Submitted to: Agricultural Sciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/17/2014
Publication Date: 10/29/2014
Citation: Bartholomew, P.W. 2014. Self-seeding warm-season legumes for low-input forage production in the southern Great Plains of the USA. Agricultural Sciences. http://dx.doi.org/10.4236/as.2014.512121.
Interpretive Summary: The quality and quantity of feed on grass pastures in the southern Great Plains generally declines throughout the summer, as grass matures and growth slows in drying soil. This results in either reduced animal performance or increased cost for purchase of supplementary feedstuffs. Introduction of legume forages into the pasture system can mitigate both quality and supply problems, but annual cultivation and sowing may not be desirable or feasible for many producers. Few legumes are truly perennial under the temperature and moisture stresses of the southern plains, so crops that are able to survive from year to year by self-seeding may be useful in this environment. To assess the suitability of two species of warm-season legume, Korean lespedeza and Verano stylo, for the southern Great Plains, the effects of temperature and shading on their germination and seedling growth were measured in controlled environment and their forage productivity and capacity for self-seeding were evaluated in field plot trials. For a given level of accumulated temperature, germination of Korean lespedeza was the same with day/night temperatures of 59/59, 72.5/45.5, 77/68 and 86/59°F. In contrast, at similar accumulated temperatures, germination of Verano stylo was very limited at 59/59, but was increased with higher daytime maximum temperature up to 86°F. The difference in response to temperature means that the growing season for lespedeza in the southern Great Plains is potentially about eight weeks longer than for Verano stylo. Seedling growth of both species was reduced by shading, in proportion to the reduction in light energy input. Seedling growth of Korean lespedeza up to five weeks after emergence was greatest under a 72.5/45.5°F day/night temperature regime but that of Verano stylo was greatest at 86/59°F. In the field Korean lespedeza was a prolific seeder and productive of forage, though susceptible to significant loss of leaf material in late summer and fall. Verano stylo did not reseed effectively and was not a reliable forage producer for the southern Great Plains.
Technical Abstract: In the southern Great Plains (SGP) of the USA warm-season legumes can improve the quality of available forage in pasture systems based on perennial warm-season grasses. Legumes that persist through self-seeding may be especially useful in low-input systems where resources for annual replanting are limited. The productivity and capacity for self-seeding of Korean lespedeza (Kummerowia stipulacea [Maxim.] Makino) and Verano stylo (Stylosanthes hamata [L.] Taub.) were tested in controlled environment and in field plots in the SGP. At similar levels of accumulated temperature, germination of Korean lespedeza was unaffected by day/night temperature regimes between 15/15°C and 30/15°C. In contrast, at similar accumulated temperatures, germination of Verano stylo increased with higher daytime maximum temperature up to 30°C. Seedling growth of both species was reduced by shading, in proportion to the reduction in photosynthetic flux density. Growth of Korean lespedeza up to five weeks after emergence was greatest under a 22.5/7.5 °C temperature regime but that of Verano stylo was greatest at 30/15 °C. In the field Korean lespedeza was a prolific seeder and productive of forage though susceptible to significant loss of leaf material in late summer and fall. Verano stylo did not reseed effectively and was not a reliable forage producer.