Foliar spray of Si and Ti nanoparticles affected enzymatic antioxidants in rapeseed (Brassica napus L.)

Some beneficial nanoparticles such as silicon and titanium are encouraging in foliar feeding due to their large surface area and biocompatible properties. In current experiment, seedling of rapeseed varieties (‘Hydromel’, ‘Nathalie’, ‘Alonso’) was sprayed with titanium dioxide and silicon dioxide nanoparticles (Ti and Si-NPs) and then responses of some enzymatic antioxidant and plasma membrane integrity were evaluated. Foliar application of Si-NPs significantly increased the activity of ascorbate peroxidase compared to the control, in all three varieties. Spray of both Ti and Si-NPs increased guaiacol peroxidase activity in ‘Nathalie’ and ‘Alonso’ varieties while in ‘Hydromel’ only Si-NPs spray had positive effects on activity this antioxidant. Behaviors of superoxide dismutase (SOD) isozymes under different foliar treatments and in varieties were different, but the highest activity of total SOD isozyme in ‘Hydromel’ and ‘Alonso’ varieties was obtained by foliar application of Si-NPs and Ti-NPs, respectively. The lowest amount of hydrogen peroxide was obtained by foliar application of Ti-NPs. Examination of malondialdehyde (MDA) also showed that the most vulnerable membrane belonged to ‘Hydromel’ variety and foliar application of Si-NPs and Ti-NPs could improve membrane integrity. These results suggest that foliar application of both Si-NPs and Ti-NPs improves the scavenging capacity of reactive oxygen species (ROS), although the response of the enzymatic antioxidants was largely influenced by the variety.