ISSN:
1573-2932
Source:
Springer Online Journal Archives 1860-2000
Topics:
Energy, Environment Protection, Nuclear Power Engineering
Notes:
Abstract Cadmium and Ni (1, 2.5, and 5 ppm) and Cu and Zn (1, 5, and 10 ppm) applications inhibited N2 fixation by soybeans in sand culture. In general, the degree of toxicity was Cd 〉 Ni 〉 Cu 〉 Zn. Cadmium greatly reduced nodule number, dry weight and N2 fixation. Although nodulation on Ni-treated plants was adequate, N2 fixation was very low. Copper reduced nodulation, but inhibited N2 fixation directly at only 5 and 10 ppm. Zinc reduced nodulation, but only slightly inhibited N2 fixation. Very low levels of leghemoglobin (LHb) were found in the Cd- and Ni-treated nodules, but the Cu- and Zn-treated ones had LHb levels much closer to those of the control. Ammonia accumulated in most cases, paralleling the concomitant decrease in N2 fixation. Ammonia, a repressor of nitrogenase synthesis, could be important in limiting N2 fixation in soybean nodules when plants are grown in the presence of relatively high levels of heavy metals.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00213536
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