Effect of Plant Growth Regulators on Growth and Quality of Fruits in Triploid Hybrid Grapes

This study has been conducted to investigate the effect of gibberellic acid and several plant growth regulators on growth and quality of fruits in triploid grapes. The gibberellic acid (GA(3), 50 and 100 mg L-1 and GA(3) (100 mg L-1) with other plant growth regulators such as streptomycin (SM, 200 mg L-1), mepiquat chloride (MC, 880 mg L-1), and N-(2-chloro-4-pyridyl)-N'-phenylurea (CPPU, 2.5 mg L-1) were treated to grapes. There were no noticeable differences in fruit growth and quality of grapes when only GA(3) were treated as 50 or 100 mg L-1 in all of triploid hybrid grapes. Statistically significant effects on the enlargement of cluster weight and berry size were shown in 'KB0120', 'KN200110', 'KS20015', 'KTS011', 'YRB9803' triploid hybrids treated with 100 mg L-1 GA(3)+ 2.5 mg L-1 CPPU. In combined treatment of 100 mg L-1 GA(3) and 2.5 mg L-1 CPPU treatment, harvest time was delayed for up to 10 days. The sugar content and organic acid varied depending oil the hybrid conditions. The decline or total sugar content was the highest in 100 mg L-1 GA(3)+ 200 mg L-1 SM for all hybrid grapes. There were no differences between 100 mg L-1 GA(3)+ 2.5 mg L-1 CPPU and GA(3) alone treatment in organic acid and total sugar contents. The results indicated that combined berry treatment of 100 mg L-1 GA(3) and 2.5 mg L-1 CPPU seem to be useful for the production of high quality fruit in triploid hybrid grapes.