In vitro antifungal activities of Cymbopogon citratus, Cymbopogon martini, Pogestemon cablin and Curcuma longa essential oils against spoilage fungi isolated from tomatoes

Abstract

Tomatoes (Solanum lycopersicum L.) have highmoisture content (93–95%), making them more vulnerable to various types of spoilage fungi. Numerous medicinal plants' essential oils are known to have antifungal properties that combat these spoilage fungi. Therefore, this study aimed to investigate the potential antifungal activity of essential oils from some indigenous plants in Bangladesh to prevent the fungal attack on tomatoes. Using potato dextrose agar medium, 4 species of spoilage fungi from tomatoes were identified. ITS (Internal transcribed spacer) region-specific sequencing was used to identify the fungal species as Aspergillus welwitschiae, Aspergillus tamari, Penicillium citrinum and Rhizopus arrhizus. Assessment on antifungal activity was conducted for four essential oils extracted from plants: turmeric leaf (Curcuma longa), patchouli (Pogestemon cablin), palmarosa (Cymbopogon martini) and lemongrass (Cymbopogon citratus). The GC-MS method was used to analyze these essential oils to ascertain their chemical content. A pathogenicity test determined the severity and % of rot on tomatoes. A. welwitschiae caused the most severe spoilage (80%) after 21 days, while R. arrhizus damaged 26% of the tomatoes within 5 days. The minimal fungicidal concentration (MFC) and minimal inhibitory concentration (MIC) of the essential oils were determined after analysis. Lemongrass oil fully suppressed the growth of all the isolates at a concentration of 12 ????l/ml. Finally, the essential oils of palmarosa and lemongrass may be used as a preventative measure against tomato fungal rot.