Comparison of potassium uptake by four plant species grown in sand and in flowing solution culture.
In trials in flowing solution culture, the growth rate of Anthoxanthum odoratum was similar over the entire range of K concentrations tested (0.1-3.3 X 10-5M), whereas that of Dactylis glomerata, Trifolium pratense and Medicago lupulina increased over the range 0.1-0.3 X 10-5M but not at higher concentrations. In concurrent sand culture the growth of A. odoratum and M. lupulina increased with increasing level of K up to 69 X 10-5M and that of the other 2 species up to 208 X 10-5M. The greater rate of K uptake by A. odoratum from the most dilute solution appeared to be due to its greater root surface area; a comparatively greater proportion of absorbed K was translocated to the shoots in this species. The higher concentration of K needed for maximum growth in sand culture was the result of slow diffusion, and the reduced uptake under these conditions was attributed to the smaller root system compared with that in flowing culture.