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1.
BACKGROUND: In Chile, rice is cultivated under water‐seeded and continuously flooded conditions. Because herbicide dynamics in paddy fields and non‐flooded fields is different, 3 year experiments were performed to study the dissipation of molinate and penoxsulam in water and sediment. RESULTS: In field experiments, both herbicides dissipated by 45–55% from the initial applied amounts during the first 6 h after application in all crop seasons; in lysimeter experiments, dissipation amounts were approximately 10% for penoxsulam and 16% for molinate. Penoxsulam field water DT50 values varied from 1.28 to 1.96 days during the three study seasons, and DT90 values from 4.07 to 6.22 days. Molinate field water DT50 values varied from 0.89 to 1.73 days, and DT90 values from 2.82 to 5.48 days. Sediment residues were determined 2 days after herbicide application into the paddy water, and maximum concentrations were found 4–8 days after application. In sediment, DT50 values varied from 20.20 to 27.66 days for penoxsulam and from 15.02 to 29.83 days for molinate. CONCLUSIONS: Results showed that penoxsulam and molinate losses under paddy conditions are dissipated rapidly from the water and then dissipate slowly from the sediment. Penoxsulam and molinate field water dissipation was facilitated by paddy water motion created by the wind. Sediment adsorption and degradation are considered to have a secondary effect on the dissipation of both herbicides in paddy fields. Copyright © 2011 Society of Chemical Industry  相似文献   

2.
BACKGROUND: Fenoxaprop‐P‐ethyl is a herbicide used on cereals and in particular on rice, the degradation of which leads to several relevant metabolites. The herbicide is used together with an agronomic safener such as isoxadifen‐ethyl, which also generates some metabolites. The present work was aimed at developing and validating an analytical method for the determination of the above parent compounds and their main metabolites in the edible fractions of rice. Parent compounds were extracted in acetonitrile and determined by gas chromatography with a mass spectrometer detector, while metabolites were extracted in acetonitrile and analysed by liquid chromatography tandem mass spectrometry. RESULTS: The method was validated through recovery tests in rice straw, grain and plant: accuracy was in the range 76–86% and 90–103% for parent compounds and metabolites respectively. Precision, as relative standard deviation, was in the range 3–11% and 6–17% for parent compounds and metabolites respectively. The limit of detection was 0.01 mg kg?1 for each analyte, while the limit of quantification was set at 0.05 mg kg?1. CONCLUSION: The analytical method is suitable for quantitative determination of each analyte considered in rice commodities. Copyright © 2010 Society of Chemical Industry  相似文献   

3.
The microsome-NADPH system of mouse liver oxidizes each of benthiocarb, butylate, cycloate, EPTC, molinate, pebulate, and vernolate herbicide chemicals to the corresponding thiocarbamate sulfoxide which is then cleaved by the liver soluble-glutathione system. These sulfoxides are also detected as transient metabolites in the liver of mice injected with EPTC, molinate, pebulate, and vernolate but not with the other three thiocarbamates. Thiocarbamate sulfones are not detected as metabolites of the thiocarbamates. Studies in vivo and in vitro with [14C]EPTC and -pebulate or their corresponding sulfoxides and/or sulfones further indicate that sulfoxidation is the initial metabolic step in cleavage of the thiocarbamate ester group. Sulfoxidation appears to be a detoxification mechanism for thiocarbamate herbicides in mammals.  相似文献   

