Low root temperature,calcium, and nitrate ion interactions on nonexchangeable rubidium,cesium, and sodium absorption by bush beans

Summary When nonexchangeable absorption of Rb⁸⁶, Na²², and Cs¹³⁷ by bush bean (Phaseolus vulgaris L. var. Improved Tendergreen) was determined at different root temperatures and with and without Ca additions or pretreatments, a strong interaction between temperature and Ca was observed. Ca inhibited Rb⁸⁶ absorption markedly at low temperatures but had less effect on Cs¹³⁷. Absorption of Na²² was inhibited by Ca at both low and high temperatures. Little effect for Ca with sometimes a Viets effect was observed at high temperature for Rb but not for Cs or Na. Ratio pairs of Rb, Ca, and Na were used as an index of similarity of absorption mechanisms. Cs and Rb, and Na and Rb appeared to be absorbed by different mechanisms at 10⁻³ M as indicated by temperature and Ca responses. Nitrate-N stimulated uptake of Rb only at high temperature with or without Ca but not at low temperature. Ca in the pretreatment tended to result in greater long distance transport to shoots of Rb⁸⁶ and Cs¹³⁷ for the high temperature but Ca in the test solution slightly decreased the long distance transport. The data are discussed in terms of the Viets effect and of a possible role of Ca in synthesis of transport proteins.