No abstract

This study aimed to evaluate the effects of a biostimulant on the morphogenesis, structure, productivity, and chemical composition of Urochloa brizantha cv. Marandu, managed under two nitrogen fertilization levels. Collections were carried out during the dry (June to September) and the rainy season (September to April). The experimental area was divided into 48 plots of 8 m2 each, using a randomized block design in a 4 × 2 factorial arrangement (0, 1, 2, and 3 L ha−1 of biostimulant × 50 and 150 kg N ha−1 year−1), and subdivided over time into dry and rainy seasons. Treatments were applied in a single dose. An interaction was observed between biostimulant and nitrogen fertilization for the total forage dry matter production and daily forage dry matter production, in which an increase of 30.1 and 25.3% was observed in the total dry matter production and 33.7 and 27.6% in the daily dry matter production when using 1 and 2 L ha−1 of biostimulant, respectively, compared to the non-application of biostimulant and with fertilization of 50 kg N ha−1 year−1. The leaf life-span showed a triple interaction (biostimulant × nitrogen fertilization × season), and a decomposition of the interaction showed that the fertilization of 150 kg N ha−1 year−1 provided a shorter leaf life-span during the dry season, with no difference for the other combinations of factors. No interactions were found for the chemical-bromatological composition, with no differences for the biostimulant application. Biostimulant doses of 1 and 2 L ha−1 increase the dry matter production per hectare in the nitrogen fertilization of 50 kg N ha−1 year−1, but its action is not effective with the highest nitrogen fertilization (150 kg N ha−1 year−1).