Sensitivity to soil salinity during beet seed germination is among the main tackles for plant deployment in fields. To study this, a research was conducted in greenhouse in a factorial experiment based on randomized complete blocks design with three replications. The first factor included stress levels and the second factor included genotypes. To apply salinity stress sodium chloride 16 dS/m was used. Seeds were planted in plastic pots in greenhouse conditions and plants irrigation was done by Hoagland nutrient solution. The proline and chlorophyll of shoots were measured by the end of growth stage. Results suggested that genotype No. 4 with a mean of 19.25 had the highest rate of chlorophyll and genotype No. 1 with mean of 13.25 had the lowest chlorophyll rate. Also, genotype No. 3 with a mean of 5.86 had the highest proline rate. Results indicated that salinity stress application could decrease chlorophyll rate while it increases proline rate. Decrease in plant chlorophyll decreases the photosynthetic activity. Increase in proline along with increase in salinity level specifies the osmotic balance maintenance in low water potential. Results generally showed that increase in proline production as an osmotic regulatory mechanism in high salinity levels which decreases the seedling growth.
