Desempenho agronômico da cultura do trigo após inoculação da semente com Azospirillum brasilense

Abstract

Nitrogen (N) is a crucial element for cultivars to express their yield potential and grain quality. The use of nitrogen fertilizer, however, besides increasing production costs, may contribute to contamination of agroecosystems. In this context, the search for sustainable production models has been considered the usability of diazotrophs in fixing atmospheric N for grasses such as wheat. Thus, we intended to evaluate in this work, under field conditions, the agronomic performance of wheat after seed inoculation with Azospirillum brasilense alone or associated to N levels in the Northern region of Rio Grande do Sul, in randomized blocks design in factorial 3 x 4 with four replications. Factor A comprised N doses (0,0; 67,5 and 135,0 kg ha-1) and factor B doses of A. brasilense (0,0; 100; 200 and 300 mL ha-1). Prior to harvest the number of spikes m-2 and plant height (cm) of wheat were evaluated. After harvesting the ear length (cm), number of filled and sterile grains per ear, a thousand grain weight (g), grain yield (kg ha-1) and hectolitre mass were also determined (kg hl-1). Inoculation of wheat seeds with A. brasilense associated to doses of N affects differently wheat yield components. Positive effects were observed on variables with use of 160 mL ha-1 or higher doses of A. brasilense combined to 0,0 kg ha-1 of N. A. brasilense affected plant height and ear number. The number of filled and total grains per ear, a thousand grain weight and yield were positively influenced by use of doses between 170 and 200 mL ha-1 of the A. brasilense and absence fertilizer N. The association of A. brasilense and N affected wheat grain yield, being higher yields observed only when A. brasilense is applied in absence of N.