Inoculação com Azospirillum brasilense associada a redução na adubação nitrogenada de cobertura em cultivares de trigo

Abstract

The survey was conducted during the 2011 growing season in the region of Guarapuava-PR, aiming to obtain information about the use of the bacteria Azospirillum brasilense on wheat croop, inoculated in the seeds, with and without the reduction of nitrogen topdressing. For this it was experiment used two cultivars (BRS Tangara and Quartzo) in two cultivation sites, the experimental field CEDETEG - UNICENTRO and Farm Três Capões Company MLCV - Santa Maria Group. The aim of this paper was to evaluate the effect of different treatments with A. brasilense on morphological and agronomic characteristics; determining the association of genotypes studied; analyzing the effect of reduced nitrogen, associated with the inoculation on the quality of the flour produced. The experimental design was a randomized block design in a factorial 7x2, seven combinations of N and doses of A. brasilense, two cultivars and five replications, totaling 70 plots. The treatments were 110 kg.ha?¹ of N associated with 300 ml.ha?¹, 100 ml.ha?¹ and 0 ml.ha?¹ of A. brasillense, 55 kg.ha?¹ of N associated with 300 ml.ha?¹, 100 ml.ha?¹ and 0 ml.ha?¹ of A. brasillense and treatment with 0 kg.ha?¹ of N and 0 mL.ha?¹ of A. brasillense. The morphological characteristics, number of tillers and spikes were obtained before harvesting. Grains per spike and agronomic characteristics, hectoliter weight, thousand grain weight and grain yield were obtained after harvest. For the analyzes of quality of flour it was used the laboratory of flour quality belonging to Moageira Irati, where the tests were falling number, wet gluten, farinograph and alveography (absorption only). The cultivation local influenced the morphological number of tillers and ears per plant of wheat cultivars evaluated and it has influenced the results obtained for agronomic hectoliter weight and thousand grain weight, with and without the reduction of nitrogen application and use of A. brasilense, this factor is associated with higher soil fertility, previous crop, historic crop rotation and total rainfall of Farm Três Capões. The choice of cultivar influenced the morphological and agronomic characteristics evaluated, BRS Tangara being higher for number of tillers and spike and lower for grains per spike, hectolitre weight, thousand grain weight and grain yield. The use of the bacterium A. brasilense and reduction nitrogen fertilization did not result in reduction of agronomic characteristics evaluated. Grain yield was not affected by the reduction of topdressing with nitrogen when used A. brasilense, and the cultivar Quartzo, more responsive to the use of inoculation. For quality flour, the results obtained demonstrate that the local culture influenced the evaluated parameters which shows the better effect of soil fertility, preceding crops and rainfall of Farm Três Capões, however it did not influenced with the same magnitude the parameters analyzed. It was possible to detect the effect of cultivar, in all tests quality flour, and BRS Tangara that showed the best results for all parameters with the exception of extensibility (L) and falling number, which demonstrates the importance of for genotype obtaining a particular type of flour. There was an interaction of growing site with the evaluated cultivar and their association with the bacterium A. brasilense to the parameters tenacity (P), relative tenacity/extensibility (P/L), strength of gluten (W), falling number and absorption. For isolated treatments should be highlighted the positive effect of inoculation with the bacterium A. brasilense it was observed to tenacity (P) and relative tenacity/extensibility (P/L), especially for BRS Tangara, and in the other remaining tests, the reduction of nitrogen fertilization did not cause losses in quality of flour. The characteristic strength of gluten, analyzed in Farm Três Capões, was influenced by topdressing with nitrogen, it is not recommended reduction to not compromise this parameter.