Ion distribution in relation to leaf age inLeptochloa fusca^*(L.) Kunth (Kallar grass)

Abstract

SUMMARYUsing 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 Beld, 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 leafage, 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 inLeptochloa fusca(L.) Kunth* (Kallar grass) II. Anions*†

“…Fresh weights and biomasses of leaf laminae and sheaths were decreased at 100 compared with 10 mM NaCl (see Fig. 1 in Bhatti et al, 1993).…”

“…The f. and d. wt of the leaves inserted sequentially on the tiller shoots at the time of harvest, which occurred before the onset of the elongation of the culm, have been given in the preceding paper (Bhatti et al, 1993). In all experiments the youngest harvested leaf was at an early stage of development (having reached c. 10% of its final d. wt) and was fully enclosed by the sheath of the preceding leaf.…”

“…The culture methods (a)-(c) have been described in Bhatti et al (1993) and will not be repeated here. Essential details were: (a) Field-grown plants from a recently reclaimed salt affected soil of the Biosaline Research Substation of the Nuclear Institute for Agriculture and Biology, at Lahore, were harvested in April 1991.…”

Collection and composition of xylem sap and root structure in two halophytic species

“…The 'xylem sap', which was collected from the major veins apparently was a mixture of external solution and xylem sap. We concluded this from: (a) the similar K/Na ratio in the fluid collected (0.51 + 0,06) and in the nutrient medium (0.6), although L. fusca roots were shown earlier to discriminate against Na + (Sandhu et al, 1981;Bhatti et al, 1993), and (b) the movement of the dye Lichtgrtin, which is poorly permeable (Epel and Bandurski, 1990), into the fluid moving along the air cavities of the leaves.…”

“…Plants were watered daily, salt treatment was for 30 d. Growth conditions have been detailed recently (Bhatti et al, 1993).…”