As two newly important components for plant tissue culture, the impacts of iron nanoparticle and potassium silicate were studied on the regeneration and growth of grape cuttings var. Khoshnaw under salinity condition. The treatments consisted of salinity stress (0, 50, and 100 mM NaCl), iron nanoparticles (0.0, 0.08, and 0.8 ppm) and potassium silicate (0, 1, and 2 mM) under an in vitro environment. The overall results indicated that salinity significantly (p ≤ 0.05) increased soluble carbohydrates and carotenoid contents. On one hand, it reduced all studied morphological and physiological traits including shoot number, shoot and root length, shoot and root fresh weight, root volume, and leaf area, along with relative water content (RWC) and chlorophylls’ content. On the other hand, the application of iron nanoparticles and potassium silicate, alone or in combination, could significantly compensate the deleterious effects of salinity on morphological traits, leading to increase their mean values compared to control condition (p ≤ 0.05). Soluble carbohydrate content showed negative significant (p ≤ 0.05) correlation with RWC, chlorophyll a, and all morphological parameters. Chlorophyll b and total chlorophyll contents showed positive significant (p ≤0.01) correlation with RWC. The application of higher concentrations of potassium silicate resulted in a greater ability of plants to tolerate salinity; moreover, the results suggest that moderate concentrations of iron nanoparticles may be more profitable for increasing salinity tolerance.
