Essential oils as control agents of postharvest alternaria and Penicillium rots on tomato fruits

The antifungal activity of the essential oils of ajowan, fennel and caraway was evaluated in vitro and in vivo conditions against growth of Alternaria alternata (Fr.: Fr.) Keissler. and Penicillium digitatum Sacc., two postharvest pathogens of tomato fruits. In vitro tests showed that ajowan and fennel oils exhibited the highest antifungal activity against A. alternata and P. digitatum, respectively. But caraway exhibited poor antifungal activity against two fungal species tested. Ajowan oil possessed the highest antifungal activity among tested oils in in vivo condition. Gas chromatography-mass spectrometry analysis of essential oils revealed that thymol (63%), trans-anethole (64%) and 2-caren-10-al (34%) were the main components of essential oils of ajowan, fennel and caraway, respectively. Therefore, essential oils may be used as an alternative for the synthetic chemicals for control of postharvest phytopathogenic fungi and for increasing the shelf life of plant products. Because the plant essential oils have low mammalian toxicity, are biodegradable, multifunctional, nonpersistent in the environment and are cheap to produce, the possibility of developing essential oils for use in crop protection may be an attractive venture. This study demonstrates the potential of essential oils as antifungal preservatives for tomato fruits that are susceptible to postharvest decay caused by fungi. Examination of various concentrations of essential oils from ajowan (Carum copticum L.), fennel (Foeniculum vulgare Mill.) and caraway (Carum carvi L.) on Penicillium digitatum and Alternaria alternata in this study showed promising prospects for the utilization of essential oils. In vivo experiments showed that essential oils used could reduce postharvest diseases on tomato fruits caused by P. digitatum and A. alternata. So, essential oils can be used as a potential source of sustainable eco-friendly botanical fungicides, after successful completion of wide-range trials.