Genetic variations in antioxidant content and chlorophyll fluorescence of chickpea (Cicer arietinum L.) genotypes exposed to freezing temperatures

Studying the diversity of plant physiological and biochemical responses to freezing stress is a prerequisite for the breeding process for greater low-temperature tolerance. The present study was conducted to evaluate the response of 11 chickpea genotypes to freezing temperatures (− 3, − 6, − 9, − 12, − 15, − 18, and − 21 °C). Leaf electrolyte leakage (EL), malondialdehyde (MDA), and hydrogen peroxide (H 2 O 2 ) content were increased when exposed to freezing temperatures. The more tolerant genotypes showed higher antioxidant content (ascorbate peroxidase, catalase, peroxidase, and superoxide dismutase), and proline content, and lower temperatures of 50% EL leakage (LT 50EL ) (− 8.2 °C), 50% dry matter reduction (RMDT 50 ) (− 11.7 to − 12.7 °C), and lethal temperature of 50% of plants (LT 50Su ) (− 8.2 °C). In MCC797, FLIP86-05C, and MCC736, F v '/F m ' and F q '/F m ' (light - adapted maximum efficiency of PSII and PSII operating efficiency, respectively) decreased less compared with the other genotypes at a respective temperature and recovered faster during the recovery period. The results of principal components (PCA) and clustering analysis showed that the genotypes can be divided into three groups: (i) MCC505 (freezing-sensitive), (ii) MCC769, MCC775, MCC741, and FLIP98-121C (intermediate), and (iii) the other genotypes (freezing-tolerant). Among the tolerant genotypes, MCC797, FLIP86-05C, and MCC736 showed the highest freezing tolerance. The results revealed genetic variations among the genotypes in response to freezing stress, which could be beneficial for plant breeding programs to screen and introduce freezing-tolerant genotypes for fall cultivation, especially in cold regions.