Effect of Polyethylene Cover and Sulfer Pad on Storage Life of Grapevine Vitis vinifera) cv. Rasha (Siah-e-Sardasht)

To determine the effect of type of polyethylene bags and position of sulfur pads on decay control, fruit quality and sulfite residue in grape cv. Rasha during cold storage in 2007 and 2008. Three different levels of SO2 generating pads (one on top, half on top and half on bottom of the packaged grapes and without sulfur pad) that composed of 1g kg‑¹ sodium metabisulfite combined with two types of polyethylene bags (perforated and imperforated) during cold storage (135 days) on some traits such as: berry weight loss (%), bleaching, fungal rot (%), rachis desiccation, shriving, taste and sulfite residue was measured. Results showed that SO2 generating pads treatment during the storage significantly decreased berry weight loss, rachis and berry shriving, decay rate and fungal rots. Whereas, off flavors, bleaching and sulfite residue in grapes were increased. Imperforated bags treatments significantly decreased berry weight loss, rachis and berry shriving. The highest sulfite residue, 17.5 and 15.6 ppm, were observed in one and two sulfur pads treatments with perforated bags, respectively. Whereas in imperforated bags, sulfide residue was 9.3 ppm at both sulfur pad treatments. To increase the shelf life, decrease bleaching and off flavor of grape cv. Rashe in cold storage, one SO2 generating pad on top of packaged grapes with perforated polyethylene bags or half pad with imperforated bags is recommended .