Effects of plasma activated solution on soybean seed quality and sprout disinfection

Abstract

Plasma technology which has been applied already evidenced how a large variety of seeds treated with both gaseous and liquid plasmas can be proven to promote seed germination, seedling growth and improve diseased resistance. Presently, plasma activated solution (PAS) is gradually becoming a hot topic in plasma medicine and agricultural aspects due to the better convenient process and environmentally friendly without gaseous phase and a greater degree of mobility than plasma activated water (PAW) and atmospheric cold plasma (CAP) do, respectively. The effect of PAS-H2O2 on black soybean seed cv. Sukhothai 3 (ST.3) and its sprouts' quality were investigated. The results revealed that the optimum PAS-H2O2 treatment condition for base application was acquired with 6 watt UV-C (254 nm. Germicidal UVC) at the constant flow rate of 0.5 lmin-1 which gave more energy (720 Kjm-3) than those of higher flow rate of solution (1.5 lmin-1). The concentration of hydrogen peroxide (H2O2), a substrate of the solution in an alkaline area (1 % sodium bicarbonate) which were 0.05 0.1 0.5 ,and 1.0 % expressed the optimum PAS -H2O2 condition in terms of the best values of physicochemical properties. For individual treatment, using 0.05 % H2O2 concentration at the constant flow rate of 0.5 lmin-1, as well as in combination with hydropriming method by soaking seeds for 5 hours and drying for 72 hours at 40 oC + 1. for 5 minutes of exposure time illustrated the best conditions for improving soybean seed enhancement in terms of seed germination, seed vigor, seedling growth, microorganisms inactivation, and the change of seed coat features. However, in the case of microbial control, the single PAS-H2O2 treatment had more potential than those of the combination methods. In order to save energy and reduce energy costs, the treatment time could be shortened to 1 and 3 minutes and applied with other disease control methods for single treatment and combination with hydropriming, respectively. In addition, the individual PAS-H2O2 treatment condition for the maximum improvement of soybean sprouts both physical appearance and microbial quality especially for Escherichia coli strains could be pretreated seeds by using 0.05 % H2O2 concentration at the constant flow rate of 0.5 lmin-1 for 7 minutes of exposure time. While, household production, the treatment time could be shortened to 5 minutes in order to obtain germinated soybean with a standard germination rate of 90% or higher while maintaining good characteristics of hypocotyl length and high protein content. Therefore, PAS-H2O2 in terms of single treatment and combination with hydropriming method could apply as a beneficial pre-sowing treatment for seed emergence and further development of soybean.