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11.
Masaki Hiraki Wim J. Vredenberg Jack J.S. van Rensen Ko Wakabayashi 《Pesticide biochemistry and physiology》2004,80(3):183-191
Chlorophyll fluorescence induction curves of isolated thylakoids were measured in the absence and in the presence of various concentrations of photosystem II-inhibiting herbicides. A mathematical program was applied to simulate the curves. Based on these simulated curves a new method is developed to determine the concentration effect (pI50) of the herbicides. The results of the new method correspond well with reported values in the literature. The method is very convenient and time-saving. 相似文献
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Jeff R. Powell Rachel G. Campbell Kari E. Dunfield Robert H. Gulden Miranda M. Hart David J. Levy-Booth John N. Klironomos K. Peter Pauls Clarence J. Swanton Jack T. Trevors Pedro M. Antunes 《Applied soil ecology》2009,41(1):128-136
Most soybeans grown in North America are genetically modified (GM) to tolerate applications of the broad-spectrum herbicide glyphosate; as a result, glyphosate is now extensively used in soybean cropping systems. Soybean roots form both arbuscular mycorrhizal (AM) and rhizobial symbioses. In addition to individually improving host plant fitness, these symbioses also interact to influence the functioning of each symbiosis, thereby establishing a tripartite symbiosis. The objectives of this study were to (1) estimate the effects of glyphosate on the establishment and functioning of AM and rhizobial symbioses with GM soybean, and (2) to estimate the interdependence of the symbioses in determining the response of each symbiosis to glyphosate. These objectives were addressed in two experiments; the first investigated the importance of the timing of glyphosate application in determining the responses of the symbionts and the second varied the rate of glyphosate application. Glyphosate applied at recommended field rates had no effect on Glomus intraradices or Bradyrhizobium japonicum colonization of soybean roots, or on soybean foliar tissue [P]. N2-fixation was greater for glyphosate-treated soybean plants than for untreated-plants in both experiments, but only when glyphosate was applied at the first trifoliate soybean growth stage. These data deviate from previous studies estimating the effect of glyphosate on the rhizobial symbiosis, some of which observed negative effects on rhizobial colonization and/or N2-fixation. We did observe evidence of the response of one symbiont (stimulation of N2-fixation following glyphosate) being dependent on co-inoculation with the other; however, this interactive response appeared to be contextually dependent as it was not consistent between experiments. Future research needs to consider the role of environmental factors and other biota when evaluating rhizobial responses to herbicide applications. 相似文献
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Water, Air, & Soil Pollution - 相似文献
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Beth A. Snyder Breno Leite John Hipskind Larry G. Butler Ralph L. Nicholson 《Physiological and Molecular Plant Pathology》1991,39(6)
Microspectrophotometry was performed on intact, pigmented vesicle-like inclusions within living sorghum cells that were accumulating phytoalexins as a response to attempted fungal infection. The results indicate that the deoxyanthocyanidin phytoalexins are present in inclusions. Moreover, the phytoalexin concentration within a single inclusion, based on luteolinidin, was calculated to be 0·15 m. The amounts of luteolinidin and apigeninidin in cells involved in the phytoalexin response at individual infection sites were also determined. The data showed that luteolinidin accumulated to levels of 0·48–1·20 ng/cell whereas apigeninidin accumulated to levels of 0·24–0·91 ng/cell. The results of both analyses confirmed that at the infection site the deoxyanthocyanidins accumulate to levels in substantial excess of those required for inhibition of the fungus Colletotrichum graminicola. 相似文献
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Blagburn BL Vaughan JL Butler JM Parks SC 《American journal of veterinary research》1999,60(12):1513-1515
OBJECTIVES: To identify the lowest single dose of lufenuron injected s.c. that results in a 90% disruption of the flea (Ctenocephalides felis) life cycle for 6 months in cats. ANIMALS: 40 domestic shorthair cats (20 males, 20 females) between 5 and 7 months old. PROCEDURE: Cats were randomly assigned to 1 of 5 eight-cat groups and experimentally infested with C. felis on days -8, -7, -6, and -4. On day 0, cats in the 4 treatment groups were treated with an injectable formulation of lufenuron at doses of 2.5, 5, 10, or 20 mg/kg of body weight, respectively. Control cats received the injectable formulation without lufenuron. Experimental infestations were repeated and flea eggs collected at various intervals for 196 days after treatment. Eggs were placed in media and incubated in an insectary for 28 days to determine effects of injectable lufenuron on egg and larval development. Number of adults that emerged from eggs were compared among groups. RESULTS: Lufenuron injected once at a dose of 10 or 20 mg/kg, but not at 2.5 or 5 mg/kg, resulted in a 90% decrease in number of adult fleas emerging from eggs for 196 days after treatment. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicate that control of flea egg and larval development for at least 6 months can be achieved in cats with a single s.c. injection of lufenuron (10 mg/kg). The injectable formulation may provide veterinarians and cat owners an alternative to the tablet formulation of lufenuron. 相似文献