Effect of kaolin on the sunburn damage and qualitative characteristics of pomegranate fruit cv. Malas-e-Torsh-e-Saveh

Sunburn damage is a physiological disorder, which reducing pomegranate fruits quality and result to huge loss to the gardeners yearly. In this study, the effects of kaolin on maintaining fruit quality and decreasing sunburn damage of Malas-e-Torsh-e-Saveh pomegranate was investigated. Processed Kaolin (surround® WP) with 0, 2.5, 5 and 10 % (w/v) was sprayed over the whole canopy and fruits at 45, 75 and 105 days after fruit set. The results indicated that kaolin significantly decreased fruit sunburn damage. Total soluble solid (TSS), total flavonoid content, total anthocyanin content and activity of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) enzymes reduced in kaolin treated fruits in compared to control. Furthermore, cyanidin 3-glucoside, cyanidin 3,5-diglucoside, delphinidin 3,5-diglucoside and pelargonidin 3,5-diglucoside content in kaolin treated fruits were lower than control. In contrast, fruit total phenolic content increased, but no significant difference was found for titratable acidity (TA), TSS/TA, pH, antioxidant activity and delphinidin 3-glucoside and pelargonidin 3-glucoside of pomegranate juice. Overall three times spraying with 5% kaolin concentration at 30 days intervals recommended for control of sunburn damage of pomegranate fruits.