IMPROVING THE THERMO TOLERANCE OF WHEAT PLANT BY FOLIAR APPLICATION OF ARGININE OR PUTRESCINE

The exposure of wheat plants cv. Giza 168 to high temperature stress (35 degrees C +/- 2) for 4 or 8 hours significantly decreased the growth parameters, the yield components, putrescine (Put), total endogenous polyamines (PAs) contents, total amino acid and total essential amino acid contents, where as, the endogenous spermidine (Spd) and spermine (Spm), ethylene, NH+4, glutamic acid, arginine, proline were increased. Treatment of wheat plants before their exposure to high temperature with arginine or putrescine (1.25 and 2.5 mM) enabled the plants to tolerate the injurious effect induced by high temperature stress via increasing the endogenous Put, Spd, the total PA contents, the content of total amino acids, essential amino acids and the ratio of essential to non-essential amino acids and decreasing the ethylene and NH+4 contents as compared with plants exposed to the high temperature stress or the untreated plants. These effects were much more pronounced by applying 2.5 mM of either arginine or putrescine.