# Corresponding author’s emails: boudiarreda@yahoo.fr; r.boudiar@crbt.dz Received 25/9/2019; Accepted 28/11/2019 DOI: 10.21608/agro.2019.17341.1182 ©2019 National Information and Documentation Center (NIDOC) V IGOROUS seedling growth is important for good crop establishment, particularly under drought conditions. Our study was set out to identify useful traits and genotypes to enhance early drought tolerance of durum wheat. Two experiments were carried out. In the frst one, thirty-fve genotypes (Landrace and improved) were tested in a phytotron at germination and early seedling stages, subjected to three osmotic stress levels induced by polyethylene glycol PEG 6000 (0, -3, -6 bar). The second experiment was conducted in the feld, with 27 out of the 35 genotypes. Root and shoot traits were measured at seedling stage in both experiments. High PEG 6000 treatment decreased fnal germination percentage (FGP) by 2.7% and delayed the time to reach 50% germination (t50) by 2.9h. Shoot length was the trait most affected by drought (40% reduction) as compared with other root traits, which even increased under drought, like root to shoot length ratio, root to shoot weight ratio, root dry weight and root number. Coleoptile length (CL) showed a contrasting relationship with other traits, it was negatively correlated in general under no stress, but with positive correlations under stress. Based on drought susceptibility index (DSI), Algerian wheat landraces were the most tolerant compared to modern genotypes. Correlations between traits measured in feld and controlled conditions were low. CL could be a potential trait for screening drought tolerant genotypes. Algerian wheat landraces presented a clearly distinct ability for early drought tolerance, and could be a good resource for breeding programs. Keywords: Early growth, Polyethylene glycol, Durum wheat seedlings, Drought susceptibly index. Assessment of Early Drought Tolerance of Algerian Durum Wheat Reveals Superiority of Landraces Ridha Boudiar (1,2)# , Abdelhamid Mekhlouf (1) , Adel Bachir (3) , Amar Rouabhi (1) , Ernesto Igartua (4) (1) Laboratoire d’Amélioration et de Développement de la Production Végétale et Animale (LADPVA), University of Ferhat ABBAS (UFAS- Sétif1), Setif 19000, Algeria; (2) Biotechnology Research Center (CRBt), UV 03 BP E73, Nouvelle Ville Ali Mendjli, Constantine, Algeria; (3) Technical Institute for Field Crops (ITGC), Sétif 19000, Algeria; (4) Estación Experimental de Aula Dei, EEAD-CSIC, Avenida Montañana 1005, 50059 Zaragoza, Spain. Egypt. J. Agron. Vol. 41, No. 3, pp. 275-292 (2019) Egyptian Journal of Agronomy http://agro.journals.ekb.eg/ 22 Introduction In Mediterranean-type environments, sowing is typically practiced when soil moisture is ensured by the frst rain (Rebetzke et al., 2008). Early growth vigor has been proposed as a trait that could enhance crop water-use effciency and yield in these environments (López-Castañeda & Richards, 1994; Coleman et al., 2001). One of its possible benefts could occur through increased root growth early in the season (Liao et al., 2004). Early drought restricts germination (Misra et al., 1990), emergence and early seedling growth (Al- Karaki, 1998), which may lead to crop failure in the West Asia and North Africa (WANA)- region (Abdel-Ghani et al., 2015). In regions characterized by short periods of appropriate soil moisture, seeds with high germination percentage may be advantageous for ensuring a good plant establishment (Brar et al., 1991). Drought stress is a stage specifc phenomenon, as it has been described that tolerance at plant establishment phase is poorly correlated with tolerance at other stages (Mano et al, 1996; González et al., 2008;