Effects of CO2 concentration and moisture content of sugar-free media on the tissue-cultured plantlets in a large growth chamber

The dynamic fluctuations of CO2 concentration in the tissue culture growth chamber after transplantation of petunia, chrysanthemum and tomato plantlets were recorded with a real-time control system to determine the critical CO2 concentration levels of 35 μl l−1 at which CO2 enrichment is needed. The experimental data showed that the tissue-cultured plantlets of petunia, chrysanthemum and tomato had the same CO2 concentration dynamics. The results indicated that CO2 enrichment was proper on the second day after transplantation. Petunia plantlets were used to conduct experiments under PPFD of 80 μmol m−2 s−1, and CO2 concentrations of 350 ± 50 μl l−1, 650 ± 50 μl l−1 and 950 ± 50 μl l−1 as well as medium moisture contents of 60%, 70% and 80%, with the result that plantlets grew better under CO2 concentration of 650 ± 50 μl l−1 than under the other two concentrations with all the different media water contents. Three media water contents under the same CO2 concentration produced plantlets with the same quality. The impacts of CO2 concentrations on plantlets are more important than those of the media water contents. Sugar-free tissue culture, as compared with the conventional culture, showed that CO2 enrichment to 350 ± 50 μl l−1 can promote the growth of the cultured plantlets. Sugar-free tissue culture produced healthy plantlets with thick roots, almost equivalent to the common plantlets.