Effect of ammonium: nitrate ratio on fatty acid composition and proline accumulation of canola cultivars grown under salinity stress

The effects of NaCl salinity stress (100, 150 and 200 mM) and NH4:NO3 ratio (0:100, 25:75, 50:50 and 75:25) on fatty acid composition and proline accumulation of canola (Brassica napus L.) cultivars SLM046, Licord and Okapi were studied when salinity stress and ammonium and nitrate ratio were applied together. The results show that there were significant differences among cultivars in response to salinity stress and nitrogen sources. In addition, fatty acids composition varied as a result of different salinity levels. Generally, among different ratios of ammonium and nitrate nitrogen sources, 50:05 ratios produced more oleic, linoleic and linolenic. Also, the results indicate that there was a negative correlation between oleic acid and linoleic acid and similarly between linoleic and linolenic acid, while there was positive correlation between oleic and linolenic acid. Proline accumulation increased dramatically due to salt stress. Finally, application of ammonium and nitrate at 50:50 ratios is recommended to earn high quality canola seed.