Response of Certain SeededVitis ViniferaVarieties to Gibberellin Application at Postbloom Stage

In Vitis vinifera 9Bhokri9 grapes, increase in cluster and berry weights from GA application (25-100 ppm) was greater from sprays 20-21 days after full boom than from sprays 7-8 clays after full bloom. No adverse effects were noticed in Bhokri even with sprays 7-8 days after full bloom. GA sprays (50-150 ppm) 20-21 days after full bloom to the cultivars Bhokri, Gros Colman (Pusa) and Anab-e-Shahi resulted in increased cluster weights, berry weights, and berry size without producing adverse effects of any kind. Application to Bharaf Early, Black Hamburg, Black Muscat, and Alamwick, however, did not increase cluster and berry weights. In Bharat Early and Black Hamburg cultivars, GA application (25-75 ppm) 7-8 days after full bloom decreased cluster and berry weights, producing adverse effects such as shot berry formation. The differential response of these varieties to GA application is attributed to physiological differences in these two sets of cultivars.