Effects of Sulfur Dioxide on Postharvest Quality and Quantity of Table Grapes cvs. "Keshmeshi Seedlesss" and "Shahroudy" in Cold Storage

The effects of four levels of SO2 (0.0%, 0.06%, 0.125% and 0.25%) on the qualitative and quantitative characteristics of two Persian grape cultivars “Keshmeshi seedless” and “Shahroudy” were evaluated during the cold storage in 1995-1997. This research was carried out in a factorial experiment in a completely randomized design in cold storage at the laboratory of Horticultural Department, College of Agriculture, Tehran University. The results showed that the effect of SO2 on decay was significant at 1%, and maximum control was obtained at 0.25%. No significant difference was observed when treated with 0.125% SO2 However, increasing SO2 concentration resulted in increased quantity and intensity of bleaching on the berries. At these increased concentrations, a linear relation was observed between bleaching on the berries and SO2 concentration so that the highest bleaching occurred at a concentration of 0.25%. Increased storage periods also increased bleaching. The effect of SO2 on weight loss, shattering, and rachis colour was also significant, decreasing rachis colour and shattering of berries.