Oldman saltbush (
Atriplex nummularia LINDL.) is native to the Australian arid and semi-arid areas and is used as an important grazing grass for sheep. Experiments were carried out in plants grown in a container/pot with sandy soil in the glasshouse of the Sand Dune Research Institute, the plants were irrigated with four kinds of water, i. e. fresh water (control), simple saline water (NaCl), compound saline water and sea water during four cropping seasons (Tables 1 and 2) .
The amount of applied was 1.1mm, 2.7mm, 0.9mm and 3.0mm/a day for the first, second, third and fourth cropping seasons respectively. Electric conductivity (EC) and NaCl % of the water showed a decrease in the following order: NaCl water 2.7%>Sea w. 75% (NaCl 2.3%) >Sea w. 50% (NaCl 1.6%) >NaCl w.1.4%>NaCl w. 1%>Sea w. 25% (NaCl 0.82%) >NaCl 0.7%≅Compound saline w. 1% (NaCl 0.68%) (Table 2) . The results obtained are as follows:
1.The increment of plant growth and yield was more pronounced in plants grown in the various saline water plots as compared with those grown in fresh water except for the plot with a concentration of 2.7% of NaCl in water and in the 75% sea water plot. Irrigation of plants with water containing salt at various concentrations increased the fresh weight, dry leaf weight, leaf/stem ratio and water content per unit leaf area, and decreased the percentage of dry matter as compared with the values of the corresponding parameters in the control (Table 3 and Figs. 1 and 2) .
Yield increment was 7-43% for the plants grown in the plots with 0.7, 1 and 1.4% of NaCl in water, 48-61% in the plots with 25 and 50% of sea water and 54-79% in the plot with 1% of compound salt in water, respectively as compared with the values of the control. Therefore watering in using compound saline water was more effective than when simple saline water was used. Due to reduction in plant growth caused by the treatment with water containing high salt concentrations, the yield decreased by 10% inv the plot with 75% of sea water and by 40% in the plot with 2.7% of NaCl in water, respectively as compared with the values of the control. These results indicate that
A. nummularia exhibites a high tolerance to salinity.
2.Contents of minerals increased in the leaves as compared with the values in the stems (Table 5 and Fig. 3) . Though the contents of P and K decreased with the increase of the salt concentrations, the values of Na, Cl, Ca, and Mg particularly Na and Cl in the leaves increased in all the saline water plots as compared with the values of the control when the salt concentration increased. The content of Na was highly correlated with that of Cl (Table 7) .
Contents of Na and Cl in the plant also markedly increased in all the saline water plots as compared with the values of the control when the salt concentration increased. The highest value of Na plus Cl was 26% both in the plot with 1.4% of NaCl in water and in that with 75% of sea water. Total contents of minerals also increased in all the saline water plots as compared with the values of the control (Table 6) . On the other hand, comparison between all the saline water plots and fresh water plots, showed that in the forms the K/Na ratio ranged between 0.16 and 0.58 in the former, whereas the K/Na ratio was much higher in the latter and ranged between 0.79 and 3 (Table 6) . The results presented above illustrate the special characteristics of this halophyte plant.
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