Sward structure, light interception and herbage accumulation in forage peanut cv. Belmonte subjected to strategies of intermittent grazing management

ABSTRACT. Nitrogen fertilization ensures productivity and persistency of pastures, but may be expensive. Perennial forage peanut, becomes an interesting alternative for N supply. Little is known about its use under grazing. The objective of this study was to evaluate regrowth process of forage peanut using an experimental protocol analogous to tropical forage grasses under rotational grazing. Treatments corresponded to two pre- (95% and maximum canopy light interception - LI95% and LIMax) and two post-grazing (post-grazing heights of 40 and 60% of pre-grazing height) conditions, in a 2x2 factorial arrangement in a randomized complete block design (n = 4). Targets of LI pre-grazing affected pre-grazing height and LI post-grazing. The residual sward LAI did not vary, resulting in similar grazing interval. Greater rates and total herbage accumulation were recorded for LIMax target, consequence of the greater accumulation of stolons at the lower strata of the swards. Greater percentage of leaflets was recorded for the LI95% target. Given the stoloniferous growth habit of forage peanut, stolon accumulation in the lower strata of the sward do not represent a limitation to leaf accumulation and morphological composition. The greater pre-grazing sward height associated with the LIMax target facilitate herbage prehension and intake, further investigation is needed.

摘要。氮肥施用可保障牧场的生产力与持久性，但成本往往较高。多年生饲用花生因此成为氮素供给的极具潜力的替代方案。目前针对其在放牧条件下的应用研究尚少。本研究旨在采用与热带牧草轮牧试验相似的试验方案，评估饲用花生的再生过程。试验采用2×2析因设计，设置2个放牧前处理（冠层光照截获率95%，即LI95%，以及最大冠层光照截获率LIMax）与2个放牧后处理（放牧后高度为放牧前高度的40%、60%），并采用随机完全区组设计，重复数n=4。放牧前冠层光照截获率目标会影响放牧前高度与放牧后冠层光照截获率。剩余草地群落的叶面积指数（Leaf Area Index, LAI）无显著变化，因此放牧间隔期相近。LIMax目标组的牧草累积速率与总累积量均更高，这是由于其草地群落下层匍匐茎累积量更大。LI95%目标组的小叶占比更高。鉴于饲用花生具有匍匐生长的习性，草地群落下层的匍匐茎累积并不会限制叶片累积与形态组成。与LIMax目标对应的更高放牧前草地群落高度，更便于牧草的采食与摄取，仍需开展进一步研究。