New Zealand Journal of Agricultural Research abstracts
Effect of rhizobia from caucasian clover (Trifolium ambiguum)
on nodulation and nitrogen fixation of white clover (Trifolium repens)
H. N. Pryor1
R. M. Elliot2*
W. L. Lowther1
C. W. Ronson2
1AgResearch
Invermay Agricultural Centre
Private Bag 50 034
Mosgiel, New Zealand
2Department of Microbiology
University of Otago
P.O. Box 56
Dunedin, New Zealand
*Present address: Tatua R&D Laboratory, Centre for Innovation, University
of Otago, P.O. Box 56, Dunedin, New Zealand.
Abstract Three glasshouse trials investigated N2 fixation
in white clover following inoculation with rhizobia from caucasian clover.
We grew white clover in agar, vermiculite/perlite and soils low in available-N
and with no detectable rhizobia. Media were subsequently treated with inoculum
containing rhizobia effective on either (i) caucasian clover, (ii) white
clover, or (iii) mixtures of the two. The percentage of ineffective nodules
on white clover increased as the proportion of rhizobia from caucasian clover
in the inoculant mix increased. However, the percentages of ineffective nodules
on white clover were less than the proportion of ineffective rhizobia in
the inoculant, indicating that the ineffective rhizobia were less competitive
in nodule formation. Foliage yield and symbiotic N2 fixation in
white clover were not significantly affected when ineffective rhizobia from
caucasian clover made up 67% or less of the inoculant. However, when ineffective
rhizobia made up a high proportion of the inoculant mix (>92%), both foliage
yield and N2 fixation were significantly reduced compared with
plants inoculated with only white clover rhizobia. Extrapolation of the present
glasshouse results to the field is difficult and further field trials are
required to determine if rhizobia from caucasian clover have any effect on
symbiotic N2 fixation of white clover in pastoral situations.
Keywords caucasian clover; competition; nitrogen fixation;
nodulation; rhizobia; Trifolium ambiguum; Trifolium repens;
white clover
A03019; Received 3 April 2003; accepted 15 August 2003; online publication
date 26 February 2004
New Zealand Journal of Agricultural Research, 2004, Vol. 47: 75-83
0028-8233/04/4701-0075 © The Royal Society of New Zealand 2004
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