Acclimation of whole-plant Acacia farnesiana transpiration to carbon dioxide concentration

Abstract

Transpiration per unit leaf area of Acacia farnesiana (L.) Willd. plants grown at a CO2 concentration ([CO2]) of 385 μmol mol-1 was about twice that of plants grown at 980 μmol mol-1. However, when plants grown for more than a year at 980 μmol mol-1 were exposed to 380 μmol mol-1 for 9 days, they transpired at half the rate of those that had been grown at 380 μmol mol-1. Similarly, plants grown at 380 μmol mol-1, when exposed to 980 μmol mol-1, transpired at twice the rate of those grown at 980 μmol mol-1. Thus, the effects of elevated [CO2] on whole-plant transpiration, like those on photosynthesis, respiration and stomatal conductance, cannot reliably be extrapolated from measurements made during short-term exposure to elevated [CO2].