To investigate the effects of salinity stress on durum wheat cultivars at the critical stages of germination and seedling establishment under salinity stress, a study was conducted on eight durum wheat cultivars (Karim, Khiar, Inrat100, Maali, Monastir, Portodur, Razeg, and Salim) subjected to an increasing salinity concentration by using sodium chloride (NaC) (0, 2, 4, 6, and 10 g L⁻¹). Germination and seedling physiological parameters were measured and thoroughly analyzed. Salinity stress significantly decreased germination capacity (GC), germination rate (GR), final germination capacity (FGC), germination index (GI), mean daily germination (MDG), and velocity coefficient (Vc), whereas mean germination time (MGT) and the stress index (SI) increased. Plantlet growth and initial vigor (IV) were also significantly hampered. Regarding all these traits, the cultivars’ differences were revealed: Karim and Salim were the least affected, whereas Razeg and Maali were the most affected, and the other cultivars occupied an intermediate position. Depending on cultivar, salinity stress decreased the germination capacity and delayed its initiation. At low salinity stress (2–4 g L⁻¹ NaCl), the osmotic effect (OE) was the main cause of germination inhibition, whereas at high salinity stress (6–10 g L⁻¹ NaCl), the toxic effect (TE) dominated and irreversibly inhibited the germination process. The initial vigor and the stress index that clearly discriminate among the studied cultivars are useful traits for screening tolerant genotypes. Otherwise, durum wheat showed a higher plasticity with salinity at the germination stage, allowing it to develop better tolerance at this stage, as compared to early stage plantlet growth.

The salinity of soils and irrigation water is among the main factors that limit plant productivity worldwide. Several alternatives have been proposed to get around this problem. However, these alternatives have faced difficulties in their implementation. As an alternative, the adverse effects of salinity on crop yield can be minimized by selecting species and varieties better adapted to salinity and/or by finding priming agents that give plants a certain tolerance during the vegetative and reproductive stages. The latter are strictly dependent on germination and seedling establishment. For this purpose, a laboratory experiment was conducted on three Tunisian wheat cultivars (Karim, Razeg, and Maali) subjected to moderate salinity stress (MSS, 5 g L⁻¹ NaCl), severe salinity stress (SSS, 10 g L⁻¹ NaCl), or control (0 NaCl) after soaking the seeds in a solution of KNO₃ or ZnSO₄ (0.5 g L⁻¹). Salinity stress significantly decreased germination capacity (GC) and induced osmotic stress under MSS, which declined under SSS in favor of toxic stress. Pretreatment of seeds with KNO₃ or ZnSO₄ alleviated the toxic effect, and seedlings recovered initial vigor and GC even under SSS. The Karim cultivar showed better tolerance to salinity and a higher ability to react to priming agents. The calculated sensitivity tolerance index (STI) based on germination capacity, seedling growth, and initial vigor decreased in all cultivars under salt stress; however, this parameter clearly discriminated the studied cultivars. Karim was the most tolerant as compared to Razeg and Maali. We conclude that halopriming provides a benefit by alleviating the harmful effects of salt toxicity and that cultivars differ in their response to priming and extent of salt stress. KNO₃ and ZnSO₄ effectively alleviated the inhibitory effect of salt stress on seed germination and seedling establishment while significantly improving initial vigor.