Summary
When nitrate was maintained in continuous supply in solution cultures at concentration 0.02 mM to 2 mM it reduced the numbers of curled root hairs and of nodules. But the addition of indole-3-acetate with the inoculum overcame the nitrate-inhibition of curling without affecting nodulation; and there was no quantitative connection between numbers of curled hairs and of nodules when nitrate treatments of limited duration were applied at different times in relation to inoculation
Nitrate reduced nodule number to some extent even if present only before inoculation, or only on the first, second or third day after inoculation, so that reduction in nodule number was difficult to attribute solely or chiefly to interference with any one phase of the nodulation process. However, nitrate inhibited formation of infection threads and augmented the proportion of arrested infection threads, to such an extent that this could be important in limiting nodule number.
Nitrate also delayed nodulation. The delay occurred early after inoculation and corresponded with delay in the appearance of infection threads.
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References
Gibson, A. H. and Nutman, P. S., Studies on the physiology of nodule formation VII. Ann. Botany N.S.24, 420–433 (1961).
Kefford, N. P., Brockwell, J. and Zwar, J. A., Symbiotic synthesis of auxin by legumes and nodule bacteria. Australian J. Biol. Sci.13, 456–467 (1960).
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. II. Compensating effects of nitrate and prior nodulation. Plant and Soil28, 246–257 (1968).
Nutman, P. S., Observations on root-hair infection by nodule bacteria. J. Exptl. Botany10, 250–263 (1959).
Nutman, P. S., Relation between root-hair infection byRhizobium and nodulation inTrifolium andVicia. Proc. Roy. Soc. London B.156, 122–137 (1962).
Raggio, M. and Raggio, Nora, Root nodules. Ann. Rev. Plant Physiol.13, 109–128 (1962).
Raggio, M., Raggio, Nora and Torrey, J. G., Interaction of nitrate and carbohydrates in rhizobial root nodule formation. Plant Physiol.40, 601–606 (1965).
Sahlman, Karin and Fahraeus, G., Microscope observations on effects of indole-3-acetate on the root hairs ofTrifolium repens. Kungl. Lantbrukshogsk. Ann.28, 261–268 (1962).
Tanner, J. W. and Anderson, I. C., An external effect of inorganic nitrogen on root nodulation. Nature198, 303–304 (1963).
Thornton, H. G., Action of sodium nitrate on infection of lucerne root hairs by nodule bacteria. Proc. Roy. Soc. London B119, 474–492 (1936).
Valera, Concepcion L. and Alexander, M., Reversal of nitrate inhibition of nodulation by indole-3-acetic acid. Nature206, 326 (1965).
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Munns, D.N. Nodulation ofMedicago sativa in solution culture. Plant Soil 29, 33–47 (1968). https://doi.org/10.1007/BF01393910
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DOI: https://doi.org/10.1007/BF01393910