Abstract
A pot experiment was conducted to evaluate the effect of urea on nitrogen metabolism and membrane lipid peroxidation in Azolla pinnata. Compared to controls, the application of urea to A. pinnata resulted in a 44% decrease in nitrogenase activity, no significant change in glutamine synthetase activity, 660% higher glutamic-pyruvic transaminase, 39% increase in free amino acid levels, 22% increase in malondialdehyde levels, 21% increase in Na+/K+- levels, 16% increase in Ca2+/Mg2+-ATPase levels, and 11% decrease in superoxide dismutase activity. In terms of H2O2 detoxifying enzymes, peroxidase activity did not change and catalase activity increased by 64% in urea-treated A. pinnata. These findings suggest that urea application promotes amino acid metabolism and membrane lipid peroxidation in A. pinnata.
Highlights
Azolla is a floating aquatic fern that is widely distributed throughout temperate and tropical freshwater ecosystems
It may be used for the production of hydrogen fuel, the production of biogas, the control of weeds, the control of mosquitoes, and the reduction of ammonia volatilization which accompanies the application of chemical N fertilizer [4]
glutamine synthetase (GS) is a key enzyme in the assimilation and control of N metabolism; it is the first enzyme involved in the conversion of inorganic to organic N in most organisms [26]
Summary
Azolla is a floating aquatic fern that is widely distributed throughout temperate and tropical freshwater ecosystems. It establishes symbiotic associations with nitrogen (N)-fixing bluegreen algae, and this association is mainly responsible for its high productivity and its ability to fix N at high rates [1]. Besides its utilization as a green manure, Azolla can be used as an animal feed, a human food, a medicine, and a water purifier It may be used for the production of hydrogen fuel, the production of biogas, the control of weeds, the control of mosquitoes, and the reduction of ammonia volatilization which accompanies the application of chemical N fertilizer [4]
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