effect of nano chitosan particles on physiological and phytochemical parameters of tea plant (camellia sinensis (l.) kuntze) kashef cultivar under drought stress

Background: tea cultivation faces growing challenges due to drought, a problem worsened by climate change. one potential method to enhance drought tolerance is the foliar application of chitosan and nano chitosan. objective: this study investigates the effects of nano chitosan particles (ncp) on mitigating drought stress in tea plants (kashef cultivar) while maintaining quality. method: four concentrations of ncp solution (0, 25, 50, and 100 mg l-¹) were applied twice during the dry season in summer 2021 at the lahijan tea research centre in iran. physiological, biochemical, and metabolic parameters were measured under severe drought conditions (25% soil field capacity) and compared to control plants (no drought stress or ncp treatment). results: the data showed that ncp increased the total polyphenol and flavonoid content, except for catechin. under drought conditions, ncp treatment significantly enhanced relative water content (rwc), total chlorophyll, shoot numbers, green leaf yield, proline, and protein levels. antioxidant enzymes such as catalase (cat) and superoxide dismutase (sod) were activated to counter oxidative stress. application of the highest ncp concentration (100 mg l-¹) significantly enhanced polyphenol accumulation, contributing to improved drought tolerance and tea quality. conclusion: these findings suggest that ncp could be an eco-friendly and effective tool for improving drought resilience in tea plants.