Time sequence studies on uptake and distribution of Na+and Cl–indiplachne fusca(Kallar grass) grown in NaCl

The time sequence of uptake and distribution of labelled Na and Cl– in osmotically adjusted “Kallar”; grass was studied at low (10 mM) and moderately high salinity (100 mM) in nutrient solutions. Increasing NaCl raised the concentrations of Na+ and Cl– in the tissue of tops and roots but had little or no effect on plant growth. On the leaves no toxic symptoms were obvious, not even in plants grown at salt stress of 200 mM NaCl. In all treatments, the young and the old leaves extruded 30–60% and 30–70% of their total Na+ and Cl–. As the amounts of Na+ and Cl– in the tissue increased with time, their extrusion also increased, however, as a proportion of the total Na+ and Cl– it did not change much with time. Autoradiographs revealed that the extruded salts were distributed equally on the upper and lower surface of all leaves, parallel to veins. There seemed to be a more intense distribution of Na+ and Cl– in the leaf sheaths as well as in the apical region of the roots. However, the net transfer rates, even after only 6 hours of uptake, did not indicate a strong retention mechanism in the roots.