A comparison of caesium uptake kinetics in eight species of grass

The Michaelis-Menten kinetic parameters (I-max, K-m and C-min) of Cs uptake were estimated using a solution-depletion method, after 0, 1 and 4 d It-st arvation in eight mature grass species of different relative growth rates ( Bromus sterilis L., Elymus repens (L.) Gould, Poa annua L., Lolium perenne L. var. 'Taya', Anthosanthum odoratum L., Festuca gigantea (L.) Vill., Fest uca ovina L. and Nardus stricta L.). There were species differences in I-ma x and C-min, a positive relationship between K-m and RGR (r(2) = 0.53; p = 0.03), and a negative relationship between C-min and RGR (r(2) = 0.89; p = 0.001) in 0 d K starved plants. In general, I-max increased with K starvati on, as previously reported for K uptake kinetics. K-m increased with It sta rvation, contrasting with reported studies on It, and C-min decreased, alth ough all species did not respond similarly. (C) 1999 Elsevier Science Ltd. All rights reserved.