Diffusion and absorption of ions in plant tissue. I. Observations on the absorption of ammonium by cut discs of potato tubes as compared to maize roots

NHi-absorption by maize plants and by cut discs of potato tuber was studied in relation to NHi-concentration, pH and concentration of added mono- and polyvalent cations. Striking differences in the behaviour of the two objects became apparent. The results are tentatively explained on the assumption that during steady state absorption in potato discs a gradient of NH4-concentration is maintained in the free space. Several explanations for the different behaviour of maize roots are discussed.