Effect of cutting management on yield and quality of different selections of Guinea grass [Panicum maximum (Jacq.) L.] in a humid subtropical environment
Keywords:Panicum maximum, Forage yield, Genotype selection, Digestibility, Crude protein
AbstractSix genotypes (PGG-1, 4, 5, 6, 7, and 8) of Guinea grass [Panicum maximum (Jacq.) L.] were compared regarding the impact of cutting frequency on the yield-quality relationship, in a humid subtropical environment, to determine the extent of the variation that occurs between genotypes and to identify morphological attributes closely associated with forage yield and quality. The genotypes fell into two groups on the basis of their dry matter (DM) production and digestibility. High-yielding lines (PGG-1, PGG-4, and PGG-8) were able to build up a higher leaf area index (>6) during a 30-day cutting interval than low yielders (PGG-5, PGG-6, and PGG-7) which were slower in replenishing their leaf canopies. Forage produced by the high-yielding lines had higher DM digestibilities. The morphological features that most closely correlated with DM yield and digestibility were leaf number and leaf area expressed on a per tiller or per plant basis, i.e., 'leafiness.' Tiller number was negatively correlated with yield and quality. The results suggest that measures of 'leafiness' are very useful indicators of the yield and nutritive value of the forage produced by P. maximum genotypes.