Summary
The time course of increase in nodule number was observed in solution cultures of controlled composition, over periods of 5 to 7 weeks following the inoculation of 8-day-old seedlings. The plants produced successive crops of nodules two to three weeks apart. Maintaining nitrate at concentrations of 0.2 or 0.5mM greatly reduced the number of nodules in the first crop but only slightly or not at all in the larger following crops, relative to the numbers in nil-nitrate control cultures. This was not due to any decrease in the sensitivity of nodulation to inhibition by nitrate. Nodulation in the nil-nitrate controlplants was restrained following their abundant first-crop nodulation. The experiments ceased to be simple tests of effects of nitrate on rate of nodule production as soon as the first crop of nodules appeared. Subsequent nodule production was then inhibited approximately equally, by prior nodulation in the abundantly nodulated control-plants, and by nitrate in the sparsely nodulated plants in the nitrate treatment.
When the effect of nitrate was tested on plants comparable in size and in number of previously established nodules, it inhibited nodule production by 70–80%, whether the plants were seedlings or month-old plants, previously nodulated or not.
This is a preview of subscription content, log in via an institution to check access.
Similar content being viewed by others
References
Bergersen, F. J., The bacterial components of soybean root nodules: Changes in respiratory activity. J. Gen. Microbiol.19 312–323 (1958).
Dart, P. J. and Pate, J. S. Nodulation studies in legumes. III. Australian J. Biol. Sci.12 427–444 (1959).
Gibson, A. H. and Nutman, P. S., Studies on the physiology of nodule formation VII. Ann. Botany N. S.24 420–433 (1960).
Hewitt, E. J., Sand and water culture methods in the study of plant nutrition (2nd edition). Commonwealth Agr. Bureaux, Farnham Royal, England (1966).
Johnson, C. M. and Ulrich, A., Analytical methods for use in plant analysis. California Agr. Exp. Sta. Bull.766 (1959).
McConnell, J. T. and Bond, G., A comparison of the effect of combined nitrogen on nodulation in legumes and non legumes. Plant and Soil8 378–388 (1957).
Munns, D. N., Nodulation ofMedicago sativa in solution culture. I. Acid-sensitive steps. Plant and Soil28 129–146 (1968).
Munns, D. N., Nodulation ofMedicago sativa in solution culture. Effects of nitrate on root hairs and infection. Plant and Soil29, (in press) (1968).
Nutman, P. S., Studies on the physiology of nodule formation. III. Experiments on the excision of root-tips and nodules. Ann. Botany N.S.16 79–101 (1952).
Nutman, P. S., Relation between root hair infection by Rhizobium and nodulation inVicia andTrifolium. Proc. Roy. Soc. London B.156 122–137 (1962).
Pate, J. S. and Dart, P. J., Nodulation studies in legumes IV. Plant and Soil.15 329–346 (1961).
Raggio, M. and Raggio, Nora, Root nodules. Ann. Rev. Plant Physiol.13 109–128 (1962).
Richardson, D. A., Jordan, D. C., and Garrard, E. H., Influence of combined nitrogen on nodulation and nitrogen fixation byRhizobium meliloti. Canadian J. Plant Sci.37 205–217 (1957).
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Munns, D.N. Nodulation ofMedicago sativa in solution culture. Plant Soil 28, 246–257 (1968). https://doi.org/10.1007/BF01880242
Received:
Issue Date:
DOI: https://doi.org/10.1007/BF01880242