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Some consequences of imposing different continuousgrazing pressures in the spring on tiller demography and leaf growth

Published online by Cambridge University Press:  27 March 2009

J. R. B. Tallowin ,
J. H. H. Williams  and
F. W. Kirkham
J. R. B. Tallowin
Affiliation:
AFRC Institute for Grassland and Animal Production, North Wyke, Okehampton, Devon EX20 2SB
J. H. H. Williams
Affiliation:
AFRC Institute for Grassland and Animal Production, North Wyke, Okehampton, Devon EX20 2SB
F. W. Kirkham
Affiliation:
AFRC Institute for Grassland and Animal Production, North Wyke, Okehampton, Devon EX20 2SB
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Summary

The effects of different severities of continuous grazing imposed during the spring, followed by a uniform continuous grazing management from mid-summer onwards, were examined in relation to changes in tiller demography and leaf growth of perennial ryegrass (Lolium perenne). Two grazing severities were imposed, based upon maintaining a constant sward height of either 35 mm (severe) or 75 mm (lenient). From 1 June onwards, a uniform grazing pressure with a sward height of 60 mm was imposed.

Differences in the age class structure of the tiller populations developed during the spring between the two grazing treatments, principally through the suppression of daughter tiller development under the more lenient grazing. The demographic differences between the treatments were further increased during the remainder of the grazing season, under the common grazing management, largely because of the greater production of secondary daughter tillers in the sward which had been leniently grazed. The demographic differences between the swards had little effect on net pasture production during the treatment season, with lamina growth rates being virtually unaffected across a wide range of steadystate, continuous-grazing pressures. However, longer-term effects on pasture development, due to the demographic differences between the swards, did appear in the following season; the more severe grazing pressure treatment resulted in earlier inflorescence development in the subsequent season.

Type
Research Article
Information
The Journal of Agricultural Science , Volume 112 , Issue 1 , February 1989 , pp. 115 - 122
Copyright
Copyright © Cambridge University Press 1989

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