A one-step procedure for in vitro micropropagation of stevia (Stevia rebaudiana Bertoni)

Most studies about stevia micropropagation are based on a two phased procedure; in vitro shoot proliferation followed by root induction and expression. We propose a one-step procedure which allows obtaining simultaneously, in a thirtydays period, in vitro rooted plantlets and nodal shoot segments to start a new micropropagation cycle. The auxin indole-3-butyric-acid (IBA) was tested for root induction capacity and the anti-gibberellin paclobutrazol (PBZ) was tested for its capacity to control shoot elongation and internode length. All growth regulators were used in different concentrations aiming to achieve the optimal response. Data on shoot and internode number, shoot length, and rooting rates, were recorded. In vitro rooted plants were easily acclimatized in a plant growth chamber under 25/20°C day/night temperatures and 75% humidity, after being potted on a 3:1 (v:v) peat/perlite substrate moistened with Complesal®, a liquid 5:8:10 (N:P:K) commercial fertilizer. After one month, acclimatized plants were transferred into a water-cooling equipped greenhouse