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1.
Ambrona J Maqueda M Zamora E Ramírez M 《Journal of agricultural and food chemistry》2005,53(19):7438-7443
Winemaking with selected yeasts requires simple and cheap techniques to monitor the yeast population dynamics. We obtained new sulfometuron (smr) resistant mutants, easy to detect by replica-plate assay, from selected wine yeasts. The mutations were dominant and were located at the ilv2 locus that encodes for acetolactate synthase enzyme. The mutants were genetically stable and maintained the killer phenotype of the parent yeast strain. They were genetically improved by elimination of recessive growth-retarding alleles followed by spore clone selection according to the must fermentation kinetics and the organoleptic quality of the wine. Some mutants were tested in industrial winemaking and were easily monitored during must fermentation using a simple plate assay. They accounted for more than 95% of the total yeasts in the must, and the resulting wine had as good a quality as those made with standard commercial wine yeasts. 相似文献
2.
Undabeytia T Recio E Maqueda C Morillo E Gómez-Pantoja E Sánchez-Verdejo T 《Pest management science》2011,67(3):271-278
BACKGROUND: Metribuzin is a widely used herbicide that has been identified as a groundwater contaminant. In this study, slow‐release formulations of metribuzin were designed by encapsulating the active ingredient in phosphatidylcholine (PC) vesicles and adsorbing the vesicles onto montmorillonite. RESULTS: The maximum active ingredient content in the slow‐release formulations was 246 g kg?1. Infrared spectroscopy results revealed that the hydrophobic interactions between metribuzin and the alkyl chains on PC were necessary for encapsulation. In addition, water bridges connecting the herbicide and the PC headgroup enhanced the solubility of metribuzin in PC. Adsorption experiments in soils were performed to evaluate the relationship between sorption and leaching. Funnel experiments in a sandy soil revealed that the herbicide was not irreversibly retained in the formulation matrix. In soil column experiments, PC–clay formulations enhanced herbicide accumulation and biological activity in the top soil layer relative to a commercial formulation. PC–clay formulations also reduced the dissipation of metribuzin by a factor of 1.6–2.5. CONCLUSIONS: A reduction in the recommended dose of metribuzin can be achieved by employing PC–clay formulations, which reduces the environmental risk associated with herbicide applications. Moreover, PC and montmorillonite are non‐toxic and do not negatively affect the environment. Copyright © 2010 Society of Chemical Industry 相似文献
3.
The effect of beta-cyclodextrin (beta-CD) on the removal of the herbicide norflurazon (NFL) from soils has been investigated. The interaction of NFL with beta-CD in solution yielded the formation of a water-soluble inclusion complex at 1:1 stoichiometric ratio, which gave an increase in NFL solubility. Desorption studies of NFL previously adsorbed on six soils of different characteristics have been performed in the presence of 0.01 M beta-CD or 0.01 M Ca(NO(3))(2) as extractant solutions. Positive hysteresis was observed in all soils when 0.01 M Ca(NO(3))(2) solution was used, indicating that desorption of NFL from these soils was not completely reversible. On the contrary, the application of beta-CD solutions to soils where NFL had been previously adsorbed increased very much its desorption, and a negative hysteresis was obtained for all soils studied; that is, more NFL was desorbed with respect to NFL adsorption isotherm. A clear relationship was observed between the physicochemical characteristics of the soils and the beta-CD concentration necessary to remove the herbicide, the percentages of desorption observed for each soil being inversely related to the values obtained for the Freundlich sorption capacity parameter of the herbicide, K(f). In general, high desorption yields can be obtained with very low beta-CD concentrations, which is an important advantage from an economic point of view, although in those soils that present an extremely high NFL adsorption, higher amounts of beta-CD should be used. The results obtained indicate the high extracting power of beta-CD toward the herbicide previously adsorbed on the soils and the potential use of beta-CD for in situ remediation of pesticide-contaminated soils. 相似文献
4.
