Role of brassinosteroid on biochemical and qualitative characteristics of  Washington Navel orange fruit during storage

Orange fruits were treated with 0 (control), 0.75 and 1.5 mgL-1 brassinosteroid for 5 Min and then stored at 3±1°C and 85-90 % relative humidity for 5 month. Characteristics of chilling injury, ion leakage, lipid peroxidation, hydrogen peroxide, total soluble solids, titratable acidity, pH, ascorbic acid, and activity of antioxidant enzymes (peroxidase and catalase) have been evaluated. Results showed that fruits treated with brassinosteroid significantly reduced the chilling injury, ion leakage, lipid peroxidation and hydrogen peroxide, compared to control. According this results, total soluble solids, pH, and ascorbic acid, of treated and control fruits increased during storage while titratable acidity of fruits decreased. The pattern of mentioned changes reduced in brassinosteroid treatments lower than to control. The activity of antioxidant enzymes of fruits treated with brassinosteroid highly increased compared to control during storage. Fruits treated with 1.5 mgL-1 brassinosteroid showed highest quality and activity of antioxidant enzymes, with lowest chilling injury.