Structure and nutritional value of BRS Zuri grass under shading

ABSTRACT The objective was to determine the structural and nutritive parameters for Panicum maximum cv. BRS Zuri under a Eucalyptus shading system, in rainy and dry seasons. At the beginning of each season, the treatments (foliar fertilization levels of 0, 3, 6 and 9 L ha-1) were applied and evaluated at 28, 56, and 84 growing days. The treatments did not affect significantly (p ≥ 0.05) the evaluated parameters. The systems (shading and full sun) and seasons did not change (p ≥ 0.05) forage and root masses. The leaf crude protein content was higher (p ≤ 0.05) in the dry season. Height, leaf mass, stem and dead material, neutral and acid detergent fiber contents, and in vitro dry matter digestibility were affected (p ≤ 0.05) by the system x season. The growing days did not affect (p ≥ 0.05) forage mass. The mass of dead material decreased (p ≤ 0.05) over the evaluated intervals. The other parameters were affected (p ≤ 0.05) by system × growing days. Based on the results, the forage and root masses show that the cv. BRS Zuri is adapted to the shading in the proposed experimental conditions. These masses added to the crude protein content indicate adaptation to low rainfall, inherent to the dry season, while foliar fertilization applied at the beginning of seasons did not affect the structural and nutritive parameters of BRS Zuri grass.

摘要 本研究旨在明确桉树（Eucalyptus）遮荫系统下，雨季与旱季中BRS Zuri品种大黍（Panicum maximum cv. BRS Zuri）的结构与营养参数。于每个季节初期施加叶面施肥水平为0、3、6、9 L·ha⁻¹的处理，并在生育期第28、56、84天开展测定评估。结果显示，各试验处理对所测定的参数无显著影响（p≥0.05）。遮荫与全光照两种系统以及季节对饲草与根系生物量无显著影响（p≥0.05）。旱季叶片粗蛋白含量更高（p≤0.05）。株高、叶片生物量、茎秆与枯落物生物量、中性洗涤纤维（neutral detergent fiber）与酸性洗涤纤维（acid detergent fiber）含量以及体外干物质消化率（in vitro dry matter digestibility）受系统×季节交互作用显著影响（p≤0.05）。生育天数对饲草总生物量无显著影响（p≥0.05）。枯落物生物量随测定周期显著降低（p≤0.05）。其余参数受系统×生育天数交互作用显著影响（p≤0.05）。基于试验结果，饲草与根系生物量表明BRS Zuri品种大黍在本试验设置的条件下可适应遮荫环境。结合粗蛋白含量来看，该品种可适应旱季固有的低降雨环境；而季节初期施加的叶面肥并未对BRS Zuri饲草的结构与营养参数产生显著影响。