Morphological composition of cultivar of Urochloa brizantha under light intensities

Abstract

The implementation of silvopastoral systems (SSP) is a management option that gives good results for animal production, but the shading of the trees can alter production, growth behavior and morphological composition of the forage. The aim of the study was to evaluate the morphological composition of Urochloa brizantha cultivars Marandu and Piatàunder natural light and artificial shading of 30 and 60%. The experiment was conducted at FMVZ - UNESP, Botucatu. The experimental design was a randomized block in factorial arrangement 3 x 2 (three shading levels: 0, 30 and 60% and two cultivars: Marandu and Piatã) with three replications and repeated measures in time (3 cuts). Sample collection occurred when the cultivars reached in 35 cm of height. Significant effects (P<0.05) of cultivar x shade x cut interaction were observed on the dry matter production of leaves and stems (Table 1). The higher production of leaves and stems (P<0.05) occurred for Piatàunder natural light in the third cut (3731 and 1920 kg/ha, respectively). The absence of shade favored greater leaf production, 35 and 27% higher than the reductions of 30 and 60% respectively. The increment of stems for Piatàunder natural light is related to the increase of inflorescences. The leaf:stem ratio was higher (P< 0.05 ) for Marandu under natural light (Table 2), with effect from the interaction cultivar x brightness level. A significant effect (P<0.05) cultivar x level of light reduction for light interception parameter was detected (Table 2). For Marandu, light levels were not influenced (P<0.05 ) light traps (Table 2), being close to the 95% criterion used for pasture management, justified by the collection at the point of balance between forage productivity and nutritional content, and strong relationship with high input grazing. The results indicate that the morphological composition of the cultivars is modified by reducing the light intensity.