Articles
PHOTOAUTOTROPHIC GROWTH OF DIANTHUS CARYOPHYLLUS IN VITRO AS AFFECTED BY PHOTOSYNTHETIC PHOTON FLUX AND CO2 CONCENTRATION
Scarlet Bell plantlet as affected by three levels of PPF, 35, 70 and 140 μmol m-2 s-1, and two levels of CO2, 1,000 and 2,000 μmol mol-1, was studied.
Explants of nodal cutting with leaves were obtained from photomixotrophically micropropagated plantlets.
Four explants were cultured in each 4.0 x 10-4 m3 glass bottle.
The culture bottle had a clear plastic screw cap on which a 10 mm diameter hole was drilled and sealed with a microporous filter to increase number of air exchange per hour of the vessel to 2.0. At the beginning of the experiment, each culture vessel contained 0.4 x 10-4 m3 Murashige and Skoog agar medium with no added sugar.
The explants were cultured for 35 days under 16 h d-1 photoperiod, at 24±1°C air temperature and 70–80% relative humidity.
Fresh and dry weights, and leaf area significantly increased, while plantlet height and number of leaves significantly decreased, with increasing PPF. While plantlet height and leaf area were not affected, fresh and dry weights, % dry matter, and number of leaves significantly increased with raised CO2 level.
Fresh weight increase with raised PPF was greater with 2,000 than 1,000 μmol mol-1 CO2. Percent dry matter was significantly lower in the 70 than in the 35 or 140 μmol m-2 s-1 treatment.
Percent dry matter was the highest at 140 μmol mol-1 PPF when CO2 concentration was 1,000 μmol mol-1, while it was the highest at 35 μmol mol-1 PPF when CO2 concentration was 2,000 μmol mol-1. Chlorophyll concentration in the leaf was affected neither by PPF level nor by CO2 concentration.
The results indicate that raised PPF drastically enhanced growth of carnation in vitro under photoautotrophic conditions, especially with 2,000 μmol mol-1 CO2.