Diversidade e controle alternativos de fungos associados a grãos de feijão-caupi comercializados no Nordeste brasileiro

Abstract

Cowpea grains play an important role in the human diet, being one of the main sources of protein for families in the North and Northeast regions of Brazil, and can be consumed in the form of green or dry grains. In addition to the nutritional aspect, the cultivation of cowpea is a source of employment and income for needy populations. The present work aimed to study the diversity of fungi associated with the deterioration of cowpea grains sold in the Northeast region of Brazil and to evaluate the use of eugenol, propolis extract, citronella essential oil and lemongrass essential oil. in the control of Aspergillus species associated with cowpea grains. For this, collections of cowpea grains, with brown tegument, sold in six states of the Northeast Region (Pernambuco, Alagoas, Piauí, Maranhão, Ceará and Paraíba) were carried out. For each sample, a seed health test was carried out with a total of 400 grains per sample. Fungal structures emerging from the grains were quantified and identified at the genus level. When the presence of structures similar to those of the genus Aspergillus was observed, isolation was carried out. The presence of fungi belonging to the genera Aspergillus, Penicillium, Fusarium and Macrophomina was verified in cowpea grains sold in six states of the Northeast region of Brazil. Molecular identification of Aspergillus isolates revealed the presence of A. tamarii (n=06), A. niger sensu stricto (n=18) and the presence of isolates that did not have accurate molecular identification, grouping with isolates-types of A. flavus and A. oryzae (n=23). In vitro and in vivo tests were carried out in order to evaluate the fungitoxic effect of eugenol, propolis extract, citronella essential oil and lemongrass essential oil on Aspergillus isolates and on the frequency of fungi associated with bean grains. cowpea. In the in vitro assay, concentrations of 0.0 (control), 15.62, 31.25, 62.50, 125 μL/L for eugenol and 0, 25, 50, 75, and 125 μL/L for eugenol were tested. propolis extract, citronella EO and lemongrass EO. In the in vivo test, 200 cowpea grains from the state of Ceará were immersed in solutions of eugenol, propolis extract, citronella EO, lemongrass EO and then incubated according to the seed health test. The results indicate that all tested compounds have fungitoxic activity for Aspergillus isolates and may be an alternative for the treatment of fungi associated with cowpea. In the in vivo test (grains) all tested treatments reduced the frequency of fungi associated with cowpea grains by up to 40% compared to the control, constituting an alternative for the treatment of cowpea grains with natural fungal infestation.