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.

scholarly journals A Convenient, Soil-Free Method for the Production of Root Nodules in Soybean to Study the Effects of Exogenous Additives

2018 ◽  
Author(s):  
Swarup Roy Choudhury ◽  
Sarah M. Johns ◽  
Sona Pandey
Keyword(s):  
Nitrogen Fixation ◽  
Biological Nitrogen Fixation ◽  
Root Nodules ◽  
Growth Conditions ◽  
Nodule Development ◽  
Nodule Formation ◽  
Legume Crop ◽  
Simple Protocol ◽  
Biological Nitrogen

Legumes develop root nodules that harbour endosymbiotic bacteria, rhizobia. These rhizobia convert nitrogen to ammonia by biological nitrogen fixation. A thorough understanding of the biological nitrogen fixation in legumes and its regulation is key to develop sustainable agriculture. It is well known that plant hormones affect nodule formation; however, most studies are limited to model legumes due to their suitability for in vitro, plate-based assays. Specifically, it is almost impossible to measure the effects of exogenous hormones or other additives during nodule development in crop legumes such as soybean as they have huge root system in soil. To circumvent this issue, the present research develops suitable media and growth conditions for efficient nodule development under in vitro, soil free conditions in an important legume crop, soybean. Moreover, we also evaluate the effects of all major phytohormones during soybean nodulation under identical conditions. This versatile, inexpensive, scalable and simple protocol provides several advantages over previously established methods. It is extremely time-and resource-efficient, does not require special training or equipment, and produces highly reproducible results. The approach is expandable to other large legumes as well as for other exogenous additives.

scholarly journals The value of N-fixation to pastoral agriculture in New Zealand

1996 ◽  
Vol 6 ◽  
pp. 115-118
Author(s):  
T.W. Walker
Keyword(s):  
Nitrogen Fixation ◽  
New Zealand ◽  
Biological Nitrogen Fixation ◽  
High Energy ◽  
Drainage Water ◽  
N Fixation ◽  
Animal Products ◽  
Agriculture Sustainability ◽  
Grass Growth ◽  
Biological Nitrogen

White clover in New Zealand fixes nitrogen equivalent to 4.5 million tonnes of urea annually. Experiments on the tactical use of about 50 kg N ha-1 yr-1 to stimulate grass growth when clovers are less active indicate that it is generally profitable, but much heavier dressings have rarely been shown to pay at current cost/price structures. The significance of biological nitrogen fixation (BNF) cannot be measured solely by dry matter yields as the quality of herbage is influenced by the contribution of clover and affects yields of animal products and health. Our dependence on BNF gives us a relatively low energycost system of pastoral farming because of the high energy cost of producing fertiliser-N and is therefore more sustainable. The heavy use of fertiliser-N suppresses clover growth and N-fixation, increases losses of ammonia and nitrous oxide to the air and nitrate in drainage water. The extra stock carried leads to greater emission of methane. Reliance on clovers may give lower production but lessens damage to the environment. Keywords: biological nitrogen fixation, energy costs, environment, fertiliser nitrogen, pastoral agriculture, sustainability

scholarly journals Isolation and Enumeration of Bradyrhizobium Species Dwelling In the Root Nodules of Soybean Plant

2020 ◽  
pp. 17-25
Author(s):  
Ishaq Z. ◽  
Keyword(s):  
Nitrogen Fixation ◽  
Biological Nitrogen Fixation ◽  
Root Nodule ◽  
Low Cost ◽  
Root Nodules ◽  
Selective Medium ◽  
Soybean Plant ◽  
Plant Infection ◽  
Soybean Plants ◽  
Biological Nitrogen

