Reduction of Chilling Injury and Peroxide Hydrogen Accumulation in Thompson Grape (Vitisvinifera L.)Fruit by Proline and Ascorbic Acid DuringStorage

This experiment was carried out to determine the effects of proline and ascorbic acidon chilling injury, electrolyte leakage, lipid peroxidation, peroxide hydrogen and antioxidant enzymes activityof Thompson grape (Vitisvinifera L.) fruit. Grape fruits were treated by 0 (control), 250 and 500µM proline and 0 (control), 2 and 4%ascorbic acidandtheir combinations, then stored at 1°C and90-95 % relative humidity for 28 days. Grapes treated with 500 µM proline and its combination with2 and 4% ascorbic acidhadthe lowest amount of lipid peroxidation and peroxide hydrogen and lower chilling injury and electrolyte leakagethan non-treated fruits.Moreover, grapes treated with 500 µM proline and its combination with 2 and 4% ascorbic acidsignificantlyincreased ascorbateperoxidase,superoxide dismutase,catalaseand peroxidase enzyme activity.The present study can be regarded as the first evidence that proline and ascorbic acid enhance grape fruit tolerance to cold stress and therefore fruit quality.