Epsilon Open Archive

Abstract

Seedlings of Pinus sylvestris, grown in low humified peat, were exposed to different soil water potentials (?s) and soil temperatures. The water potential and temperature were controlled by the use of a semi-permeable membrane system, and the seedlings were placed in a growth chamber during the experiments. Needle water potential (?s), needle conductance (g,) and plant water conductance (Gp) were measured on the seedlings. When the soil water potential decreased to - 0.1 MPa, the g, decreased to about 25% of the maximum whereas the Gp decreased even more. The results are discussed in relation to resistance to water flow in the soil and in the root-soil interface. Soil temperature in an interval of 5-25°C did not markedly change the relative response of g, and Gp on (?s). However, water uptake was considerably lower at lower soil temperatures, Gp at 7°C only being about 30% of that at 25'C soil temperature. Water uptake was negatively affected by replanting in combination with drying the roots especially at low soil water potentials.