Abstract
Absorption of K-ion in passive and active processes were studied using maize and sorghum. The results obtained were: (1) In passive uptake: Either H- or Al-ion arrested the absorption of both crops, more badly to sorghum which is susceptible to soil acidity. By adding both ions of Al and H to the solution, absorption of K-ion was interfered still more than a single use of each ion. In the solutions with neither Ca-ion nor Mg-ion, absorption of K-ion slightly increased. (2) In active uptake: K-ion was released from root of both crops to external solution by adding NaCN; it was more significant for sorghum. Low pH-value or deficiency of Ca and Mg reduced the uptake of K-ion, being larger in sorghum. The reduction of uptake of K-ion was larger in sorghum than in maize as Al or both Al and low-pH were added in the solution. These results related with the depression of respiration. (3) In mature crops: Al- and H-ions gave smaller interference with the absorption of K-ion to mature crops than to the younger one both in passive and active processes.
