Evidence for an ion uptake controller in Helianthus annuus

Abstract

In the period 1935–60 many investigations concerning the uptake of ions by roots were carried out on excised roots. It was then believed that excision left the root in its normal condition for many hours after its severance from the rest of the plant. In the 1960s however, a number of experiments were carried out, the results of which challenged this assumption. In 1963 Koster reported that there was a rapid decline in the uptake of nitrate and ammonium ions by soy bean plants a few hours after they were bark ringed [1]. Ricinus communis plants were found to show a decline in potassium uptake only 65 min after ringing [2]. Bowling (1968) found that potassium uptake by Helianthus annuus fell rapidly if a length of the stem was cooled to just above 0 °C. Potassium uptake was restored when the cooling coil was removed [3].