The effect of drought stress on some morpho-physiological traits and to identify the microsatellite (SSR) molecular markers related to these traits were studied in a population of 151 F 3 and F 4 lines derived from a cross between the drought tolerance (Oste-Gata) and susceptible (Massara-1) durum wheat genotypes. Field trails were conducted as randomized complete block designs either under stress and non-stress moisture conditions at reproductive growth stage in 2003 and 2004. The families were evaluated for the following traits: plant height, peduncle length, spike length, awn length, length and width of flag leaf, heading date, days to pollination, days to maturity, grain weight per spike, grain number per spike, spike number per m 2 , 1000 grain weight, spike weight, grain yield, biomass, harvest index, spike harvest index, test weight, grain protein content, relative water content (RWC), leaf water content (LWC) and excised leaf water retention (ELWR). The means of traits relating to reproductive growth stage such as yield, yield components, harvest index, days to maturity, RWC and LWC were higher under non-stress condition than strss-condition. The results of phenotypic evaluation revealed significant differences among families especially for traits related to reproductive developmental stage. The multivariate analysis showed different mechanisms for drought tolerance viz early heading with shorter vegetative growth period, stem reserve mobilization in tall plants, increasing grain filling period and physiological traits relating to reduction of water use. Analysis of variance (ANOVA) and combined ANOVA revealed significant genotypic variation for all traits and the presence of genotype × environment interaction for most of the traits. The estimation of genotypic and phenotypic correlation indicated significant relationship between grain yield and plant height, peduncle length, yield components and physiological traits under two environmental conditions. Identification of the associated SSR markers and QTLs with the studied traits were performed based on single marker analysis and composite interval mapping (CIM) using 23 SSR markers in the mapping population. The results of stepwise regression were similar to CIM in some conditions. Xbarc4 5-2B and Xbarc124 -2B markers significantly associated with plant height under both stress and non-stress conditions. Associated markers with traits evaluated under drought conditions were Xcfd22 -7B for 1000 grain weight and spike length, Xbarc101 -3B for peduncle length, Xgwm148 -2B for length of flag leaf and harvest index, and Xwmc166 -7B for grain yield. A strong QTL controlling 49, 37 and 31% of phenotypic variations of plant height, peduncle and spike length was detected near Xbarc124 -2B in two environments, respectively. Some QTLs
