Defoliation heights for palisade grass cv. Marandu in silvopastoral system

ABSTRACT The objective was to test the response of Urochloa brizantha cv. Marandu in monoculture and in silvopastoral system (SPS), at two distances from the trees, and define the best defoliation height for SPS. Four intermittent defoliation heights (25, 35, 45 and 55cm) and two distances from tree lines (2.5 and 5.0m) were evaluated in the SPS with a control defoliated with 25cm in full sun. The experiment was performed in a randomized block design with 3 replicates in a 4 × 2 + 1 split plot scheme. The control had higher forage accumulation (46.9kg/ha. day) than the SPS (31.1kg/ha. day). The bulk density was also higher in the control (0.89mg/cm³) than in SPS (0.48mg/cm³). The percentage of leaves (78.06%) and leaf/stem ratio (6.04) did not differ among the treatments. In the SPS, there was an increase of 31.07% in forage accumulation from 25 to 55cm. The forage accumulation and bulk density of Urochloa brizantha cv. Marandu in monoculture is greater than in the SPS regardless of the management goal and the distance from trees. The goal of 55cm in the SPS presented greater forage accumulation.

摘要 本试验旨在探究单播模式与林牧复合系统（silvopastoral system, SPS）中，不同距树行距离条件下马兰杜氏臂形草（Urochloa brizantha cv. Marandu）的生长响应，并明确林牧复合系统下的最优刈割高度。本试验在林牧复合系统中设置4个间歇刈割高度水平（25、35、45和55cm）与2个距树行距离水平（2.5m和5.0m），并以全光照条件下采用25cm刈割的单播处理作为对照。试验采用含3次重复的4×2+1裂区随机区组设计。结果表明：对照处理的牧草累积量为46.9kg/ha·d，高于林牧复合系统各处理的31.1kg/ha·d；对照的牧草容重为0.89mg/cm³，同样高于林牧复合系统的0.48mg/cm³。各处理间的叶片占比（78.06%）与叶茎比（6.04）无显著差异。在林牧复合系统中，当刈割高度从25cm提升至55cm时，牧草累积量增加了31.07%。无论管理目标与距树行距离如何，单播条件下马兰杜氏臂形草的牧草累积量与容重均高于林牧复合系统。林牧复合系统中，55cm刈割高度处理的牧草累积量最高。