Response of morphological and physiological traits of canola (Brassica napus L.) to application of stabilized zero-valent iron nanoparticles under salinity stress

In order to study the effect of zero-valent iron nanoparticles on morphological and physiological traits of canola (Brassica napus L. cv. 'Hayola 401') under salinity stress, a research was conducted under controlled conditions in factorial based on completely randomized design in three replicates. In the first phase, the zero-valent iron nanoparticles were synthesized and in the second phase, their optimal concentration was determined. In the third phase, the application effect of zero-valent iron nanoparticle in the optimum concentration along with iron chelates and control were evaluated under different levels of salinity (0, 30, 60, 90 and 120 mM NaCl). According to the results of preliminary phase, 16 mg L-1 of zero-valent iron nanoparticle was determined as the optimum concentration. In addition, the results of regression equations showed that when salinity increased, plants treated by zero-valent iron nanoparticle had lower reducing slopes for root length, stem diameter, plant dry weight, root dry weight and chlorophyll a + b (-0.0183, -0.011, -0.0064, -0.0022 and -0.0027 per unit respectively) or increasing slope for electrolyte leakage (0.0743 per unit) than both the control and iron chelates. Also, the most activity of the antioxidant enzymes, Catalase (CAT) and Guaiacol peroxidase (GPX) up to 90 mM NaCl and Ascorbate peroxidase (APX) up to 120 mM NaCl achieved with using zero-valent iron nanoparticles. Overall, our findings indicated that the application of zero-valent iron nanoparticles under salinity stress had a positive effect on canola growth and performance as compared with the control and iron chelates.