In order to investigate the changes in fatty acids composition of rapeseed lines under Chitosan application, a factorial split-plot experiment was conducted based on RCBD in 3 replications during 2 years (2014-2016) in Karaj, Iran. Irrigation and Chitosan as main plots and cultivar in sub-plots were considered. In this study, treatments included irrigation at 2 levels (normal irrigation and cut off irrigation after flowering stage), Chitosan at 2 levels (pure water and foliar application of Chitosan 250 mg/l), and rapeseed cultivars (BAL104, DIE710/08, BAL101, BAL102, QUIE03/11, and OKAPI). The result of ANOVA showed irrigation and cultivar had a significant effect on fattiest acids. Results exhibited cut off irrigation after the flowering stage reduced the oleic acid content compared to normal irrigation. Results also indicated that erucic acid and grain glucosinolate contents were different among the mentioned varieties and they were influenced by irrigation regimes. Cut off irrigation at the flowering stage increased erucic acid and grain glucosinolate in all varieties. On the other hand, the lowest erucic acid and grain glucosinolate were observed in cv. Okapi under normal irrigation, and it might be considered useful rapeseed to include in the diet as it contains low specific glucosinolate and erucic acid. Moreover, var. DIE710/08 had the lowest erucic acid and grain glucosinolate under drought stress conditions. پرونده مقاله