Demography and density of signalgrass tillers grazed under intermittent stock grazing

Abstract

The objective of this work was to assess the effects of grazing intensities and defoliation frequencies on the demography and density of signalgrass (Urochloa decumbens syn. Brachiaria decumbens) tillers under intermittent stocking. Two grazing intensities (5 and 10 cm after‑grazing stubble height) and two defoliation frequencies (rest periods determined by 95 or 100% of light interception, LI) were evaluated, from August 2007 to August 2008. It was used the completely randomized design, in factorial arrangement with four replicates. Tiller densities and appearance and survival rates of basal (TDb, ARb, SRb, respectively) and aerial+basal tillers (TDab, ARab, SRab) were evaluated. The highest ARb and ARab, in the autumn, were observed in pastures defoliated at 10 cm. Nevertheless, in the late spring and in the summer, the 5 cm intensity resulted in higher rates, which promoted higher TDb. The SRb was higher in the summer for pastures managed at 10 cm. The pasture grazing management that promotes the highest TDab, ARab and SRab, during periods of fast pasture growth, is the combination of 10 cm grazing intensity and 95% LI of defoliation frequecy.