Physiological Studies on the Tolerance of Rice Plants to Salinity : 3. Mechanism of translocation of chloride ion in rice plants

Abstract

The present investigation was undertaken to obtain some information on the mechanism of translocation of chloride ion in rice plants, using Oryza sativa L. ver. Eiko as material. Rice plants which were raised in a water culture, were transferred to 0.2 M NaCl solution for 24 hrs for the saline treatment. The experimental results obtained may be summarized as follows; Chloride ion was translocated very rapidly from roots to shoots of rice plants. A considerable amount of chloride ion was found to be localized in leaf blades, leaf sheaths and stems, while roots contained less amount of chloride ion than that in any other part of rice plants except ears. The accumulation of chloride ion in comparatively younger leaf sheaths was less than that in older ones. Particularly, physiologically active leaf blades contained a larger amount of chloride ion than that in the comparatively younger leaf blades or older leaf blades. It seems very reasonable to assume from these data that the accumulation of chloride ion is vitally important in the metabolism or the physiological activity of the organ of rice plants. When rice plants were transferred to the saline solution, a certain amount of chloride ion was found to be accumulated even in the leaf blades and sheaths, which had already withered prior to the saline treatment. So it seems highly probable that some fractions of the translocation and accumulation of chloride ion may not be directly correlated with metabolism of leaves. Similarly the amount of chloride ion accumulated in leaf blades does not run parallel with that of the transpiration.