Light quality, symbiotic nitrogen fixation and growth in white clover plants

1983 ◽  
Vol 73 (1) ◽  
pp. 117-128 ◽  
Author(s):  
J. E. Sheehy ◽  
C. Vazzana ◽  
F. R. Minchin
Keyword(s):  
Nitrogen Fixation ◽  
White Clover ◽  
Light Quality ◽  
Symbiotic Nitrogen Fixation

scholarly journals Inoculation for successful establishment of Caucasian clover

1994 ◽  
pp. 101-105 ◽  
Author(s):  
Heather N. Patrick ◽  
W.L. Lowther ◽  
K.D. Trainor
Keyword(s):  
Nitrogen Fixation ◽  
White Clover ◽  
Symbiotic Nitrogen Fixation ◽  
Gum Arabic ◽  
Trifolium Ambiguum ◽  
Successful Establishment ◽  
Low Levels ◽  
Very High

Results from oversowing trials in the tussock grasslands have shown that nodulation problems can limit the establishment of Caucasian clover (Trifolium ambiguum). They also strongly suggest that previously reported difficulties with establishment of Caucasian clover, in areas where white clover (T. repens) had established sucessfully, were likely to be due to inoculation failures due to low numbers of rhizobia on the seed, or in the case of tetraploid cultivars, to the use of an unsatisfactory strain. With the tetraploid cultivar Treeline, inoculation with the recommended strain ICMP4074b resulted in low levels of effective seedling nodulation even with very high levels of rhizobia/seed at sowing (149 000). Treeline seedling nodulation was increased when inoculated with strain ICMP4073b, the approved strain for hexaploid cultivars, and the strain was effective at symbiotic nitrogen fixation. Effective seedling nodulation of both tetraploid Treeline and hexaploid Monaro cultivars inoculated with ICMP4073b increased as the number of rhizobia on the seed at sowing was increased. Low levels of seedling nodulation occurred when populations of rhizobia on the seed were in the range likely to be present when seed is slurry inoculated, or inoculated and pelleted and stored for several days before oversowing. To maximise effective nodulation, seed should be inoculated at least 5 times the recommended rate, with the incorporation of gum arabic in the slurry or pellet and oversown within one day. Keywords: Caucasian clover, establishment, inoculation, nodulation, rhizobia, Trifolium ambiguum

Issues affecting the competitiveness of white clover rhizobia in New Zealand pastures

1996 ◽  
Vol 6 ◽  
pp. 87-90
Author(s):  
C.W. Ronson ◽  
W.L. Lowther
Keyword(s):  
Nitrogen Fixation ◽  
New Zealand ◽  
White Clover ◽  
Symbiotic Nitrogen Fixation ◽  
Genetic Interactions ◽  
Indigenous Populations ◽  
Nodule Occupancy ◽  
Rhizobial Strain ◽  
Specific Host ◽  
Inoculant Strain

Research into improving symbiotic nitrogen fixation of white clover in New Zealand pastures through the introduction of effective rhizobia is reviewed. Naturalised populations of rhizobia are usually highly diverse and of reduced effectiveness compared to inoculant strains, and large increases in nitrogen fixed have been found in situations where high nodule occupancy by an inoculant strain was obtained. The likelihood of an inoculant strain initially forming a high proportion of nodules is dependent on the size of the naturalised and inoculant populations, and the strain of rhizobia. Lack of persistence of the inoculant strain in competition with naturalised rhizobia also limits improvement of symbiotic nitrogen fixation in pasture through inoculation. Recent studies suggest that genetic instability of inoculant strains and exchange of symbiotic plasmids contribute to the diversity of naturalised populations and lack of inoculant persistence. Therefore, it is necessary to understand the ecology of naturalised populations, including their genetic interactions with inoculant strains, in order to develop strategies to improve the competitiveness and persistence of inoculant strains. Alternatively it may be possible to increase the effectiveness of indigenous populations through gene transfer from the inoculant strain. The possibility of breeding specific host cultivar/rhizobial strain combinations also merits further research. Keywords: competition, genetic stability, inoculation, nitrogen fixation, rhizobia, white clover

