Micropropagation is particularly relevant to A. xanthorrhiza because this crop is traditionally propagated by crown buds, with very low field multiplication rates and a high incidence of systemic pathogens, whereas in vitro culture enables rapid clonal multiplication, sanitation, and long-term conservation of elite and regional genotypes. Micropropagation of A. xanthorrhiza remains hindered by physiological disorders such as hyperhydricity and low shoot proliferation, often associated with limited gas exchange and inadequate culture systems. This study evaluated the effects of different gas exchange regimes and liquid culture methods on in vitro morphogenetic and structural responses. Forced ventilation at 81.3 gas exchanges per day reduced hyperhydricity to 8.3%, while sealed vessels exhibited a hyperhydricity rate of 65.8%. RITA® bioreactors resulted in the highest shoot multiplication rate (6.5/explant), which is a 48.2% increase over semi-solid medium (4.4 shoots/explant). Additionally, RITA® systems enhanced leaf expansion, reduced oxidative symptoms, and improved shoot morphology. These findings demonstrate that combining ventilation and immersion control is a promising strategy to improve micropropagation efficiency in A. xanthorrhiza, providing quantitative evidence that complements and extends prior qualitative studies on in vitro ventilation and liquid culture systems.
Marques et al. (Sat,) studied this question.