Limpograss Breeding Line Responses To Grazing Frequency In South Florida.

Limpograss (Hemarthria altissima [Poir.] Stapf & C.E. Hubb.) is a warm-season grass used for grazing, hay, and haylage production. Limpograss is widely used in South Florida due to its tolerance of poorly drained soils. A breeding effort was conducted to hybridize two cultivars of limpograss, ‘Floralta’ and ‘Bigalta’, with the objective to achieve plants with greater nutritive value and herbage accumulation. A clipping study was conducted to evaluate 50 limpograss hybrids entries for 2 yr. and 5 entries were selected based on their superior herbage accumulation, nutritive value, and persistence. The objective of this study was to evaluate herbage accumulation, nutritive value, and persistence of the five selected entries (1, 10, 4F, 62, 41), Floralta, and Bigalta under two grazing frequencies (2 and 4 wk) in a completely randomized design with three replicates. The experiment was conducted at the UF/IFAS Range Cattle Research and Education Center, Ona, FL from May to November 2010 and 2012. The plots were established in 2009 and 2011 and fertilized with 120 kg N ha^-1 divided in three applications of 40 kg ha^-1 in May, June, and August 2010 and 2012. Plots were 5 × 5 m and grazed using the mob stocking technique to a post-grazing stubble height of 17 cm. Entry 10 had the greatest total annual herbage accumulation (6.6 Mg ha^-1), followed by Floralta and 1 (5.8 Mg ha^-1), which had greater herbage accumulation than 4F, 62, 41, and Bigalta (5.0 Mg ha^-1). Plots grazed every 4 wk had greater total annual herbage accumulation than plots grazed every 2 wk (4.6 vs. 2.9 Mg ha^-1). There was no difference in crude protein (CP) concentrations among entries (105 g kg^-1); however, Floralta and Entry 10 had greater in vitro digestible organic matter (IVDOM) concentrations than 1, 4F, 62, 41, and Bigalta. Plots grazed at 2 wk had greater CP and IVDOM than at 4 wk (120 vs. 100 g kg^-1 and 550 vs. 525 g kg^-1 for CP and IVDOM concentrations, respectively). There was no difference in limpograss ground cover among entries (79%) at the end of the experimental period. In addition, ground cover between plots grazed at 2 and 4 wk regrowth interval were similar (78%). Entry 10 presented superior attributes and has potential to be released as a new limpograss cultivar in Florida.