Quantitative bioassays for determining residues and availability to plants of sulphonylurea herbicides

Abstract

Summary A bioassay procedure for quantitative determination of sulphonylurea herbicides is described. Turnips (Brassica rapa) were found very suitable as test plants and gave results within 10 days. Six sulphonylurea compounds were investigated for their activity in three widely differing soils. The potential availability to plants was calculated from the dose‐response curves of vermiculite (non‐sorptive substrate) and the corresponding ED50‐values of the soils. The dose‐response relationship (logistic curve) was described by a computer model by a position parameter, the slope of the curve and the minimum and maximum fresh weights of plants. The limit of quantitative detection in the range of ED30 in vermiculite was 0·06 μg 1−1 for sulfometuron and 1·03 μg 1−1 for DPX‐L5300, methy12‐([4‐methoxy‐6‐methyl‐1,3,5‐triazin‐2‐yl (methyl)carbamoyl]‐sulphamoyl) benzoate. Results with turnips showed that sulfometuron was the most active compound in all substrates (ED50 in vermiculite 0·12 μg 1−1) followed by chlorsulfuron, metsulfuron‐methyl, triasulfuron, DPX‐M6316, methyl 3‐([(4‐methoxy‐6‐methyl‐1,3,5‐triazin‐2‐yl)aminocarbamoyl]‐aminosulphaphamoyl)‐2‐thiophenecarboxylate, and DPX‐L5300 which had ED50 or 1·98 μg 1−1, The Horotiu sandy loam soil showed the highest ED50‐values and the lowest plant availability for all compounds compared to the other soils. Probit and logistic evaluation methods for deriving dose‐response relationships are compared and their applicability is discussed.

The Use of Geochemical Speciation Modelling to Predict the Impact of Uranium to Freshwater Biota

“…A four-parameter logistic model [15] was employed to best fit the sigmoidal relationship between the selected behavioural response (i.e. duration of valve gape) and the measured total uranium exposure concentration.…”

Bioassay for Determining Sensitivity to Sulfosulfuron on Seven Plant Species

“…[3][4][5][6][7][8][9] In many instances the visual effects were obvious in plants, but no reduction could be recorded in the fresh weight; [23] however Jettner has shown plant sensitivity based on shoot fresh weight with atrazina and chlorsulfuron. [24] Blacklow and Pheloung [10] improved precision and sensitivity of the assay assessing root growth effects after sulfonylurea treatments.…”

Simultaneous analysis of triasulfuron, metsulfuron-methyl and chlorsulfuron in water and alkaline soils by high-performance liquid chromatography

“…Therefore, the analytical methods to detect the herbicide residues at ug/1 or ug/kg levels in soil and water corresponding to field application rates are required. • Both chemical (Ahmad, 1987;Cotterill, 1992;Galletti et al 1995;Li et al 1996;Marek and Koskinen, 1996;Bernal et al 1997 andDicorcia et al 1997) and bioassay (Gunther et al 1989;Strek et al 1989) methods have been developed for detecting residues of sulfonylurea at trace levels. Although bioassays are sensitive enough (detection limit of 0.1 ug/kg) to detect phytotoxic levels of sulfonylurea herbicides in soil, they are non-specific, time consuming and are affected by soil variability.…”