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Environmental influences on the cultivation of Crassulacean acid metabolism (CAM) plants, which are especially well adapted to arid regions with limited rainfall, were evaluated with respect to two aspects of global climate change. