A highly reliable, quantitative and sensitive analytical method for determining the residues of the fungicide, hexaconazole in black tea is described. The proposed method is based on liquid-liquid extraction followed ...A highly reliable, quantitative and sensitive analytical method for determining the residues of the fungicide, hexaconazole in black tea is described. The proposed method is based on liquid-liquid extraction followed by gas chromatographic determination, using nitrogen phosphorus detector (GC-NPD) for the identification and quantitation of hexaconazole. The most appropriate solvent mixture for extracting hexaconazole residues from black tea was n-hexane:acetone at 1:1 (v/v). The extract was cleaned up by adsorption column chromatography using activated florisil. Performance of the method was assessed by evaluating quality parameters such as recovery value, repeatability, reproducibility, linearity and limits of detection and quantitation. When the method was assessed for repeatability, the percentage of recovery ranged between 86% and 96% while the relative standard deviation was between 0.30% and 2.35%. In studies on reproducibility the recovery ranged from 81% to 85% and relative standard deviation from 1.68% to 5.13%, implying that the method was reliable. A field trial was conducted to verify the application of this method with real samples. Results prove that the validated method was suitable for extracting hexaconazole residues.展开更多
Bacterial strain RV9 recovered from greengram nodules tolerated 2400 μg/mL of hexaconazole and was identified by 16 S rDNA sequence analysis as Bradyrhizobium japonicum(KY940048). Strain RV9 produced IAA(61.6 μg/mL)...Bacterial strain RV9 recovered from greengram nodules tolerated 2400 μg/mL of hexaconazole and was identified by 16 S rDNA sequence analysis as Bradyrhizobium japonicum(KY940048). Strain RV9 produced IAA(61.6 μg/mL), ACC deaminase(51.7 mg/(protein·hr)), solubilized TCP(105 μg/mL), secreted 337.6 μg/mL EPS, and produced SA(52.2 μg/mL) and 2,3-DHBA(28.3 μg/mL). Exopolysaccharides produced by strain RV9 was quantified and characterized by SEM, AFM, EDX and FTIR. Beyond tolerance limit,hexaconazole caused cellular impairment and reduced the viability of strain RV9 revealed by SEM and CLSM. Hexaconazole distorted the root tips and altered nodule structure leading thereby to reduction in the performance of greengram. Also, the level of antioxidant enzymes, proline, TBARS, ROS and cell death was increased in hexaconazole treated plants.CLSM images revealed a concentration dependent increase in the characteristic green and blue fluorescence of hexaconazole treated roots. The application of B. japonicum strain RV9 alleviated the fungicide toxicity and improved the measured plant characteristics. Also,rhizobial cells were localized inside tissues as revealed by CLSM. Colonization of B.japonicum strain RV9 decreased the levels of CAT, POD, APX, GPX and TBARS by 80%, 5%,13%, 13% and 19%, respectively over plants grown at 80 μg/(hexaconazole·kg) soil. The ability to detoxify hexaconazole, colonize plant tissues, secrete PGP bioactive molecules even under fungicide pressure and its unique ability to diminish oxidative stress make B.japonicum an attractive choice for remediation of fungicide polluted soils and to concurrently enhance greengram production under stressed environment.展开更多
基金Project supported by the National Tea Research Foundation, Kolkata,India
文摘A highly reliable, quantitative and sensitive analytical method for determining the residues of the fungicide, hexaconazole in black tea is described. The proposed method is based on liquid-liquid extraction followed by gas chromatographic determination, using nitrogen phosphorus detector (GC-NPD) for the identification and quantitation of hexaconazole. The most appropriate solvent mixture for extracting hexaconazole residues from black tea was n-hexane:acetone at 1:1 (v/v). The extract was cleaned up by adsorption column chromatography using activated florisil. Performance of the method was assessed by evaluating quality parameters such as recovery value, repeatability, reproducibility, linearity and limits of detection and quantitation. When the method was assessed for repeatability, the percentage of recovery ranged between 86% and 96% while the relative standard deviation was between 0.30% and 2.35%. In studies on reproducibility the recovery ranged from 81% to 85% and relative standard deviation from 1.68% to 5.13%, implying that the method was reliable. A field trial was conducted to verify the application of this method with real samples. Results prove that the validated method was suitable for extracting hexaconazole residues.
基金the financial support received in the form of UGC NonNET fellowship granted by University Grants Commission (D. O.No.F.1993/2006 (CU) dated 01.02.2007), New Delhi
文摘Bacterial strain RV9 recovered from greengram nodules tolerated 2400 μg/mL of hexaconazole and was identified by 16 S rDNA sequence analysis as Bradyrhizobium japonicum(KY940048). Strain RV9 produced IAA(61.6 μg/mL), ACC deaminase(51.7 mg/(protein·hr)), solubilized TCP(105 μg/mL), secreted 337.6 μg/mL EPS, and produced SA(52.2 μg/mL) and 2,3-DHBA(28.3 μg/mL). Exopolysaccharides produced by strain RV9 was quantified and characterized by SEM, AFM, EDX and FTIR. Beyond tolerance limit,hexaconazole caused cellular impairment and reduced the viability of strain RV9 revealed by SEM and CLSM. Hexaconazole distorted the root tips and altered nodule structure leading thereby to reduction in the performance of greengram. Also, the level of antioxidant enzymes, proline, TBARS, ROS and cell death was increased in hexaconazole treated plants.CLSM images revealed a concentration dependent increase in the characteristic green and blue fluorescence of hexaconazole treated roots. The application of B. japonicum strain RV9 alleviated the fungicide toxicity and improved the measured plant characteristics. Also,rhizobial cells were localized inside tissues as revealed by CLSM. Colonization of B.japonicum strain RV9 decreased the levels of CAT, POD, APX, GPX and TBARS by 80%, 5%,13%, 13% and 19%, respectively over plants grown at 80 μg/(hexaconazole·kg) soil. The ability to detoxify hexaconazole, colonize plant tissues, secrete PGP bioactive molecules even under fungicide pressure and its unique ability to diminish oxidative stress make B.japonicum an attractive choice for remediation of fungicide polluted soils and to concurrently enhance greengram production under stressed environment.
