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Tolerance and co‐tolerance of the grass Chloris barbata Sw. to mercury, cadmium and zinc
Author(s) -
PATRA JITA,
LENKA MAHESWAR,
PANDA BRAHMA B.
Publication year - 1994
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/j.1469-8137.1994.tb03999.x
Subject(s) - cadmium , mercury (programming language) , zinc , chemistry , catalase , metal , peroxidase , environmental chemistry , botany , zoology , horticulture , biology , biochemistry , enzyme , organic chemistry , computer science , programming language
summary Races of Chloris barbata Sw. from a mercury‐contaminated site in the vicinity of a chloralkali plant and from a non‐contaminated site were tested for their relative tolerance to mercury, cadmium and zinc. Pre‐rooted tillers of each of the races were grown in calcium nitrate solution, Ca(NO 3 ) 2 , 4H 2 O, l gl −1 with or without HgCI 2 (0.001, 0.01, 0.05, 0.1 and mgl −1 ), CdSO 4 .8H 2 O (0.05, 1.0, 2.5 and 5 mg l −1 and ZnSO 4 7H 2 O (1, 5, 10, 20 and 40 mg l −1 ) for a period of 5 d, Metal tolerance was evaluated by the effects of the metal on root elongation. Races from the contaminated site were found to be metal‐tolerant, as indicated by higher tolerance indices (TIs) than races from the non‐contaminated site. Mercury and cadmium at lower concentrations and zinc at all concentrations stimulated root growth in tolerant races, resulting in a TI of more than 100%. This indicated a requirement of the metal ion for better root growth. Compared to non‐tolerant races, the tolerant races exhibited higher catalase, peroxidase and acid phosphatase activities as well as higher thiol levels. The over‐all study thus indicated that races of C. barbata from the mercury‐contaminated site were not only tolerant to mercury but also co‐tolerant to cadmium and zinc. Biochemical studies provided evidence that the tolerant races were physiologically distinct from the intolerant races.