Produção, qualidade fisiológica e industrial de sementes de trigo: associação de azospirillum brasiliense com nitrogênio

Abstract

The objective of this work was to evaluate the effect of different strains of the bacterium of the genus Azospirillum sp., Associated with the application of nitrogen doses in the wheat crop, and its reflection on the agronomic, physiological and industrial quality of seeds produced. The experiment consisted of a randomized block design in a double factorial scheme, 4x5 with four replications, totaling 80 experimental units. The treatments were composed of four combinations of two strains of the bacterium Azospirillum brasilense and five doses of nitrogen: control (zero); 30; 60; 90 and 120 kg of nitrogen per hectare. The evaluation of the agronomic characteristics, physiological and industrial quality of the seeds produced will be carried out, during the development of the crop, the leaves will be collected for biochemical analysis. It was found that inoculation with the ABb5 and ABv5 strains in isolation and associated, provided an increase in spike weight and length, as well as in a greater number of fertile tines when compared to the control. The inoculation with the strains ABv5 and ABv6, both in isolation and in association, were highlighted in relation to the control for the variables weight, weight of one thousand seeds and grain yield. For the first germination count, interaction between doses and inoculation forms was observed. The isolates ABv5 and AVb6 both in isolated and associated ways provided better results for germination, accelerated aging and electrical conductivity when compared with the control. However, when the inoculation was performed with the association of the strains (ABv5 + ABv6), the results were higher than the other treatments, showing a mean difference of 11 pp for G, 15 pp for AE and 6.68 μS.cm-1. g-1 for CE. For these same variables, it was verified that the different doses of nitrogen influenced positively ,. The aerial part length, root and total seedlings and dry mass of shoot, root and total seedlings did not statistically differ in relation to the inoculation the applied nitrogen doses. It was verified that the strains of the bacterium Azospirillum brasilense positively influenced the index of total leaf chlorophyll, nitrogen content in the leaf and protein content when applied in isolation, however, if the best result was obtained when they were applied in a way (ICFT) and 0.0286 g.Kg-1 of nitrogen in the leaf and 0.024 mg.g-1MF of protein in the leaf. For amino acid variables, there was interaction between treatments, in relation to total soluble sugar, inoculation with the two strains (ABv5 + ABv6) accumulated more sugars in the leaf, in relation to the other treatments. Nitrate reductase activity was higher in the inoculated plants with the association of the strains (ABv5 + ABv6), and for each applied Kg-1 of N increased 0.0181 nmol NO2-.g-1MF.h-1. The variables protein in the grain, number of fall and gluten strength, positively responded to the inoculation via seeds with strains ABv5 and ABv6, individually inoculated and associated with the control. It was observed a positive linear trend, where for each Kg of N applied, it provided increment 0.0122 and 0.127% for protein in the grain, number of fall respectively. As for gluten (W), a quadratic trend was evidenced, with the highest technical efficiency dose of 79.9 kg.ha-1 of nitrogen. For stability, extensibility and toughness, the best results were obtained when the inoculation was performed with the strains in an associated manner (ABv5 + ABv6), presented an increase of 3.78; 12.98 and 13.52 percentage points in relation to the control. Positive results were also observed in relation to the applied nitrogen rates in coverage. The addition of strains ABv5 and ABv6 via seed inoculation, as well as nitrogen doses, improves the agronomic traits, the physiological quality of wheat seed produced and the better expression of the technological quality of wheat flour.