Azospirillum brasilense na produção e composição mineral da forragem de azevém anual (Lolium multiflorum Lam.)

Abstract

The aim of the study was to evaluate, under greenhouse conditions, the effects of Azospirillum brasilense, strains AbV5 e AbV6, inoculation associated to different nitrogen fertilization levels on structural characteristics, dry matter production and ryegrass nutrient levels (Lolium multiflorum Lam.) BRS Ponteio. The experimental units corresponded to vessels with a capacity of 2.43 dm³, totaling forty vessels, allocated in a completely randomized design with four replications.Nitrogen fertilizer was applied 20% at the time of sowing, and 80% in covering, at tillering. The ryegrass seeds were inoculated using a commercial product called MASTERFIXL® Gramíneas at a dosage of 300 mL.ha-1 . In this work, the following variables were analyzed: extended plant height, number of tillers/vessels, number of leaves growing, expanded senescent and dead/tiller, leaf:stem ratio in leaf area, dry matter of leaf, stem and total, and the aerial and root nutritional composition (nitrogen, phosphorus, potassium, calcium and magnesium).The results were submitted to analysis of variance and mean comparison Tukey test or linear regression (p ≤ 0.05). Nitrogen fertilization increased leaf area, leaf:stem ratio and the number of tillers of ryegrass. Azospirillum brasilense inoculation leveraged tillering ryegrass with at least 50% of the recommended nitrogen fertilization. Meanwhile, the nitrogen fertilization level had no effect on the development of aerial and root systems, increasing only the accumulated phosphorus.