effect of pre harvest sprays of ethephon on fruit quality attributes of ghizil uzum grape (vitis vinifera l.)

application of ethephon is an effective way in increase of grape fruits quality. in this study the effect of preharvest application of ethephon solution at four levels (0, 150, 250 and 300 mg/l)and application time at two levels (10-20% and 50-70% of berry coloring), were evaluated on quality indices of ghizil uzum grape cultivar at harvest time. evaluated indices were soluble solids content, titratable acidity, palatability, total phenolics, tissue firmness and fruit color. different concentrations of ethephon were effective on all quality attributes of berries. but ethephon spray times were effective only on titratable acidity, palatability, total phenolics and fruit firmness.results showed that 250 ppm of ethephon and treatment time of 50 – 70 % of berry coloring had the highest effect on berry quality. based on obtained results application of ethephon with the optimum concentration in the proper time can be an effective strategy in pre harvest technology of grapes from the point of color and optimum quality of berries.