Influence of nitrogen levels on leaf anatomy and nutritive value of millennium grass

Resumo

The objective of this study was to evaluate the influence of nitrogen levels (control = without N, 150, 300 and 450 kg N/ha), on proportions of tissues of leaf blades and the nutritional value of Millennium grass, on grazing system with intermittent stocking during the summer of 2007 in a completely randomized design. The last and penultimate expanded leaves of vegetative tillers were collected for this study. The proportion of abaxial epidermis (EPIaba) and vascular tissue (VT) decreased linearly with increasing levels of nitrogen. The percentage of sclerenchyma (SC) was 40,8% e 36,4% lower in pasture fertilized with 150, 300 kg N/ha and 25% lower for those with 450 kg in comparison to pasture without fertilization. The percentage of mesophyll (MES) increased linearly with nitrogen levels, with up to 20,3% higher for pasture with 450kg of N in relation to control level. The morphological characteristics, leaf area (LA), specific leaf area (SLA) and length, increased linearly with increasing nitrogen levels. The percentage of crude protein (CP ) and in vitro digestibility of dry matter (IVDDM ) were higher for treatments with higher fertilization (300 and 450 kg). The EPIaba and the levels of acid detergent fiber (ADF) and neutral detergent fiber (NDF) had positive correlation. The same occurred between IVDDM and parenchyma bundle sheath (PBS). The nitrogen applied to pasture has influence on improving the nutritive value of leaf blades of millennium grass and on the proportion of tissues considered of high digestibility.