Evaluation of Limpograss [Hemarthria Altissima] Breeding Lines for Use in Florida Forage-Livestock Systems.

Limpograss is used to extend the grazing season and as stockpiled forage for winter grazing in poorly drained soils of the Florida peninsula. A single cultivar, ‘Floralta’, occupies nearly all area planted to limpograss. In order to increase genetic diversity and with the goal of improving persistence and nutritive value of available cultivars, a limpograss breeding program developed 50 hybrids. After initial evaluation, the five best lines were compared in two experiments to determine their performance under a range of grazing frequencies and intensities and to measure their productivity and nutritive value when stockpiled. Breeding lines 1, 4F, 10, 32, and 34 plus Floralta were tested under mob stocking comparing a combination of two grazing frequencies (initiation of grazing at 80 and 95% pre-grazing canopy light interception [LI]) and two post-grazing stubble heights (SH; 20 and 30 cm). Herbage accumulated (HA) was greater for Entry 10 (11.6 Mg ha^-1) than for 32, 1, and 34 (≤ 8.4 Mg ha^-1) but not different from 4F and Floralta (10.4 and 9.5 Mg ha^-1, respectively). Entry 10 also had the lowest weed frequency and longest grazing season. Total-season HA was not different among LI levels, but 95% LI resulted in tall, stemmy limpograss canopies with high levels of lodging and trampling. The stockpiling experiment tested four entries (1, 4F, 10, and Floralta) fertilized with 50 or 100 kg N ha^-1 and stockpiled for 8, 12, or 16 wk. Entries 4F and 10 had greater HA than Floralta, and 4F had the highest digestibility (590 g kg^-1). Digestibility across entries decreased only from 584 g kg^-1 at 8 wk to 552 g kg^-1 at 16 wk. Experiments show that Entries 10 and 4F are superior to Floralta and that 95% LI is not well suited as a target for initiation of grazing limpograss.