Evolution of the biomass and the profile of organic reserves during regrowth of “Brachiaria brizantha” cv. Marandu submitted to levels of nitrogen

Abstract

The regrowth of forage plants is supported by organic compounds synthesized by them. In this way, the objective was to evaluate the nitrogen (N) effect on dry biomass evolution and the profile of organics compounds on the botton of Brachiaria brizantha cv. Marandu represented by non structural carbohydrates and nitrogen compounds. Treatments were distributed in a randomized blocks design, under factorial scheme (3 x 6), with three levels of N (0, 20 e 40 mg /dm3 soil/week N) and six dates of regrowth (0, 2, 4, 8, 16 e 32 days after the uniformization cut) in a greenhouse with three repetitions for each treatment. N had positive effect (P<0.05) on the evolution of the biomass of the plants during the regrowth. Non structural carbohydrates content reduced after defoliation, which was stimulated by N levels. From the compounds that contributed to non structural carbohydrates, the reduced sugars were more sensible followed by starch and non reduced sugars which decreasing of 84, 40 and 14% respectively. N level increased the nitrogen compounds content and the highest reduction of the content after cut was showed by plants that did not received N.