title: Accumulation, tolerance and impact of aluminium, copper and zinc on growth and nitrate reductase activity of Ceratophyllum demersum (Hornwort).
abstract: Ceratophyllum demersum (homwort) was subjected to toxic concentrations of Al (3 and 9 mg l(-1)), Zn (3 and 9 mg l(-1)) and Cu (2.5 and 7 mg l(-1)) in culture solutions for 15 days. The higher dose of Al enhanced the chlorophyll content significantly (p<0.05) in the first 6 days of treatment while other treatments caused marked reductions. Nitrate reductase activity (NRA) was significantly reduced (p<0.05) byAl, Cu and Zn toxicity and ceased completely in plants treated with Cu by the 6th day of treatment. Dry biomass and relative growth rate were reduced significantly (p<0.05) by metal treatment. Tolerance index of the plant was low for Cu (21.62 and 13.43% at low and high doses, respectively) and moderate for Zn (63.74 and 54.85%) and Al (72.83 and 68.79%). Accumulation ofAl, Zn and Cu was threefold at higher doses compared with the lower doses but the bioconcentration factors (BCF) were very low indicating that this plant is not a hyper accumulator of these metals.
authors.affiliation: Department of Botany and Microbiology, University of Lagos, Akoka Yaba, Lagos, Nigeria. cumebese@yahoo.com
authors.forename: C E
authors.initials: CE
authors.lastname: Umebese
authors.forename: A F
authors.initials: AF
authors.lastname: Motajo
mesh_terms: D000535:Aluminum / Q000493:pharmacokinetics / Q000633:toxicity*; D002734:Chlorophyll / Q000378:metabolism; D003300:Copper / Q000493:pharmacokinetics / Q000633:toxicity*; D004305:Dose-Response Relationship, Drug; D004361:Drug Tolerance; D004781:Environmental Exposure; D019684:Magnoliopsida / Q000187:drug effects* / Q000201:enzymology / Q000254:growth & development*; D050901:Nitrate Reductase / Q000378:metabolism*; D013997:Time Factors; D014874:Water Pollutants, Chemical / Q000493:pharmacokinetics / Q000633:toxicity*; D015032:Zinc / Q000493:pharmacokinetics / Q000633:toxicity*
chemical_list: D014874:Water Pollutants, Chemical; D002734:Chlorophyll; D003300:Copper; D000535:Aluminum; D050901:Nitrate Reductase; D015032:Zinc