Alternative preservation methods against Sclerotium tuber rot of Jerusalem Artichoke using some natural essential oils

Abstract

The Sderotium Tuber Rot Fungus (Sclerotium Rolfesii Sacc.) represents a serious problem for Jerusalem Artichoke (JA) tubers during storage condition. The aim of this study was to examine the possibility of using some essential oils as alternatives to the chemical fungicides to inhibit the fungal growth, increase shelf life time, and keep nutritive value and quality and storability of JA fresh tubers under storage conditions. In vitro antifungal activity assessment was carried out using four essential oils (caraway, clove, mint and artemisia) at four concentrations (1, 2, 3, and 4 ml.L). Among the tested oils, complete inhibition of the fungal growth was obtained using caraway or clove oils at 1 ml.L. In the storage experiment, two preservation methods were applied using clove and caraway oils. In the first method, JA tubers were treated with clove or caraway oils at 1 ml.L , kept in perforated Polyethylene bags and stored at 4 °C and 90% relative humidity (RH). In the second method, JA tubers were treated rnI.L1, kept between two peatrnoss layers and stored at room temperature (25/10°C, day/night) and 70% RH. Comparing with the infected control, tubers treated with caraway oils and kept in peatmoss at 25/10°C and 70% RH exhibited lower incidence of Sclerotium Tuber Rot, sprouting percentage, weight loss, and decay percentage. On the other hand, this treatment led to an increase in the dry matter and contest of carbohydrates, protein, inulin, total phenols and activity of the peroxidase and polyphenol oxidase enzymes. Based on the obtained results we recommend the use of caraway oil and peatmoss layers when storing JA tubers at room temperature to prevent the chemical fungicide and save cooling energy.