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One of the most vital environmental factors that restricts plant production in arid and semi-arid environments is the lack of fresh water and drought stress. Common bean (Phaseolus vulgaris L.) productivity is severely limited by abiotic stress, especially climate-related constraints. Therefore, a field experiment in split-plot design was carried out to examine the potential function of ascorbic acid (AsA) in mitigating the adverse effects of water stress on common bean. The experiment included two irrigation regimes (100% or 50% of crop evapotranspiration) and three AsA doses (0, 200, or 400 mg L−1 AsA). The results revealed that water stress reduced common bean photosynthetic pigments (chlorophyll and carotenoids), carbonic anhydrase activity, antioxidant activities (2,2-diphenyl-1-picrylhydrazyl free radical activity scavenging activity and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) radical cation assay), growth and seed yield, while increased enzymatic antioxidants (peroxidase), secondary metabolites (phenolic, flavonoids, and tannins), malondialdehyde (MDA), and crop water productivity. In contrast, the AsA foliar spray enhanced all studied traits and the enhancement was gradual with the increasing AsA dose. The linear regression model predicted that when the AsA dose increase by 1.0 mg L−1, the seed yield is expected to increase by 0.06 g m−2. Enhanced water stress tolerance through adequate ascorbic acid application is a promising strategy to increase the tolerance and productivity of common bean under water stress. Moreover, the response of common bean to water deficit appears to be dependent on AsA dose.

Increment of salt stress brought about a clear enhaneement of the oxidative activities in tolerant plant species. Five cultivais ol llax {Linum llsitatissimum L.) Sakha-1, Sakha-2, Gi/a-S (Egyptian origin), Alfa-B (Lithanian origin), and Ariane (French origin) wcic tested I'or salt stress tolerance. Plants were subjected hydroponically to stxliuni chloride (0.00 and 100 niM NaCI) lor 21 days. Parameters of oxidative stress such as activity of antioxidant enzymes peroxidase (POD). Superoxide dismutase (SOD) and ascorbate peroxidase (APX) together with lipid peroxidation were determined. Electrophoretic isozyme profiles detection and total soluble protein SDS-PAGE were used as biochemical markers for assessing plant sail tolerance.Plant growth of Ariane was improved at 100 niM NaCI as compared lo control (0.0 NaCI) whereas plant growth of Sakha-1 and Sakha-2 was decreased by I(K) niM NaCI level. No response was observed on planl growth of Giza-8 and Alfa-B cultivars under salt stress. Nutrients eoneeniration ratios H. S. El-Boltagi is aftiliated with the were disturbed under high level of NaCl (100 mM). The relative salt tolerance of Sakha-1 and Ariane cultivars was associated with high antioxidant enzymes activity POD, SOD. and low MDA content. Salt stress caused an inhibition in the synthesis of polypeptide in the leaves of flax cultivars. In addition, electrophoretic profiles of POD and SOD showed differences under salt stress. From this study, it could be concluded that Ariane and Sakha-1 cultivars showed salt tolerance for the high capacity to limit oxidative damage hy increasing their activity of antioxidant enzymes together with the low content of MDA and the decrease of Na/K concentration, which may play as a part of biochemical and physiological role involved in salt tolerance and impair the oxidative damage resulted from salinity salt stress. Ariane and Sakha-1 cultivars were found to be more tolerant to salinity salt stress.

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