title: The functional role of the photosynthetic apparatus in the recovery of Brassica napus plants from pre-emergent metazachlor exposure.
abstract: Metazachlor is a chloroacetamide herbicide, frequently used in Brassica napus cultivations around the world. Its primary target is the inhibition of very long chain fatty acid biosynthesis. This study included a morphological and physiological screening of hydroponically grown B. napus, exposed to a concentration range of 0, 0.25, 0.50, 0.75 and 1.0kg metazachlor per hectare. The results indicate that within a month after application, growth and development of B. napus are severely affected by low metazachlor doses. At intermediate metazachlor concentrations, loss of phosphorous and potassium from the plant tissues suggests destabilisation of cellular membranes, which may be a direct consequence of metazachlor application. This membrane instability could be indirectly linked with alterations of electron transport and a reduction of carbon assimilation. At increased metazachlor doses of 0.75kga.i.ha(-1), pigment concentrations are strongly reduced. However, chlorophyll fluorescence parameters seem to remain unaffected at metazachlor doses up to 0.75kga.i.ha(-1). At a metazachlor concentration of 1.0kga.i.ha(-1), negative effects are observed on all tested parameters, resulting in limited survival. The results indicate photosynthesis is assured at intermediate metazachlor concentrations for the cost of growth and development. It is clear that photosynthesis plays a key role in the survival strategy of young plants to overcome initially induced chemical stress.
authors.affiliation: Hasselt University, Centre for Environmental Sciences, Agoralaan Building D, 3590 Diepenbeek, Belgium.
authors.forename: H
authors.initials: H
authors.lastname: Vercampt
authors.affiliation: Agricultural University of Plovdiv, 12 Mendeleev Street, 4000 Plovdiv, Bulgaria.
authors.forename: L
authors.initials: L
authors.lastname: Koleva
authors.affiliation: Agricultural University of Plovdiv, 12 Mendeleev Street, 4000 Plovdiv, Bulgaria.
authors.forename: A
authors.initials: A
authors.lastname: Vassilev
authors.affiliation: Belgian Nuclear Research Centre (SCK-CEN), Biosphere Impact Studies, Boeretang 200, 2400 Mol, Belgium.
authors.forename: N
authors.initials: N
authors.lastname: Horemans
authors.affiliation: Federaal Agentschap voor Nucleaire Controle (FANC), Ravensteinstraat 36, 1000 Brussel, Belgium.
authors.forename: G
authors.initials: G
authors.lastname: Biermans
authors.affiliation: Hasselt University, Centre for Environmental Sciences, Agoralaan Building D, 3590 Diepenbeek, Belgium.
authors.forename: J
authors.initials: J
authors.lastname: Vangronsveld
authors.affiliation: Hasselt University, Centre for Environmental Sciences, Agoralaan Building D, 3590 Diepenbeek, Belgium. Electronic address: ann.cuypers@uhasselt.be.
authors.forename: A
authors.initials: A
authors.lastname: Cuypers
mesh_terms: D000081:Acetamides / Q000633:toxicity*; D029688:Brassica napus / Q000187:drug effects* / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D006540:Herbicides / Q000633:toxicity*; D010788:Photosynthesis / Q000187:drug effects*
chemical_list: D000081:Acetamides; D006540:Herbicides; C521990:metazachlor
keywords: Brassica napus; Chloroacetamide herbicide; Chlorophyll fluorescence; Crop injury; Gas exchange; Metazachlor; Photosynthesis; Recovery