight, biomass, and harvest index were - 0.92, - 0.87, and - 0.74, respectively. In conclusion, the chickpea genotypes with high antioxidant potential and water soluble carbohydrates were able to sustain carbon fixation and growth, and yielded well under freezing stress. The same traits may be used in mass screening of chickpea genotypes for tolerance to freezing stress.