The work was carried out at Coronel Pacheco, MG, Brazil, from October 2002 to April 2003 with the objective of evaluating the effects of two post-grazing residues (50 and 100 cm) on the interception of photosynthetically active radiation (PAR) and light extinction coefficient; relative contribution of tiller classes (basal and aerial) to leaf area index (LAI) and herbage accumulation of elephant grass swards (Pennisetum purpureum Schum.) cv. Napier subjected to grazing intervals of 30 days. The experimental design was a complete randomized block, and treatments were allocated to experimental units using a split plot arrangement, with four replicates. Post-grazing residues were allocated to plots and tiller classes to sub plots. Sward LAI, PAR interception and light extinction coefficient were affected by heigth of post-grazing residue. The intercepted PAR was higher in the summer than in the spring, with higher values recorded for the 100 cm residues. Variations in LAI and intercepted PAR were not consistently associated throughout the experimental period. LAI and herbage accumulation showed seasonal variations related to the varying contribution of aerial and basal tillers to sward tiller population.
Pennisetum purpureum; herbage accumulation; light extinction coefficient; canopy light interception; stubble height
