Inoculação de Azospirillum brasiliense em trigo, sob doses de nitrogênio

Abstract

The southern region is the main producer of wheat (Triticum aestivum) in the country, the culture provides one of the best soil coverings for the direct planting system, and its cultivation improves the sustainability of the agricultural system, reducing the proliferation of weeds and still contributes a lot to farmers' income. Nitrogen is the nutrient that most affects wheat productivity and currently fertilizers account for a high proportion of crop costs. Therefore, a greater profitability of the culture is sought, through the better use of nitrogen. For this, much has been studied and used diazotrophic bacteria, which carry out the process of biological fixation of nitrogen gas. Thus, this work sought to study the best use of nitrogen, through the use of a commercial inoculant (Azospirillum brasiliense), under different doses of nitrogen. The experimental design used was in randomized blocks, with five treatments and four replications. The treatments are: T1 (without application of mineral N), T2 (150 mg dm-³), T3 (300 mg dm-³ - recommended dose), T4 (450 mg dm-³) and T5 (600 mg dm-³), all noculated with the commercial inoculant (Azospirillum brasiliense 2x10¹¹ CFU/L). The data were submitted to analysis of variance and regression analysis, so it was found that increasing doses of nitrogen in wheat inoculated with Azospirillum brasiliense provided a greater number of tillers, shoot dry mass and grain yield. For plant height and thousand-grain weight there was no statistical difference, possibly due to nitrogen supply through biological nitrogen fixation performed by bacteria Azospirillum brasiliense.