Agroecological biopreparations (Nettle extract and Efficient microorganisms): in vitro evaluation of traits related to biological control and plant growth promotion.

BURGES PABLO; HIRSCH MAILÉN; WYSS BEATRIZ; VILLARREAL NATALIA; MARINA MARÍA

Chapadmalal

Congreso; XVIII Congreso de la Sociedad Argentina de Microbiología General; 2023

Sociedad Argentina de Microbiología General (SAMIGE)

Nettle extract (NE) and efficient microorganism (EM) biopreparations are made by agroecological producers from the fermentation (anaerobic or aerobic, respectively) of various organic materials Bio-inputs provide macro and micronutrients to crops, thus improving the nutritional status of plants, seeking sustainability to make agricultural activity economically viable and socially and ecologically fair. Within these biopreparations are several microorganisms that can be beneficial to plants either as biocontrol agents (BCA) or as plant growth promoters (PGP) through different mechanisms (direct or indirect). The objectives of this work were to evaluate the in vitro activity of the microorganisms present in NE and EM and to understand the possible mechanisms of BCA or PGP. Therefore, we evaluate the biopreparations’ capacity to decrease the phytopathogenic fungi growth (Botrytis cinerea, Rhizopus stolonifer, and Fusarium graminearum) by confrontation assays in APG medium. Moreover, we evaluated the inhibitory capacity of biopreparations free of microorganisms, filtered (FNE and FEM) or autoclaved (ANE and AEM). In general, the biopreparations with microorganisms showed more fungal inhibition than the same free of microorganisms. Therefore, microorganisms present in NE and EM might have a direct effect on fungal growth. Although, some indirect mechanisms should not be discarded as the inhibition was also evident when the microorganisms were not in the biopreparations. The activity of hydrolytic enzymes in NE and EM was evaluated. Cellulase and protease activity were evidenced in both EM and NE, while lipase, glucanase, and chitinase activity were only in NE. On the other hand, the in vitro capacity of these biopreparations to solubilize phosphate and zinc, as well as the production of siderophores were studied. The presence of a translucent halo around the inoculum in mineral Tris medium with 0.1% ZnO evidenced the ability of EM to solubilize Zn, not only in EM but also in AEM and FEM. Concerning NE, only when the microorganisms were present there were evident the production of siderophores due to the presence of a yellow halo around the inoculum in O-CAS medium. Finally, an LC-MS-MS analysis of EM and NE evidenced the presence of indole 3-acetic acid, abscisic acid, gibberellic acid, gibberellin, salicylic acid, zeatin, and jasmonic acid. The microorganisms present in EM and NE showed activity as BCA and PGP, both by direct and indirect mechanisms which could benefit the nutrition and development of the crops in which they are applied.