Abd AL-razaak Hussain Asoud
General Commission for Scientific Agricultural Research (GCSAR) , Administration of Crop Research
Faculty of Agriculture, Damascus University 

ABSTRACTE

This study was carried out in Izraa research station, General Commission for Scientific Agriculture Researches (GCSAR), during the growing Season of 2010-2011 and 2011- to identify some morph-physiological traits related to yield in durum wheat under water stress condition over three phynological stages (tillering,stem elongation heading, and grain filling)and to determine the genotypes which yield better under waterstress conditions.
Twelve durum wheat genotypes weregrown using split plot design, with three replication, The first season had higher amount of rain fall so results showed that control and other treatments had higher grain yield in the first season compared with the second.Stem elongation and heading stage was more sensitive to drought stress in all studied traits reducing grain yield by 24.8%and 22.8% in the two growing season respectively.The drought stress at tillering stage caused reduction in number of spikes.m-² and biological yield causing lower sources and lower manufactured dry matter and ultimately loss in grain yield .Grain filling stage highly affected with drought stress leading to decrease in 1000 grain weight and more loss in grain yield.High yielding genotypes had higher values in physiological traits (TFm, Fv/Fm, Chc,LWP, RWC and stability of cellular membrane) and higher values in PH, PL and SL.This study explained the importance of flag leaf and awns in improving durum wheat grain yield especially under drought conditions.The genotypes (H.8150,D.41282,Acsad1273, and Cham5) had higher grain yield under control and water stress treatments during different stages of crop growth in the two seasons because they had better physiological, morphological and productivity traits which contribution in rising the efficiency of thesis genotypes for drought stress tolerance. Results showed appositive significant relative ship between grain yield and source elements (Plant high, Peduncle length) under water stress over all growth stage (tillaring, heading, grain filling)Relationship coefficient values at tillaring stage were (r=0.571*, r=0.563* respectively) and (r= 0.837**, r=0.781** respectively) at stem elongation and heading, and (r=0.518*, r=0.557* respectively) at filling period grain yield. Related positively and significantly with Fv, Fv/Fm, (r=0.794** , r=0.730** respectively) at tillering stage (r=0.909**,r=0.895** respectively) at stem elongation and heading stage, and (r=0.681* ,r=0.647*respectively) at filling period grain yield.