Improving activity of antioxidant enzymes and vigor in rapeseed by salicylic acid and gum arabic seed priming

Deterioration is an irreversible feature of the seed that threatens its viability. Seed priming is one of the methods which improves vigor by modifying the structure and performance of deteriorated seeds. In this regard, at the first step, the best priming combination of different concentrations of salicylic acid, thiourea, and gum arabic was selected by germination and seedling traits in deteriorated seeds of canola var. Okapi. Then, using conventional experimental designs, its effect was tested on germination indices, seedling growth, antioxidant enzymes' catalase (CAT), superoxide dismutase (SOD), ascorbate peroxidase (APX), guaiacol peroxidase (GP), and alpha-amylase (α-amylase). The results of the Taguchi method introduced a combination of 1 mM salicylic acid and 0.75% gum arabic as the best treatment, and its effectiveness was confirmed by subsequent experiments. The stimulating effect of this treatment on germination rate, root and seedling length, and seedling weight was significant compared to the control treatment (p≤0.01). The length and weight of seedlings increased by 30 and 60%, respectively. Enzymatic results showed that the activity of SOD, APX, and α-amylase enzymes was significantly (p≤0.01) increased by the selected treatment by 14, 22.7, and 5.5%, respectively, compared to the control treatment. In general, priming the seeds with a combination of salicylic acid and gum arabic stimulates the defense system and remobilization of reserves, which is reflected in the improvement of germination and seedling indices. Enhancing these factors provides a suitable condition for the optimal establishment of canola in environmental conditions.