A Comparison of the Horizontal and Vertical Positions of the PET Bioreactor for In Vitro Commercial Propagation of Vanilla

Temporary immersion systems represent an efficient, biotechnology-based alternative for micropropagation. This study compares the in vitro propagation of vanilla shoots in semisolid and liquid media using a polyethylene terephthalate (PET) bioreactor in both horizontal and vertical positions. During the multiplication stage, these PET bioreactors were evaluated by measuring the following development variables: chlorophyll content, stomatal density, percentage of closed stomata, and dry matter percentage. Additionally, survival percentage was evaluated during the acclimatization stage. Our findings indicate that the different culture systems exert differential effects on the evaluated variables during in vitro multiplication. Both horizontal and vertical PET bioreactors yielded a higher number of shoots per explant, as well as increased dry matter percentage, stomatal density, and closed stomata. The longest shoots, featuring more leaves and higher chlorophyll content, were achieved in the horizontal PET bioreactor. Furthermore, plantlets cultured in the PET bioreactors exhibited the highest survival rates during greenhouse acclimatization. In conclusion, the in vitro multiplication of vanilla using PET containers as temporary immersion bioreactors represents an economical and efficient alternative for the micropropagation of this species on a commercial scale.