Diurnal Photosynthesis and Transpiration of Ficus benjamina L. as Affected by Length of Photoperiod,CO2 Concentration and Light Level |
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| Authors: | Leiv M Mortensen |
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| Institution: | S?rheim Research Station, N-4062 Klepp stasjon and Department of Horticulture , Agricultural University of Norway , ?s, Norway |
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| Abstract: | Abstract The diurnal net photosynthesis of Ficus benjamina L., cultivar Cleo, was studied at different daylengths (12, 18 and 24 h day?1), photosynthetic photon flux densities (40 and 120 μmol m?2 s?1 PPFD) and CO2 concentrations (350 and 700 μmol mol?1). Net photosynthesis increased to a maximum after 5–6 and 6–7h of light at 12 and 18h day?1photoperiods, respectively, followed by a decrease towards the end of the photoperiod. At a photoperiod of 18 h day?1 similar diurnal curves were found at 350 and 700 μmol mol?1 CO2, and at 40 and 120 μmol m?2 s?1 PPFD. Five days after the photoperiod was changed from 18 to a 24h day?1the diurnal rhythm disappeared. Transpiration followed the same diurnal rhythm as that for photosynthesis. The water-use efficiency was enhanced by raising the CO2 concentration. A decrease in the CO2 concentration from 700 to 350 μmol mol?1after six days at high CO2 first significantly decreased the photosynthesis, but three days later it reached the same level as that at high CO2. |
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| Keywords: | CO2 concentration diurnal rhythm Ficus benjamina light level photoperiod photosynthesis transpiration |
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