Interrelations of Calcium and Rubidium Absorption by Excised Roots of Barley and Plantain

Abstract

AbstractThe uptake rates of Rb and Ca, applied alone or together, by excised barley and plantain roots were compared. The barley roots absorbed Rb at a faster rate than Ca, whereas the reverse was true for plantain roots. The presence of Ca increased the rate of Rb uptake by barley roots, but the presence of Rb had very little effect upon the Ca uptake. The uptake rate of either ion by plantain was reduced by the presence of the other ion.Calculations indicate that the depressing effect of one ion on the uptake of the other by plantain was due predominantly to ionic competition when the ions were present in the concentration range of 10‐2N, but factors in addition to competition were responsible in the concentration range of 10‐4N. The significance of the differences in response of the two species is discussed.