EFFECTS OF SALINITY AND HEAT-SHOCK ON WHEAT SEEDLING GROWTH AND CONTENT OF CARBOHYDRATES, PROTEINS AND AMINO-ACIDS

The effects of salinity (0, 50, 100, 150, and 200 mM NaCl) and heat-sh ock (42 degrees C) and their interactions on germination, seedling gro wth, and some relevant metabolic changes of two cultivars (cv. Giza 15 5 and cv. Stork) of wheat (Triticum vulgaris L.) were studied. Germina tion studies indicate that plants tolerated salinity up to 100 mM NaCl . The lengths of roots and shoots and their water content, as well as fresh and dry matter yield of cv. Giza 155 seedlings remained more or less unchanged up to 100 mM NaCl and of cv. Stork up to 50 mM NaCl. Sa linity induced progressive increase in soluble carbohydrates, soluble proteins and proline in cv. Giza 155 and in soluble proteins, proline and other free amino acids in cv. Stork. However, under the higher sal inity levels, in cv. Giza 155 increase in soluble carbohydrates was ac companied by lose in other free amino acids, whereas in cv. Stork an o pposite effect was obtained. Heat-shock treatment (42 degrees C for 24 h) induced a significant decrease in the final germination percentage , the shoot and root lengths, fresh matter yield and the water content . The dry matter yield of the two cultivars was considerably increased as compared with the corresponding treatments with NaCl only. Heat-sh ock treatment resulted in a significant increase in the amount of solu ble carbohydrates and proline in salt treated seedlings of both cultiv ars. The pattern of changes in amino acids was opposite to that of sol uble proteins, indicating that the increase in soluble proteins was at the expense of other amino acids in cv. Giza 155 and vice versa in cv . Stork.