There have been many different views about the physiological relationship between calcium and nitrogen in the crops among the reporters. In order to clarify this point, we should investigate the relationship between the forms as well as the contents of nitrogen and those of calcium in the crops.
In these points of view, we attempted this experiment to clarify the relationship between nitrogen and calcium in the rice crop, which was planted in the water culture solution of the various concentration of nitrogen. In this experiment, we observed H_2O-soluble-Ca, CH_3COOH-soluble-Ca, HCl-soluble-Ca and insoluble-Ca in the tops of the rice crop, and also we analysed protein-N and non-protein-N in them.
As increasing the concentration of nitrogen in the water culture solution, the rice crop increased the contents of total-N and protein-N, but it decreased the ratios of protein-N to total-N. The contents of various forms of calcium in this rice crop are as follows:
(1) The contents of total-Ca were decreased by raising the concentration of nitrogen in the water culture solution.
(2) The contents of H_2O-soluble-Ca were increased by raising the concentration of nitrogen in the water culture solution, but their ratios to total-Ca were increased.
(3) The contents of CH_3COOH-soluble-Ca were decreased by raising the concentration of nitrogen in the water culture solution, but their ratios to total-Ca were decreased. We recognized it was this form of calcium that caused the total-Ca to decrease by raising the concentration of nitrogen in the water culture solution under this experiment.
(4) The contents of HCl-soluble-Ca and insoluble-Ca were almost constant, independently of the concentration of nitrogen in the water culture solution, but the ratios of HCl-soluble-Ca and insoluble-Ca to total-Ca were increased.
The contents of the various forms of calcium and their ratios to total-Ca increased according to the following order : CH_3COOH-soluble-Ca, H_2O-soluble-Ca, HCl-soluble-Ca and insoluble-Ca, independently of the concentration of nitrogen in the water culture solution.