Different defense responses and brown rot control in two Prunus persica cultivars to essential oil vapours after storage

Abstract

The effectiveness of thyme and cinnamon oil vapours on the control of Monilinia laxa in peaches was compared by investigating the induction of defense-related and antioxidant enzymes, and the production of phenolic compounds after different storage times.In Experiment 1, ‘Spring Princes’ and ‘Sonnet’ peaches were exposed to thyme or cinnamon oil vapours when harvest at commercial maturity. Before or after the treatments fruit were inoculated with M. laxa and held for 3 and 5 d at 25°C. In Experiment 2, fruit were inoculated after thyme or cinnamon oil vapour treatment and stored at 0°C for 12 d, followed by 2 d shelf life at 15°C. In Experiment 3, naturally infected fruit were exposed to thyme or cinnamon oil vapour treatment and then stored as mentioned in Experiment 2 for 12 d at 0°C after which they were removed from cold storage held at 15°C for 5 d to simulate the retail shelf condition. Thyme oil vapour increased activities of defense-related enzymes, total phenolic content and significantly reduced the incidence and severity of brown rot in ‘Spring Princess’ and ‘Sonnet’. The other treatments, cinnamon oil vapour, and iprodione fungicide spray were less effective. However, the control of brown rot was more effective with thyme oil vapour than the cinnamon oil vapour in ‘Spring Princess’. Thyme oil vapour as botanical fungicide showed good potential for practical application for organic markets to reduce the brown rot decay at postharvest stage. However, its effectiveness and related host responses can vary with cultivar.