[Kinetic characteristics of Zn uptake by Potentilla griffithii Hook. f. var. velutina Card].

The kinetic characteristics of Zn uptake by Potentilla griffithii Hook. f. var. velutina Card. were studied with hydroponic culture under different Zn supply and its exposure time. When the Zn supply was 10 mg x L(-1), the Zn concentration in shoot and root reached the peak on the 8th day, being 2.49 x 10(3) mg x kg(-1) and 2.21 x 10(3) mg x kg(-1), respectively; while when the supply was 100 mg x L(-1), the Zn concentration in shoot reached the maximum (1.23 x 10(3) mg x kg(-1)) on the 16th day, but that in root did not exhibit saturation. The Zn concentration in leaf and leafstalk increased with increasing Zn supply from 0 to 160 mg x L(-1), but had no increase or even decreased when the Zn supply was higher than 160 mg x L(-1). The Zn concentration in root exhibited a positive correlation with Zn supply and its exposure time, and the kinetic curve of Zn uptake fitted linear-quadratic (LQ) model, i. e., fast linear uptake first and slow saturation uptake later, with the dividing point at about 1-2 hours' exposure, which could be related with the Zn adsorption on root cell wall and the Zn transportation across the cell membrane.