Morphophysiology and nutritive value of signalgrass under natural shading and full sunlight

Abstract

The objective of this trial was to evaluate the morphophysiological traits and nutritive value of Brachiaria decumbens, during 2003 and 2004 rainy seasons, in a silvopastoral system, with grass alone (30 m width), alternated with grass plus trees (Acacia mangium, A. angustissima, Mimosa arthemisiana, Leucaena leucocephala x L. diversifolia, Eucalyptus grandis) strips (10 m width). The experimental design was a randomized block arranged in a split plot design (morphophysiological traits) or split-split plot (nutritive value traits), and replicated four times. The level of shading was 65% of incident radiation out of the wood in 2003, and 35% in 2004 after harvesting of some Eucalyptus trees. Under shade, tiller population leaf area and forage mass index were higher in the second year than in the first. Forage neutral detergent fiber value was higher at full sunlight than in the shade, while the crude protein content and in vitro dry matter digestibility were higher under the trees. Moderate shading increases crude protein and reduces neutral detergent fiber, therefore improving forage digestibility of grasses growing under trees.