How Does Plant Population Density Affect the Forage Yield of Eastern Gamagrass?

Abstract

Eastern gamagrass [Tripsacum dactyloides (L.) L.] is a perennial, warm‐season bunchgrass native to the Americas. Although much is known about the effects of fertilization and harvest frequency on the yield of eastern gamagrass, information on the effects of plant density on yield is lacking. Our objectives were to investigate the effects of plant population density on annual dry matter (DM) yield, vegetative shoot density, and basal area of plant crowns of irrigated eastern gamagrass. Cumulative forage DM yield varied significantly with year × density interactions (P < 0.01). Higher plant densities produced greater DM yields with the highest sustained forage yields obtained at a density of 4.8 plants m−2 Variation in number of vegetative shoots per square meter was attributed to year (P < 0.05) and density (P < 0.01). Higher plant densities also had a greater number of vegetative shoots; however, plots with higher initial stand densities reached equilibrium much faster than plots with lower stand densities. Variation in crown area was associated to year × density interactions (P < 0.01). Mature shoots near the edge of the crown probably produce a greater number of tillers until an equilibrium is reached. This is suggested by our data where the number of vegetative shoots per plant increased with decreasing plant density. Most planting recommendations for eastern gamagrass call for seeding into wide rows. These recommendations were developed to enhance seed production stands and facilitate the use of field equipment. Narrower row spacings may facilitate stand establishment while increasing forage production early in the life of the stand.