The effect of potassium on growth of <i>Carex</i> species from swamp habitats varying from oligotrophic to eutrophic and comparison of physiological reactions of <i>Carex</i> species to P stress and K stress

Abstract

In a growth experiment at potassium levels varying between 0.001 m M and 3.0 m M potassium, relative growth rate (RGR) and other growth parameters were determined in Carex species: C. rostrata Stokes, C. limosa L., C. lasiocarpa Ehrh., C. diandra Schrank and C. acutiformis Ehrh., listed in order of increasing nutrient availability of their habitats. Carex species of nutrient poor sites did grow faster at low potassium concentration than species from nutrient rich habitats. The RGR of C. limosa was not affected by the K concentration, even at the lowest potassium concentration (0.001) m M ) used. At high potassium availability Carex species from nutrient‐rich sites responded with greatly increased RGR, whereas the Carex from nutrient‐poor sites absorbed potassium in excess of immediate growth requirements: luxury consumption. A comparison is made of the physiology of the Carex species as affected by stress and abundance of phosphate and potassium.