Submitted to: Canadian Journal of Plant Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/11/1999
Publication Date: N/A
Citation: Interpretive Summary: White clover is the predominant legume of pastures in temperate climates, including the northeastern United States. Orchardgrass is commonly recommended for seeding pastures in the northeastern U.S. because of its better drought tolerance and winterhardiness compared to perennial ryegrass. Dairy producers, however, have begun to use perennial ryegrass- white clover mixtures because of the high nutritive value of this mix and partly because of popular press reports of the nutritive value and productivity of this combination in Europe and New Zealand. The objective of our study was to examine the effects of different orchardgrass and ryegrass cultivars on grass-legume plant morphology and yield. Our data indicate that grass species and cultivar can affect compatibility with white clover. Although clover yields were affected by the maturity class of the grass species, it appeared that structural features of the grass were more important than maturity per se in determining compatibility. Grass species and cultivars that produce an erect, less dense canopy would be more compatible with white clover.
Technical Abstract: Grass species and cultivars may differ in their competitiveness with white clover (Trifolium repens L.). We conducted a greenhouse experiment to evaluate the competitiveness of two cultivars of perennial ryegrass [Lolium perenne L., 'Bastion' (early maturity) and 'Rosalin' (late maturity)] and orchardgrass [Dactylis glomerata L., 'Dawn' (early maturity), and 'Pennlate' (late maturity)] with 'Will' white clover. Fourteen plants of each cultivar in monoculture were established from seed in 28-cm-diam. by 30-cm-deep pots. Mixtures of grass (seven plants) and clover (seven plants) were also established from seed in pots. After an initial harvest at 6 wk of growth, plants were harvested every 2 or 4 wk at a 4 or 8 cm height for 8 wk. Summed for all harvests, individual grass plant yields were greater (P < 0.01) in mixture with clover than in monoculture (1.92 vs 0.99 g dry matter plant-1, respectively). Individual ryegrass plants yielded more (P < 0.01) than individual orchardgrass plants in mixture wit clover because of increased (P < 0.01) tillering (29 vs 18 tillers plant-1, respectively). Clover plants in monoculture yielded more dry matter, had more growing points, branches, nodes, stolons, and longer stolons than clover plants in mixture. Yields of clover in grass mixtures were affected by grass species but not maturity of the grass cultivar at the initial harvest. During regrowth, clover yields were greater (P < 0.01) with early than with late maturity grass cultivars (0.82 vs 0.76 g dry matter plant-1) which probably resulted from more leaf production and a tendency for taller clover plants when grown with early vs late grass cultivars. Early maturing grass cultivars had fewer leaves per plant and were taller than late maturing cultivars, resulting in a less dense canopy, which allowed