4.
Lignin biosynthesis is essential for plant growth. 4‐Coumarate CoA ligase (4‐CL, EC6.2.1.12) is involved in the monolignol synthesis and occupies a key role in regulating carbon flow into the phenylpropanoid metabolism pathway. Naringenin, one of the metabolites in this pathway, is known as a potent in vitro inhibitor of 4‐CL. The growth of rice (Oryza sativa L. cv. Koshihikari), maize (Zea mays L. cv. Yellow corn) and Echinochloa oryzicola Vasing seedlings at the 2nd leaf stage was inhibited after continuous root application with 0.1 mmol L?1 naringenin for 1 week, although naringenin did not kill these gramineous plants. The highest inhibition of fresh weight increase was observed in maize, followed by rice and E. oryzicola. The symptoms in these plants were root browning, delay of leaf/root development and shoot dwarfing. Naringenin treatment increased the contents of 4‐CL substrates, cinnamic acid, 4‐coumaric acid, caffeic acid and ferulic acid from 1.2 to 7.2 times and from 1.2 to 3.5 times in shoots and roots, respectively, except for ferulic acid in E. oryzicola roots. It also caused a slight decrease of the lignin content and alteration of lignin constitutions in rice plants. These results suggested that the monolignol pathways after 4‐CL towards lignin has the possibility to be the novel action sites of plant growth retardants, although further investigations are needed to clarify the mode of action.  相似文献   

5.
The introduction of imidazolinone‐tolerant rice varieties has made selective Oryza sativa (weedy rice) control possible. We hypothesised that Italian weedy rice populations have variable degrees of susceptibility to imazamox prior to imidazolinone‐tolerant variety introduction. To this end, 149 Italian weedy rice populations collected from fields never before cultivated with imidazolinone‐tolerant varieties were tested in a glasshouse‐based, whole‐plant response screening study. Imazamox was applied to all populations post‐emergence at a rate of 70 g a.i. ha?1, resulting in 70–90% shoot biomass reduction in the majority of cases. The results prompted a second study of the seedling dose response of four weedy rice populations from the initial study group. Three imidazolinone‐tolerant and one conventional rice variety were also included. The seedling roots were cut six days after germination and exposed to different concentrations of imazamox. The root regrowth associated with each concentration‐exposure was then measured. Imazamox concentrations to inhibit weedy rice root growth by 50% varied by about two orders of magnitude, or between 0.0018 and 0.12 mm . Even with this result, imidazolinone‐tolerant varieties were at least 31.8 times less susceptible than weedy rice populations, suggesting that Italian weedy rice populations were not tolerant to imazamox before introduction of these varieties.  相似文献   

6.
H. H. HOPPE 《Weed Research》1980,20(6):371-376
Effect of diclofop-methyl on the growth und development of Zea mays L. seedlings Diclofop-mcthyl, a diphenoxypropionic acid herbicide, had no effect on the germination of maize (Zea mays) seed. Prc-ger-minated maize embryos showed inhibited radicle growth when treated with the herbicide, but those of beans were considerably less sensitive. The inhibitory effect of the herbicide on maize radicle growth was reversed when the embryos were transferred to herbicide-free medium within 24 h of treatment. The higher concentrations of diclofop-methyl tested (≥10?6 M) induced necrosis on the second day of treatment, which first appeared in the meristematic and elongation zone of the root tip and then via the rest of the root to the grain. The herbicide increased the fresh and dry weight as well as the dry matter content of the radicle tips of Zea mays. These effects were attributed in an accumulation of cell wall material in the herbicide-treated root lips. In the presence of hydroxyurea, a selective inhibitor of cell division, the effect of diclofop-melhyl on radicle elongation was reduced but did not cease complelely. From these results it can be concluded that diclofop-methyl interferes with the processes that effect both cell division and cell elongation.  相似文献   

7.
Potential genotoxicity of sulcotrione 2-(2-chloro-4-(methylsulfonyl)benzoyl)-1,3-cyclohexanedione, a selective triketonic herbicide was evaluated on Vicia faba seedlings in hydroponic culture conditions. Sulcotrione (10−5, 10−4 and 2 × 10−4 M) treatments for 45 h, caused a dose dependent increase in micronuclei frequencies in root meristematic cells. Cytological analysis of root tips cells showed aneugenic effects of the sulcotrione on the plant root meristems. Sulcotrione induced chromosomal alterations at the lowest concentration used (10−5 M) when incubated for 42 h, indicating the potent mutagenic effect of this element. This is the first report for the genotoxicity of such a sulcotrione herbicide.  相似文献   

