To study the effect of salt stress on quantitative and qualitative parameters of canola (Brassica napuse. L) cultivars, and determine the possible mechanisms of salt tolerance and the best salt tolerance indices, an experiment was conducted a hydroponic culture in Greenhouse of university of Tabriz and also To investigate the effect of salinity resulted from sodium chloride on rapeseed and selection of the most tolerant and susceptible genotypes, 12 canola (Brassica napus L.) cultivars were evaluated under three salinity treatment (0, 150 and 300 mM NaCl) arranged in split plot design under hydroponic culture system. Salinity stress was significantly affected all the traits under study. Proline is the major amino acid associated with environmental stresses (salinity, extreme temperatures, UV radiation and heavy metals). When exposed to drought or a high salt content in the soil (both leading to water stress), many plants accumulate high amounts of proline, in some cases several times the sum of all the other amino acids. Free proline content in leaves increased significantly by increasing of NaCl concentration. Accumulation of K+ in shoot instead of proline might be a way in which the genotypes perform osmotic adjustment under salinity. Tolerance index was identified as a good criterion to select the tolerant genotypes under high salinity stress. According to this index, Heros and Comet were identified as salt-sensitive and Craker and Amica as salt-tolerant genotypes. Results indicated that, pod per plant is the more influencing trait on seed yield under both normal and salinity conditions. Cluster analysis were classified the genotypes into the three groups in which Heros and Comet were blong to the cluster with low mean with respect to all the traits. These results suggest an ample genetic variability between rapeseed genotypes which could be used in breeding programs. Furthermore, by identification of contrasting genotypes, molecular dissection of tolerance to salinity stress and identification of corresponding genes would be amenable.
