Atmospheric CO2 enrichment enhances survival of Azolla at high temperatures
1989
Idso, S.B. | Allen, S.G. | Anderson, M.G. | Kimball, B.A.
In 2 years of experimentation with Azolla pinnata var. pinnata at Phoenix, Arizona, growth rates of this floating aquatic fern first decreased, then stagnated, and finally became negative when the mean air temperature rose above 30°C. When the atmospheric CO2 content above the plants was increased from the meam ambient concentration of 340 μmol CO2/mol air to 640 μmol CO2/mol air, however, the debilitating effects of high temperatures were reduced: in one case to a much less severe negative growth rate, in another case to merely a short period of zero growth rate, and in a third case to no discernible ill effects whatsoever—in spite of the fact that the ambient treatment plants in this instance all died. With the double verification of this phenomenon provided by both weekly biomass and periodic net photosynthesis determinations, it would appear that atmospheric CO2 enrichment may be capable of preventing the deaths of some plant species in situations where their demise is normally brought about by either the direct effects of unduly high temperatures or by associated debilitating diseases.
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