Undabeytia T Sanchez-Verdejo T Morillo E Maqueda C 《Journal of agricultural and food chemistry》2004,52(14):4493-4500
The influence of two organic amendments consisting of an urban waste compost (SUW) and a commercial amendment from olive mill wastes (OW) was assessed on the sorption properties and leaching of the ionizable herbicide imazaquin on four soils with different physicochemical characteristics. A loamy sand soil (CR), a loam soil (P44), a silt loam soil (AL), and a clay soil (TM), with low-medium organic matter contents, were chosen. Sorption-desorption experiments were performed on the original soils and on a mixture of these soils with the organic amendments at a rate of 6.25% (w/w). These mixtures were used just after preparation and after aging for 3 months. Imazaquin adsorption was higher on AL soil because of its high content of amorphous iron oxides, whereas it was related to the soils' organic matter (OM) contents on TM and CR soils and to acid pH on P44 soil. Addition of exogenous OM to soils caused a decrease in the adsorption of the herbicide with the only exception of CR soil, due to blocking of adsorptive surfaces and/or equilibrium pH rise. The extent of this decrease was dependent only on the nature of the added amendment on AL soil. The adsorbed amounts of imazaquin on aged organic fertilized soils were usually fairly close to that on original soils. Results of soil column experiments indicate that addition of exogenous organic matter cannot be considered as a regular practice for retarded movement of imazaquin. 相似文献
5.
Villaverde J Morillo E Pérez-Martínez JI Ginés JM Maqueda C 《Journal of agricultural and food chemistry》2004,52(4):864-869
The formulation of inclusion complexes of the herbicide norflurazon as guest and beta-cyclodextrin (beta-CD) as host has been studied as a first step in the use of cyclodextrins to obtain improved formulations of this herbicide. The interaction of norflurazon with beta-CD produced the formation of an inclusion complex in solution and in solid state. The inclusion of norflurazon in beta-CD in solution was studied by phase solubility, and an apparent stability constant of 360 M(-)(1), a 1:1 stoichiometric ratio for the complex, and up to 5-fold increase in norflurazon solubility were determined. Three processing methods (kneading, spray drying and vacuum evaporation) were used to prepare norflurazon-beta-CD solid inclusion complexes. X-ray diffraction, infrared spectroscopy, differential scanning calorimetry, and scanning electron microscopy techniques were used to study the solid complexes. From the different solid systems, an increase of norflurazon aqueous dissolution rate was obtained in comparison to the uncomplexed herbicide. This finding is a first step to obtain controlled release and/or protective formulations of norflurazon, which allow a more rational application of norflurazon, diminishing the use of organic solvents and increasing its efficacy. 相似文献
6.
FTIR study of glyphosate-copper complexes 总被引：4，自引：0，他引：4
Complexes of the herbicide glyphosate (GPS) and the heavy metal Cu were studied by infrared spectroscopy under controlled pH, in order to know the mechanisms involved in the formation of these complexes. In CuGPS(-), the IR spectrum shows participation of the carboxylate and phosphonic moieties of the GPS molecule. The formation of the complex produces a lower symmetry in the phosphonate group because of loss of the resonance situation of PO(3)(2)(-) groups, with a subsequent split of their absorption bands. Carboxylate groups are participating by forming unidentate complexes. No conclusion is reached about the involvement of the amino group, but previous EPR findings indicate coordination of GPS to Cu via nitrogen. Consequently, glyphosate in this complex functions with a tridentate character by forming two chelate rings. A study of the CuGPSH species was not possible due to overlapping of its absorption bands with those of free GPS species. 相似文献
7.
BACKGROUND: The development of controlled‐release formulations of alachlor to extend the period of weed control was studied. This extended duration reduces the need for high herbicide application rates that could lead to environmental contamination. For this purpose, the influence of formulation, as well as the influence of soil characteristics, on alachlor efficacy and persistence in soil of a commercial formulation (CF) and different ethylcellulose microencapsulated formulations (MEFs) was evaluated. RESULTS: Higher alachlor rates yielded an enhanced initial herbicidal activity. The prolonged release of alachlor provided by the MEFs resulted in a higher herbicidal efficacy and a longer period of weed control compared with the effects of CF in the two soils tested (at 40 days after treatment, oat growth inhibition for CF and MEFs was 1.96% and 93.5% respectively). Soil characteristics strongly influenced alachlor efficacy and weed control by MEFs. The highest alachlor efficacy and persistence were observed in the soil with lowest microbial activity and clay and organic matter content. CONCLUSIONS: The use of MEFs can be advantageous because they permit the maintenance of the desired concentration of the herbicide in the soil for longer periods of weed control. Copyright © 2009 Society of Chemical Industry 相似文献
8.
