Plant Density and Environment Effects on Orchardgrass–White Clover Mixtures

Abstract

ABSTRACTEarlier research indicated that orchardgrass (Dactylis glomerata L.) cultivars affected white clover (Trifolium repens L.) stolon structure during establishment. We conducted a field study to determine if plant density and environment modified the effect of orchardgrass cultivars on white clover. ‘Dawn’ and ‘Pennlate’ orchardgrasses were established at 10‐, 20‐, or 40‐cm spacings in mixture with ‘Will’ white clover in a systematic plant spacing design. Plots were established in September 1996 on a Hagerstown, Berks, or Rayne soil in central Pennsylvania. Orchardgrass was harvested monthly from May to September 1997 and 1998 to determine yield and tiller number per plant. White clover plants were dug from each plant spacing and site in the fall to determine stolon structure. Orchardgrass cultivar did not affect white clover stolon structure. Orchardgrass and white clover plants were larger and more complex on the Hagerstown soil than on the lower fertility Berks and Rayne soils. The highest stolon densities occurred at the 40‐cm plant spacing on the Hagerstown soil in 1998 with >22 m of main stolon m−2 along with 8 m of first‐order branches and 1 m of second‐order branches. On the Rayne soil, plant spacing had little effect on stolon structure. Weed competition was greater on the Rayne soil (788 plants m−2 from 33 species) than on the higher fertility Hagerstown soil (157 plants m−2 from 19 species). Interspecific competition, edaphic factors, and climate interacted to govern the structure of white clover stolons and overwhelmed orchardgrass cultivar effects.