ADVANCED PLASMA PROCESSING FOR AGRICULTURE APPLICATIONS

Cereals and agricultural crops are frequently affected by contamination from pathogenic and mycotoxigenic fungal species, causing significant phytopathological, toxicological, and economic impacts. In this context, the present thesis focused on the development of innovative and eco-sustainable strategies for crop protection, in line with the European Green Deal directives, through the use of Aerosol Assisted Atmospheric Pressure Plasma (AA-APP) processes for the deposition of bioactive substances on agricultural materials. In the first part, bio-composite coatings containing fungicides and spores of Bacillus velezensis N3.2, a strain known for its antimicrobial activity against phytopathogenic microorganisms, were developed. The AA-APP process was employed to deposit organic films on casted spores and fungicides, in order to evaluate their antifungal activity against Fusarium graminearum. The coatings embedding fungicides showed strong antifungal efficacy, even higher than that of the pure fungicide, demonstrating the potential of plasma-based technologies as sustainable tools for seed coating. Subsequently, this process was applied to maize seeds. The coatings embedding Bacillus spores retained their viability after the plasma deposition. Moreover, the superimposed plasma-polymerized film did not limit the antifungal activity of the spores, and the resulting bio-composite coatings were effective in inhibiting the growth of the toxigenic phytopathogenic fungus Fusarium graminearum. Furthermore, during the Ph.D. course, zinc-based nanocomposite films were developed via AA-APP and deposited on polymeric substrates and wheat seeds. These coatings exhibited antibacterial activity against Erwinia carotovora, the causal agent of soft rot in potato, representing a valid alternative to conventional chemical treatments. The same process, when applied to wheat seeds, also limited fungal colonization by Fusarium graminearum, Fusarium culmorum, and Fusarium moniliforme. Another relevant research topic of this thesis concerned the coating of porous materials such as zeolites, aimed at encapsulating highly volatile Cassia essential oil. The nematicidal activity of these coated materials was tested in soil against Meloidogyne incognita, a nematode that attacks tomato plant roots, demonstrating the potential of this approach for soil pest management. Finally, the decontamination of maize seeds using cold plasma processes was investigated, targeting the reduction of fungal contamination and mycotoxins produced by Aspergillus flavus and Fusarium proliferatum. Treatments, performed both in remote mode and using plasma-activated water, led to a marked reduction in conidial germination and a significant decrease in aflatoxin and fumonisin levels. Overall, the results demonstrated that cold atmospheric plasma technologies are highly versatile and sustainable tools with great potential for agricultural applications, enabling the reduction of fungal, bacterial, and mycotoxin contamination while supporting the development of environmentally friendly crop protection strategies.