ISHS Acta Horticulturae 449: II International Symposium on Irrigation of Horticultural Crops
THE EFFECTS OF VAPOUR PRESSURE DEFICIT (VPD) AND ENRICHMENT WITH CO2 ON WATER RELATIONS, PHOTOSYNTHESIS, STOMATAL CONDUCTANCE AND PLANT GROWTH OF SWEET PEPPER (CAPSICUM ANNUM L.) GROWN BY NFT |
| Authors: | A.W. Zabri, S.W. Burrage |
| Keywords: | Transpiration rate, stomatal conductance, photosynthesis, Capsicum annuum L., water use efficiency |
| Abstract:
The effects of VPD and elevated CO2 on the growth and physiological processes of sweet pepper (Capsicum annuum L.) were studied in two experiments. In the first the plants were grown at low VPD (0.39–0.40 kPa), ambient VPD (1.20–1.50 kPa) and high VPD (1.80–1.90 kPa) at three levels of solution conductivity (1.5 mS, 3.0 mS and 6.0 mS), the second at low VPD (0.34–0.50 kPa) and high VPD (1.88–2.32 kPa) with elevated CO2 (900±50 μmol mol-1) and ambient VPD (1.32–1.44 kPa) with ambient CO2 concentration (350±20 μmol mol-1). At low VPD sweet pepper growth was enhanced by increased net photosynthesis. Increase in stomatal conductance and improvement of water status at low VPD were the most likely contributors to this effect. High VPD and high conductivity solution reduced plant growth by reducing leaf conductance and leaf expansion. Enrichment with CO2 increased photosynthetic rate at high VPD in spite of the decreased stomatal conductance due to the increase in CO2 gradient between the substomatal cavity and the air. Enrichment with CO2 also resulted in an improvement in water use efficiency compensating for the effect of water stress. | |
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