ION DISTRIBUTION IN RELATION TO LEAF AGE IN LEPTOCHLOA-FUSCA (L) KUNTH (KALLAR GRASS) .2. ANIONS

Using Leptochloa fusca (L.) Kunth (Kallar grass) plants, the distribut ion of Cl-, NO3-, H2PO4-, SO42- and malate between leaves of various a ges has been studied. Plants grown in a reclaimed, salt-affected field , in solution culture and in soil at 10, 100 and 125 mm NaCl have been analyzed. Apparently due to excretion by salt secreting glands on L. fusca leaves and to phloem export, Cl- concentrations did not increase strongly with leaf age. On a leaf f. wt basis, chloride secretion was constant over the series of increasingly aged mature leaves. If it wa s related to the chloride increments in the leaves, chloride secretion increased strongly from younger to mature leaves and reached between 150 and 200 % of the concurrent Cl- deposition in the lamina. Changes in the tissue concentrations of nitrate and phosphate with leaf age sh owed a maximum in recently matured leaves. Decreases in older leaves w ere attributed to nitrate reduction and export of reduced nitrogen and to retranslocation of phosphate. In leaves of field-grown L. fusca ni trate was non-detectable. Sulphate and malate concentrations in lamina e continued to increase from the youngest to the oldest leaves. The in creasing negative charge resulting from these increases in divalent an ions can be accounted for by the loss of charge occurring in connectio n with reduction of nitrate and export of phosphate. Higher external s alinity led, apart from increases in tissue Cl-, to noticeable decreas es in tissue nitrate and phosphate but not in sulphate and malate conc entrations, the latter being even increased at higher external NaCl. T he observed changes in anion concentrations are compared with and disc ussed in relation to changes found in Ricinus communis and in Atriplex hortensis.