FORAGE ACCUMULATION DURING THE STOCKING PERIOD ON PASTURES SUBJECTED TO INTERMITTENT STOCKING

Abstract The aim of this study was to evaluate the forage accumulation during the stocking period on Kikuyu grass pastures (Pennisetum clandestinum Hochst. Ex. Chiov) subjected to intermittent stocking. Treatments consisted of four defoliation levels (removal of 40, 50, 60, and 70% relative to the initial height) starting from the same pre-grazing height (20 cm). The following variables were evaluated: leaf and stem elongation rates (evaluated during four times across the period of occupation), leaf area index, and forage accumulation rates. Additionally, ten tillers/strip were evaluated for the same variables into exclusion cages. The linear, quadratic and cubic effects of severity of defoliation were evaluated by orthogonal polynomials contrasts with 5% of significance level. There was a linear and inverse relationship between the proportion of removed leaf area index with leaf elongation and herbage accumulation rate. The leaf elongation rate in individual tillers and the forage accumulation rates of tillers on excluded areas from grazing were greater than those under grazing. During the stocking period on pastures submitted to intermittent grazing, forage accumulation was observed and it was linear and negatively correlated with the proportion of leaf area removed.

摘要 本研究旨在评估间歇放牧（intermittent stocking）条件下，基库尤草（Kikuyu grass，*Pennisetum clandestinum* Hochst. Ex. Chiov）牧场在放牧期内的饲草积累量。试验设置4种刈割强度，即相对于预放牧初始高度分别刈割40%、50%、60%和70%，所有处理的预放牧初始高度统一为20 cm。本研究测定的指标包括：叶茎伸长速率（在放牧占用期内分4次测定）、叶面积指数（leaf area index）以及饲草积累速率。此外，在免牧笼（exclusion cages）内的每个样带选取10个分株，对上述相同指标进行测定。采用正交多项式对比法评估刈割强度的线性、二次及三次效应，显著性水平设定为5%。研究发现，刈除的叶面积占比与叶伸长速率及饲草积累速率呈线性负相关关系。单株分株的叶伸长速率以及免牧区分株的饲草积累速率均高于放牧区植株。在间歇放牧牧场的放牧周期内，观测到饲草积累量与刈除的叶面积占比呈线性负相关关系。