Inoculation with Azospirillum brasilense associated with the use of silicon and nitrogen doses in corn and wheat crops

Abstract

It is necessary to increase the efficiency of nitrogen fertilization in corn and wheat crops, that is, it is necessary to reduce the amount of nitrogen to be applied via fertilizer, thus allowing a greater profitability for the rural producer and less environmental pollution, to be more sustainable.In this context, is included the use of inoculants containing diazotrophic bacteria, such as Azospirillum brasilense, which besides propitiating the biological fixation of N2 especially in grasses, has been highlighted by the phytohormonal action, thus promoting, further development of the root system, water and nutrients uptake, with positive effects on growth and grain yield. Another practice, which exerts numerous benefits on grasses, especially when the plants are subjected to biotic and abiotic stresses, is the use of silicon, which can be beneficial in adverse climatic conditions, which are increasingly frequent and acidic soils such as the Cerrado Brazilian. The silicon can also improve the architecture of the plant with possible increase of the photosynthetic rate, increase the efficiency of water use, resistance to lodging and attack of pests and diseases, the latter commonly observed in the simple hybrids of corn and wheat cultivars more productive. In view of the above and due to the lack of information, it is believed that there may be a synergistic effect between the inoculation with A. brasilense and the application of silicon, thus enabling a higher efficiency of nitrogen fertilization. Therefore, the objective of this research will be to evaluate the effect of N rates in topdressig and inoculation with A. brasilense associated to the application of silicon in the form of acidity corrective, in the foliar nutrients concentration, production components and grain yield of corn and wheat in the Cerrado, as well as changes in soil chemical attributes in the arable layer and the economic performance of production systems with cost and profitability analyzes. The experiment will be developed under no - tillage system in an Oxisol with clayed texture, in Selvíria - MS. The experimental design will be in randomized blocks with four replicates, arranged in a factorial scheme 2 x 5 x 2, being: two soil corrective sources (dolomitic limestone PRNT = 80% and Ca and Mg silicate as source of Si PRNT = 88% and Si total = 10%); five N rates (0, 50, 100, 150 and 200 kg ha-1, in the form of urea) applied in topdressig; with and without inoculation of the seeds with A. brasilense strains AbV5 and AbV6 (guarantee of 2x10 8 CFU per mL). The following evaluations will be carried out: nutrients and Si leaf concentrations, leaf chlorophyll index, plant height, production components, grain yield and corn and wheat straw, agronomic efficiency, and the economic performance of the production systems with cost and profitability analyzes. Besides the Si content and soil chemical attributes after the cultivation of these grains. (AU)