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Publication Date
1981
Description
Limpograss (Hemarthria altissima [Poir] Stapf. et C.E. Hubb), introduced into the U.S. in 1964, has been evaluated for use as a pasture grass. Under Florida conditions it has shown yield potential equal to or greater than other tropical pasture grasses. The cultivar Bigalta has higher in-vitro organic-matter digestion (IVOMD) than other tropical grasses at comparable growth stages. Early evaluations of limpograss involved only three clones, but additional genotypes were collected and introduced during the late 1960s and early 1970s, and an evaluation scheme for this germ plasm was undertaken. Our objectives were to evaluate rapidly the available germ plasm of limpograss for genetic diversity in traits of importance as a component of a forage-livestock system, to compare clipping and grazing as evaluation techniques, and to select superior genotypes for animal performance experiments. Following preliminary testing of 53 clones in greenhouse and small-plot clipping trials, 22 clones were selected for evaluation by clipping and 27 by grazing. Greater winter-stand loss was observed with grazing than with clipping, and by autumn of the second year some genotypes were eliminated. Others yielded from 880 to 15,800 kg/ha, and IVOMD ranged from 59% to 73% for 5-week regrowth forage. Eight genotypes selected from these experiments were then evaluated at four frequencies of grazing (3, 5, 7, and 9 weeks) in a third experiment. Persistence was poorest at the 3-week grazing frequency. Total seasonal yields were similar at the 5- and 7-week grazing frequencies. The tetraploid genotypes Bigalta and P.I. 364888 had markedly higher yields at the 5- and 9-week grazing frequency. P.I. 364888 was generally the highest-yielding entry at all grazing frequencies and was not significantly lower in IVOMD than Bigalta. Bigalta was significantly lower in persistence at the 5- and 7-week rest interval than P .I. 364888. From this research, it is evident that limpograss is a forage with good potential for utilization in the humid tropics on soils that may be intermittently flooded. It is often superior to other tropical grasses in subtropical regions because it initiates regrowth earlier in spll'ing and grows later in autumn. Newly collected germ plasm shows genetic diversity for traits not present in the released cultiva:rs. During the last 6 years over 50 introductions of limpograss have been evaluated, and one genotype (P.I. 364888) has been identified that has superior yield and persistence under grazing and is moderately high in digestion. The utilization of grazing animals in the early phase of evaluation has shortened the time necessary to advance plant germ plasm from plant introductions to cultivar release.
Citation
Quesenberry, K H.; Ocumpaugh, W R.; and Ruelke, O C., "Hemarthria altissima: A Pasture Grass for the Tropics" (1981). IGC Proceedings (1977-2023). 1.
(URL: https://uknowledge.uky.edu/igc/1981/section12/1)
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Hemarthria altissima: A Pasture Grass for the Tropics
Limpograss (Hemarthria altissima [Poir] Stapf. et C.E. Hubb), introduced into the U.S. in 1964, has been evaluated for use as a pasture grass. Under Florida conditions it has shown yield potential equal to or greater than other tropical pasture grasses. The cultivar Bigalta has higher in-vitro organic-matter digestion (IVOMD) than other tropical grasses at comparable growth stages. Early evaluations of limpograss involved only three clones, but additional genotypes were collected and introduced during the late 1960s and early 1970s, and an evaluation scheme for this germ plasm was undertaken. Our objectives were to evaluate rapidly the available germ plasm of limpograss for genetic diversity in traits of importance as a component of a forage-livestock system, to compare clipping and grazing as evaluation techniques, and to select superior genotypes for animal performance experiments. Following preliminary testing of 53 clones in greenhouse and small-plot clipping trials, 22 clones were selected for evaluation by clipping and 27 by grazing. Greater winter-stand loss was observed with grazing than with clipping, and by autumn of the second year some genotypes were eliminated. Others yielded from 880 to 15,800 kg/ha, and IVOMD ranged from 59% to 73% for 5-week regrowth forage. Eight genotypes selected from these experiments were then evaluated at four frequencies of grazing (3, 5, 7, and 9 weeks) in a third experiment. Persistence was poorest at the 3-week grazing frequency. Total seasonal yields were similar at the 5- and 7-week grazing frequencies. The tetraploid genotypes Bigalta and P.I. 364888 had markedly higher yields at the 5- and 9-week grazing frequency. P.I. 364888 was generally the highest-yielding entry at all grazing frequencies and was not significantly lower in IVOMD than Bigalta. Bigalta was significantly lower in persistence at the 5- and 7-week rest interval than P .I. 364888. From this research, it is evident that limpograss is a forage with good potential for utilization in the humid tropics on soils that may be intermittently flooded. It is often superior to other tropical grasses in subtropical regions because it initiates regrowth earlier in spll'ing and grows later in autumn. Newly collected germ plasm shows genetic diversity for traits not present in the released cultiva:rs. During the last 6 years over 50 introductions of limpograss have been evaluated, and one genotype (P.I. 364888) has been identified that has superior yield and persistence under grazing and is moderately high in digestion. The utilization of grazing animals in the early phase of evaluation has shortened the time necessary to advance plant germ plasm from plant introductions to cultivar release.