8.
Methyl 2-[4-(2,4-dichlorophenoxy)phenoxy]propanoate (dichlofop-methyl) is a selective herbicide for wild oat (Avena fatua L.) control in wheat (Triticum aestivum L.). Dichlofop-methyl inhibited IAA-stimulated elongation of oat and wheat coleoptile segments by 51 and 13%, respectively, at 10 μM concentrations. Dichlofop-methyl alone had no auxin activity at concentrations of 0.1, 1.0, and 10 μM. The inhibitory effect of dichlofop-methyl was overcome partially by increasing the IAA concentration or by application of 3,6-dichloro-o-anisic acid (dicamba), a herbicide with weak auxin activity. The de-esterified free acid metabolite, 2-[4-(2,4-dichlorophenoxy)phenoxy]-propionic acid (dichlofop), at 10 μM inhibited auxin-stimulated oat coleoptile elongation by 23%, but it did not affect wheat coleoptile elongation at the same concentration. Both dichlofop-methyl and dichlofop inhibited root growth in excised shoots and seedlings of wild oat but had no effect on wheat. Dichlofop was a more effective inhibitor of root growth than dichlofop-methyl. The results suggest that dichlofop-methyl functions as a strong auxin antagonist, while the metabolite, dichlofop, inhibits root growth and development by another mechanism. The herbicidal effect of dichlofop-methyl may be the net effect of two biologically active forms of the compound each with a different mode of action acting at different sites within a susceptible plant.  相似文献   

9.
稗对水稻生长和产量性状的影响及其经济阈值   总被引：20，自引：4，他引：20       下载免费PDF全文
稗Echinochloa crusgalli Beauv.在稻田的发生危害对水稻生产造成了严重威胁.为明确稗对水稻生长的影响及其经济危害允许水平,采用添加系列试验和模型拟合的方法研究了不同稗草密度下水稻各产量性状的变化规律.研究结果表明,水稻在稗的竞争干扰下,植株的分蘖数、有效穗数、千粒重及产量均随稗草密度的增加而逐渐降低.指数模型y=beax可以较好地拟合稗对水稻分蘖数(y=493.74e-0.0164x,P＜0.0001)、有效穗数(y=437.2e-0.0165x,P＜0.0001)及千粒重(y=21.876e-0.0006x,P＜0.005)的影响,而对数模型y=aLnx b拟合稗与水稻产量(y=-1250.4Lnx 6375.4,P＜0.0001)及产量损失(y=18.844Lnx 3.9182,P＜0.0001)间的关系最佳.稻田使用乙苄、丁草胺、禾大壮、二氯喹啉酸等药剂进行化学除草时,稗的经济危害允许水平在0.71%～1.10%之间,经济阈值在0.85株/m2左右.  相似文献   

10.
R. A. CHRIST 《Weed Research》1985,25(3):193-200
The elongation rates of single attached leaves of rice (Oryza saliva L.) were recorded. The effect of pretilachlor on the elongation rates and the safening effect of CGA 123407 [4, 6-dichloro-2-phenyl-pyrimidine] were evaluated. Both chemicals were applied to the roots in a nutrient solution. Pretilachlor reduced leaf elongation in concentrations as low as 300 μg?1 (9–6 × 10?7 M) but. for combination trials with the safener, 3 mg 1?1 (9–6 × 10?6 M) was used. in combination with pretilachlor the safener prevented damage in very low concentrations. The ratio of pretilachlor to safener, 30:1, was sufficient when both chemicals were given to roots in nutrient solution, although for field work the ratio of 3:1 is recommended. The safener alone did not influence the elongation rate of rice leaves in the concentrations used. When pretilachlor was given to the roots and CGA 123407 to the shoot, some delay in the herbicidal action was recorded but even with high concentrations of the safener no continuous safening effect was achieved. CGA 123407 was also effective when given previous to the herbicide. This proved true even with a 2-day interval between safener uptake and application of the herbicide. When pretilachlor was given first, the safener effected recovery to various degrees when given 1–4 days after the herbicide application. When pretilachlor was given for a limited period of time only (1–3 days) and was subsequently removed from the nutrient solution, recovery of the plant occurred. It is speculated that the safener either helps this recovery or else competitively prevents the herbicide from occupying the sites of action or from keeping them occupied for a long period of time.  相似文献   

