PHOTOSYNTHETIC ADAPTION IN CO₂ ENRICHED AIR AND THE EFFECT OF INTERMITTENT CO₂ APPLICATION ON GREENHOUSE PLANTS

Different plant species have been included in the study of the effect of CO₂ enrichment on photosynthesis and growth.
Short-term measurements (within a few hours) of net photosynthetic rate (P_N) on small plant stands have been carried out in a semi-closed cuvette system.
Long-term growth experiments (several weeks) have been carried out in growth chambers or growth rooms.
Net photosynthetic rates have been found to be increased 50–100 % by rising the CO₂ concentration from 330 to 1000–1500 vpm in short-term experiments.
The mean relative growth rates (RCR) in experiments over several weeks, however, were enhanced only 10–26 %. Experiments with Chrysanthemum x morifolium have shown that this discrepancy between short-term and long-term experiments might be explained by a negative adaption of plants to prolonged exposure in CO₂ enriched air.
Results with Chrysanthemum x morifolium and Saintpaulia ionantha indicate that intermittent CO₂ application (1 h with, followed by 1 h without enrichment) may reduce this negative adaption to high CO₂ concentrations.

Symposium on CO2 Enrichment

Leiv M. Mortensen

https://doi.org/10.17660/ActaHortic.1984.162.15