In Vitro and In Vivo Control of Alternaria alternata in Barberry (Berberis vulgaris) by Some Essential Oils

In recent years, the use of natural components such as essential oils has been introduced as a new way to control fungal infections. In this study, the effect of the essential oils of anise, chamomile, marjoram, black caraway, and thyme on inhibiting the growth of Alternaria alternata fungi in barberry under in vitro and in vivo conditions was tested, using a completely randomized design involving five concentrations (0, 200, 400, 600, and 800 μL L−1) with three repetitions. In vitro results showed that by increasing the concentration of all essential oils, their antifungal activity increased. The best inhibitory effect on A. alternata fungi was related to the use of thyme essential oil, followed by black caraway, marjoram, chamomile, and anise, respectively, such that the growth of the fungus was stopped at a concentration of 400 μL L−1 for thyme essential oil. In in vivo conditions, the lowest percentage of fruit weight loss was observed with thyme treatment at 600 μL L−1 and a 0.02% concentration. The content of total soluble solids was highest with black caraway treatment (200 μL L−1) and was lowest with the control treatment. The highest acidity was obtained in barberry treated with thyme oil at 400 μL L−1, with a pH of 2.10. The highest antioxidant content was observed with chamomile essential oil at 200 μL L−1 (80.4 mg L−1), and the lowest was seen with anise essential oil at 600 μL L−1 (21.0 mg L−1). The highest phenol content was obtained with marjoram oil at 400 μL L−1 (83.18 mg L−1). Treatment with anise (151.10 mg L−1) and marjoram (22.91 mg L−1) essential oils yielded the highest and the lowest anthocyanin content, respectively. Overall, the best results were found with treatment with thyme and black caraway oils (800 μL L−1). The use of essential oils of medicinal plants to prevent the growth of A. alternata fungus in laboratory conditions and the effect of these oils on controlling contamination in barberry fruit are new aspects of this project. Recent studies have shown that plant essential oils can be used to control plant diseases in agriculture.