title: Basis for antagonism by sodium bentazon of tritosulfuron toxicity to white bean (Phaseolus vulgaris L.).
abstract: White bean (Phaseolus vulgaris L.) was used to study the antagonism caused by Na-bentazon on the phytotoxic action of the sulfonylurea (SU) herbicide tritosulfuron. After 168 h, uptake and translocation of [14C]tritosulfuron were reduced by 60 and 89%, respectively, when Na-bentazon was added to the mixture. Addition of (NH4)2SO4 or replacement of Na-bentazon with NH4-bentazon completely eliminated the negative effects on [14C]tritosulfuron uptake but not on its translocation. Scanning electron microscopy revealed that a mixture of Na-bentazon plus tritosulfuron plus DASH HC (0.156%) formed a rough layer of grain-like crystals on the leaf surface, whereas the addition of (NH4)2SO4 or replacement of Na-bentazon with NH4-bentazon resulted in amorphous deposits that may be more easily absorbed. The antagonism of tritosulfuron's phytotoxicity by Na-bentazon involves two separate processes, chemical (uptake effect) and biochemical (translocation effect).
authors.affiliation: Department of Environmental Biology, University of Guelph, Ontario, N1G 2W1 Canada.
authors.forename: Tsafrir
authors.initials: T
authors.lastname: Weinberg
authors.forename: Gerald R
authors.initials: GR
authors.lastname: Stephenson
authors.forename: Michael D
authors.initials: MD
authors.lastname: McLean
authors.forename: Norbert M
authors.initials: NM
authors.lastname: Satchivi
authors.forename: J Christopher
authors.initials: JC
authors.lastname: Hall
mesh_terms: D001581:Benzothiadiazines / Q000494:pharmacology*; D002250:Carbon Radioisotopes; D006540:Herbicides / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D006845:Hydrocarbons, Fluorinated / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D046529:Microscopy, Electron, Transmission; D027805:Phaseolus / Q000187:drug effects*; D014227:Triazines / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D014508:Urea / Q000031:analogs & derivatives* / Q000037:antagonists & inhibitors / Q000494:pharmacology
chemical_list: D001581:Benzothiadiazines; D002250:Carbon Radioisotopes; D006540:Herbicides; D006845:Hydrocarbons, Fluorinated; D014227:Triazines; D014508:Urea; C002003:bentazone; C520886:tritosulfuron