Bacteria Disinfection of Rice Seeds by Ultraviolet Light Irradiation in a Biosafe Flow Cabinet

Abstract

Easy-to-use methods to disinfect microbes on seeds are not available. In the present study, rice seeds were irradiated by 274-nm germicidal ultraviolet (UV) protons in a biosafe flow cabinet. Seeds without any barrier, in a sterilized mesh bag, or in a sterilized coin envelope were removed each day with sterilized forceps for 7 days after UV irradiation and placed in nutrient agar media in a dark incubator at 29°C for 3 days, after which the number of seeds contaminated with bacteria and/or fungi were counted. At the same time, 10 seeds each time were removed from each UV treatment and kept in a dark incubator at 40°C for 5 days to determine the germination rate. Both bacterial and fungal infection rates declined significantly over time. The germination rate, with an average of 90 ± 7.1%, did not change significantly over time. There was no significant difference among treatments for germination rate or fungal infection rate. The UV irradiation of seeds in mesh bags had the strongest effect on reducing bacterial infection rates over time, whereas the direct UV irradiation had a weaker effect on bacterial infection rates than the UV irradiation of seeds in mesh bags. We suggest that UV irradiation of seeds in mesh bags be used to reduce seed bacterial contamination.