Aplicação da radiação UV-C em fungos de armazenamento de sementes de feijão

Abstract

Common bean (Phaseolus vulgaris L.) is extensively cultivated in Brazil; however, seed quality can be compromised during storage due to fungal contamination, particularly by species of the genera Aspergillus, Penicillium, and Fusarium. In this context, short-wave ultraviolet (UV-C) radiation has emerged as a promising physical method for microbiological control. This study aimed to evaluate the effects of UV-C radiation on the fungi most frequently isolated from bean seeds and their impact on microbiological, physiological, and chemical seed quality immediately after treatment and following 180 days of storage. Initially, microorganisms associated with the seeds were identified using the blotter test method. Spore suspensions of the primary isolated fungi, adjusted to a concentration of 10⁶ CFU mL⁻¹, were then exposed to UV-C radiation according to a 2² Face-Centered Central Composite Design, varying radiation intensity and exposure time, to determine the optimal range for fungal inactivation. Subsequently, commercial seeds were characterized, assessed for fungal contamination, and irradiated under the established parameters using a Central Composite Design (CCD). Seed quality was evaluated in terms of microbiological load, physiological parameters (germination, vigor, and electrical conductivity), and chemical composition (total phenolics, antioxidant activity, reducing sugars, and protein content), both immediately after irradiation and after 180 days of storage. Results indicated an incidence considered high (>25%) of Aspergillus, Penicillium, and Fusarium in the seeds analyzed. UV-C treatment significantly reduced fungal load, with efficacy dependent on the combination of radiation intensity and exposure time. Seed germination and vigor were generally unaffected, although higher UV-C doses caused some negative physiological effects. After 180 days of storage, irradiated seeds exhibited lower fungal incidence compared to untreated controls. These findings indicate that UV-C radiation is an effective alternative for controlling fungal contamination in bean seeds when applied under appropriate conditions.