Effects of Gibberellic acid (GA3) on reduction of rot disease and physico-chemical quality of 'Pinot Noir' grape

Abstract

Pinot Noir' grape shows sensitivity to cluster rot (Botrytis cinerea) because bunches are small and compact, causing economic and qualitative losses in vinery and fresh grapes. The objective of this work was to evaluate the effect of different doses of gibberellic acid (GA3) on rot incidence of 'Pinot Noir' grapevine. The experiment was carried out for two years. The treatments were GA3 doses of 0; 2; 4; 6 and 8 mg L-1 applied at the developed inflorescence (DI) on 14-year-old plants. The results showed that rot percentage in the two crops decreased from 24.75% to 20.72% with application of GA3. The clusters length was higher when GA3 doses of 4; 6 and 8 mg L-1 were applied, compared to the control and 2 mg L-1 of GA3. The rachis length increased after 4; 6 and 8 mg L-1 of GA3 application doses, when compared to the control and 2 mg L-1 of GA3. The cluster width increased after application of GA3 doses, compared to control. Larger rachis width was observed after application of 4, 6 and 8 mg L-1 GA3, compared to the control. Bunch mass was increased with the use of GA3 at 2 and 4 mg L-1 doses, compared to the control and GA3 6 and 8 mg L-1 doses. Regarding the soluble solids, there were higher values in the control and 2 mg L-1 of GA3. Thus, in the 'Pinot Noir' grapevine, application of GA3 decreased clusters rotting and increased clusters and rachis lenghts.