Interaction between elevated atmospheric concentration of CO2 and humidity on plant growth: comparison between cotton and radish |
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Authors: | Wong Suan-Chin |
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Institution: | (1) Plant Environmental Biology Group, Research School of Biological Sciences, Australian National University, GPO Box 475, 2601 Canberra, ACT, Australia |
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Abstract: | 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.Abbreviatios DAE
day after emergence
- LAD
leaf areal density (leaf dry weight/leaf area)
- LAR
leaf area ratio (leaf area/plant dry weight)
- NAR
net assimilation rate
- ci
internal CO2 concentration
- PPFD
photosynthetic photon flux density
- RGR
relative growth rate
- RLAGR
relative leaf area growth rate
- VPD
vapour pressure deficit |
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Keywords: | Cotton Net assimilation rate CO2 humidity Radish Relative growth rate |
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