Rape seed (Brassica napus L.) is the third important oil plant in the world. The sensitivity to salinity at the germination stage is known as the main obstacle of desirable establishment of the plant in the fields. To this aim an experiment in a greenhouse in a random factorial block design was done. The experiment was repeated three times. The first stress factor was in the five levels (1- Control, 2- 50 mM, 3- 75 mM, 4- 100 mM and 5- 150 mM) and the second genotypes factor included (1: Talaye 2: Okoti and 3: Tasiv). At the end of the growth stage, the Proline of air organs was measured. Results showed that the amount of proline of Okoti genotype with the average of 0.7367 gets the maximum value. The results showed that salinity stress increases the proline. The increase of proline with salinity increase shows the importance of the osmotic balance in low water potential condition. In general the results of the experiments showed that increase in production of proline - as an osmotic regulatory mechanism for survival in high salinity levels- can lead to reduced growth of the seedling.
