Improvement of the Raisins Quality Using Plant Growth Regulators

In order to improve the quantity and quality of raisins made from Sultani seedless grapes using plant growth regulators, an experiment was conducted in a randomized complete block design in a commercial vineyard near Bonab city (West Azarbaijan Province, Iran). For this purpose, spraying was carried out at fruit set stage using a combination of CPPU and GA3. Then the produced fruits were turned to raisin using alkaline solutions (Tizabi method) and all assessments in this study were performed on these raisins. It was found that the growth regulator treatments significantly increased the diameter, mass, volume, surface area and wrinkling of raisin, however, these treatments did not affect dry matter and moisture content of the raisins. Significant color changes were observed in all treated raisins and color values of the treated raisins ​​were significantly lower than the control. The interacting effect of the two plant growth regulators was found to be significant for raisins length and total soluble solids, i.e. application of 7.5 mg L-1 of CPPU and 20 mg L-1 GA3 led to the smallest value for the total soluble solids. All treatments increased the raisins length. It could be concluded that application of CPPU and GA3 on grapes results in improvement of the quality of the raisins.