Hormonal regulation of growth, fruit set and yield of grapevine cultivar Cabernet Sauvignon (Vitis vinifera L.).

The effects of foliar application of paclobutrazol (PC), chlorcholinechloride (CC) and gibberellic acid (GA3) on vegetative growth, fruit set and yield of grapevine cultivar Cabernet Sauvignon were evaluated. Results indicate that application plant growth regulators carried out during the period of intensive vegetative growth considerably influence the shoot growth, berry set, number of berries per cluster, berry weight and skin to pulp ratio. PC and CC strongly inhibited shoot growth and increased berry set. The number of berries per cluster, cluster weight and grape yield per m2 were increased. Smaller berries resulting from applied growth inhibitors treatments increase the skin-to-pulp ratio, may resulting in wines with deeper color and more concentrated flavors. The achieved increase in grape yield was significant in the PC1000, CC2000 and CC1000 variant compared with a control. Aplication of GA3 reduced the degree of berry settings. Number of berries per cluster was decreased while berry weight was increased. The GA3 concentration 150 mg/l produced significant decrease in grape yield. The effect of growth regulators is directly dependent on the applied concentraction.