Abstract
A controlled environment pot experiment was conducetd to evaluate the effects of water stress on wheat crop. A number of parameters were estimated; two physiological functions; photosynthesis and dark respiration, two osmolytes (amino acid & free proline & Abscisic acid ABA) and the chlorophyll contents. Four cultivars of wheat used in this study were Al-gaimi, Sindy-1, Sindy-2 and Hab-ahmar. The plants were subjected to three water regimes (1) well-waterd plants at 80% of the field capacity of soil (FC) and two levels of water stress; (2) moderate stress at 50% FC and (3) severe stress at 30% FC. The water stress reduced the photosynthesis rates in Hab-ahmar and Sindy-2, but not in Al-gaimi and Sindy-1. The dark respiration was increased as a result of water stress in all cultivars, except Hab-ahmar. Chlorophyll content was reduced in all cultivars, except Al-gaimi. Both free proline and ABA showed generally an increase under water stress conditions. The differences between the wheat varieties in tolerance to water stress are discussed. (C) 2011 Friends Science Publishers