HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Wickliff, C. Articles by Russell, S. A. Search for Related Content PubMed Articles by Wickliff, C. Articles by Russell, S. A. Agricola Articles by Wickliff, C. Articles by Russell, S. A.

Cadmium Effects on the Nitrogen Fixation System of Red Alder¹

ABSTRACT

Red alder (Alnus rubra Bong.) was grown in sand culture in the greenhouse to obtain data on the effects of cadmium (Cd) on a symbiotic nitrogen (N) fixation system which contributes to the fertility of forest soils. Treatment of red alder seedlings for 11 weeks with 0.545 to 136 µM CdCl₂ in N-free nutrient solution decreased in situ nitrogenase activity 25 to 89%, N fixation 23 to 98%, and the number of nodules per plant 29 to 74%, when compared to plants receiving no Cd. Similar reductions were observed in plant growth. Treatment with 0.054 to 0.545 µM CdCl₂ decreased nitrogenase activity 6 to 31%.

When non-nodulated A. rubra seedlings were inoculated in the presence of 0.054 and 0.109 µM CdCl₂, N fixation decreased 52 and 89%, respectively. Plant growth decreased in a similar fashion. When non-nodulated seedlings were given 0.545 µM CdCl₂ and 6 mM NH₄NO₃ or Ca(NO₃)₂, nitrate reductase activity decreased 22 and 24%, respectively, when compared to plants receiving no CdCl₂. Nitrogen accretion and plant dry weights were decreased by treatments in which plants were supplied with Ca(NO₃)₂ and 0.273 and 0.545 µM CdCl₂, when compared to controls without CdCl₂.

These results suggest that Cd can inhibit nitrogenase activity and therefore N fixation. Growth, nodulation, and nitrate reductase activity are also inhibited by Cd.

Key Words: nodules • nitrogenase • acetylene reduction • CdCl₂ inhibition

¹ Contribution from the Terrestrial Systems Div., Corvallis Environ. Res. Lab., Office of Res. and Dev., USEPA, 200 S.W. 35th Street, Corvallis, OR 97330.

² Biologist, Terrestrial Div.; Professor of Plant Physiology, and Research Assistants, Lab. for Nitrogen Fixation Res., Oregon State Univ., Corvallis, OR 97331, respectively.

Received for publication June 25, 1979.