Maintenance of post-harvest antioxidant quality in ‘Niagara Rosada’ grape using salicylic acid

Salicylic acid is a plant growth regulator used in grapes to maintain postharvest quality. ‘Niagara Rosada’, a table grape, although much appreciated for its flavor, has a short shelf life. We evaluated the influence of postharvest application of different doses of salicylic acid on the quality of ‘Niagara Rosada’ after harvest in an effort to control rates of berry drop and decay, as well as to maintain the quality of grape bunches during refrigerated storage. Freshly harvested bunches of ‘Niagara Rosada’ (Vitis labrusca x V. vinifera) were immersed in salicylic acid solutions at concentrations of 0.0, 0.28, 0.55, 0.83, and 1.10 g L-1, and then refrigerated (5 ± 1 °C and 95 ± 5 % RH) for 20 days. Physical and chemical analyses of grapes were performed at 5-day intervals. Salicylic acid maintained the postharvest quality of ‘Niagara Rosada’ grapes throughout storage. The lowest concentration of salicylic acid (0.28 g L-1) effectively induced the synthesis of phenolic compounds and improved the antioxidant capacities of both grapes and stems. High levels of salicylic acid (0.83 and 1.10 g L-1) resulted in an increase in anthocyanin content in fruit and enzyme activities (peroxidase and superoxide dismutase) in stems, enhancing conservation and reducing levels of decay and berry drop.