Morfologia, valor nutritivo e anatomia de Brachiaria brizantha sob doses de fósforo e idades de corte

Abstract

Aiming to evaluate the effect of phosphorus doses and cutting ages on the morphology and nutritive value of Brachiaria brizantha Stapf cv. Marandu and to correlate anatomical characteristics with nutritional value, a completely randomized experiment was conducted with 4 replications, in a 3 x 5 factorial scheme, with 3 cutting ages (28, 56 and 84 days) and 5 doses of P (20, 200, 400, 600 and 800 mg.dm-3). Marandu grass was cultivated in 4 dm3pots. Morphological characteristics were measured. Leaf slides were made and the photomicrographed sections wereareas of sclerenchyma (ESC), parenchymal sheath of bundles (BPF), metaxylem (MET), phloem, bulliform cells, thickness of mesophyll (MES), epidermis and distance between bundles were measured in leaves. The DM production, crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), lignin, in vitro dry matter digestibility (DIVMS) were determined. The increase in P doses and cutting ages provided an increase in DM and a reduction in DIVMS and CP. There were positive correlations between MET and FDA; mesophyll, bulliform cells and BPF with DIVMS and PB; and were negative between phloem, MET and ESC and PB.