ISHS Acta Horticulturae 711: V International Symposium on Artificial Lighting in Horticulture
THE INFLUENCE OF CARBON DIOXIDE CONCENTRATION DURING HIGH-TEMPERATURE PERIODS ON NET PHOTOSYNTHESIS OF CUT ROSES |
| Authors: | L.M. Mortensen, H.R. Gislerod |
| Keywords: | CO2 concentration, cut roses, net photosynthesis, photon flux density, temperature |
| Abstract:
The aim of this study was to examine the effect of CO2 concentration on net photosynthesis during 6-h periods of high temperatures in small stands of cut roses. In a first experiment, net photosynthesis decreased to zero when the temperature was raised from 22°C to 32°C, when the CO2 concentration was lowered from 800 to 380 µmol mol-1 and photon flux density (PFD) was kept constant. If the CO2 concentration was held high, only a small reduction in photosynthesis took place with this temperature increase. In a second experiment, the PFD in one plant stand was increased from 200 to 800 µmol m-2 s-1 and the temperature was raised from 20°C to 32°C while maintaining CO2 at 800 µmol mol-1. In another stand, the CO2 concentration was lowered to 380 µmol mol-1 while the temperature was kept at 22°C -- the combination of high temperature and high CO2 concentration producing a much higher photosynthesis rate (50%) than low temperature/low CO2. In a third experiment, three combinations of temperature and CO2 concentration were studied during the period of high PFD. A temperature increase to 32°C, with CO2 maintained at 800 µmol mol-1, resulted in much higher photosynthesis rates than a temperature increase to 24°C when CO2 concentration was decreased from 800 to 380 µmol mol-1. On increasing the temperature to 37°C while keeping CO2 concentration at 800 µmol mol-1, photosynthesis rates fell between the other two treatments. The results are discussed in relation to climate control strategies in greenhouses in order to maximize photosynthesis and light-use efficiency of roses. | |
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