Rendimento e ação inibitória de extratos vegetais sobre o fungo fitopatogênico cladosporium sp

Abstract

The presence of phytopathogenic fungi in agriculture affects productivity and causes significant economic losses. The control of these microorganisms is commonly performed through chemical agents, however, even with their efficiency, these products are considered contaminants of soil, air, water, and can also compromise the health of handlers. Thus, the demand for the development of sustainable alternatives for the control of these biological agents has been established. In this scenario, plants and their secondary metabolites emerge as a prominent alternative due to their fungitoxic potential. Based on this assumption, the objective was to evaluate the yield and potential toxicity of hydroethanolic plant extracts on the phytopathogenic fungus Cladosporium sp. To carry out the research, the phytopathogenic fungus Cladosporium sp. was collected from Okra (Abelmoschus esculentus) plants. The establishment of fungal culture and subsequent isolation, identification and inhibition test took place in the Microbiology Laboratory of the Center of Social and Agrarian Human Sciences (CCHSA) of the Federal University of Paraíba (UFPB). The hydroethanolic vegetal extracts from garlic bulb (Allium sativum), ginger root (Zingiber officinale) and bell pepper fruit (Piper nigrum) were obtained in the Phytosanitary Clinic of CCHSA-UFPB by maceration method using 70% ethanol as solvent. The inhibition test was organized in an Completely Randomized Delineation with a 4x3 factorial scheme, with factor 1 being the three plant extracts tested: A. sativum, Z. officinale, P. nigrum and the control (BDA) and factor 2 the three concentrations: 5%, 10% and 15%. For the inhibition test, the plant extracts were added, in different concentrations, to the BDA medium and, after plating and cooling, a 100 µ suspension was inoculated in the center of the plate, containing 1x102 spores of Cladosporium sp/mL, allowing the direct exposure of the fungus to the extracts. The evaluation was performed by assessing the diameter of the established fungal colonies. The mycelial growth index (MPI) and the percentage of mycelial inhibition (PIC) were calculated. The yields obtained from the production of hydroethanolic plant extracts of A. sativum, Z. officinale and P. nigrum were 48.27%, 36.83% and 47.42%, respectively, highlighting the plant extract of A. sativum with the highest yield. All plant extracts showed toxicity on Cladosporium sp. The extract of A. sativum also stood out presenting the lowest MCI, 5.56 in the 10% concentration and 3.20 in the 15% concentration, and the highest PIC, 86.65% and 94.82%, in the concentrations of 10% and 15%, respectively, presenting itself as the extract with the highest toxicity for Cladosporium sp. when compared to the other extracts. The plant extracts can be considered a potential alternative for the control of phytopathogenic fungi such as Cladosporium sp.