Species Interactions with Quackgrass and Their Effects on Forage Production
2005
Brenly-Bultemeier, T. L. | Barker, D. J. | Sulc, R. Mark | Harrison, S. K. | Regnier, E. E.
Quackgrass [ (L.) Nevski] (QG) is a troublesome weed in row crop production but has some ideal forage characteristics for pastures. The competitive interactions of QG with other forage species under varying defoliation frequencies are not clearly understood. Our objective was to determine the competitiveness of QG with orchardgrass (L.) (ORG) and/or white clover (L.) (WC) under 2- or 6-wk cutting frequencies. Two replacement series experiments were conducted in a greenhouse between January and November 2002. Proportional mixtures (100:0, 33:66, 66:33, and 0:100) of QG:ORG and QG:WC, and a 33:33:33 mixture of all three species were established by planting tillers, rhizome shoots, or rooted stolons from ORG, QG, and WC, respectively. Results were similar across duplicate experiments so data were combined for the analysis. Yield for the 6-wk cutting frequency was almost twice that of the 2-wk cutting frequency (≤ 0.05). No yield differences (> 0.05) were found among the QG:ORG mixtures at the 6-wk cuttings. A quadratic response (≤ 0.05) for the QG:WC mixtures under the 6-wk cutting frequency showed 23% greater yield from the two QG:WC mixtures than WC or QG monocultures. Yield of species mixtures did not differ significantly at the 2-wk cutting frequency. We concluded that QG was a productive forage species that yielded best when grown with a complementary species (i.e., WC) rather than with a species likely to compete directly for the same resources (i.e., ORG).
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