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51.
52.
An immunoassay (ELISA) for analysis of metsulfuron‐methyl was evaluated as a method for quantifying residues in soil. Soil samples were extracted with phosphate buffered saline (PBS), PBS + acetone (80 + 20 by volume) or ammonium carbonate and were analyzed with both ELISA and LC‐MS. A tendency for the ELISA to overstimate the metsulfuron‐methyl content was noted and matrix effects were pronounced, particularly in PBS + acetone or ammonium carbonate extracts. Dilution of extracts before analysis improved the situation but reduced the sensitivity of the assay. Using light standard concentrations it was shown that the extracts in PBS on dilutions exhibited a curve parallel with the standard curve, indicating no significant interference due to matrix effects. A working range of 10–250 ng litre−1 was found for ELISA on this type of extracts. © 2000 Society of Chemical Industry 相似文献
53.
A bird's eye review was tried to select the bio‐rational targets from known and novel plant‐specific ones for the molecular design of modern herbicides, which exhibit efficient phytotoxicity at a low‐use rate and preserve a good environment in the 21st century. In phytotoxic sites in the photosynthetic electron transport (PET) system discussed in the present article (Part 1), the generally called bleaching herbicides interfering with the biosynthesis of photosynthetic pigments, chlorophylls and carotenoids, and the biosynthesis of plastoquinone, were considered to be good models for the molecular design of modern herbicides. The PET itself was still considered as an interesting target site for new herbicides, although they need to exert their action in all green leaves of weeds to achieve herbicidal efficacy. Because these herbicides never form a tight binding with D1‐protein, their use‐rate cannot be expected to be as low as the herbicides inhibiting chlorophyll or branched amino‐acid biosynthesis. Other herbicidal targets found in chloroplasts, namely ATP and NADPH formations, have already been omitted from the worldwide biorational molecular design program of herbicides targeting the PET system. 相似文献
54.
Breeding of herbicide-resistant foxtail millet (Setaria italica (L.) Beauv.) is desirable in modern agriculture because no selective herbicide is available for this crop. Trifluralin-resistant millet lines obtained from a interspecific cross between a resistant green foxtail (Setaria viridis (L.) Beauv.) and a foxtail millet cultivar were tested for response to five dinitroaniline herbicides in greenhouse and field experiments. The results in the greenhouse study showed that the resistant type was cross-resistant to all tested herbicides. ED50 values indicated that the highest resistance was obtained with trifluralin, the resistant biotype being seven and 33 times more resistant than the parent cultivar at the emergence and seedling stages, respectively. However, the doses recommended for efficient weed control resulted in some detrimental effects on emergence and growth in the field. Strategies for use of this resistance to control weeds in millet fields are proposed. © 1997 SCI. 相似文献
55.
Maria J. Gil Jos M. Zabalza Javier Navarro Maria A. Maú Alberto Gonzlez Víctor Martínez Merino Arantxa Canal Mercedes Royuela Pedro M. Aparicio-Tejo 《Pest management science》1997,49(2):148-156
Several ethyl 2,3-dihydro-3-oxoisothiazolo[5,4-b]pyridine-2-alkanoate derivatives were synthesized as herbicides. Only 5-methyl derivatives inhibited both hypocotyl and root growth in the lettuce (Lactuca sativa L.) seedling test at 100 mg litre-1. Only ethyl propionate and valerate derivatives showed significant inhibition at 0·1 mg litre-1, whereas ethyl acetate or butyrate derivatives were inactive. Contrary to unoxidized derivatives, the inhibitory effect of 1-oxide and 1,1-dioxide derivatives was strongly dependent on concentration; ethyl 2,3-dihydro-5-methyl-3-oxoisothiazolo[5,4-b]pyridine-2-propionate 1,1-dioxide inhibited 100% of germination at 100 mg litre-1 and 45% of lettuce seedling growth at 0·1 mg litre-1. Quantitative structure–inhibition of growth relationship analysis carried out by adaptive least-squares (ALS) method gave a good correlation with small and hydrophobic 5-substituents as well as with odd carbon-chain ethyl alkanoates in position 2. Active compounds did not show auxin-like activity from 0·1 to 100 mg litre-1. © 1997 SCI. 相似文献
56.
Degradation of three benzonitrile herbicides, bromoxynil (3,5-dibromo-4-hydroxybenzonitrile), ioxynil (3,5-diiodo-4-hydroxybenzonitrile), dichlobenil (2,6-dichlorobenzonitrile), and their mixtures by the soil micro-organism Agrobacterium radiobacter 8/4 was studied in batch cultures. Bromoxynil was found to be most rapidly degraded, while dichlobenil had the lowest toxicity to our strain. All transformations of studied benzonitriles were performed by the nitrile hydratase which has been shown to act on a broad range of substituted aromatic nitriles. © 1997 SCI. 相似文献
57.
