, Volume 104, Issue 1, pp 211–221

Interaction between elevated atmospheric concentration of CO2 and humidity on plant growth: comparison between cotton and radish

  • Suan-Chin Wong
Response to CO2 Enrichment: Interaction With Soil and Atmospheric Conditions


Cotton plants (Gossypium hirsutum L. var Deltapine 90) and radish plants (Raphanus sativus L var Round Red) were grown under full sunlight using a factorial combination of atmospheric CO2 concentrations (350 µmol mol-1 and 700 µmol mol-1) and humidities (35% and 90% RH at 32 °C during the day). Cotton plants showed large responses to increased humidity and to doubled CO2. In cotton plants, the enhanced dry matter yield due to doubled CO2 concentration was 1.6-fold greater at low humidity than at high humidity. Apart from the direct effect of elevated CO2 level on photosynthesis, the greater effect of doubled CO2 concentration on dry matter yield at low humidity was probably due to: (1) increased leaf water potential caused by reduction of transpiration resulting from the negative CO2 response of stomata to increased CO2 concentration the consequence being greater leaf area expansion; (2) reduction of CO2 assimilation rate at low humidity and normal CO2 concentration as a result of humidity response of stomata causing reduction of intercellular CO2 concentration. In contrast, apart from the very early stage of development, radish plants do not respond to increased humidity but had a relatively large response to doubled CO2 concentration. Furthermore, due to the determinate growth pattern as well as having a prominent storage root, the extra photoassimilate derived at doubled CO2 level is allocated to the storage root.


Cotton Net assimilation rate CO2 humidity Radish Relative growth rate 



day after emergence


leaf areal density (leaf dry weight/leaf area)


leaf area ratio (leaf area/plant dry weight)


net assimilation rate


internal CO2 concentration


photosynthetic photon flux density


relative growth rate


relative leaf area growth rate


vapour pressure deficit


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Copyright information

© Kluwer Academic Publishers 1993

Authors and Affiliations

  • Suan-Chin Wong
    • 1
  1. 1.Plant Environmental Biology Group, Research School of Biological SciencesAustralian National UniversityCanberraAustralia

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