干旱区生态环境知识资源中心

We determined ionic composition, anatomical characteristics, and ultrastructure of the assimilating organs, photosynthetic and respiratory gas exchange, photo-synthetic metabolism, and osmotic pressure of the cell sap in plants of solonchaks of the Ararat valley. Succulent C-4 species, the majority of which belong to the family Chenopodiaceae, are widely represented in the investigated region. With respect to ultrastructure, a significant number of C-4 halophtes belong to the NAD-ME* group. Osmotic pressure is elevated and the photosynthetic and respiratory rates depressed in plants dwelling on the most saline plots (regardless of the type of photosynthetic metabolism). Photosynthetic metabolism for the most part reflects ultrastructural characteristics, but is more mobile, a circumstance that promotes plant adaptation to conditions of salinity. It is concluded that high values of cell sap osmotic pressure in halophytes enable them to survive on arid saline territory. Advantages of the C-1 syndrome are manifested in combination with the annual life form. Plants of the C-3 type can survive under conditions of salinity only in the form of perennials.