EFICIÊNCIA DO SISTEMA HIDROPÔNICO COMO METODOLOGIA PARA A SELEÇÃO DE CEPAS SOLUBILIZADORAS DE CaHPO4, UTILIZANDO GLYCINE MAX COMO MODELO

Abstract

The sustainable development of agriculture can be stimulated by a higher bio-inputs market availability, including phosphate-solubilizing microbial strains. However, these strains selection is currently carried out using imprecise and questionable solubilization methodologies in solid or liquid media. This work tested the hypothesis that the hydroponic system could be a more efficient methodology to select phosphate solubilizing strains, notably plant growth promoters. This methodology was tested using Glycine max plants as a model and the potential growth promoter of isolates was compared with that observed for the commercial microbial mixture Biomaphos®. The results of CaHPO4 solubilization obtained through the use of a hydroponic system were inconsistent with those observed in solid medium and liquid medium, however, the tests in liquid medium attest the poor performance of Codinaeopsis sp. (328EF) and Hamigera insecticola (33EF) in reducing the pH and solubilizing CaHPO4, which corroborates the effects of biotic stress observed in G. max plants inoculated with these isolates. On the other hand, the hydroponic system allowed to characterize Paenibacillus alvei (PA12), as efficient in solubilization in liquid medium, and also the bacteria Lysinibacillus fusiformis (PA26), as the most effective in CaHPO4 solubilization, due to the best effects on phosphorus absorption, growth promotion and physiological performance observed in plants inoculated with these bacteria. The hydroponic method proved to be superior in the selection of solubilizing strains, allowing the assessment of patterns of nutritional levels in plants, growth patterns and photosynthetic performance, anatomical patterns or even the detection of biotic stress responses to inoculation, obtaining strains with potential higher than Biomaphos® for growth promotion. This work proposes a less questionable and more efficient methodology for solubilizers selection, potentially destined for the bio-input market, useful in the P availability for important crops, such as soybeans.