The pesticide norfluazon has been microencapsulated using ethyl cellulose to develop controlled-release formulations that decrease its mobility through the soil and protect it from photodegradation. Ethyl cellulose microspheres loaded with norfluazon were prepared by the solvent-evaporation method. To obtain the microspheres, certain conditions (pesticide/polymer ratio, percentage of emulsifying agent and solvent) were varied. The shape and size of the microspheres obtained were studied by scanning electron microscopy. Other parameters, such as solids recovery, encapsulation efficiency and pesticide loading, were also studied. The release rate of norfluazon from the different microspheres was slower than that of pure norfluazon. In particular, microspheres obtained with o-xylene, which provided the largest diameter, retarded the initial release of the pesticide relative to microspheres obtained with chloroform, or to pure norfluazon. Moreover, the studies showed that the pesticide/polymer ratio controlled the release of norfluazon, which was slower when this ratio was low. Release rates conformed to a generalised kinetic equation for a diffusion-controlled release mechanism, and the time taken for 50% of the active ingredient to be released into water, t50, was calculated. 相似文献
9.
Morillo E Undabeytia T Cabrera A Villaverde J Maqueda C 《Journal of agricultural and food chemistry》2004,52(4):884-890
Adsorption-desorption studies of norflurazon on 17 soils of very different characteristics have been performed using a batch equilibration method and correlated to its mobility, activity, and persistence in soils. The influence of different soil properties and components on norflurazon adsorption was determined. The significant variables were organic matter (OM) content and iron and aluminum oxides, which accounted for 85 and 11% of the variability, respectively. Norflurazon desorption from soils was hysteretic in all cases, being more irreversible at the lowest herbicide concentrations adsorbed. The percentage of norflurazon eluted from columns of selected soils reached almost 100% in soils with sand content >80% and OM <1%, but in the soil which gave the highest sorption, herbicide residues were not detected at depths >16 cm. The herbicidal activity of norflurazon was followed by measuring its bleaching effect on soybean plants, and the herbicide concentration required to give 50% chlorophyll inhibition (CI(50)) was calculated. CI(50) was achieved on a sandy soil with 0.08 mg x kg(-)(1), whereas 1.98 mg x kg(-)(1) was necessary for the soil that presented maximum norflurazon adsorption. 相似文献
10.
Controlled release of the herbicide norflurazon into water from ethylcellulose formulations 总被引：4，自引：0，他引：4
Sopeña F Cabrera A Maqueda C Morillo E 《Journal of agricultural and food chemistry》2005,53(9):3540-3547
The herbicide norflurazon was encapsulated in ethylcellulose (EC(40)) microspheres by the solvent evaporation technique to obtain controlled release formulations. The kinetics of release of the active ingredient into the aqueous solution from different preparations was determined. It was found that the percentage release of the incorporated herbicide was a function of the composition and formation conditions of the formulations (amount of emulsifying agent, EC(40)/herbicide ratio, stirring speed, and percentage of pore-forming agent). The percentage of the herbicide release was related to the properties of the different microspheres obtained, such as particle size distribution, herbicide loading, or surface morphology. The release percentage depended inversely on the particle size of the microspheres and directly on the content of active ingredient and emulsifying and pore-forming agents. An empirical equation was used to fit the herbicide release data, indicating that the release of norflurazon from the various formulations is controlled by a diffusion mechanism. The time taken for 50% of the active ingredient to be released into water (T(50)) was calculated, showing a wide variation among the different preparations (0.95-16.4 days). 相似文献