Essential oil from orange peel in the control of Botrytis cinerea and in the postharvest conservation of ‘Benitaka’ table grape

Abstract

The objective of this work was to evaluate the efficiency of essential oil from orange peel in the refrigerated conservation of the ‘Benitaka’ table grape, as well as to evaluate its in vitro effectiveness on Botrytis cinerea, the causal agent of gray mold. Grapes were harvested from a commercial field in the municipality of Cambira, Paraná, during the 2022 and 2023 seasons. The experimental design was completely randomized, with four treatments and five replications of five bunches per plot. The treatments were: a) control; b) essential oil from orange peel at 4.0 mL of the commercial product (c.p.) L-1; c) dual phase SO2-generating pads containing 1 and 4 g of the active ingredient (a.i.) in the fast and slow phases, respectively; and d) essential oil from orange peel at 4.0 mL c.p. L-1 associated with the dual phase SO2-generating pads containing 1 and 4 g of the a.i. in the fast and slow phases, respectively. A commercial product containing 61.14 g L-1 (6% w/v) of 4-isopropenyl-1-methylcyclohexane, the source of orange essential oil, was applied by spraying it directly onto the bunches. After drying, the grape bunches were stored in a refrigerated chamber at 1.0±1°C and 95% relative humidity. The following variables were assessed 30 and 45 days after the beginning of cold storage: the incidence of gray mold on berries, loss of bunch mass, stem browning, shattered berries, and bleaching. The minimum inhibitory concentration for the development of B. cinerea was determined, and fungal mycelia were observed using scanning electron microscopy to evaluate the in vitro efficacy of orange essential oil. The data were subjected to analysis of variance, and the means were compared using Fisher's difference test at 5% probability. The effectiveness of orange essential oil in suppressing the development of B. cinerea was demonstrated both in vivo and in vitro, making it a safe alternative for the postharvest conservation of 'Benitaka' table grapes.