Abstract
The effect of CO2enrichment in the culture room, photosynthetic photon flux (PPF), and the presence or absence of sucrose in the medium on the growth of tobacco seedlingsin vitroand plantletsin vitrowas investigated. Seedlings and explants were cultured on half strength MS medium in glass test tubes closed with relatively loose, formed plastic caps. All experiments were carried out under a 16 h photoperiod and a temperature of 25°C.
The growth curves of seedlings and plantletsin vitrowere similar when cultured under the same environmental conditions. The dry weight increase of seedlings and plantletsin vitrowas greater in CO2enriched treatments than in CO2nonenriched treatments. In the CO2enriched treatments, the dry weight increase was greater in high PPF treatments than in low PPF treatments. The dry weight increase was greater in medium containing sugar than in sugar free medium both in low and high PPF treatments but the difference in dry weight was smaller in CO2enriched treatments than in CO2nonenriched treatments.
Steady state CO2concentration during the photoperiod in the vessel closed with the plastic cap was between 100 and 200 ppm in CO2nonenriched treatments 30 days from the start of the experiment. Net photosynthetic rate per seedling and plantlet and net photosynthetic rate per leaf dry weight were greater in CO2enriched treatments than in CO2nonenriched treatments.
The effect of thein vitroenvironment on the fresh weight, leaf area, relative growth rate and dark respiration rate of seedlings and plantlets is also discussed and some suggestions are made for further promotion of photoautotrophic growth.
