ISHS Acta Horticulturae 148: III International Symposium on Energy in Protected Cultivation
EFFECTS OF LIGHT AND CO2 ON THE GROWTH OF YOUNG TOMATO AND CARNATION PLANTS |
| Author: | G.T. Bruggink |
| Abstract:
Studies on light and CO2 response of plant growth are extremely important in energy efficient greenhouses. The effect of these two factors and their interaction were studied in a growth analysis experiment with young tomato and carnation plants grown in a greenhouse, from October till March. Every two weeks for tomato and every four weeks for carnation a new series of plants was sown/planted and plants were grown for 8 weeks with weekly harvests (biweekly for carnation). It appeared that Net Assimilation Rate for both tomato and carnation increased with 0.9% per % increase in incoming radiation in midwinter and with 0.7% in spring. Raising the CO2 concentration from 350 to 1000 ppm increased NAR for tomato with 0.02 mg/cm2.day, which in midwinter is an 18% increase and in spring an 8% increase. For carnation there was no significant effect of CO2. For both plants an increase in NAR was counteracted by a decrease in Leaf Area Ratio, irrespective if this change was brought about by a change in light or CO2 concentration. This effect was strongest at high NAR values and much stronger for tomato than for carnation. This means that Relative Growth Rate for tomato reacts less sensitive to changes in incoming radiation than RGR for carnation. Preliminary results of photosynthesis measurements suggest that photosynthesis is depressed in plants grown at high CO2 concentrations, this may explain the relatively small effect of CO2 enrichment on the growth of young tomato and carnation plants. | |
