Effects of gamma irradiation treatment against pathogens of shallot

Abstract

Indonesia is known as shallot-producing countries, but also imported shallot in a large numbers. The high rate of import may increase the risk of entry and spread of quarantine pests from the country of origin into the territory of Indonesia. Some of those quarantine pests are Cercospora duddiae, Pseudomonas syringae pv. syringae and Erwinia carotovora subsp. atroseptica. Gamma irradiation (cobalt-60) is a developing technique of quarantine treatment for eliminating the quarantine pests. The aims of this study are to see the effectiveness of gamma irradiation for eliminating quarantine pests and its effect on tuber’s germination as well as marketable tubers, to determine the feasibility of gamma irradiation as one of quarantine treatment techniques. In this experiment, the quarantine pests were replaced with non quarantine pathogen as a model, which are C. personata, E. carotovora, and fluorescence Pseudomonads. Dose of 50 Gy shows its effectiveness in inhibiting the germination percentage of shallot up to 10.3% and increasing the percentage of marketable tubers during storage up to 8.7%. The effective doses to eliminate fluorescence Pseudomonads, C. personata, and E. carotovora were 1500 Gy, 2000 Gy, and more than 5000 Gy, respectively. But those doses, caused more than 80% un-marketable. Based on those data, gamma irradiation could not be recommended as a quarantine treatment for imported shallot.