Bactérias promotoras de crescimento na cultura do trigo

Abstract

The inoculation of growth-promoting rhizobacteria (GPR) is a sustainable management strategy capable of increasing the availability and absorption of nutrients by plants. However, the influence of the form of application (furrow or aerial part) and the level of soil fertility (P content) need to be better understood, which is the objective of this work. The study was divided into two experiments: The 1st one, carried out at UTFPR, involved three different factors. Factor A: Different bacteria, including: (Azospirilllum brasilense, Pantoea agglomerans), applied alone and together. Factor B: soil with high and low phosphorus concentrations. Factor C: application methods, via furrow and foliar. The three-factorial design was run in a two-factor format (Factor A vs B vs C), with a randomized block design with three replications. The 2nd experiment, evaluated different bacteria (Azospirilllum brasilense, Pantoea agglomerans, Bacillus subtilis, Bacillus velezensis and Pseudomonas flourescens) applied via furrow on a wheat field and was carried out on an agricultural property in a randomized block design with 3 replications. Treatments with A. brasilense and P. agglomerans, both isolated and in combination, stood out by promoting significant increases in vegetative development and plant productivity, especially in soils with high phosphorus content and/or high fertility. Soils with low P concentration and/or low fertility presented limitations in the full expression of the benefits of GPR, highlighting the need for complementary practices, such as pH correction and nutritional enrichment, to obtain the benefits of using GPR. The combination of these two bacteria proved to be particularly effective, presenting a synergistic effect that enhanced the gains in plant height, root length and dry mass. Regarding the application method, the results indicated that application via planting furrow resulted in greater accumulation of dry mass in both the root and shoot for most of the microorganisms tested in relation to aerial application. However, application via aerial part also showed benefits, especially for B. subtilis. Thus, the best strategy may depend on the specific microorganism and field crop conditions. In the field experiment, all treatments showed higher wheat yields than the control, demonstrating the benefit of these bacteria in plant development. The results obtained in this study demonstrate the relevance of GPR in sustainable agricultural management, showing that their effectiveness is influenced by several factors, such as soil fertility, the application method and the interaction between the microorganisms used.