Bromatological characterization and contamination by deoxynivalenol-DON of wheat cultivated under nitrogen management strategies

Abstract

Chemical composition and contamination of wheat kernels (Triticum aestivum L.) directly affect the quality of the flour obtained from them, determining its acceptability and use by industry. Field trials were conducted to evaluate the effect of agricultural practices on wheat kernel quality. Cultivation of wheat was carried out following maize or soybean cultivation (crop succession), with application of nitrogen doses in topdressing (0, 30, 60, 90, and 120 kg ha^-1), using seeds inoculated or not inoculated with Azospirillum brasilense. The parameters evaluated consisted of chemical composition (protein, lipid, ash, starch, and total carbohydrate) and natural occurrence of contamination by deoxynivalenol-DON. Data were subjected to analysis of variance (ANOVA), comparison of means by Tukey’s test (<0.05), and regression to nitrogen doses. Crop succession resulted in changes to kernel composition (p <0.05), except for lipid content, and contamination by DON. Lower protein (-21.6%) and higher total carbohydrate content (+4.5%) were observed when wheat was cultivated after maize, in comparison with soybean succession, and no application of nitrogen in topdressing (0 kg ha^-1). Protein content was the factor with the greatest variation (12.7 to 16.5%, an increment of 30.3%) and directly correlated with nitrogen fertilization (r >0.80; p <0.05). In terms of contamination by DON, 83.1% (133/160) of the samples presented contamination below the current maximum tolerated limit stablished by the Brazilian legislation for whole wheat flour (<1250 ug kg^-1). Management of nitrogen availability can be recommended as an additional procedure to obtain raw materials with the desired chemical profile.