Ion distribution in relation to leaf age in Leptochloa fusca* (L.) Kunth (Kallar grass): I. K, Na, Ca and Mg.

Using Leptochloa fusca (Kallar grass) plants, the distribution of K, Na, Mg and Ca between leaves of various ages has been studied. Plants grown in a salt-affected, reclaimed field, in a solution culture and in soil in pots at 10, 100 and 125 mM NaCl have been analyzed. Despite the presence of salt-secreting glands on Leptochloa fusca leaves, Na concentrations increased strongly with leaf age, while K concentrations were highest in young leaves and decreased with increasing leaf age. This was due to K retranslocation, which was clearly intensified at higher external NaCl concentration. The data point to the importance of K recycling in this halophyte and also to the use of Na by this salt-secreting species for turgor maintenance in mature and old leaves. Both Mg and particularly Ca concentrations increased with leaf age, indicating that xylem import surpassed phloem export even for the phloem-mobile ion, Mg. In young leaves, Mg concentrations exceeded those of Ca.

Ion distribution in relation to leaf age in Leptochloa fusca (L.) Kunth* (Kallar grass) II. Anions*†.

Using Leptochloa fusca (L.) Kunth (Kallar grass) plants, the distribution of Cl- , NO3 - , H3 PO4 - , SO4 2- and malate between leaves of various ages 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 was related to the chloride increments in the leaves, chloride secretion increased strongly from younger to mature leaves and reached between ISO and 200% of the concurrent Cl- deposition in the lamina. Changes in the tissue concentrations of nitrate and phosphate with leafage showed a maximum in recently matured leaves. Decreases in older leaves were attributed to nitrate reduction and export of reduced nitrogen and to retranslocation of phosphate. In leaves of field-grown L. fusca nitrate was non-detectable. Sulphate and malate concentrations in laminae continued to increase from the youngest to the oldest leaves. The increasing negative charge resulting from these increases in divalent anions can be accounted for by the loss of charge occurring in connection with reduction of nitrate and export of phosphate. Higher external salinity led, apart from increases in tissue Cl- , to noticeable decreases in tissue nitrate and phosphate but not in sulphate and malate concentrations, the latter being even increased at higher external NaCl. The observed changes in anion concentrations are compared with and discussed in relation to changes found in Ricinus communis and in Atriplex hortensis.