Tiller Population Density and Forage Mass of Mulato II Brachiariagrass Under Contrasting Growth Rates and Canopy Heights Maintained By Continuous Stocking.

Understanding forage plant development is important for characterizing the production potential of a given genotype and also to define its potential use in pasture-based animal production systems. The aim of this study was to evaluate tillering dynamics and forage mass of hybrid brachiariagrass (Brachiaria spp) cv. Mulato II (also known in Brazil as Convert HD 364) in response to two growth rates (generated by 50 and 250 kg N ha^-1 yr^-1) and three canopy heights (10, 25 and 40 cm) kept constant by continuous stocking. The experimental design was a randomized complete block, with a 3 x 2 factorial arrangement, with three replications. Tiller population density (TPD), average tiller weight (ATW) and forage mass (FM) were evaluated during the summer (Jan to Apr 2013) in Piracicaba, SP, Brazil. ATW and FM were affected by growth rate and canopy height, while TPD was only affected by canopy height. ATW increased from 0.73 to 0.88 g tiller^-1 and FM increased from 8155 to 9415 kg DM ha^-1, when growth rate was increased by N application. Taller swards resulted in both higher ATW (1.31 g tiller^-1) and FM (13620 kg DM ha^-1). TPD was higher in shorter swards (1240 tillers m^-2) whereas swards at 25 and 40 cm had 1113 and 1023 tillers m^-2, respectively. Tillering dynamics and forage mass of Mulato II brachiariagrass are modified by changes in growth rate due to N fertilization, and by altering canopy height.