Effects of Low Temperature on Respiration and Uptake of Rubidium Ions by Excised Barley and Corn Roots

Abstract

The effect of temperature upon ion uptake and respiration was investigated with excised roots of corn (Zea mays) and barley (Hordeum vulgare). A strong inhibition (Q10 = 5-8) of ion uptake was observed at temperatures below 10.degree. C. At higher temperatures more normal temperature dependencies (Q10 = 1.3-2) were obtained. When the data were plotted according to the Arrhenius relationship, 2 different activation energies were indicated above and below 10.degree. C. Other studies have related such changes with temperature in the activation energy of processes to changes in membrane properties induced by temperature. Apparently such phase transitions may affect ion uptake processes. If so, then differences among species in their capacity to maintain normal root function at low soil temperature and to resist low temperature stress may be related to differences in the physical properties of cellular membranes.