PROMOÇÃO DE CRESCIMENTO DE PLANTAS DE TOMATE MEDIADA POR ISOLADOS BACTERIANOS

Abstract

The trend of modern agriculture is to conduct its management practices that allow a good productive performance even if the plants are subjected to adverse conditions. The objective of this work was to evaluate the ability to promote the growth of tomato plants by bacterial isolates, as well as to elucidate the mechanisms of action of these microorganisms by verifying the synthesis of indole-3-acetic acid (IAA) and solubilization of phosphates. The tests were performed in two stages. The first stage was in a greenhouse condition, where the bacterial isolates were evaluated for the ability to promote the growth of cv. Santa Clara, considering two forms of application, via soil and foliage. Seven variables were evaluated: neck diameter, plant height, leaf area, SPAD index, root length, fresh mass and root dry mass. The experimental design was a randomized complete block design with two modes of application. Subsequently, in the second assay, these microorganisms were evaluated in vitro for the ability to synthesize IAA and solubilize phosphate. The IAA production was quantified by reading the absorbance spectrophotometer. For solubilization of phosphate the solid culture media NBRIP, GL (P) and YED were used. The finding of solubilizing colonies was identified by the presence of a transparent halo around the colonies. Isolates GF264, GF274 and GF451 were shown to be promising for most of the morphological characteristics evaluated. However, it was not possible to relate the promotion of plant growth with the synthesis of IAA and solubilization of phosphates. Thus, the results of this work suggest the realization of other studies to elucidate which mechanisms of action are responsible for the growth of plants by the evaluated bacterial isolates.