Thermal stress-mediated changes in pollen germination, pollen tube growth and antioxidant defence system in mango (Mangifera indica L.)

Rising temperatures and the increasing frequency of extreme temperature events under climate change are expected to reduce mango productivity by disrupting flowering and impairing pollen viability. Given the high sensitivity of mango flowering phenology to temperature extremes, pollen function is a critical determinant of reproductive success. The present study evaluated the effects of temperature on pollen germination, tube growth, and antioxidant responses associated with pollen thermotolerance in mango cultivars. Pollen from eleven cultivars was evaluated across 14–38 °C (2 °C intervals) with three replications under controlled conditions during the flowering season (February–March 2025). Pollen germination, tube length, antioxidant enzyme activities, and lipid peroxidation were quantified, and cardinal temperatures were estimated using regression models. A modified bilinear model best described the temperature response of pollen traits. ‘Pusa Arunima’ and ‘Pusa Surya’ were identified as tolerant, whereas ‘Bombay Green’ and ‘Neelum’ were sensitive to both low (16 °C) and high (36 °C) temperature stress. Tolerant cultivars maintained higher activities of superoxide dismutase, catalase, peroxidase, non-enzymatic antioxidants (total phenols, flavonoids), along with total antioxidant activity (DPPH) while sensitive cultivars showed significant reductions under stress. Lipid peroxidation increased under stress, particularly at low temperatures, and remained higher in sensitive cultivars, while tolerant cultivars showed non-significant changes. These findings highlight the role of antioxidant-mediated protection in maintaining pollen function under temperature stress. Integrating pollen-based screening with antioxidant markers enables identification of mango cultivars suited to temperature stress–prone regions; it also facilitates selection of climate-resilient genotypes to sustain productivity under changing climatic scenarios.