Biological Nitrogen fixation is one of the important aspects of organic agriculture gaining considerable attention globally. Information about the number of viable indigenous Bradyrhizobia in soils planted with legumes and their capacity to nodulate is a valuable tool in developing strategies to improve biological nitrogen fixation. Such strategies could potentially lead to increased soybean yields at low cost. This study was conducted to isolate and enumerate Bradyrizobium species dwelling in the root nodule of soybean plant using Bradyrhizobium japonicum selective medium (BJSM). Twenty (20) strains of Bradyrizobium species were isolated from the root nodules of soybean plants harvested from Ahmadu Bello University farm site, located at Bomo district of Sabongari local government area, Kaduna State, Nigeria. This was achieved using the streak method of isolation on BJSM. Ninety percent (18) of these isolates were confirmed as Bradyrizobium species using the plant infection test as they were able to nodulate the roots of soybean plants. The enumeration of the indigenous Bradyrizobium species gave a count ranging from 2.07x105 - 4.0x106 CFU/mL. Thus, the number of Bradyrhizobia obtained in the soil of this study is sufficient to achieve satisfactory results on nodulation and nitrogen fixation. Key words: Soybean, Bradyrhizobium species, Nodulation, Nitrogen fixation

The inorganic biochemistry of molybdoenzymes

1988 ◽  
Vol 21 (3) ◽  
pp. 299-329 ◽  
Author(s):  
Robert C. Bray
Keyword(s):  
Nitrogen Fixation ◽  
Trace Element ◽  
Xanthine Oxidase ◽  
Biological Nitrogen Fixation ◽  
Root Nodules ◽  
Atmospheric Nitrogen ◽  
Mammalian Enzyme ◽  
The 1950S ◽  
Biological Nitrogen

Molybednum-containing enzymes (Coughlan, 1980; Spiro, 1985) occupy a significant place in the development of the field now termed inorganic biochemistry. The importance of the metal as a biological trace element depends on its involvement in the known, and perhaps other as yet unknown, molybdoenzymes. That it plays a role in biological nitrogen fixation, the process whereby the enzyme nitrogenase in the root nodules of plants converts atmospheric nitrogen into ammonia, was recognized in the 1930s. The metal is also a constituent of a variety of other enzymes, having first been found in a mammalian enzyme, xanthine oxidase, in the 1950s.

scholarly journals Biological Nitrogen Fixation and Productivity of Soybean in Maize-Soybean Intercrop under Tillage and Bradyrhizobium Inoculation on Alfisols of Northern Guinea Savanna, Nigeria

2020 ◽  
pp. 15-24
Keyword(s):  
Nitrogen Fixation ◽  
Biological Nitrogen Fixation ◽  
Block Design ◽  
Conventional Tillage ◽  
N Fixation ◽  
Tillage Practices ◽  
Main Plot ◽  
Four Levels ◽  
Biological Nitrogen ◽  
Bradyrhizobium Inoculation

A field study was conducted in the 2011 cropping season to investigate the effect of tillage and bradyrhizobium inoculation of soybean on biological nitrogen fixation (BNF) and yield components in maize-soybean intercropping systems. Treatments comprised of two tillage practices (conventional tillage (CT) and reduced tillage (RT)) as the main plot and bradyrhizobium inoculation at four levels (inoculated sole soybean, inoculated soybean/maize intercrop, uninoculated sole soybean, and uninoculated soybean/maize intercrop) as sub-plot. The treatments were laid in a split-plot under a randomized complete block design with three replications. Results showed that BNF and nitrogen derived from atmospheric (Ndfa) were significantly higher under RT than CT by 4.18 and 0.10 %, respectively. The BNF was consistently higher in the maize-soybean intercropping system with soybean inoculated with bradyrhizobium than in the uninoculated. BNF was 28.0 % higher in inoculated sole soybean and 80.2 % higher in inoculated maize-soybean intercrop than the uninoculated sole and intercropping system. Similarly, grain yield was 31.0 % higher in the inoculated sole soybean than the uninoculated sole and 33.7 % higher in inoculated maize/soybean intercrop than in the uninoculated intercrop. Biomass yields under inoculatedsole soybean and maize-soybean intercrop, respectively, were significantly higher than in uninoculated sole soybean and maize-soybean intercrop by 30.99and 33.66% for inoculated and uninoculated soybean sole and 34.44 and 30.40 % for inoculated and uninoculated intercrop. The results demonstrated that integrating bradyrhizobium inoculants and tillage will improve N fixation and productivity in maize-soybeanbased intercropping systems in Alfisols of Northern savannah.

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