Effects of drought stress on abscisic acid, mannitol, K+ and Ca2+ content in two lines of wheat (Triticum aestivum L.)

Experiments were conducted to determine the level of ABA, K+ and Ca2+, mineral content and mannitol in the leaves of two lines of wheat (Triticum aestivum L.) under field condition in order to find any relationship between them and the tolerance of the plant against drought stress and to know if we can use one or mare of them in determining tolerant or sensitive plant. The resistance of the plants was affected by the studied factors and all of them changed under drought conditions. Both K+ and Ca2+ have an important role in determining the stomatal situation, however, the ratio of K+/Ca2+, may regulate the position of stomata in different conditions. The existence of an inverse relation between this ratio and the rate of mannitol confirms the validity of this hypothesis, When the ratio is low, stomata are closed and when it is higher than the control, the stomata are open. Thus we could suggest this ratio to determine tolerant and sensitive lines, as well as the tolerant or sensitive stages of the plant development