Salinity considered one of abiotic stress affected to crop productivity. The present investigation aimed to give insights about the effect of NaCl saline on two cultivars sunflower plants (Helianthus annuus. L) and determine the usefulness of increasing relative salt tolerance by auxin treatment. Different responses of two sunflower cultivars Sakha 53 and China and differently susceptible to salinity stress levels by NaCl treatment in hydroponic culture experiment were investigated. The cultivar more tolerant (Sakha 53) showed less reduction in height , fresh and dry weight of the different plant organs, membrane stability, plastid pigments contents and more expression of antioxidant enzymes under high salinity level (175 mM NaCl) compared with China cultivar. Also the growth parameters were significantly increased due to IAA treatments. The physiological mechanisms of tolerance to salinity are descussed at the cellular, organ was studied. The use of plant hormones in two sunflowers under NaCl stress, improved plants salt tolerance through an improvement of relative water content, membrane stability, enhancement of chlorophyll and carotenoids biosynthesis, some antioxidant enzymes, which reflect an increase the most growth parameters of sunflower. Thus, our tested phytohormones prevent the harmful effects of NaCl in two sunflowers.

A hydroponic experiment was carried out to investigate the effect of cadmium (Cd) on differential expression, oxidative stress and some antioxidant enzyme activities in two Lactuca sativa cultivars (Balady, related Romaine Group and Great leaks, related Crisp Group). Cd phytotoxicity was shown by growth retardation of Balady and Great leaks. Results showed that Great leaks showed more sensitivity to Cd toxicity than Balady cultivar. Increasing Cd supply markedly reduced the total chlorophyll, dry matter of both Lactuca cultivars and these decreases were more marked in great leaks. Increased Cd accumulation in various plant parts in both the Lactuca cultivars was observed as Cd concentration increased. Cd accumulated in the roots was much higher than in the shoot in the two cultivars, but more observed in the case of Balady cultivar. Balady cultivar had less uptake of Cd by shoot about two times than Great leaks shoot cultivar indicating that there are coordination of gene expression, regulation ion transport process operating in different root layer more efficient in Balady cultivar compared with Great leaks. Moreover, the induction of expression and activities of antioxidant enzymes and non protein thiol (NPT) increased in Balady cultivar more than Great leaks leading to H2O2 burst, lipid peroxidation, and growth inhibition. These gene expression and activities of antioxidant enzymes confer Balady cultivar some measure of Cd tolerance and presence of strong Cd-binding proteins in the roots. In conclusion, these results may be regarded as an indication of better tolerance mechanism of Balady cultivarmore than that of Great leaks to Cd contamination.

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