Effect of exogenous abscisic acid on antioxidant activity and salt tolerance in rapeseed (Brassica napus) cultivars

In this experiment, the response of two canola (Brassica napus) cultivars, Fornex (salt tolerance) and Okamer (salt sensitive) under two salinity levels (0 and 120 mM NaCl solution) to ABA foliar application (0, 15 and 30 mu mol/l) was investigated. Results indicated salt stress decrease, shoot dry matter and shoot K+ concentration in canola cultivars but increased antioxidant enzyme activity and leaf Na+ concentration. The results showed that ABA foliar application (15 mu mol/l) under salinity condition improved shoot dry matter, photosynthesis rate, peroxidase, catalase activity and shoot K+ concentration, while decreased shoot Na+ concentration in Okamer. In fact, ABA foliar application (15 mu mol/l) increased salinity tolerance in Okamer compared to absence of ABA but the high level of ABA treatments (30 mu mol/l) reduced growth in this cultivar. ABA foliar application showed negative effect on Fornex cultivar under salinity condition and non-salinity condition.