title: Effect of Plant Growth Regulators on Phytoremediation of Hexachlorocyclohexane-Contaminated Soil.
abstract: The influence of three plant growth regulators, indolebutyric acid (IBA), thidiazuron (TDZ) and gibberellic acid (GA3), either individually or in pair-wise combinations, on the ability of waxy corn plant to remove hexachlorocyclohexane (HCH) from contaminated soil was studied. Waxy corn seeds were immersed for 3 h in solutions of 1.0 mg/l IBA, 0.01 mg/l TDZ, 0.1 mg/l GA3, or a mixture of two of the growth regulators, and then inoculated in soil contaminated with 46.8 mg/kg HCH for 30 days. Pretreatment of corn seeds with the plant growth regulators did not enhance corn growth when compared with those immersed in distilled water (control), but the pretreatment enhanced HCH removal significantly. On day 30, HCH concentration in the bulk soil planted with corn seeds pretreated with GA3 or TDZ+GA3 decreased by 97.4% and 98.4%, respectively. In comparison, HCH removal in soil planted with non-pretreated control waxy corn seeds was only 35.7%. The effect of several growth regulator application methods was tested with 0.01 mg/l TDZ. The results showed that none of the methods, which ranged from seed immersion, watering in soil, or spraying on shoots, affected HCH removal from soil. However, the method of applying the growth regulators may affect corn growth. Watering the corn plant with TDZ in soil led to higher root fresh weight (2.2 g) and higher root dried weight (0.57 g) than the other treatments (0.2-1.7 g root fresh weight and 0.02-0.43 g root dried weight) on day 30. Varying the concentrations of GA3 did not affect the enhancement of corn growth and HCH removal on day 30. The results showed that plant growth regulators may have potential for use to enhance HCH phytoremediation.
authors.affiliation: a Biology Program, Department of Science , Faculty of Science and Technology Nakhonsawan Rajabhat University , Nakhonsawan , Thailand.
authors.forename: Waraporn
authors.initials: W
authors.lastname: Chouychai
authors.affiliation: b Department of Biology , Faculty of Science, Mahidol University , Bangkok , Thailand.
authors.forename: Maleeya
authors.initials: M
authors.lastname: Kruatrachue
authors.affiliation: c School of Environmental Sciences, University of Guelph , Guelph , Ontario , Canada.
authors.forename: Hung
authors.initials: H
authors.lastname: Lee
mesh_terms: D001673:Biodegradation, Environmental; D005875:Gibberellins / Q000494:pharmacology; D001556:Hexachlorocyclohexane / Q000378:metabolism*; D007211:Indoles / Q000494:pharmacology; D007306:Insecticides / Q000378:metabolism*; D010671:Phenylurea Compounds / Q000494:pharmacology; D010937:Plant Growth Regulators / Q000494:pharmacology*; D012989:Soil Pollutants / Q000378:metabolism*; D013830:Thiadiazoles / Q000494:pharmacology; D003313:Zea mays / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism*
chemical_list: D005875:Gibberellins; D007211:Indoles; D007306:Insecticides; D010671:Phenylurea Compounds; D010937:Plant Growth Regulators; D012989:Soil Pollutants; D013830:Thiadiazoles; C016785:thidiazuron; C014612:indolebutyric acid; D001556:Hexachlorocyclohexane; C007842:gibberellic acid
keywords: auxins; cytokinin; gibberellin; organochlorine; phytoremediation