Relationships Between Nitrate and Oxygen Supply in Symbiotic Nitrogen Fixation by White Clover

1986 ◽  
Vol 37 (8) ◽  
pp. 1103-1113 ◽  
Author(s):  
F. R. MINCHIN ◽  
M. INES MINGUEZ ◽  
J. E. SHEEHY ◽  
J. F. WITTY ◽  
L. SKØT
Keyword(s):  
Nitrogen Fixation ◽  
White Clover ◽  
Oxygen Supply ◽  
Symbiotic Nitrogen Fixation

NEW CLOVER CULTIVARS FOR WAIKATO DAIRY PASTURE: ESTABLISHMENT, PRODUCTION AND NITROGEN FIXATION DURING THE FIRST YEAR

1988 ◽  
pp. 207-211
Author(s):  
S.F. Ledgard ◽  
G.J. Brier ◽  
R.N. Watson
Keyword(s):  
Nitrogen Fixation ◽  
White Clover ◽  
Dairy Cow ◽  
Red Clover ◽  
First Year ◽  
Buried Seed

Clover cultivars grown with ryegrass were compared in an establishment year under dairy cow grazing. There was no difference in total annual productton but summer production was greater with Pawera red clover and with Kopu or Pitau white clovers. Clovers differed little in the proportion of nitrogen fixed, except during summer when values were highest for Pawera. Pawera was less prone to nematode attack than white clover cultivars but was more susceptible to clover rot. Resident clovers and high buried seed levels (e.g., 11-91 kg/ha) made introduction of new clover cultivars difficult. Sown clovers established best (50-70% of total clover plants) when drilled into soil treated with dicamba and glyphosate. Keywords: white clover, red clover, nematodes. nitrogen fixation, pasture renovation

scholarly journals Plasmids Related to the Symbiotic Nitrogen Fixation Are Not Only Cooperated Functionally but Also May Have Evolved over a Time Span in Family Rhizobiaceae

2020 ◽  
Vol 12 (11) ◽  
pp. 2002-2014
Author(s):  
Ling-Ling Yang ◽  
Zhao Jiang ◽  
Yan Li ◽  
En-Tao Wang ◽  
Xiao-Yang Zhi
Keyword(s):  
Nitrogen Fixation ◽  
Gene Transfer ◽  
Horizontal Gene Transfer ◽  
Symbiotic Nitrogen Fixation ◽  
Gene Families ◽  
Time Span ◽  
Soil Conditions ◽  
Gene Gain ◽  
Nitrogen Fixing ◽  
Pan Genome

Abstract Rhizobia are soil bacteria capable of forming symbiotic nitrogen-fixing nodules associated with leguminous plants. In fast-growing legume-nodulating rhizobia, such as the species in the family Rhizobiaceae, the symbiotic plasmid is the main genetic basis for nitrogen-fixing symbiosis, and is susceptible to horizontal gene transfer. To further understand the symbioses evolution in Rhizobiaceae, we analyzed the pan-genome of this family based on 92 genomes of type/reference strains and reconstructed its phylogeny using a phylogenomics approach. Intriguingly, although the genetic expansion that occurred in chromosomal regions was the main reason for the high proportion of low-frequency flexible gene families in the pan-genome, gene gain events associated with accessory plasmids introduced more genes into the genomes of nitrogen-fixing species. For symbiotic plasmids, although horizontal gene transfer frequently occurred, transfer may be impeded by, such as, the host’s physical isolation and soil conditions, even among phylogenetically close species. During coevolution with leguminous hosts, the plasmid system, including accessory and symbiotic plasmids, may have evolved over a time span, and provided rhizobial species with the ability to adapt to various environmental conditions and helped them achieve nitrogen fixation. These findings provide new insights into the phylogeny of Rhizobiaceae and advance our understanding of the evolution of symbiotic nitrogen fixation.

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