11.
Varietal susceptibility of winter wheat to chlortoluron, 1-(3-chloro-4-methylphenyl)-3,3 dimethylurea, has been studied in two varieties, Corin (susceptible) and Clement (tolerant). After a 24-hr root absorption of the herbicide, phytotoxicity was estimated from growth measurements. When administered at 12 to 96 μM concentrations, the herbicide reduced the growth of both varieties. A significant selective effect was found at 96 μM. Measurements of chlorophyll fluorescence-induction kinetics allowed to discriminate between the two varieties treated with 12 to 48 μM chlortoluron. The metabolism of chlortoluron was studied following absorption of 24 μM solutions. Both varieties produced the same pattern of metabolites but the tolerant variety degraded the herbicide and the phytotoxic mono-N-demethylated metabolite at a slightly higher rate. An unexpected result was that the more susceptible variety possessed a very significant ability to metabolize chlortoluron. In conclusion, it appears that further studies are necessary before deciding whether the differences in susceptibility of the two varieties can be explained by the only metabolic factor.  相似文献   

12.
Root growth inhibition of rice by bensulfuron   总被引：1，自引：0，他引：1  
Bensulfuron inhibited root growth of waterseeded rice (Oryza sativa L.) plants in a solution culture system. Rice root growth was more sensitive to bensulfuron than was shoot growth. A1 2.5 × 10-9 M bensulfuron, plant height, number of leaves and number of roots were not significantly affected, while root growth was reduced, Seedlings treated 3 or 4 days after emergence showed a significant reduction of total root length by the second day after treatmeni. Root growth inhibition was proportional to duration of treatment; however, treatment for 2 days was necessary to affect root growth, Bensulfuron decreased the mitotic index and the mitotic height in root tips. At 5 days after treatment, only 0.7% of the cells were dividing and mitotic height was 68% of control  相似文献   

13.
Adverse effects of the rice herbicide molinate on Japanese carp (Cyprinus carpio) can be effectively reduced by treating the fish with certain dichloroacetamides added to the water habitat or incorporated into the fish food. The preferred treatment is to add dichloroacetamide and ascorbic acid to the food. The protective effect of the dichloroacetamides was associated with elevated levels of glutathione in the liver and elevated levels of molinate mercapturic acid in the bile.  相似文献   

14.
The herbicide mefenacet has recently been developed for pre–emergence control of graminaceous and some dicotyledonous weeds in rice. Whereas mefenacet is known to inhibit root growth, its effect on the components of growth, cell division and cell enlargement, have not been determined. The purpose of this study was to evaluate the influence of mefenacet on growth, cell enlargement and cell division in Chlamydomonas (a green alga) and oats. Cell division in Chlamydomonas was completely inhibited and cell enlargement was inhibited by an average of 18% during the first cell cycle period when cells were treated with 6–7 μM mefenacet. The rate of oat root growth in sand culture between 12 and 24 h after initiation of treatment was reduced 90% at 10 μM mefenacet. Cell enlargement of oat coleoptile sections in culture solution was inhibited 25% at 10 μM. Mefenacet inhibited mitotic entry rather than disrupted the mitotic sequence. Cell division in oat roots was inhibited 54% by 10 μM mefenacet. This shows cell division inhibition occurs in G1, S, or G2 of the cell cycle. The action of mefenacet is most like that of the chloroacetamides among the herbicide classes known to inhibit growth.  相似文献   

