Avaliação in vitro de bactérias promotoras de crescimento vegetal isoladas da orquídea cimbídio

Abstract

Abstract The diversity of Cymbidium hybrids, and the growing commercialization of orchids, reinforces the need for sustainable production, and the bioprospecting of diazotrophic bacteria can demonstrate potential for agricultural use. The objective of this study was to evaluate in vitro diazotrophic bacteria, isolated from rhizospheric soil and tissues of the Cymbidium orchid, and to analyze the solubilization capacity of phosphorus, potassium and phytohormones production. Leaves, pseudobulbs and rhizospheric soil were isolated in five different semi-solid and semi-selective mediums, NFb, JNFb, LGI, JMV and FAM, in order to verify the biological nitrogen fixation capacity, through the indicative movie on the surface of the medium. The bacteria were grouped, according to their morphological characteristics, in a dendrogram, and selected at 75% similarity, testing them for the production of indoleacetic acid (IAA). The isolates that stood out in terms of the production of the aforementioned phytohormone were tested for their ability to solubilize phosphorus and potassium, usage phosphate rock powder, AO-15, and potassium, phonolite, as a source, respectively. The 66 isolated strains fixed nitrogen, and the 18 strains with 75% similarity produced AIA. The 8 strains that stood out in the production of indoleacetic acid, in the absence and presence of tryptophan, did does not solubilize phosphorus, with the strains UNIFENAS 100-589, UNIFENAS 100-591, UNIFENAS 100-600, UNIFENAS 100-604, being able to solubilize potassium, demonstrating the potential agricultural use of growth -promoting bacteria in the cultivation of the Cymbidium orchid.