Effect of Growth Regulators on Optimization of Stevia (Stevia rebaudiana) Production in vitro

Stevia rebaudiana (Bertoni) Bertoni importance and value have been proved in the world because of its alternative potential as natural sugar and in vitro production benefits. Tissue culture of this plant was considered in order to get the best regeneration condition. In this study, proliferation of branches and rooting were measured as a factorial based on a randomized complete block design with four replications. There were two types of shoot induction hormone treatments including BAP and Kin in 0 (control sample), 0.25 and 0.5 mg/lit concentrations and two root induction hormone treatments of IBA and NAA in vitro condition. Traits were measured after 45 days on branch, leaf and root. Results showed the most branch length and root volume with 0.25 mg/lit of Kin hormone and the most root length with 0.25 mg/lit concentration of IBA. The highest rooting was related to IBA hormone in 0.5 mg/lit concentration. According tocorrelation analysis between traits, positive and significant correlation was reported. Cluster analysis grouped shoot treatment with BAP in two 0.25 and 0.5 mg/lit concentrations in one group and Kin with 0.25 and 0.5 mg/lit concentrations in another group. Also, these treatments showed the most similarity. Also, IBA root treatment with 0.25 mg/lit concentration had the most difference in comparison with other hormone treatments. According to the HPLC results, increasing of rooting hormones concentrations (NAA and IBA) leaded to leaf Stevioside increasing. Totally, hormone treatments resulted significant differences between control and treated plants. That had positive effects on plant regeneration.