Protection against Seed-Borne Diseases Using Atmospheric Gas Plasma

Abstract

Potential crop diseases and yield loss occur due to seed-borne plant pathogens; therefore, the control of these pathogens is an important issue in food production. Seed disinfection is one of the basic control measures for these diseases. Plasma treatment has been widely used for the sterilization of medical instruments and treatment of material surfaces, but its application to agricultural products has just started in recent years. In this study, authors evaluated the effect of atmospheric gas plasma on the inactivation of two seed-borne pathogens, Rhizoctonia solani, which causes damping-off of Japanese hornwort, and Pyricularia oryzae, which causes rice blast disease. Atmospheric argon plasma was generated by AC high voltage discharge, and applied voltage to electrodes and gas flow rate were 10 kV and 3 L/min, respectively. The mycelium of R. solani and the conidia of P. oryzae were treated with atmospheric gas plasma: Post treated mycelial growth and conidial germination were measured after an incubation period of 1 to 4 days. Under these conditions, when the distance of the plasma source to the sample surface was 5 cm, no effect was found on the mycelial growth of R. solani compared with the non-treated one, even when the treatment time was as long as 15 min. However, when the distance was 3 cm, the inactivation effect of mycelial growthwas observed in time depended manner. The 5 min treatment time at a 3 cm distance decreased the growth rate, and the longer treatment time (10 min) markedly inhibited the growth of R. solani. The plasma treatment at a distance of 3 cm for 10 min strongly inhibited the conidial germination of P. oryzae, as well. These results indicated that gas plasma treatment from an appropriate distance is effective in inactivating the two plant-pathogenic fungi. Therefore, this technology could be useful in seed disinfection.