Document Type : Research Article
Authors
1
Department of Horticulture Science, Faculty of Agriculture and Natural Resources, University of Hormozgan, Bandar Abbas, Iran.
2
Department of Horticulture, University of Hormozgan, Bandar Abbas, Iran,
10.22067/ifstrj.2026.99527.1597
Abstract
Introduction
Gray mold, caused by Botrytis cinerea, is one of the most destructive postharvest diseases of bell pepper, resulting in severe quality deterioration and substantial economic losses during storage and marketing. Growing concerns about the adverse effects of synthetic fungicides, together with the increasing demand for safe and environmentally sustainable preservation strategies, have stimulated interest in natural plant-derived alternatives. Essential oils extracted from medicinal plants possess antimicrobial and antioxidant properties that can inhibit pathogen development while enhancing the fruit's natural defense mechanisms. Therefore, this study aimed to evaluate the efficacy of selected medicinal plant essential oils in preserving postharvest quality and mitigating oxidative stress in bell pepper fruits artificially inoculated with B. cinerea.
Materials and Methods
A Botrytis cinerea isolate (IRAN4283C) was obtained from the Iranian Research Institute of Plant Protection and cultured on potato dextrose agar (PDA) under sterile conditions. Essential oils of Shirazi thyme (Zataria multiflora), garden thyme (Thymus vulgaris), lemongrass (Cymbopogon citratus), and cinnamon (Cinnamomum verum) were extracted using a Clevenger apparatus, and their purity (100%) was verified by the manufacturers. Healthy, uniform bell pepper fruits harvested from a commercial greenhouse in Jiroft, Kerman Province, Iran, were surface-disinfected with 1% sodium hypochlorite and inoculated with a B. cinerea spore suspension (1 × 10⁶ spores mL⁻¹). After 24 h, the fruits were immersed for 2 min in 0.5% or 1% essential oil solutions, Luna Sensation® fungicide, or distilled water (control). The treated fruits were packed in perforated polyethylene containers and stored at 6 ± 1°C and 85–90% relative humidity for 30 days. Fruit quality parameters were evaluated at 0, 10, 20, and 30 days of storage. The experiment was arranged as a factorial design with two factors (treatment and storage time) in a completely randomized design. Data were analyzed using SAS software (version 9.4), and treatment means were compared using Duncan's multiple range test at P ≤ 0.05.
Results and Discussion
Storage duration significantly reduced fruit quality, as indicated by decreases in vitamin C content, chlorophyll a and b concentrations, and the activities of catalase (CAT) and glutathione reductase (GR). In contrast, malondialdehyde (MDA) content and the activities of phenylalanine ammonia-lyase (PAL) and polyphenol oxidase (PPO) increased throughout storage. However, the magnitude of these changes varied among treatments. Among all treatments, 1% garden thyme essential oil exhibited the greatest protective effect against storage-induced deterioration. Compared with the control, this treatment increased vitamin C content by 36%, chlorophyll a by 21%, chlorophyll b by 67%, CAT activity by 403%, and GR activity by 136%. Conversely, it reduced MDA content by 39%, PAL activity by 23%, and PPO activity by 53%. In addition, it suppressed carotenoid accumulation, suggesting delayed fruit ripening and senescence during cold storage. These findings indicate that garden thyme essential oil effectively enhanced the antioxidant defense system, mitigated oxidative damage, and maintained the postharvest quality of B. cinerea-infected bell pepper fruits during cold storage.
Conclusion
Application of 1% garden thyme essential oil effectively preserved the postharvest quality and extended the storage life of bell pepper fruits infected with Botrytis cinerea by enhancing antioxidant defense mechanisms and reducing oxidative stress. These findings suggest that garden thyme essential oil has considerable potential as an environmentally friendly alternative to synthetic fungicides for postharvest disease management. Further research should focus on validating its effectiveness under commercial storage conditions, developing nano formulations and edible coating systems, and evaluating its applicability to other horticultural crops.
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