This book is about the study that was conducted to investigate the effect of salinity and nitrogen in three growth stages on Superoxide dismutase enzyme activity and some physiological properties of two wheat cultivars. Under controlled conditions, it was conducted in Research Greenhouse of Nuclear Research Institute of Agriculture. The experiment was conducted as a factorial experiment in a completely randomized design with three replications. Treatments included two wheat cultivars [Tajan (salinity sensitive) and Bam (salt tolerant)] and five salinity levels and two levels Nitrogen fertilizer. The relative water content, chlorophyll content, and Superoxide dismutase activity, leaf soluble protein, Malondialdehyde, and finally seed weight and grain yield were evaluated.