INFLUENCE OF BRASSINOLIDES ON PLANT PHYSIOLOGY AND YIELD OF CANTALOUPE UNDER HIGH TEMPERATURE STRESS

Cantaloupe is a high value crop growing in greenhouse. Economical crop yield reduction due to heat stress, caused by global warming is an emerging issue of cantaloupe. High temperature significantly decreases the plant performances and finally effect on the crop yield. Brassinosteroids (BRs) regulates cellular and physiological processes and environment response to abiotic stress of plants. To find out the best concentration of BRs for alleviate the high temperature stress of cantaloupe, plant physio-chemical behaviors and yield responses were evaluated after the application of four concentrations of exogenous BRs (24-epibrassinolide, EBR) to cantaloupe plants grown under 47 ± 3 °C. Chlorophyll a, chlorophyll b, total chlorophyll content, rates of photosynthesis and transpiration, stomatal conductance, intercellular CO 2 concentration, proline and malondialdehyde contents, electrolyte leakage, catalase and peroxidase activity, fruit position, fruit yield, total soluble solid content and fruit firmness were significantly differed according to the type of cultivar and EBR concentration. EBR concentration at 0.1 - 0.2 mg L -1 given significant results in order to reduce the impacts of high temperature under greenhouse environment. Higher EBR concentrations