Introduction | Materials & methods | Experimental | Observations | Conclusions

Introduction Current problems in micropropagation are: In the case of hermetically closed containers: Problems caused by poor gas exchange. CO2, O2 and especially ethylene-concentrations can be far from optimal. Hyperhydricity is also a result of poor gas exchange. In the case of loose covers: Secondary infections, transported by air or by mites and trips.

Empty Microbox with filter

Microboxes with healthy plants

Materials and methods Containers: all incubations were performed in standard polypropylene boxes, provided with different types of closures. Type 1: loose cover without filter, which is snapped on, but not sealed Type 2: plain cover being hermetically sealed to the box Type 3: Microbox-cover, which is equipped with a series of depth filters, and which is hermetically closing the box (figures below). Investigated species: Anthurium andreanum cultivar Mylene, which is known to be sensitive for ethylene gas. We prepared shoot cultures with heavy cutting, in order to produce as much ethylene as possible. Medium: a modified medium according to Murashige and Skoog (1962), solidified with agar. Environmental conditions: Incubation temperature: 25°C Light intensity: approx. 60 µmol.m-2.s-1. a day and night rhythm of 12 h dark and 12 h light was applied. Adequate ventilation prevented the CO2 concentration to rise above 0.2% Contamination pressure: the boxes were placed in an environment, which was heavily contaminated with mites and spores of Aspergillus sp. Analytical methods: CO2 concentration was measured with an infra red gas sensor (Engicom Systems) O2 concentration was determined with a paramagnetic sensor (Engicom Systems) Ethylene was detected by means of gas chromatography according to Smalle and Van der Straeten (1997).

Experimental This preliminary experiment was carried out in order to evaluate the Microbox as an in vitro culture container. All measurements were taken at the beginning of the light phase. Carbon dioxide concentrations day/night cycle Oxygen concentrations day/night cycle Ethylene concentrations

Observations As could be expected, the carbon dioxide concentration never rose above 0.6 % in all vented containers, which is considered beneficial for plant production. The oxygen concentration was in all containers almost at the same level, allowing dark reactions. The ethylene concentration was in all vented systems lower than the detection limit of 0.0625 ng/ml of gas phase, which is too low to have a visible effect on the plantlets. In our comparative series with completely closed containers ethylene concentrations as high as 1.5 ng/ml were measured. On photographs 1 and 2 the effect of high ethylene concentrations are clearly visible, such as long internodia, pale green leaves, adventitious air roots and shoot formation in the medium. The Microbox shows an even better gas exchange than the non sealed cover (about 4 gas exchanges per day).

Photo 1: the Microbox, provided with hermetically sealed cover with filter batteries Photo 2: healthy plantlets in Microbox Photo 3: hermetically sealed container, cover without filter Photo 4: effect of high ethylene concentration and hyperhydricity

Detail of filter

Conclusions Gas exchange capacity: with respect to gas exchange the Microbox was found to be at least as good, if not better than the classically used containers with non welded cover. Barrier against pests and diseases: a very important advantage of the Microbox is the perfect protection against micro-organisms, mites and trips.

Exchange of gases through microfilter

Back to top

© 2007 COMBINESS nv - info@combiness.com
Rozenstraat 1A - 9810 Nazareth (Eke) - Belgium
T: +32 (0)9 280 09 80 or +32 (0)496 217 617 - F: +32 (0)9/280 09 16