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Salinity and osmotic stresses are prime reasons of plant growth and productivity reduction in semi-arid regions and cause complex series of physiological, cellular, and molecular changes. Since osmotic and ionic effects are correlated and initiated by salinity, separating both is an important step in understanding the basis of salt tolerance. Barely seedlings(cultivar Giza 134)were treated with either NaCl(150 mM)or iso-osmotic polyethylene glycol 6000 (19.5% PEG). Treatments were applied two times before sampling and collected after two weeks from emergence. Results showed decreasing of fresh matter in treated seedlings, especially those treated with PEG. Furthermore, significant increase of non-enzymatic antioxidants, oxidative markers in addition to enzymatic antioxidants examined (peroxidase (POX), and polyphenol oxidase (PPO)) was detected with PEG treatment. The osmoregulators including proline (Pro) and glycine betaine(GB) increased in the root tissue, in conjunction with enhancement in the antioxidant status of leaves by applying PEG. Based on molecular analysis using real-time RT-PCR, HvNHX gene (coding for Na+/H+ antiporter) was highly expressed after 48 h from treatment in the roots under salinity, but it was expressed in PEG-treated leaves rather than salt-treated ones, and the opposite was true for HvGORK gene (regulate voltage-gated K+-permeable channels).On the other hand, HvDREB gene(coding for dehydration responsive element binding protein)has recorded higher expression in the roots under PEG treatment compared to control. Taken together, the current study suggests that the studied barley cultivar possesses higher tolerance to salt stress than osmotic stress imposed by PEG, so it could be more suitable for cultivation under salinity conditions.

A pots experiment was conducted in the greenhouse of Botany Department, Faculty of Science, TantaUniversity, Gharbiya governorate during the winter season 2015-2016 to study the response of salt-stressed safflower to extracts of two types of naturally growing costal halophytes, Z. album and H. strobilaceum. Safflower seeds were presoaked either in distilled water or 1% halophytic extract for 24 hrs then sown in plastic pots containing 2:1 w/w clay sandy soil according to the Randomized Complete Block Design until reaching the preflowering stage. After the initiation of cotyledonary leaves, seedlings were divided into two main groups: the first was treated with 1% halophytic extracts as presoaking (pre-treatment) or foliar spray application (post-treatment), while the second was specific for control treatments. Each of which was then divided into two subgroups; unstressed and stressed. Results showed that salt stress imposed negative consequences on growth and metabolic properties of safflower, whereas the extracts have helped the plant to adjust and enhance its performance under salt stress through induction of osmoprotectants, redox homeostasis and membrane integrity.