Residues of glyphosate and its metabolite AMPA in canola seed following preharvest applications

Abstract

. 2000. Residues of glyphosate and its metabolite AMPA in canola seed following preharvest applications. Can. J. Plant Sci. 80: [425][426][427][428][429][430][431]. Residue data for glyphosate and its major metabolite aminomethylphosphonic acid (AMPA) in canola seed following preharvest application of glyphosate were lacking when this 2-yr study was initiated. Residues of glyphosate and AMPA were measured in the seed of canola (Brassica rapa L.) at maturity following preharvest application at rates of 0.45, 0.9 or 1.7 kg acid equivalent ha -1 at four sites in western Canada. Herbicide treatments were applied in early August to mid-September at four stages of crop development, which encompassed seed/pod moisture contents ranging from 74 to 12%. Rate of glyphosate application and the physiological maturity of the crop at application played important roles in determining the magnitude of glyphosate and AMPA residues in the seed of preharvest-treated canola. In general, for a given site, mean residues of glyphosate and AMPA in the seed increased with increasing application rate, and decreased with application at later stages of crop development. In 1989, mean residues of glyphosate in the seed for all application rates at the latest stage of development at each site were <1 mg kg -1 . In 1988, when seed/pod moisture content generally declined very slowly from stage 1 to stage 3 and then decreased rapidly, corresponding mean residues were higher and varied from <1 to 19.7 mg kg -1 . Seed/pod moisture was not a reliable indicator of stage of canola development and, consequently, the magnitude of glyphosate and AMPA residues in the seed.Key words: Glyphosate residues, AMPA residues, canola, preharvest treatment Cessna, A. J., Darwent, A. L., Townley-Smith, L., Harker, K. N. et Kirkland, K. J. 2000. Importance des résidus du glyphosate et de son métabolite AMPA dans les graines de navette canola résultant des traitements de prérécolte. Can. J. Plant Sci. 80: 425-431. Nous avons mesuré pendant 2 ans la présence des résidus du glyphosate et de son principal métabolite, l'acide aminométhylphosphonique (AMPA), dans les graines de navette canola (Brassica rapa L.) à la suite de traitements herbicides de prérécolte. Trois doses de traitement au glyphosate, 0,45, 0,9 et 1,7 kg équivalent acide par hectare, étaient comparées à 4 emplacements de l'ouest canadien. Les traitements, échelonnés du début d'août à la mi-septembre, étaient exécutés à 4 stades phénologiques de la culture durant lesquels la teneur en eau des gousses ou des graines qu'elles renferment descendait de 74 à 12 %. L'importance des résidus de glyphosate et de AMPA dépendait fortement de la dose de l'herbicide et du degré de maturité physiologique de la culture lors du traitement. Dans l'ensemble, à un emplacement donné, les quantités moyennes de résidus augmentaient avec la dose, mais elles diminuaient plus le stade de maturité lors du traitement était avancé. En 1989, les quantités moyennes de résidus de glyphosate résultant du traitement, toutes doses confond...

The impact of altered herbicide residues in transgenic herbicide‐resistant crops on standard setting for herbicide residues

“…up to approximately 7% in seed or straw of barley. The levels of AMPA by and large followed the same pattern as those of glyphosate with regard to their dependency on application rates, stage of application and other environmental factors 60–63. These authors also mentioned that, in several different crops investigated in other studies, such as strawberry, no formation of AMPA had been observed.…”

Chromatographic determination of herbicide residues in various matrices

“…Samples were milled, extracted with aqueous HCl solution and cleaned up on an anion exchange resin. The purified extract was analysed by HPLC using fluorescence detection following post-column ophthalaldehyde derivatization (Cessna et al, 2000).…”

Activation of the N‐methyl‐d‐aspartate receptor is involved in glyphosate‐induced renal proximal tubule cell apoptosis

“…Because 5‐enolpyruvylshikimate‐3‐phosphate synthase is an enzyme present only in plants and some bacteria but not in vertebrates, glyphosate was initially considered nontoxic (Williams, Watson, & DeSesso, ), with an estimated lethal dose (LD 50 ) higher than 5000 mg/kg (EPA, US, ; Mensink & Janssen, ). However, given the widespread use of glyphosate‐based herbicides, residues of glyphosate and its major metabolite AMPA have been found in surface waters, soil (Huang, Pedersen, Fischer, White, & Young, ; Struger et al, ) and some plants such as legume, cereal, rice, wheat seed, canola seed and various types of animal fodder (Arregui et al, ; Cessna et al, ; Cessna, Darwent, Townley‐Smith, Harker, & Kirkland, ; Cetin, Sahan, Ulgen, & Sahin, ; Cuhra, ; FAO/WHO, ). Glyphosate is primarily absorbed through the skin, intestine and respiratory tract, and has been detected in many human urine samples, not only in those of farmers but also in those of the general public (Acquavella et al, ; Arbuckle, Lin, & Mery, ; Niemann, Sieke, Pfeil, & Solecki, ; Krüger et al, ).…”