In vitro propagation of Gerbera jamesonii Bolus ex Hooker f. in a temporary immersion bioreactor

Abstract

In the global flower industry, gerbera (Gerbera jamesonii Bolus ex Hooker f.) is ranked within the top 10 cut ornamental flowers. Commercially, micropropagation is more important than seed or vegetative propagation. This study assessed the viability of using a temporary immersion bioreactor (TIB; BIT®) to propagate shoots in vitro. Factors such as immersion frequency (6, 8 and 12 h), additional ventilation (1 min every 2 h) and the length of duration of shoot culture (14, 21, 28 and 35 days) were tested. Immersion every 8 h with additional ventilation produced more shoots with better morphology than the control. The average multiplication rate was 9 shoots/explant across treatments. However, when shoots were immersed every 6 h, shoots had higher fresh and dry weight, but displayed hyperhydricity. No differences in shoots were found when immersion frequency was 8 or 12 h. Additional ventilation (12 min/day) reduced shoot hyperhydricity to 5.24% as compared to the ventilation-free control (31.37%). Shoots receiving additional air supply every 8 h had lower fresh and dry weight with an 89.8% decline in relative water content. The number of shoots/explant increased as culture time increased, 6.7 after 28 days, and 6.1 after 35 days (statistically equal). After 7 and 14 days, shoots were induced to root in the TIB using the same medium but supplemented with IAA. Plantlets were subsequently acclimatized. More than 87% of plantlets survived in a zeolite and sugarcane filter cake (1:1) substrate. This protocol allows for the mass production of gerbera shoots in a simple TIB, with effective rooting and acclimatization. This is the first documented TIB for gerbera.