Effect of shading and canopy height on pasture of Andropogon gayanus in silvopastoral system

Abstract

In silvopastoral systems (SPS) canopy height and the existence of shaded and non-shaded environments can provide changes in plant development. The objective in this study was to evaluate the effect of shading and canopy height on morphogenic, structural and biomass production characteristics of Andropogon gayanus in an SPS. It was adopted a completely randomized design in a 2 × 3 factorial scheme, with four replications, being two luminosity intensities (shaded and non-shaded within a SPS) and three canopy heights (45, 55 and 65 cm). The studied area was used for 21 years in SPS and grazed by goats. The luminosity in the A. gayanus canopy in shaded areas was reduced by 40% in comparison to the non-shaded area in the SPS. There was effect of the interaction between heights and environments on the dry forage biomass, with higher values in non-shaded areas and in higher canopy heights. The leaf/stem ratio, as well as the leaf percentage did not differ between the environment luminosities and canopy heights, whereas the number of tillers was lower in the shaded areas, also where final leaf length was higher. The shade from Tabebuia sp. in SPS does not compromise the growth of A. gayanus. In SPS A. gayanus should be managed at a canopy height of 65 cm in order to present higher yield and maintain its sustainability.