The effect of headspace renewal in a Temporary Immersion Bioreactor on plantain (Musa AAB) shoot proliferation and quality

The positive effect of ventilation of the culture container on in vitro shoot proliferation and quality was already proven for different species. Hereafter we report on the evolution of the headspace during in vitro culture of plantain in a Temporary Immersion Bioreactor (TIB) on the one hand, and culture on semi-solid medium on the other hand. The CO2 and C2H4 concentration reached a maximum of 12% and 0.45 mu l 1(-1), respectively in the control treatment on semi-solid medium, compared to 5.7% CO2 and 0.06 mu l 1(-1) C2H4 in TIB. The minimal O-2-concentration on semi-solid medium was 15.1%, compared to 19.3% in TIB. The multiplication rate was best in TIB, 6.4 compared to 4.3 in semi-solid conditions, and this was also the case for shoot height (4.3 cm compared to 3.3 cm), and leaf number (2.6 compared to 1.6). Moreover shoots produced on semi-solid medium showed distorted leaves. A typical day-night pattern in CO2 and O-2 concentration was observed in TIB, as well as on semi-solid medium; this is illustrative for the photosynthetic capacity of the plant material produced in both systems.