Estudo da ação antifúngica de plasmas elétricos gerados em diferentes gases em sementes de cebolas contaminadas com cepas de Penicillium sp.

Abstract

The physiology of plant development is of great relevance and consists of several stages such as germination, growth and maturation, but the successful process can be compromised by several intrinsic and extrinsic factors, such as climate, soil quality, stress and even some diseases. Among the new technologies applied to agriculture in a “clean” way, we can mention the use of electrical physical plasmas. The fungal sample selected was the strain of Penicillium sp previously isolated from onion seeds. Onion seed samples were obtained commercially and randomly separated. For the irradiation of all the samples, a sliding arc reactor was used, whose geometry allows the exhaustion of the gas in a reverse vortex and the generation of the plasma is made by a source of direct current (10 kV). The gases used were Argon, Helium and compressed air generated by a medical/dental compressor. After the irradiations, the samples were incubated under specific conditions and observed for 10 days. The irradiation of the seeds with plasma of Argon gas with Compressed Air and the compound only of Compressed Air, showed a low number of contamination, while the treatments based on Helium and Argon gases maintained high rates of fungal growth in the samples. On the other hand, Helium and Argon gases did not harm or even contributed to the increase in the number of viable seeds. The high values in temperatures, during irradiation containing compressed air, may have influenced not only the fungal metabolism, but also the germination viability of the seeds. Although the period of exposure of the samples to high temperatures was, at most, 15 minutes, the effects were permanent. In the effective treatments to inhibit fungal growth, there was also a significant reduction in the number of seeds that started the germination process, through the hatching of the husk. Thus, the application of plasma in seeds, in the parameters studied, was not promising, in view of the great drop in germination viability, but it was able to effect control of fungal growth, mainly, when there was association of inert gases with compressed air.