EFFECT OF ROOT-ZONE (RZ) CO₂ ON PRODUCTIVITY AND PHOTOSYNTHESIS IN AEROPONICALLY GROWN LETTUCE PLANTS

Effects of root-zone (RZ) CO₂ on crisphead-type lettuce (Lactuca sativa L. cv. ‘Wintergreen’ were measured in an aeroponic system under photosynthetic photon flux of 650 µmol m^-2 s^-1, 12 h photoperiod at 36°C/30°C and 28°C/22°C (day/night), with three enriched RZ CO₂ levels (2000 ppm, 10,000 ppm and 50,000 ppm). Leaf growth was monitored after elevated RZ CO₂ had been supplied for one week.
Leaf areas with elevated RZ CO₂ were greater than ambient controls at both temperatures, while shoot and root weights were also higher.
Increasing temperature reduced biomass overall, but the relative response to RZ CO₂ was greater.
Elevated RZ CO₂ stimulated photosynthetic CO₂ assimilation, with greater increase at higher temperatures.
Elevated RZ CO₂ decreased stomatal conductance at both temperatures, reducing transpiration water loss.

South Pacific Soilless Culture Conference – SPSCC

J. He, P.T. Austin, M.A. Nichols, S.K. Lee

Leaf area, Photosynthesis, CO₂ assimilation, Shoot and root weight, Stomatal conductance, Transpiration

https://doi.org/10.17660/ActaHortic.2004.648.5