Plants throughout their life cycle are exposed to different type of stresses due to their sessile nature. These stresses adversely affect the plants leading to inhibition of growth with reduced metabolism and ultimately loss in the productivity. Among various abiotic stresses salinity is one of the most important stress, limiting crop production in arid and semi-arid regions, where soil salt content is naturally high and precipitation can be insufficient for leaching. Salt stress has various effects on plant physiological processes such as increased respiration rate, ion toxicity, changes in carbon and nitrogen metabolism, mineral distribution, membrane instability and permeability and decreased efficiency of photosynthesis, reduced leaf area, dry mass and stomatal conductance. This book deals to screen out the salt tolerant and sensitive varieties of mustard in terms of photosynthetic pigments. The salt tolerant variety can then be sown in the regions with high salt concentrations and salt sensitive variety can be used as the indicator of the salt stress.