Hsu F C, Marxmiller R L, Yang A Y
E. I. du Pont de Nemours & Company, Agricultural Products Department, Experimental Station, P. O. Box 80402, Wilmington, Delaware 19880-0402.
Plant Physiol. 1990 Aug;93(4):1573-8. doi: 10.1104/pp.93.4.1573.
A pressure chamber technique was used to study the root uptake and xylem translocation of nonradiolabeled cinmethylin and its analogs in detopped soybean (Glycine max) roots. Quantifications of compounds were achieved by gas chromatography analysis using a mass spectrometry detector under selected ion monitoring. The compounds tested, with octanol-water partition coefficients (log Kow values) ranging from 0.96 to 5.3, were all nonionizable under the experimental conditions. Root efflux curves of all compounds exhibited a steady-state kinetic profile. The time required to achieve the steady state efflux concentration in the xylem sap correlated with log Kow values in a manner very similar to the root binding profile reported previously by GG Briggs et al. ([1982] Pestic Sci 13: 495-504). After reaching the steady state efflux, the concentration ratio of each compound in the xylem sap to the final concentration in the pressure chamber was taken as the transpiration stream concentration factor (TSCF). A nonlinear relationship was observed between TSCF and log Kow values. The highest TSCF value was between 0.6 to 0.8 for compounds with log Kow between 2.5 to 3.5. The range of optimal log Kow values was slightly higher than that reported earlier by Briggs et al. ([1982] Pestic Sci 13: 495-504). After taking into account the binding of the compound to soil, the apparent optimal Kow value for best root-to-shoot translocation is lowered to around 1. The relationship of root-to-shoot and phloem translocation was also discussed to promote a better understanding at the whole plant level of the uptake and translocation of a soil-applied xenobiotic.
采用压力室技术研究了去顶大豆（Glycine max）根系对非放射性烯草酮及其类似物的吸收和木质部转运。在选择离子监测模式下，使用质谱检测器通过气相色谱分析对化合物进行定量。所测试的化合物的辛醇 - 水分配系数（log Kow值）范围为0.96至5.3，在实验条件下均不可离子化。所有化合物的根系流出曲线均呈现稳态动力学特征。在木质部汁液中达到稳态流出浓度所需的时间与log Kow值相关，其方式与GG Briggs等人先前报道的根系结合特征非常相似（[1982] Pestic Sci 13: 495 - 504）。达到稳态流出后，将木质部汁液中每种化合物的浓度与压力室中的最终浓度之比作为蒸腾流浓度因子（TSCF）。观察到TSCF与log Kow值之间存在非线性关系。对于log Kow在2.5至3.5之间的化合物，最高TSCF值在0.6至0.8之间。最佳log Kow值范围略高于Briggs等人先前报道的值（[1982] Pestic Sci 13: 495 - 504）。考虑到化合物与土壤的结合后，最佳根到地上部转运的表观最佳Kow值降至约1。还讨论了根到地上部和韧皮部转运的关系，以促进在全株水平上更好地理解土壤施用的外源化合物的吸收和转运。
