Physiological and biochemical characterization of chickpea genotypes for cold tolerance at reproductive stage

Abstract

• The susceptible genotypes exhibited the highest levels of lipid peroxidation and lesser magnitude of proline increase than the tolerant ones during reproductive cold stress in chickpea. • Proline and pollen load can be used as prominent phenotypic markers in screening for cold tolerance in chickpea breeding programme. • The breeding lines GL29183-P1, GL29183-P2 and GL29183-P3 and cultivar PBG5 can be extensively evaluated in cold prone areas to identify any line for release for general cultivation. Cold stress is one of the most important abiotic stresses affecting chickpea production in Northwestern India. Further, the short-duration varieties are more susceptible to cold injury as their reproductive phase coincides with the cold spell of this zone. So, enhancing the cold tolerance of the host plant is the only viable option to resolve this issue in chickpea. The present study involved a set of 13 advanced breeding lines (with differential cold sensitivity) and three reference varieties (GPF2, PBG5, and PBG7) of chickpea which were exposed to cold stress at the reproductive stage under field conditions during the winters of 2019–20 and 2020–21. Various physiological and biochemical parameters such as proline, electrolyte leakage, photosynthetic pigments, lipid peroxidation, and 2, 2-diphenyl-1- picrylhydrazyl (DPPH) activity were measured before and after exposure to cold to delineate the mechanism of tolerance in these genotypes. Significant genotypic variations were observed for the above-mentioned traits in both years. The genotypes GL27059 P2, GL 28202-P1, and GL28202-P2 exhibited the highest lipid peroxidation and lesser magnitude of proline increase during reproductive cold stress on a pooled basis. These genotypes performed poorly for yield traits like pod set percent, filled pods plant –1 , total seeds/ plant, and seed yield/plant and hence were susceptible to cold stress. Further, a significant reduction in reproductive function of male gametophyte i.e. pollen viability and pollen load under cold stress was also observed in these susceptible genotypes. In contrast, tolerant line GL29183-P2 had significantly more pollen load and pollen viability contributing to better yield performance (viz., higher flowers/plant, pods/plant, and maximum pod set percent) among the studied advanced breeding lines. Based upon the pooled analysis, the reference variety PBG5 outperformed in yield attributes i.e., total flower/ plant, total filled pods/plant, and had a significantly higher yield than GL29183 under cold stress at the early reproductive stage. A significant increment in levels of proline (125–160%) on exposure to cold spell was observed in genotypes, GL29183 and PBG5, which contribute toward cold tolerance. Thus, an increase in proline along with maintenance of pollen load can be used as prominent phenotypic markers in screening for cold tolerance at the reproductive stage in chickpea.