Na+and Cl−: Leaf extrusion, retranslocation and root efflux indiplachne fusca(kallar grass) grown in NaCl

Groups of “Kallar”; grass plants were subjected to various treatments of 100 mM NaCl simultaneously labelled with 22Na+ and 36Cl−. On the basis of the specific activity, the distribution of Na and Cl− in the tissue was followed during and after treatment, i.e. after transfer of some groups to an identical but inactive solution. Sequential collections of leaf washes showed that both Na and Cl− were extruded at a somewhat constant rate. Leaf sheaths accumulated more Na+ and Cl− than the leaf blades and the amounts of Na+ and Cl− in the leaf sheaths as a percentage of their total plant content (i.e. 28% and 31%) approximated the amounts of Na and Cl− extruded by the leaves (i.e. 23%). Moreover, almost equivalent amounts of Na+ (21%) and Cl− (29%) were removed by root efflux which continued even several days after transfer of the plants to the inactive, saline solution. Part of the Na+ and Cl− was retranslocated from the tops to the roots and was attributed to phloem export. Tolerance of Kallar grass to NaCl was thus related to preventing the tissue from accumulating high concentration by extrusion of both Na+ and Cl− by the leaves and their efflux by the roots in addition to an equivalent retention in the leaf sheaths.