RESPOSTAS MORFOFISIOLÓGICAS DE PLÂNTULAS DE SOJA AO BIOINSUMO À BASE DE Bacillus spp.

Abstract

To effectively meet the soybean demand in Brazil, seeds must possess high physiological quality, enabling the establishment of vigorous seedlings. Abiotic stresses can limit seedling development. In this context, bio-inputs based on Bacillus spp. have stood out, as they act in promoting root growth, nutrient availability, and resistance induction. Therefore, the objective of this study was to evaluate the effects of a commercial bacterial-based bio-input containing Bacillus spp. on the physiological performance of soybean seedlings. The bio-input was inoculated into a sand substrate in trays at concentrations of 0 (distilled water); 50; 100; 150 and 200 µL, followed by sowing. Soybean seedling emergence, length and dry mass were analyzed, in addition to gas exchange, chlorophyll a fluorescence, and anatomical and histochemical analysis of the leaves. The data indicated that doses above 50 µL were able to improve seedling performance, length, and biomass. All doses of the bio-input provided optimal values for the potential quantum yield of PSII (Fv/Fm). The leaves of seedlings treated with the bio-input showed greater staining by xylidine, indicating an increase in protein compounds and, consequently, an expansion of the intercellular spaces in the spongy parenchyma, in contrast to the control group, which showed less xylidine staining. Furthermore, a strong positive correlation was found between the potential quantum yield of PSII (Fv/Fm) and the growth parameters: emergence (EM), shoot length (SL), root length (RL), shoot dry mass (SDM) and root dry mass (RDM). The results indicated that the bio-input was able to stimulate the initial growth of soybean seedlings, especially at concentrations above 50 µL. However, further studies are needed to validate its action under real cultivation conditions.