15.
We are examining the interaction of compounds with the herbicide propanil to find synergistic or additive actions that can increase efficacy against propanil-resistant barnyardgrass [Echinochloa crus-galli] (R-BYG) without substantial injury to rice. Field tests (herbicidal injury) and laboratory tests (chlorophyll quantification in excised leaves; measurement of chlorophyll fluorescence to determine PSII inhibition) have been conducted on R-BYG and rice tissue exposed to various rates of propanil and additive. Important synergistic interactions on R-BYG in laboratory and field tests were found with propanil plus either the herbicides anilophos or piperophos, or the insecticide carbaryl. In laboratory tests, the insecticide methiocarb and PPG-124 (p-chlorophenyl N-methylcarbamate) were highly effective synergists with propanil on R-BYG. Other important interactions occurred with certain concentrations/application rates when propanil was combined with the herbicides quinclorac, thiobencarb, molinate, or pendimethalin (field tests). Combinations of these or other chemicals with propanil may provide additive or synergistic action useful to control R-BYG without increasing rice injury. Such mixtures might also prevent or delay the development of propanil resistance in this weed species.  相似文献   

16.
双环磺草酮是在我国取得水稻田使用登记许可的HPPD抑制剂类除草剂,杀草谱广,尤其对抗性千金子、杂草稻等恶性杂草表现出良好的防除效果。为进一步探索双环磺草酮在直播稻田的应用前景和应用技术,采用盆栽试验法,开展了25%双环磺草酮悬浮剂 (SC) 对不同叶龄期水稻品种的安全性评价。结果表明:在水稻1~2叶期、2~3叶期和3~4叶期浅水层条件和水稻1~2叶期湿润条件下,按有效成分150~375 g/hm2剂量施用25%双环磺草酮SC,对上海地区主栽的3个常规粳稻品种南粳46、沪软1212和松香粳1018 以及申优26杂交粳稻品种生长均安全,对水稻株高、植株地上部分鲜重、根长、根系鲜重等生长指标均无显著影响。表明双环磺草酮对水稻粳稻品种安全,待进一步明确应用技术后,有望成为直播稻田优秀的除草剂品种。  相似文献   

17.
A. WALKER 《Weed Research》1973,13(4):407-415
Summary. Turnip, lettuce and ryegrass seedlings showed toxicity symptoms following shoot exposure to atrazine, linuron and aziprotryne at soil concentrations less than would be obtained from normal field applications. Responses following shoot exposure to simazine and lenacil were much less. Root exposure to all five herbicides caused seedling death at concentrations lower than those required for 'shoot-zone' toxicity. Pronamide and chlorpropham were tested against ryegrass only and at the concentrations examined were toxic only when localized in the shoot zone. Root exposure suppressed root growth, but the shoots were able to grow normally if the soil was kept sufficiently moist. Shoots contained more 14C-atrazine at emergence after shoot exposure compared with root exposure, but there was little subsequent uptake from the shoot zone. There was extensive uptake from the root zone after emergence. In the shoot-zone treatments, concentrations in the plant were high at emergence but were rapidly diluted by plant growth, whereas with root exposure, they increased throughout the experiments. The possible significance of these results to herbicide bebaviour under field conditions is discussed.
La distribution verticale des herbicides dans le sol et leur disponibilité pour les plantes: absorption comparée par la partie aèrienne et par les radnes  相似文献   

