It is possible to apply this method on root nodules and/or on Rhizobia strains (like nitrogen fixation by the free bacteria) and how for each case?
Hi Zakharia,
Yes & No. All the answers to your questions can be found in the manual by Unkovich et al. (2008), which is available to download for FREE at:
Unkovich et al. (2008) Measuring plant-associated nitrogen fixation in
agricultural systems. Canberra, Australia: ACIAR.
http://www.aciar.gov.au/publication/MN136
The use of ARA for evaluate the activity of nitrogenase is only for comparative effects and not for quantify the fixed N. If we want to compare, for example, two strains or the effect of a micronutrient in the nitrogenase activity, the ARA is a good tool.
The link above gives the practice:
http://www.colorado.edu/eeb/facultysites/barger/Linked%20PDFS/Methods/acetylene%20reduction%20assay.pdf
And can search by Boddey, R M (1981, 1987, 1995) and Boddey & Dobereiner.
Thank you so much for your answers.
My objective is to study the nitrogenase activity to select the most efficient strains of Rhizobium. For this, I have found this technique, between others, because it is a fast method to evaluate the activity of this enzyme.
If you have other method to this study, I thank you for it
Well, we have the traditional methods for comparison with strains, like weight and number of nodules, dry weight of the aerial part, production of grains, etc. In the sophisticated analysis, we have the N15, but this is very expensive. The ARA is good method for the evaluation, but isn´t secure that the results obtained for this method will be reproducible in the field. Is good for an screening. The three or four best strains obtained in ARA needs to confirm in field conditions.
Ok,thank you Mr. Solon Araujo for these informations.
Mr. Euan Kevin James, I will have use 2 legumes for this study: faba bean and lentils.
Hello Zakaria, Colleagues have sent you various methodology links. While it can be applied on both rhizobia growing in agar medium as well as nodulated plants, you may like to run assays of about 30 days old grown plants grown in Leonard jars or plastic pouches or sterile sand cups. Ultimately the increment of dry plant mass and N content is the only time averaged and weighted measure of confidently predicting rhizobial strain efficacy and not a point assay of nitrogenase activity.
For my study,I want to select the most efficient Rhizobium strains in term of nitrogenase activity so that I can after test their performance in dry and salt conditions. For this, I thought of using this technique, but the problem that I have found on this method is that I have absolutely to go through a culturing step because it is made on the root nodules. Therefore, I asked the question if it has other method to perform directly on strains?
Yes you will need to culture the strains and inoculate the plants. It is simple. You will have to grow the plants. Ex-planta nitrogense activity will not tell you much as far as symbiotic effectivity is concerned.
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