Document Type : Research Article
Authors
1
Department of Plant Protection, College of Agriculture, University of Birjand, Birjand, Iran
2
Department of Horticultural Science, Faculty of Agriculture, University of Birjand, Birjand, Iran
Abstract
Introduction
Long term storage of pomegranate fruit is compromised by pathogens that cause postharvest rots and decay. Pomegranatesare predisposed to attack from various pathogens at pre- and/or postharvest stage, which has a significant impact on fruit quality and storage life. These pathogens often cause damage to the tissues, thereby making the fruit unsaleable. A significant portion of pomegranate pre- and postharvest losses is attributed to dis-eases associated with various bacterial and fungal species. The use of plant essential oils is considered as a new idea in reducing post-harvest waste and increasing the storage life of horticultural products and controlling fungal contamination in developed agriculture. This study was conducted with the aim of determining the antifungal effect of some herbal essential oils in different concentrations on pomegranate fruit to prevent the growth of Penicillium fungus in vitro and in vivo.
Materials and Methods
In order to investigate the effect of the essential oils of some medicinal plants on the fungus Penicilliumsp. in pomegranate fruit in in vivo and in vitro conditions, a factorial experiment was conducted in the form of a completely randomized design with three replications at the Faculty of Agriculture of Birjand University in 2022. The first factor included the type of essential oil: Ginger, Zenian, Tarragon and Cardamom essential oils, and the second factor included the concentration of essential oil at five levels (0, 200, 400, 600, and 800 microliters.liter-1).The index measured in in vitro conditions was the radial growth of the fungus. The indicators measured in vivo conditions include appearance of the fruit, TSS, pH, total acidity (meq.g-1), total phenol (mg galic acid.100 g-1 FW), antioxidant (%), antocyanin (mg.g-1) and tissue firmness. Finally, the experimental data were statistically analyzed using SAS program and comparison of means was performed by LSD test at 5% probability level.
Results and Discussion
The results showed that the increase in the concentration of essential oils also increases their antifungal activity, so the highest inhibition rate was observed in Ginger essential oil and the lowest in Cardamom essential oil on the growth of the fungus colony. The strongest antifungal activity was observed with the essential oils of ginger, zedoary (Zenian), tarragon, and cardamom, in that order. Notably, no fungal growth was detected in samples treated with ginger essential oil throughout the entire sampling period. These results indicate that the tested essential oils effectively inhibited fungal colony growth and demonstrated significant antifungal potential.In in vivo conditions, the best fruit appearance was obtained in pomegranates impregnated with Zenian and Ginger essential oils, and the least was observed in Cardamom essential oil. Ginger essential oil had the highest amount of soluble solids. The highest pH value of fruit juice was obtained from Ginger essential oil and the lowest pH value was obtained from Tarragon and Cardamom essential oils. The fruits treated with Tarragon essential oil had the highest total acidity. The fruits treated with Ginger essential oil had the highest amount of total phenol. The statistical comparison of the averages showed that the highest percentage of antioxidants was observed in the Ginger essential oil treatment and the lowest antioxidant percentage was found in the Tarragon essential oil treatment. The results showed that the infected fruits treated with Zenian essential oil with a concentration of 800 microliters.liter-1 had the highest antioxidant. The results of the comparison of the averages related to the effect of the type of essential oil show that Cardamom and Ginger essential oils had the highest and lowest anthocyanin content, respectively. In this experiment, Ginger essential oil had the highest hardness of the fruit texture and the lowest index was obtained from the essential oil of Zenian.
Conclusions
In general, the results of this research showed that essential oils have antifungal properties in the control of fungal disease after harvest; in-vitro tests showed that Cardamom essential oil had a very low fungicidal effect and in the control of Penicillium sp. Ginger essential oil had the most fungicidal effect. Antifungal properties increased with increasing the concentration of essential oil, but the antifungal property of Ginger essential oil was 100% in 400-800 concentrations used. Under natural conditions, Ginger and Zenian essential oil has good antifungal activity against Penicilliumsp.Considering the biodegradability and low toxicity of plant essential oils, the use of Ginger and Zenian essential oil is recommended to increase the shelf life of food products and can be used as disease controllers in agriculture.
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