Botany Department, University of Asaiut, Asaiut, Egypt.
NITROGENASE ACTIVITY ASSOCIATED WITH THE RHIZOSPHERE OF AMMOPHILA ARENARIA L. AND EFFECT OF INOCULATION OF SEEDLINGS WITH AZOTOBACTER
Article first published online: 2 MAY 2006
Volume 84, Issue 4, pages 711–721, April 1980
How to Cite
WAHAB, A. M. A. and WAREING, P. F. (1980), NITROGENASE ACTIVITY ASSOCIATED WITH THE RHIZOSPHERE OF AMMOPHILA ARENARIA L. AND EFFECT OF INOCULATION OF SEEDLINGS WITH AZOTOBACTER. New Phytologist, 84: 711–721. doi: 10.1111/j.1469-8137.1980.tb04783.x
- Issue published online: 2 MAY 2006
- Article first published online: 2 MAY 2006
- (Accepted 6 August 1979)
A marked gain in nitrogen was obtained when plants of Ammophila arenaria L. were grown in pots in dune sand and supplied with nitrogen-free nutrient solution. Nitrogenase activity was associated with the roots but the estimated rates of nitrogen-fixation based upon the acetylene reduction technique were less than one-tenth of those obtained by the Kjeldahl method. Significant rates of acetylene reduction were also demonstrated both for detached roots taken from plants growing naturally in sand dunes and from measurements made in situ in the field, but the estimated rates of nitrogen fixation were much lower than calculated rates of nitrogen gain by actively-growing plants. Some possible reasons for this discrepancy are discussed. Acetylene reduction was greatly stimulated by the addition of glucose, suggesting that nitrogen fixation by micro-organisms in the rhizosphere is limited by the supply of root exudates. Seedlings of Ammophila grown under aseptic conditions and inoculated with Azotobacter showed greatly increased growth compared with that of uninoculated seedlings.