Christopher J. Andrews Mark Skipsey Jane K. Townson Carol Morris Ian Jepson Robert Edwards 《Pest management science》1997,51(2):213-222
Using extracts from suspension-cultured cells of soybean (Glycine max cv. Mandarin) as a source of active enzymes, the activities of glutathione transferases (GSTs) catalysing the conjugation of 1-chloro-2,4-dinitrobenzene (CDNB) and selective herbicides were determined to be in the order CDNB≫ fomesafen>metolachlor=acifluorfen>chlorimuron-ethyl. GST activities showed a thiol dependence in a substrate-specific manner. Thus, GST activities toward acifluorfen and fomesafen were greater when homoglutathione (hGSH), the endogenously occurring thiol in soybean, was used as the co-substrate rather than glutathione (GSH). Compared with GSH, hGSH addition either reduced or had no effect on GST activities toward other substrates. In the absence of enzyme, the rates of hGSH conjugation with acifluorfen, chlorimuron-ethyl and fomesafen were negligible, suggesting that rapid hGSH conjugation in soybean must be catalysed by GSTs. GST activities were subsequently determined in 14-day-old plants of soybean and a number of annual grass and broadleaf weeds. GST activities of the plants were then related to observed sensitivities to post-emergence applications of the four herbicides. When enzyme activity was expressed on a mg-1 protein basis, all grass weeds and Abutilon theophrasticontained considerably higher GST activity toward CDNB than soybean. With fomesafen as the substrate, GST activities were determined to be in the order soybean≫Echinochloa crus-galli>Digitaria sanguinalis>Sorghum halepense=Setaria faberi with none of the broadleaf weeds showing any activity. This order related well to the observed selectivity of fomesafen, with the exception of A. theophrasti, which was partially tolerant to the herbicide. Using metolachlor as the substrate the order of the GST activities was soybean>A. theophrasti≫S. halepense>Amaranthus retroflexus>Ipomoea hederacea, with the remaining species showing no activity. GST activities toward metolachlor correlated well with the selectivity of the herbicide toward the broadleaf weeds but not toward the grass weeds. Acifluorfen and chlorimuron-ethyl were selectively active on these species, but GST activities toward these herbicides could not be detected in crude extracts from whole plants. © 1997 SCI 相似文献
58.
除草剂的应用为农业生产带来便利, 但长期、单一使用某一种或相同机制的除草剂也引发了杂草对除草剂的抗性问题。抗性杂草种类逐渐增加, 抗性形成机制复杂, 导致农田杂草的治理难度增加。杂草对除草剂的抗性机制主要分为两种, 一种是除草剂靶标位点基因的突变或过量表达导致的靶标抗性, 另一种是杂草对除草剂吸收、转运、固存和代谢等一个或多个生理过程发生变化导致的非靶标抗性。本文综述了杂草对9类不同作用方式除草剂的非靶标抗性机制的生理、生化和分子基础的研究进展, 以期为抗性杂草综合治理提供参考。 相似文献
59.
Halosulfuron methyl is a sulfonylurea herbicide used worldwide for weed control in sugarcane, maize, wheat, and rice production. Considering its environmental impact, this study evaluated the effects of soil type, application rate, and temperature on the dynamics of halosulfuron methyl degradation.Additionally, as soil microbes and enzymes are reliable indicators of the impacts of anthropogenic activities on soil health, the effects of halosulfuron methyl on soil enzymatic and microbial activiti... 相似文献
60.
Zlatina Naydenova Gerd-Joachim Krauss Evgeny Golovinsky Konstantin Grancharov 《Pest management science》1999,55(8):825-830
Twelve herbicides, representatives of two chemical groups, substituted phenoxyalkanoic acids and s-triazines, were tested for their inhibitory effect on the glucuronidation of 4-nitrophenol (4-NP), phenolphthalein (PPh) and 4-methylumbelliferone (4-MU) by rat liver microsomes. One millimole MCPA, ametryn and cyanazine significantly decreased PPh UDP-glucuronosyltransferase (UGT) activity, while propazine was found to be a most potent inhibitor of 4-NP glucuronidation. Concentrations of 0.1 mM dichlorprop and cyanazine were still inhibitory against PPh-UGT. The inhibition of 4-MU glucuronidation by the herbicides was low and not specific. As a whole, s-triazine derivatives were more inhibitory than the substituted phenoxyalkanoic acids. Kinetic studies with propazine revealed a non-competitive type of inhibition towards the acceptor substrate 4-NP, with an apparent Ki value of 0.540 mM . With ametryn, an uncompetitive type of inhibition against PPh and a mixed type of inhibition towards UDPGA were found, with apparent Ki values of 0.330 mM and 0.380 mM , respectively. © 1999 Society of Chemical Industry 相似文献