الفهرس 
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Abstract
Objectives: The study aimed to evaluate the most effective treatment that can improve salinity tolerance of Cucumber plants. Methods & Results : grafting (G), application of seaweed extract (SWE) or Zinc nanoparticles (ZnNPs), applied to cucumber plants subjected to either 50 or 100 mM of NaCl-induced salinity. Grafting was carried out on salt-tolerant pumpkin. SWE was applied at 1500 ppm whereas ZnNPs was applied at the rate of 50 ppm as spraying treatments. The treatments effects were evaluated through estimating certain stress-tolerance indicative growth, anatomical, biochemical and yield parameters. The obtained data indicated that salinity significantly decreased all tested growth attributes and these attributes were alleviated by the tested treatments, especially the application of ZnNPs. In addition, salinity negatively-affected the integrity of the anatomical structure of the stem and the leaf, and this structure was restored in response to G, SWE or ZnNPs treatments. Data also indicated that salinity stress negatively-altered the metabolism of cucumber plants manifested by reducing photosynthetic rate, total carbohydrates, growth promoters (IAA, GA and CK), the intake of N, p, K and Ca, and the activity of the antioxidant enzymes CAT, POX and SOD, thereby reducing yield and its components. On the other hand, G, SWE and ZnNPs treatments counteracted the harmful effects of salinity stress on the aforementioned salinity-depressed biochemical parameters. Consequently, yield and its quality of salinity-stressed plants that treated with either G, SWE or ZnNPs was higer compared with salinity-stressed, untreated plants. Based on the obtained results, it was argued that salinity stress-alleviation effect of G, SWE and ZnNPs was founded on maintaining the plant water relationships and photosynthetic activity, elevating osmoregulators- notabably proline-, elevating endogenous phytohormone promoters (IAA, GA and CK) whereas decreasing inhibitors (ABA and phenols), enhancing the absorption of N, P, K and Ca, and elevating the activity of the antioxidant enzymes CAT, POX and SOD thereby reducing the harmful oxidative stress-related metabolites.
Conclusions:
It was concluded that grafting salinity-stressed cucumber plants on a salinity-tolerant cucurbit rootstock, or spraying plants with SWE (applied at 1500 ppm) or ZnNPs (applied at 50 ppm), preferably with the later, can induce salinity tolerance in cucumber plant hence, reducing the negative impact of salinity stress on plant growth, anatomy, metabolism and yield.