Articles
EFFECTS OF TEMPERATURE, CARBON DIOXIDE CONCENTRATION, DAY LENGTH AND PHOTON FLUX DENSITY ON GROWTH, MORPHOGENESIS AND FLOWERING OF MINIATURE ROSES
The CT and negative DIF were studied at two carbon dioxide (CO2) concentrations (360 and 900 μmol mol-1), two photosynthetic photon flux densities (85 and 130 μmol m-2s-1 PPFD) and two daylengths (12 and 18 h day-1 DL). The DROP treatment was included only at low CO2 concentration at short days.
The plant height, and particularly the plant diameter at flowering, were significantly increased by increasing the light dose (i.e. increasing DL or PPFD). Elevated CO2 concentration also increased the diameter while negative DIF had no effect on the two parameters compared to at CT. No interactive effects between temperature, CO2, DL and PPFD were found on plant height and diameter.
The DROP treatment had no effect on these two parameters as compared to the other temperature treatments.
The plant dry weight at flowering was slightly increased by negative DIF (compared to CT) at low CO2 and slightly decreased at high CO2. The DROP treatment had no effect on the dry weight.
Negative DIF compared to CT delayed flowering by a few days at low CO2 and hastened it at high CO2. The DROP treatment delayed flowering compared to the two other temperature treatments.
The total number of flowers and flower buds were slightly increased by negative DIF (compared to CT) and CO2 enrichment, and was strongly influenced by increasing the light dose (i.e. increasing DL or PPFD).
It was concluded that the morphology of miniature roses could not be controlled by negative DIF or DROP irrespective of CO2 concentration, DL and PPFD.