Pre-acclimatization in the greenhouse: An alternative to optimizing the micropropagation of gerbera

• Sucrose in the media increases in vitro development of gerbera plantlets in growth room and greenhouse conditions.
• Greenhouse growth of in vitro plantlets improved development without contamination problems.
• Sucrose concentration affected stomatal development and osteole aperture.
• Best plantlet acclimatization was in sugar-free medium in the greenhouse.
• In vitro greenhouse culture is an alternative to photoautotrophic culture with reduced micropropagation costs.

Rooting and elongation are the two stages of the micropropagation of gerbera (Gerbera jamesonii) ‘BMC101’ that use the greatest laboratory area that reduce production capacity and increase production costs. In this study, we developed an efficient method to pre-acclimatize gerbera plants in the greenhouse under photoautotrophic conditions by intercropping different stages of plants rooted in vitro in a greenhouse using natural light in small tunnels. Three different concentrations of sucrose (0, 2 and 4%) in culture media were tested as were two different growth conditions (laboratory growth chamber and greenhouse tunnels). Those plantlets grown in the greenhouse showed a significant increase (56.5%) in leaf number, leaf diameter (10.8%), rooting percentage (62.5, 93.8 and 100% with 0, 2 and 4% sucrose, respectively), root number (92%) and fresh (32.7%) and dry weight (43.4%), than those cultivated in lab conditions after culture for 30 days in vitro in rooting medium, which consisted of half-strength MS salts, 100 mg L−1myo-inositol and 0.5 mg L−1 indole-3-butyric acid. When acclimatization was complete, plantlets grown in sucrose-free rooting medium under greenhouse conditions were well acclimatized and showed good ex vitro development in paper-pot culture. An increase in sucrose concentration in the culture medium (0–4%) led to a 92% increase in leaf stomatal density, but only in plants grown under laboratory conditions.