ELEVATED CARBON DIOXIDE INFLUENCES YIELD AND PHOTOSYNTHETIC RESPONSES OF HYDROPONICALLY-GLOWN SWEETPOTATO

The response of ‘TI-155’ and ‘Georgia Jet’ sweetpotato cultivars to elevated CO₂ concentrations of 400 (ambient), 750 and 1000 μmol mol^-1 were evaluated under controlled environment conditions using the nutrient film technique (NFT). Growth chamber conditions included photosynthetic photon flux (PPF) of 600 μmol m^-2s^-1, 14/10 light/dark period, and 70%±5% RH. Plants were grown using a modified half-Hoagland nutrient solution with a pH range of 5.5–6.0 and an electrical conductivity of 0.12 S m^-1. Gas exchange measurements were made using infrared gas analysis, an open-flow gas exchange system, and a controlled-climate cuvette.
Photosynthetic (Pn) measurements were made at CO₂ ranges of 50 to 1000 μmol mol^-1. Storage root yield/plant increased with CO₂ up to 750 but declined at 1000 μmol mol^-1. Storage root dry matter (DM) and foliage dry weight increased with increasing CO₂. Harvest index (HI) for both cultivars was highest at 750 μmol mol^-1. The PPF vs Pn curves were typical for C₃ plants with saturation occurring at ≈600 μmol m^-2s^-1. CO₂ concentration did not significantly influence net Pn, transpiration, water-use-efficiency (WUE), and stomatal conductance.
As measurement CO₂ concentration increased, net Pn and WUE increased while transpiration and stomatal conductance decreased.

International Symposium on Plant Production in Closed Ecosystems

D. Mortley, J. Hill, P. Loretan, C. Bonsi, W. Hill, D. Hileman, A. Terse

Ipomoea batatas, nutrient film technique, photosynthesis, sweetpotato

https://doi.org/10.17660/ActaHortic.1996.440.6