Effect of chemically induced berry thinning on flame seedless and sharad seedless varieties of grapes (Vitis vinifera L.) under mild tropics

Most engorging and consistent results have been achieved by spraying conventional thinning agents at different concentration 25%, 50% and 100% cap fall in Flame Seedless and Sharad Seedless grape vines for reducing excessive fruit set and to improve yield and quality of both varieties. The treatments were imposed at thirteen levels in a randomized block design with five replications. Results revealed that, maximum bunch weight at 25%, 50% and 100% cap fall (367.22, 420.25, 506.19 g Flame Seedless and 379.38, 426.49, 402.83 g Sharad Seed less) bunch length (29.25, 28.80, 29.12cm Flame Seedless and 28.70, 30.14, 30, 68 cm Sharad Seedless) TSS (22.38, 23.15, 23.68°brix Flame Seedless and 22.75, 23.00, 22.85°brix Sharad Seedless) TSS/acid ratio (68.63%, 65.93%, 73.99% Flame Seedless and 65.00%, 62.20%, 68.34% Sharad Seedless) lower titrable acidity (0.32%, 0.35%, 0.31% Flame Seedless and 0.35%, 0.37%, 0.33% Sharad Seedless) yield per vine (12.46 kg, 13.22kg, 19.06 kg Flame Seedless and 14.07 kg, 14.08kg, 14.83 kg Sharad Seedless) yield tonnes per hectare (23, 07, 24, 48, 35.29 t/ha Flame Seedless and 26.05, 26.05, 27.46 t/ha Sharad Seedless). However, spraying coffee powder, olive oil and clove oil 3% at 50 and 100% cap fall and CuSO₄ at 0.5% and 0.7% concentration at 25% and 50% cap fall had clear trend on increasing the yield and quality parameter. The obtained results proved a good chance to replace coffee powder, olive oil and clove oil and CuSO₄ instead of the synthetic chemical products of GA₃.