Effect of Pomegranate Peel Extract on Green (Penicillium digitaum) and Blue Molds (P. italicum) of Mandarin Fruit

The global trend has shifted towards the reduction of synthetic pesticide application in agriculture in general and in postharvest in particular. Currently there is a growing interest in using natural antifungal compounds, like plant extracts for the preservation of foods. In order to develop fungicide formulation of natural origin as postharvest treatments, this study was conducted on the antifungal activity of pomegranate (Punica granatum L.) extract against Penicillium italicum and P. digitatum. The experiment was set up according to a completely randomized design with 4 replications using ‘Satsuma’ mandarin. The experimental factors included extract concentration (0, 25%, 50%, 75% or 100%) and the effect of treatments (preventive or curative). The fruits were wounded on the outer surface on four locations to a depth of 2 mm and a diameter of 1 mm. Preventive treatments were carried out by dipping wounded fruit into the formulations of extract and thereafter, each wound site was infected by inoculating 20 μL of the inoculum of P. italicum or P. digitatum. For curative treatments, fruits were wounded as above, and then inoculated with P. italicum or P. digitatum (20 μL of inoculum per wound site). The results showed that the 75% or 100% pomegranate extract applied to ʻSatsuma mandarin produced a significant antimicrobal effect, reduced spore or mycelium diameter, decay severity and infection index and increased sporing time and healthly fruit percentage. Our study showed that 100% pomegranate peel extract application could decrease weight loss rate during storage of “Satsuma” mandarin fruit inoculated with spores of P. digitatum or P. italicum. The obtained results showed that the tested pomegranate extract can be effectively utilized for controlling and curing infections caused by P. italicum and P. digitatum.