Many investigators have studied the influence of low temperature on ion upcake in diffenent plants (Cseh and Boszormtnyi 1964, Korouin, Sucheva and Bystrova 1963, Oberlander 1963, Sutcliffe 1962, Wallace 1963, Zhurbitzky and Shtrausberg 1958. It is a general opinion that rhe intensity of the uptake of nutrienrs varies according to the temperature, but considerable differences can be found in the absorption concerning different ions (Saric and C u~i c 1963). According to Kramer (1949) this can be best explained that there are differences in the viscosity of the plasma and in the alteration of membrane system of the cells at low temperatures.We have reported earlier that in young rice roots the Rb ion uptake decreases only up to 8 O C , but towards O O C , it increases again (Zsoldos 1967).Under similar circumstances the phosphate and bromide anions did not show this peculiarity, as their uptake is proportionately changed according to the changes in temperature.The unusual results with Rb ions may be explained by the so-called cold shock effect which causes considerable changes in the permeability of the membranes, owing mainly to the sudden fall of temperature.Since at low temperature, more exactly under the influence of a sudden fall in temperature, the results of Rb ion uptake in rice roots are rather surprising, we continued our investigations with various species of plants.
M a t e r i a l a n d M e t h o d sThe species of plants used were as follows: Cucumber (Szenzici6), sorghum (Advance-2), sugar melon (Honey-Rock), maize (MV-l), rice (Dunghan Shali), millet, wfinter wheat (F-481) and spring barley. The plants were grown up to 6-9 days (stage with 1-2 leaves) in a light thermosrat (at 6500 Lux) in a lo-, M solution of CaSO,. Excised roots were used for the examination at different temperatures, pH 5,5. The excised roots were kept in distilled water for 30 minutes before placing in aerated 12