Effects of cold plasma and salicylic acid on secondary metabolites and activity of enzymes involved in their biosynthesis in Salvia leriifolia Benth.

Seed pretreatment with the cold plasma and salicylic acid is one of the methods to improve the seed germination and quantitative and qualitative growth of plants. Therefore, an experiment was conducted to investigate the effects of seed pretreatment with the cold plasma (0 and 100 W for 4 min) and seed pretreatment and foliar application of salicylic acid in the micro and nano forms (0 and 1.5 mM salicylic acid) to improve the growth and production of secondary metabolites in Salvia leriifolia Benth. The results showed that the use of salicylic acid as seed pretreatment and foliar application increased the plant height, chlorophylls a and b, total phenol, and caffeic acid of the leaves significantly. Also, the seed pretreatment with nano salicylic acid form and foliar application of micro salicylic acid form and cold plasma increased the seedlings fresh and dry weight and phenylalanine ammonialyase and tyrosine ammonialyase enzymes by 3.48, 13.3, 227.7, and 277%, respectively compared to the control. The seed pretreatment and application of salicylic acid did not have a positive effect on increasing the amount of rosmarinic and salvianolic acids of the leaves compared to the control. According to the results, increasing the enzymes activity involved in the biosynthesis of phenolic acids could affect the amount of caffeic acid positively. Overall, the findings of the present study showed that the seed pretreatment with salicylic acid and foliar application of nano salicylic acid could improve the growth traits and activity of enzymes involved in the biosynthesis of secondary metabolites in S. leriifolia more than other treatments.