The combined effect of cold stress and polyamine supplement on some phytochemical parameters of Stevia rebaudiana (Bertoni) Bertoni.

Stevia rebaudiana (Bertoni) Bertoniis a perennial herb belongs to Asteraceae family. The plant has been cultivated in all over of the world for its sweetener compounds such as: steviol glycosides. In this study to evaluate the effects of cold stress (4ºC) combined with polyamine supplement on some phytochemical parameters an experiment was carried out in a randomized design with three replications. The phytochemical measurement were obtained by spectrophotometery methods consisted of Folinciocalteu method for tanins-phenols, aluminium chloride method for flavonoids, Anthon reagent for soluble sugars and spectrophotometer for anthocyanins and steviol glycosides. The treatments were conducted in six groups contained of cold and cold-polyamine treatments in 0, 48 and 96-hours of cold courses. The measurements were performed on the plant leaves at vegetative stage at Mohaghegh Ardabili University in May 2017. The results showed that the cold stress tends to a significant increase in all of measured parameters at p≤0.05. This increase was higher in the cold-polyamine treated plants than cold only treated groups of the plant. The results indicated that total soluble sugar and steviol glycosides were increased 233 and 35 percent, respectively, than control at 96-h cold combined with polyamine treatment. At same treatment, total flavonoid, anthocyanin, total phenol and tannin contents were increased up to 40, 100, 20 and 66 percentage than control, as well as. At the same plant group, the plant antioxidant potential was also elevated 20 percentage than control ones. It can be concluded thatcombined treatment of Stevia rebaudiana with cold and polyamine supplement can induced the secondary metabolite biosynthesis in the plant and hence might be tend to a considerably increasing in the plant pharmaceutical potential.