Muneera S. Aba Alkhail and Ansary E. Moftah
The distribution characteristics of organic and inorganic materials and the osmotic adjustment were investigated in Suaeda fruticosa (halophyte), Artemisia judaica (xerophyte), and Rumex vesicarius (mesophyte) grown in Qassim desert of Saudi Arabia. Percentage of inorganic solutes was over 90% of total solutes, while the estimated contribution of Na+ to Ψs was over 50% for S. fruticosa grown under field condition. In the field grown A. judaica, the percentages of inorganic solutes and organic solutes were 66% and 34%, respectively, and the estimated contribution of Na+ to Ψs was less than 18%, while the estimated contribution of soluble sugars to Ψs was over 20%. The contribution of proline to Ψs was less than 0.2% for all species both in field and under salt stress in a greenhouse experiment. The contribution of NO3 − to Ψs was less than 4% for all species in field condition. In greenhouse experiment, the concentration of NO3 − was higher under various NaCl treatments than that in control condition for S. fruticosa; the estimated contribution of NO3 − to Ψs was over 7% in S. fruticosa, and it was higher than that in the other species at various treatments. In conclusion, inorganic ions were more important in osmoregulation for S. fruticosa to adapt to saline and arid environment, while organic solutes, especially soluble sugars played more important role in drought adaptation in the xerophyte, Artemisia judaica. NO3 − played an important role in osmoregulation in S. fruticosa.
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