New Zealand Journal of Agricultural Research abstracts

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Short communication 

Elevated populations of effective rhizobia in the rhizoplane of white clover growing in pasture

H. N. Pryor

AgResearch
Invermay Agricultural Centre
Private Bag 50 034
Mosgiel, New Zealand

J. R. Crush*

AgResearch
Ruakura Research Centre
Private Bag 3123
Hamilton, New Zealand

*Author for correspondence.

Abstract  Rhizobium populations were counted in random soil samples from a ryegrass/clover pasture, in soil around white clover plants, and also in the rhizoplane of the white clover roots. The random soil samples contained 3 × 10⁵ cells per g dry soil of Rhizobium leguminosarum bv. trifolii effective on its host, and the same number of Mesorhizobium loti. Soil around white clover plants had 10⁶ cells per g dry soil of each Rhizobium. In the rhizoplane of white clover there were 10⁶ effective R. leguminosarum bv. trifolii per mg root dry weight, and only 10³ M. loti per mg root dry weight. The increase in the ratio of effective white clover rhizobia to M. loti in the rhizoplane demonstrates species-specific stimulation of effective rhizobia on the root surface. This would be important for the ongoing cycles of effective nodulation required by the clonal growth habit of white clover in pasture.

Keywords  Lotus corniculatus; Mesorhizobium loti; nodulation; rhizobia; Rhizobium leguminosarum; Trifolium repens; white clover

A05034; Received 26 July 2005; accepted 23 November 2005; Online publication date 7 March 2006
New Zealand Journal of Agricultural Research, 2006, Vol. 49: 85–87
0028–8233/06/4901–0085 © The Royal Society of New Zealand 2006

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