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

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.

II International Symposium on Irrigation of Horticultural Crops

A.W. Zabri, S.W. Burrage

Transpiration rate, stomatal conductance, photosynthesis, Capsicum annuum L., water use efficiency

https://doi.org/10.17660/ActaHortic.1997.449.78