Effect of Some Natural Plant Extracts & Plant Essential Oils on Suppressive of Penecillium digitatium (Pers.:Fr.) Sacc. and its enzyme activity which caused Citrus Green Mold for Navel Oranges in Egypt

摘要

Green mold of citrus, caused by Penicillium digitutum (Pers.:Fr.) Sacc. is one of the most economically important postharvest diseases of citrus worldwide. In Egypt, losses of about 10% and 15% of orange and lemons in storage, respectively, occur each year. Thyme oil at 1.0 and 2.0 % and sweet almond oil at 2.0% concentration caused a complete reduction of P. digitatum linear growth in vitro, while bitter almond oil resulting moderate effect to reducing the fungus growth if compared with other treatments and control treatment. Aloe Vera gel at all concentrations were used gave a highly significantly reduction of fungus linear growth, at high concentration was used 1.0 % and 2.0% Aloe Vera gel caused reduction of fungus growth by 63.3% and , 77.2% respectively. Means that, Olive water extract followed by aloe Vera extract result a moderate effect to reducing the fungus growth. Olive water extract (4%) gave a complete reduction of disease incidence (DI) and disease severity ( DS) after the first storage period but after 45 days and 60 days of storage gave highly significant reduction of both DI and DS by 86.8% &80.0% and 73.3% & 89.5%, respectively .Orange fruits coated with Gum Arabic (5%) resulting a moderate effect to reducing DI and DS at all storage periods if compared with control treatment and other tested plant extracts. On the other hand, at highly concentration was tested (4%) , Sweet almond, bitter almond and Thyme oil gave a complete reduction of DI and DS at the first storage period , at the second storage period , previous treatments gave a complete reduction of disease incidence (DI) but gave a highly reduction of DS, while after 60 days of storage, fruits coated with gum Arabic (5%) and Thyme oil at high concentration (4%) resulting a significantly reduction of DI by 88% and by 81.1% and on DS by 81.5 and by 89.0%. Thyme oil at 1.0 and 2.0 concentrations gave a non-activity of pectinase enzyme and result low activity of enzyme activity (10.5 U/ml) at low tested concentration was used if compared with control treatment, while, olive water waste at 0.5 and 1.0 concentrations caused low activity of pectinase enzyme (9.7, 10.9U/ ml). At high plant extract concentration (2.0) for all tested extracts caused non-effect of enzyme activity.