Low-temperature plasma applications in chemical fungicide treatment reduction

Abstract

In order to reduce the environmental burden of chemicals, various new alternatives to seed protection are being sought. Our aim was to find an environmentally acceptable solution leading to the inactivation of seed-borne phytopathogenic fungi Fusarium culmorum on the surface of wheat and barley seeds with a positive effect on their germination. As a low-temperature plasma (LTP) source, a Diffuse Coplanar Surface Barrier Discharge (DCSBD) was used. Plasma generated by DCSBD is non-equilibrium, cold, diffuse, macroscopically homogeneous even in ambient air at atmospheric pressure. Experimental results showed that LTP treatment in the range of 120—300 s significantly inhibits the growth of F. culmorum on the surface of the seeds. The efficiency of LTP treatment was compared with traditional seed protection processes using chemical fungicide and also with combined seed pretreatment by plasma and subsequent application of chemical fungicide. No growth of F. culmorum was observed after the combination of Vitavax 2000 fungicide application in the dose of 10 % and 60 s of LTP treatment even on the 5th day of incubation. Better wettability of seeds with the chemical fungicide was related to the change on seed surface, which becomes hydrophilic after 10 s of LTP application. Short LTP exposure times did not affect germination and improved the growth parameter of cereal seeds. By combining physical (LTP) and chemical (Vitavax 2000) treatments of cereal seeds, it is possible to effectively reduce the required amount of chemical fungicide and to stimulate germination and early growth seed parameters.

Germination of Phaseolus vulgaris L. Seeds after a Short Treatment with a Powerful RF Plasma

“…While longer treatments certainly increase the surface wettability, they may also negatively affect the ability of seeds to germinate [8]. Namely, the surface reactions triggered or caused by plasma are exothermic, so the seeds are likely to be heated upon plasma treatment.…”

“…Interestingly, an early paper achieved a significant improvement in germination simply with an electrostatic treatment using a high-intensity electric field, but it does mention partial discharges between seeds, so the effect may be plasma-related [52]. If plasma treatments of seeds use power or duration that is too high, they can damage the delicate seed material [8,14,53], as the reactive species dose received by the seed is too high. It is possible that this occurred at some of the treatment conditions used in our experiments, but no correlation with treatment time nor with gas pressure is evident in Figure 8.…”

“…Disinfection of seeds with plasma, particularly the removal of fungal disease agents, is common. When applied properly, the effect of plasma may reduce or eliminate the need for chemical fungicide use [8]. On the laboratory scale, this approach has been successful for many plant species, including grains such as wheat [9,10], maize [11], and rice [12], but also legumes such as soybean [13].…”

Applications of nonthermal plasma technology on safety and quality of dried food ingredients

“…Cold plasma has been demonstrated as a fast, economic and environmental‐friendly technology to improve seed performance and germination yield and showed potential to overcome limitations of traditional treatment methods (Hoppanová et al . 2020; Mujahid et al . 2020).…”

“…2018; Hoppanová et al . 2020). The improvement of the seed surface wettability can be partially attributed to oxidation of the seed surface by reactive species generated after plasma exposure, which may increase the germination speed (Filatova et al .…”