Physiochemical response of papaya genotypes exposed to low temperature regimes

615-627Susceptibility to low temperature stress is the major threat to papaya cultivation. Here, we studied a low temperature stress tolerance in papaya plant. We have investigated the effect of different low temperature regimes, 28°/18°C (day/night) to 16°/06°C (day/night) with a gradual decrease of 2°C on every two days and one set with direct exposure to the low temperature of 18°/08°C (day/night), called the acclimatized plant, in five diverse papaya genotypes (Pusa Nanha, Red Lady P-7-2, P-7-9, and P-7-14) and cold tolerant wild relative of cultivated papaya genotype (Vasconcellea cundinamarcensis V.M. Badillo) under controlled regulated conditions. It was observed that there were significant variations in thephysiological and biochemical parameters like photosynthetic gas exchange parameters, chlorophyll content, fluorescenceparameters, relative water content (RWC), membrane stability index (MSI), total sugars content, total soluble proteinscontent, lipid peroxidation, and proline accumulation in leaf tissues. Maximum stomatal conductance, chlorophyllfluorescence, RWC, MSI, total sugars, total soluble proteins, proline and lowest MDA contents were observed inVasconcellea cundinamarcensis followed by inbred P-7-9 as compared to other genotypes under low temperature stress.Among all the papaya genotypes, P-7-9 showed more adaptability to low temperature stress and it further give new insightsfor developing low temperature tolerant papaya genotypes, especially under changing climate situations