Comparisons of biological nitrogen fixation in association with white clover (Trifolium repens L.) under four fertiliser nitrogen inputs as measured using two 15N techniques

2014 ◽  
Vol 385 (1-2) ◽  
pp. 287-302 ◽  
Author(s):  
W. Burchill ◽  
E. K. James ◽  
D. Li ◽  
G. J. Lanigan ◽  
M. Williams ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
White Clover ◽  
Trifolium Repens ◽  
Biological Nitrogen Fixation ◽  
Nitrogen Inputs ◽  
Trifolium Repens L ◽  
15N Techniques ◽  
Biological Nitrogen

Nitrogen Fixation in Hybrids of White Clover (Trifolium repens L.) and Caucasian Clover (Trifolium ambiguum M. Bieb)

2000 ◽  
Vol 185 (4) ◽  
pp. 241-247 ◽  
Author(s):  
M. T. Abberton ◽  
J. H. MacDuff ◽  
S. Vagg ◽  
A. H. Marshall ◽  
T. P. T. Michaelson-Yeates
Keyword(s):  
Nitrogen Fixation ◽  
White Clover ◽  
Trifolium Repens ◽  
Trifolium Ambiguum ◽  
Trifolium Repens L

scholarly journals A reduced fraction of plant N derived from atmospheric N (%Ndfa) and reduced rhizobial nifH gene numbers indicate a lower capacity for nitrogen fixation in nodules of white clover exposed to long-term CO<sub>2</sub> enrichment

2013 ◽  
Vol 10 (12) ◽  
pp. 8269-8281 ◽  
Author(s):  
T. Watanabe ◽  
S. Bowatte ◽  
P. C. D. Newton
Keyword(s):  
Nitrogen Fixation ◽  
Elevated Co2 ◽  
White Clover ◽  
Trifolium Repens ◽  
Nifh Gene ◽  
Shoot Biomass ◽  
N Fixation ◽  
Dna Amount ◽  
Trifolium Repens L ◽  
Nifh Genes

Abstract. Using the δ15N natural abundance method, we found that the fraction of nitrogen derived from atmospheric N (%Ndfa) in field-grown white clover (Trifolium repens L.) plants was significantly lower (72.0% vs. 89.8%, p = 0.047 in a grassland exposed to elevated CO2 for 13 yr using free air carbon dioxide enrichment (FACE). Twelve months later we conducted an experiment to investigate the reasons behind the reduced N fixation. We took cuttings from white clover plants growing in the FACE and established individual plants in a glasshouse using soil from the appropriate ambient or elevated CO2 treatments. The established plants were then transplanted back into their "rings of origin" and sampled over a 6-week period. We used molecular ecological analyses targeting nifH genes and transcripts of rhizobia in symbiosis with white clover (Trifolium repens L.) to understand the potential mechanisms. Shoot biomass was significantly lower in eCO2, but there was no difference in nodule number or mass per plant. The numbers of nifH genes and gene transcripts per nodule were significantly reduced under eCO2, but the ratio of gene to transcript number and the strains of rhizobia present were the same in both treatments. We conclude that the capacity for biological nitrogen fixation was reduced by eCO2 in white clover and was related to the reduced rhizobia numbers in nodules. We discuss the finding of reduced gene number in relation to factors controlling bacteroid DNA amount, which may imply an influence of nitrogen as well as phosphorus.

Increasing biological nitrogen fixation by white clover-rhizobia symbiosis

2019 ◽  
pp. 231-234 ◽  
Author(s):  
Shengjing Shi ◽  
Laura Villamizar ◽  
Emily Gerard ◽  
Clive Ronson ◽  
Steve Wakelin ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
White Clover ◽  
Biological Nitrogen Fixation ◽  
Root Nodules ◽  
N Fixation ◽  
Nodule Occupancy ◽  
Coating Technology ◽  
Vitro Assay ◽  
Biological Nitrogen

Biological nitrogen fixation (BNF) is the process of converting atmospheric nitrogen to ammonia through legume–rhizobia symbiosis. The nitrogen fixed by rhizobia in root nodules is available for plant use. This process can be harnessed to improve N fertility on farm. Field surveys across New Zealand (NZ), within a farm and within paddocks, have revealed large spatial variability of rhizobial population size and symbiotic effectiveness with white clover. These results indicate that naturalised rhizobia may not be supporting optimal BNF. Over 500 strains of clover-nodulating rhizobia were isolated from NZ pasture soils, with more than 90 demonstrating greater N-fixation capacity with white clover than the commercial inoculant strain TA1. Seven NZ isolates were tested for nodule occupancy and all seven had significantly higher occupancy rates than TA1 in an in vitro assay, indicating increased competitiveness of those strains. In addition, novel seed-coating technology improved the survival of TA1 and isolate S10N9 from 1 month to more than 4 months compared with a standard coating formulation. There is potential to increase the symbiotic capacity of white clover in pastures through use of more effective and competitive rhizobial strains, along with their improved survival on seed provided by a new coating technology.

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