OSMOTIC PRESSURES OF NATIVE PLANTS OF SALINE SOIL IN SASKATCHEWAN

Abstract

Ranges of osmotic pressure of cell sap in 21 species of plants growing on saline soil in southern Saskatchewan are reported. These are related to salinity of soil and osmotic pressure of soil solution. The highest osmotic pressures are found in dominants of the most saline dry soils, and there is a decrease of osmotic pressure in the dominants of less saline soils. Some of the dominants of very saline soils have lower osmotic pressures than might be expected, apparently because of a more abundant supply of soil moisture near the center of some depressions. Depth of rooting of species tends to have a relationship to osmotic pressure with one shallow-rooted species having the highest value. The species associated with the dominants in all soils have considerably lower osmotic pressures than the dominant species. The effect of rainfall in reducing concentration of the soil solution was only evident in respect to a shallow-rooted species and not to a deep-rooted; the effect lasted only 4 days.