Changes in Soluble Sugars and Proline in Seedlings of A local Wheat Cultivar (Doha) Due to the Salt Stress and Temperature

Abstract

Germination of grains, and changes in the soluble sugars and proline due to salt stress under three temperatures in the germinating grains, of the local wheat cultivar (Doha) were studied. This cultivar proved resistant to salt stress during germination at both 15 and 20 °C as compared to 25 °C. In support to the above finding, chloride accumulated considerably in the wheat seedlings as sodium chloride increased around the grains at 25 °C as compared to that accumulated at lower temperatures. Moreover, high temperatures may cause further lowering in the water potential of salt solutions which might explain the osmotic effect of salts. Proline accumulated substantially in the seedlings exposed to various levels of salt stress, and its accumulation was linear with the increase in the concentration of NaCI. Temperature rise in the growth chamber caused a considerable increase in the concentration of proline in the germinating grains especially at high salt levels. Soluble sugars (TRV) and their components (DRV and sucrose) diminished in the growing seedlings exposed to various levels of salt stress. Temperatures above 15 °C caused significant sugar formation under all salt levels, which means that the degradation of starch stored in the endosperm of grains was accelerated with the rise in temperature in the growth chamber. Reduction in the TRV due to salt stress was accompanied with a considerable accumulation of proline. The possible sources of the accumulated proline in the seedlings of the wheat plants during germination were discussed.