Atmospheric Carbon Dioxide Enrichment Effects on Cotton Midday Foliage Temperature: Implications for Plant Water Use and Crop Yield
1987
Idso, S. B. | Kimball, B. A. | Mauney, J. R.
In an experiment designed to determine the likely consequences of the steadily rising carbon dioxide (CO₂) concentration of Earth's atmosphere for the foliage temperature, water use, and yield of cotton (Gossypium hirsutum L. var. Deltapine-61) plants, cotton was grown out-of-doors at Phoenix, AZ, in open-top, clear-polyethylene-wall, CO₂-enrichment chambers for three summers under mean daylight CO₂ concentrations of 340, 500 and 640 μmol CO₂ mol⁻¹ air on an Avondale clay loam soil [fine-loamy, mixed (calcareous), hyperthermic Anthropic Torrifluvent). Infrared thermometer measurements of the cotton foliage temperature (TF) indicated that a 330 to 660 μmol CO₂ mol⁻¹ air doubling of the atmospheric CO₂ content results in a midday T, increase of 1.1 °C for well-watered cotton at Phoenix in the summer. This temperature increase was predicted to produce a 9% reduction in per-unit-leaf-area plant transpiration rate and an 84% increase in crop biomass production, which compared favorably with the measured crop biomass increase of 82% for such a doubling of the air's CO₂ content. These findings, together with similar findings for a second plant species—water hyacinth [Eichhornia crassipes (Mart.) Solms]—allowed us to develop a technique for assessing the effects of a 330 μmol CO₂ mol⁻¹ air CO₂ concentration increase on the percentage yield increase (Y) of a crop via infrared thermometry by means of the equation Y = 7.6% × (IJ)⁻¹, where IJ represents the Idso-Jackson plant water stress index. If this equation holds up under further scrutiny, it could provide a rapid and efficient means for assessing the yield response of crops to atmospheric CO₂ enrichment.
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