الفهرس 
Physiological studies for mitigation of adverse effects of salinity stress on vicia faba
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Abstract
Nowadays, extensive areas of arable lands across the world are affected by salinity. Therefore, the development of new technology is seriously needed for minimizing the harmful impact of salt stress on crops. This dissertation consists of two major objectives to mitigate the impact of salt stress on faba bean. The first part monitors the role of calcium phosphate NPs (CaP-NPs), while the second objective was to elucidate the roles of salt priming.
Regarding the first objective, plants were grown in the greenhouse. Thirty days after sowing (DAS), CaP and CaP-NPs treatments were applied at 16 mg/ml in the presence and absence of 150 mM NaCl stress. During three different growth stages, we collect faba bean leaf samples for physiological and morphological traits analysis. Results showed that salinity had deleterious effects on plant yield with a 55.9% reduction compared to control. On the other hand, CaP-NPs dramatically improved plant yield by 30% compared to conventional fertilizer under salinity stress. Additionally, the nano-fertilizer reflected better mitigatory effects on plant growth parameters, photosynthetic pigments, and oxidative stress indicators (MDA and H2O2). This improvement could be attributed to the significantly higher enhancement in total soluble sugars, antioxidant enzymes (peroxidase (POX), catalase (CAT), and superoxide dismutase (SOD)), and proline content, and total phenolics recorded using the nano-fertilizer, compared to conventional one under salt stress.
Based on the results of this objective, we can conclude that the replacement of traditional fertilizers comprising Ca2+ or P with CaP-nano-fertilizers will improve plant productivity and sustainability under salt stress.
For the second objective of this study, the results reflected an increase in H2O2 generation and lipid peroxidation in unprimed plants subjected to 200 mM salt shock for one week, accompanied by a decline in growth, photosynthetic pigments, and yield. As a defense, the shocked plants showed enhancements in ascorbate peroxidase (APX), catalase (CAT), glutathione reductase (GR), peroxidase (POX), and superoxide dismutase (SOD) activities. Additionally, the salt shock plants revealed a significant increase in phenolics and proline content, as well as an increase in the expression levels of glutathione (GSH) metabolism-related genes (the L-ascorbate peroxidase (L-APX) gene, the spermidine synthase (SPS) gene, the leucyl aminopeptidase (LAP) gene, the aminopeptidase N (AP-N) gene, and the ribonucleo-side-diphosphate reductase subunit M1 (RDS-M) gene). On the other hand, priming with increasing concentrations of NaCl (50–150 mM) exhibited a little significant reduction in some growth and yield-related traits. However, it maintained a permanent alert of plant defense that enhanced the expression of GSH-related genes, proline accumulation, and antioxidant enzymes, establishing a solid defensive front line ameliorating osmotic and oxidative consequences of future salt shock and its injurious effect on growth and yield.