Effect of berry thinning, uniconazole (U.C.) and GA3 on cluster quality of Thompson Seedless grapevines.

摘要

Clusters of nine-year-old vines of Thompson Seedless grapevine cultivar were thinned to two rates by removing some branches and removing the lower part of the cluster. Clusters were thinned by leaving 8 or 14 branches including wings. GA3 was applied as spraying cluster to all treatments except untreated control; twice at 10 ppm at 5-7 cm to cluster length and again after 5-7 days and twice for sizing at 30 ppm at one week after set and again after 5-7 days. Also uniconazole (U.C.) was sprayed to vine canopy at 50 and 100 ppm at the 6th week after set. All treatments increased cluster weight, cluster wide, rachis weight. However berry weight, size, length and diameter pronounced increased compared to untreated control, the highest increment of berry weight and size with treatments of berry thinning. Spraying of U.C. at 50 or 100 ppm to canopy of the vines at the 6th week after set improved total soluble solids, total sugar and reducing sugar compared to vines treated with GA3 alone. Although theacidity was decreased. However, thinning slightly decreased acidity compared to treatments with GA3 alone. Berry thinning produced loose clusters and gave the highest berry weight and size; it also improved sugar content and gave low acidity.