Optimization of bunch load in relation to juice quality in Manjari Medika grapes

Abstract

Bunch thinning is important practice for enhancing the grape quality and yield. The effects of bunch load on yield and berry quality in ‘Manjari Medika’ juice purpose grape variety was evaluated during 2019-20. Four bunch load levels (40, 60, 80 and 100 bunches/vine) were maintained at fruit setting stage. Bunch size and berry weight were decreased with the increase in bunch load. However, Manjari Medika being a processing variety, irrespective of its reduction in berry size, juice recovery per unit area along with its juice quality in terms of antioxidant properties is important. Higher bunch load /vine delayed the maturity by a week, from the juice, compounds viz., gallic acid, quercetin hydrate, caftaric acid, resveratrol, chlorogenic acid, kaempferol, catechin hydrate, and epicatechin were analyzed. Significant variations were observed in the concentrations of these compounds across the bunch levels while, indicating a potential relationship between bunch size and phenolic compound accumulation. Higher antioxidant content was recorded at 60 and 80 bunch loads at harvest. Considering the juice recovery with maintained quality, yield and antioxidant content, 80 bunches/ vine can be more beneficial to processing industry.