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The Effect of Cadmium on Nodulation and N 2 (C 2 H 2 )‐Fixation by Dry Beans ( Phaseolus vulgaris L.)
Author(s) -
Vigue G. T.,
Pepper I. L.,
Bezdicek D. F.
Publication year - 1981
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq1981.00472425001000010019x
Subject(s) - cadmium , shoot , phaseolus , dry weight , horticulture , nodule (geology) , botany , nitrogen fixation , chemistry , zoology , biology , nitrogen , paleontology , organic chemistry
Experiments were conducted to determine the toxicity of Cd on the nodulation, N 2 (C 2 H 2 )‐fixation, and growth of dry beans. Plants were grown in the greenhouse with hydroponic solutions to which 0–500 µ m Cd/liter had been added. The total N content of shoots, nodule weight, nodule number, and N 2 (C 2 H 2 )‐fixation were significantly decreased at 10 µ m Cd/liter. Nodulation was completely inhibited at 500 µ m Cd/liter. Nodulation and the N 2 (C 2 H 2 )‐fixation rate were negatively correlated with solution Cd concentration ( r = −0.97). Cadmium uptake and translocation were slow; therefore, Cd levels were highest in the roots, much lower in the nodules, and lowest in the shoot tissue. For example, at 20 µ m Cd/liter, respective tissue Cd levels averaged 431, 80, and 35 µ g Cd/g, on a dry weight basis. Cadmium levels in roots or shoots from comparable Cd treatments were essentially the same whether the plants obtained their N by fixation or from nutrient solution NO 3 . Root Cd concentrations were exponentially correlated with nodule number, nodule weight, and acetylene reduction, with correlation coefficients of −0.99, −0.99, and −0.97, respectively. Shoot Cd concentrations were logarithmically correlated with nodule number, nodule weight, and acetylene reduction, with correlation coefficients of −0.89, −0.91, and −0.84, respectively.