A greenhouse experiment was conducted in order to investigate the possible effects of selenium dioxide, SeO2 (0.1mg kg-1 soil) on the growth and some metabolic activities of Phaseolus vulgaris grown in clay-sandy soil (2:1w/w) amended with concentrations (0.2, 0.6, 1.0 and 1.5mg kg-1 soil) of mercuric chloride (HgCl2). As compared with control, growth parameters (root depth, shoot height, fresh and dry weights and leaf area) of HgCl2 stressed Phaseolus vulgaris plants showed significant decrease throughout the entire period of the experiment (60 days). Administration of SeO2 into HgCl2 stressed media, induced significant increase in all growth parameters determined throughout seedlings and flowering stages. Except for the significant increase in carotenoid contents with the increase in HgCl2 concentrations, at seedling and flowering stages, the other photosynthetic pigment contents (chl. a, chl. b) as well as the photosynthetic activity were decreased below the control values. The opposite was true with the supplemental addition of SeO2 into HgCl2 media. The catalase (CAT) and peroxidase (POX) activities and the malondialdehyde (MDA) content in HgCl2 stressed Phaseolus vulgaris, at seedling and flowering stages, showed significant increase, while inclusion of SeO2 into HgCl2 media decreased them compared with those of the untreated plants.
Key words: Catalase, growth, lipid peroxidation, mercury stress, peroxidase, Phaseolus vulgaris, photosynthetic pigments, photosynthetic activity, Selenium
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