18.
Abstract

In Hamoul in the Nile Delta, where barnyard grass was the prevalent weed, two field trials of 12 herbicides were carried out in transplanted rice (cultivar; G12a 170). In the 1972 season granular herbicides were shown to be significantly superior to liquid formulations. In 1973 an improved technique was investigated, broadcasting herbicide/gypsum mixture by hand onto flood water. This type of application was successfully extended to some 7,000 feddans during the 1973 and 1974 seasons with the use of molinate/gypsum mixture. All herbicidal applications seemed significantly superior to hand-weeding once. Among all the tested herbicides, molinate was found to be the most beneficial, since it increased the rice grain yield by 62.5% and 108.0% over one hand-weeding and the control respectively.  相似文献   

19.
Cinidon-ethyl (BAS 615H) is a new herbicide of isoindoldione structure which selectively controls a wide spectrum of broadleaf weeds in cereals. The uptake, translocation, metabolism and mode of action of cinidon-ethyl were investigated in Galium aparine L, Solanum nigrum L and the tolerant crop species wheat (Triticum aestivum L). When plants at the second-leaf stage were foliarly treated with cinidon-ethyl equivalent to a field rate of 50 g ha−1 for 48 h, the light requirement for phytotoxicity and the symptoms of plant damage in the weed species, including rapid chlorophyll bleaching, desiccation and necrosis of the green tissues, were identical to those of inhibitors of porphyrin synthesis, such as acifluorfen-methyl. The selectivity of cinidon-ethyl between wheat and the weed species has been quantified as approximately 500-fold. Cinidon-ethyl strongly inhibited protoporphyrinogen oxidase (Protox) activity in vitro, with I50 values of approximately 1 nM for the enzyme isolated from the weed species and from wheat. However, subsequent effects of herbicide action, with accumulation of protoporphyrin IX, light-dependent formation of 1-aminocyclopropane-1-carboxylic acid-derived ethylene, ethane evolution and desiccation of the green tissue, were induced by cinidon-ethyl only in the weed species. After foliar application of [14C] cinidon-ethyl, the herbicide, due to its lipophilic nature, was rapidly adsorbed by the epicuticular wax layer of the leaf surface before it penetrated into the leaf tissue more slowly. No significant differences between foliar and root absorption and translocation of the herbicide by S nigrum, G aparine and wheat were found. After foliar or root application of [14C]- cinidon-ethyl, translocation of 14C into untreated plant parts was minimal, as demonstrated by combustion analysis and autoradiography. Metabolism of [14C]cinidon-ethyl via its E-isomer and acid to further metabolites was more rapid in wheat than in S nigrum and G aparine. After 32 h of foliar treatment with 50 g ha−1 of the [14C]-herbicide, approximately 47%, 36%, and 12% of the absorbed radioactivity, respectively, were found as unchanged parent or its biologically low active E-isomer and acid in the leaf tissue of G aparine, S nigrum and wheat. In conclusion, cinidon-ethyl is a Protox-inhibiting, peroxidizing herbicide which is effective through contact action in the green tissue of sensitive weed species. It is suggested that a more rapid metabolism, coupled with moderate leaf absorption, contribute to the tolerance of wheat to cinidon-ethyl. © 1999 Society of Chemical Industry  相似文献   

20.
Study was carried out to investigate the chronic response of cyanobacteria, Anabaena fertilissima to chlorophenoxy herbicide 2,4-dichlorophynoxyacetic Acid (2,4-D) ethyl ester at different concentrations 15, 30 and 60 ppm. The influence of 2,4-D on growth (pigments), release of metabolites such as carbohydrates, protein, amino acid, phenols and nitrate reductase and glutamine synthetase activities was analyzed. The test concentrations caused a concentration-dependent decrease in pigments. Depletion in carbohydrate and protein content was registered with rise in herbicide concentrations. However, phenols were found to rise with increased herbicide concentrations but amino acids were reported to decline. The inhibition of nitrate reductase and glutamine synthetase activity was also concentration-dependent and showed more sensitivity for substituted phenoxy herbicide. This study therefore suggests that decrease in metabolite content and enzyme activity can be used as a signal of herbicide toxicity in cyanobacteria.  相似文献   

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