Effect of Cane Regulation and GA3 Spray on Berry Thinning in 'Thompson Seedless' Grape (Vitis vinifera L.)

Abstract

A field trial was conducted during 2013-14 and 2014-15 fruiting seasons in growers' vineyards around Nashik, Maharashtra, India to improve efficacy of GA3 sprays in berrythinning. As smaller clusters have fewer berries, cluster compactness derived at by number of berries per unit length (cm) of rachis, and, berry-diameter were considered as a measure of berry-thinning. As GA3 effect in berry-thinning is stage-specific, canes uniformly thick in a vine only were retained to achieve uniformity in flowering, by inducing uniform bud-break. Cane regulation did not result in uniformity in bud-break or flowering. Blanket spray of GA3 thrice @ 20g a.i./ha, each coupled with either removal of non-uniform canes or retention of all the canes could effectively reduce cluster compactness by reducing number of berries per cluster, without increasing total length of the rachis/cluster or berry diameter. Vine yield and quality in terms of total soluble solids and acid content were not affected by the treatments. Considering cluster-compactness, yield and ease of cultural operations, retention of all the canes in a vine, coupled with three blanket sprays each of GA3 @ 20g a.i/ha, on alternate days commencing from initiation of the bloom, is recommended for 'Thompson Seedless'.

Keywords

• Cane Regulation
• GA3 Spray
• Uniform Flowering
• Cluster Compactness
• Thompson Seedless