Revista Brasileira de Zootecnia
On-line version ISSN 1806-9290
SANTOS, Manoel Eduardo Rozalino et al. Structure of signal grass pasture with height variation. R. Bras. Zootec. [online]. 2010, vol.39, n.10, pp. 2125-2131. ISSN 1806-9290. http://dx.doi.org/10.1590/S1516-35982010001000004.
This study was carried out aiming to evaluate the structural characteristics of Brachiaria decumbens cv. Basilisk pasture. Four heights of plants (10, 20, 30 and 40 cm) were evaluated within the same grazing area in a randomized block experimental design with two repetitions. Variation in the initial height of the signal grass pasture plant showed a linear and a negative response. The masses of green leaf blade mass, live stem, dead material, live forage and total forage linearly increased with heights of the plants on the pasture. However, it was observed a linear reduction in green leaf blade/live stem ratio and the height of the plants on the pasture (from 1.16 to 0.58). Plant height on the pasture had a stronger effect on the increase of live stem and the dead material masses than it had on the green leaf blade mass. Volumetric density of green leaf blade decreased (from 97.09 to 39.07 kg/cm ha DM) with plant height on the pasture. The same response was found for volumetric densities of live forage (from 181.62 to 107.85 kg/cm.ha dry matter) and total forage (from 283.39 to 195.72 kg/cm.ha dry matter). On the other hand, the plant heights on pasture did not affect volumetric density of live stem and dead material, which showed mean values 80.95 and 95.61 kg/cm.ha DM, respectively. The heights of the plants on pasture had a quadratic effect on light interception by the canopy. Grazing areas with heights of 10, 20, 30 and 40 cm showed light interception values of 56.15, 85.16, 93.39 and 96.57%, respectively. It occurs and temporal variabilities on the B. decumbens pasture structure managed under continuous stocking.
Keywords : Brachiaria decumbens; bulk density of forage; forage mass; light interception; pasture height.