Effects of degrees of grass competition on spreading of Kura clover

초록

Kura clover (Trifolium ambiguum M. Bieb.) is known to develop an extensive rhizome system when grown in monoculture. However, there is no information about the effects that competition from companion grasses could have on its rhizome development. This study was conducted to determine the difference in rhizome development of kura clover planted in grass, grass plus nitrogen (grass+N) fertilizer, or killed-grass plots, and to evaluate the effect of defoliation height on kura clover rhizome development. Using 1-year-old smooth bromegrass (Bromus inermis Leyss) and Kentucky bluegrass (Poa pratensis L.) swards, experiment 1 and 2 commenced in August 1991 and May 1992, respectively, at the University of Wisconsin Arlington Agricultural Research Station. Ten kura clover entries (populations started from seeds or from rhizomes started from clones) were transplanted into each sub-plot. Two cutting height sub-plots were superimposed on each of the three grass sward types. In each Exp., two plants from the same seed or rhizome source represented the experimental unit. Individual plants spread up to 1m in diameter over a 2-year period after transplanting when there was no grass competition. For both swards, the mean spread of kura clover by rhizome growth was highest in killed-grass plots (85cm diameter), least in the grass+N plots (29cm diameter) and intermediate (57cm diameter) in the grass only plots. The defoliation height (4cm or 10cm) of the swards did not significantly affect the spread of kura clover regardless of grass status (killed or + or -N) in either smooth bromegrass or Kentucky bluegrass. We conclude that reducing the competition from grasses is a management tool that can be used to maximize the colonizing ability of kura clover.

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