Adubação nitrogenada e partição de massa em plantas de Brachiaria brizantha cv. xaraés e Panicum maximum x Panicum infestum cv. massai

Abstract

The experiment was carried out in a greenhouse with the objective of evaluating the dry matter partition of capim-xaraés (Brachiaria brizantha) and capim-massai (Panicum maximum x Panicum infestum) submitted to four treatments of nitrogen (0, 40, 80, and 120 mg/dm3). A randomized design with four replications was applied. Both species were sowed in trays containing commercial agricultural substratum and 15 days after the emergence of five plants they were transferred to 5.8-dm3 vases. When the plants reached an average height of 35 cm, they were cut 5 cm from the soil to achieve a uniform cut. The nitrogen was applied four times. After forty-five days of free development the plants were cut and evaluated for dry matter of the leaf, stem, dead material, and root. The shoot to root and lamina to stem ratios were also evaluated. It was observed, according to the results that the nitrogen affected the dry matter partition of capim-xaraés, favoring the development of the shoot, but without effect on the roots. The total dry matter production of xaraes and massai shoot, as well as the lamina to stem ratio increased linearly with the doses of N, without affecting the root dry matter. It was also observed that nitrogen favors the lamina to stem relation and increases the dead material deposit in xaraes grass and massai grass.