| Imazamox belongs to the imidazolinone herbicides, the herbicide is the typical chiral herbicide. At present, imazamox is widely used in racemic form, which environmental risks were studied by its racemic form, but in the level of the enantiomer, the toxicity and environment risks to non-target organisms about individual enantiomers of chiral herbicides are poorly understood. The paper investigated the interaction between imazamox and plant, the corn and alfalfa as two kinds of tested plants representative (maize is sensitive plant, alfalfa is tolerant plant). On the one hand, phytotoxicity of imazamox on plants was discribed; on the other hand, the characteristics of degradation on plants to imazamox were discussed.1. Imazamox chiral enantiomers of preparation and stability analysis. In the normal phase high-performance liquid chromatography system, using a chiral OJ-H analytical column (0.46mmI.D×25cmL×5μm) for separation and analysis of the chiral sample of imazamox, preparation of samples for enantiomeric, single enantiomers of the chiral stability analysis. Evaluation of the effect of the mobile phase composition (n-hexane-isopropyl alcohol), additives trifluoroacetic acid (TFA) and temperature to chiral split. In the laboratory, the optimum separation conditions of imazamox was35℃, hexane/isopropanol75/25(V/V), the amount of trifluoroacetic acid was0.1%.2. Enantioselective phytotoxicity of imazamox on maize growth.s-enantiomer, r- enantiomer, racemate corn seedlings EC50(root lenth:1.2142,0.2460,0.4212mg/L;1.4023,0.4530,0.7114)the results showed that both the underground part of the ground portion of root length or shoot height, r-enanriomer was the most effectiveinhibitor in the damage of maize, s-enantiomer was minimal, and rac-imazamox was between the r and s enantiomer. With the higher the concentration, the greater the differences in toxicity of the enantiomers. Compared with the control, their root morphology, just like total root lengthes, lateral root numbers, root surface areasand root volumes were all poisoned.The inhibition strength: number of lateral roots> total root lengthes> root surface areas> root volumes.3. Enantioselective phytotoxicity of Imazamox on maize Seedling physiology. s-enantiomer, r-enantiomer, racemate caused maize root’s activity decreased, apical werepoisoned. By transmission electron microscopy (TEM) observation after control treatment, cell nucleuses were regelar in the apical cell, nuclears membrane integrity, nucleolus werenormal, with a large number of mitochondria, golgi apparatus and endoplasmic reticulum in the cells. All kinds of organelles shapes rules, the completed structures. But after0.1mg/L、0.5mg/Lrac-imazamox treatment, cell nucleuses were irregular, and nuleoluses were disappeared, other cells’organelles were damaged by a reduction in nunlber and size, the structures were also changed. And chlorophyll content also have changed in the plant.4. The method is established for the determination of imazamox residue in the water, and discussed its enantiomers degradation characteristics in plant-water systems.This method applied SCX solid-phase extraction(SPE) to enrich the herbicide in water samples. The average recoveries for enantiomers in water were78～95%(RSD≤8.4%, n=5). Under the optimized conditions limits of detection for imazamox enantiomers were0.025mg/L (S/N=3). With this method of alfalfa hydroponic system water samples for testing, measuring results showed greater herbicidal activity was found to degrade faster than the less active s-enantiomer, and the degradation rate of three alfalfa varieties for Suntory> CCED7>42IQ. |
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