Características produtivas e fisiológicas de capim-elefante submetido à adubação nitrogenada

Abstract

The objective of this study was to evaluate forage production in shoot and root, the in vitro activity of nitrate reductase and the content of photosynthetic pigments in plants of Pennisetum purpureum cv. Cameroon subjected to nitrogen fertilizer doses. The experiment was conducted in a greenhouse in a completely randomized design with four treatments (no nitrogen, 50, 100 and 150 Kg·ha-1 of nitrogen) and four replicates. The soil was fertilized according to the analysis of fertility. Plants were harvested 60 days after planting and evaluated for dry matter yield and in vitro activity of nitrate reductase in leaf blades and roots and pigment contents. Nitrogen fertilization increased biomass production of shoots and roots of P. purpureum, as well as nitrate reductase, in both leaf blades as the root activity. As they increased the nitrogen, we observed a higher accumulation of leaves. We also observed increased activity of nitrate reductase in the blades in relation to the roots of elephant grass, and the enzyme activity increased as they increased nitrogen fertilization. The crude protein content and the content of photosynthetic pigments linearly and positively responded to nitrogen fertilization. Nitrogen fertilization increases the production of dry matter in elephant grass plants. The acti-vity of the enzyme nitrate reductase is more pronounced in the leaves than in roots, regardless of the nitrogen levels and the application of this nutrient induces the enzyme activity and the synthesis of photosynthetic pigments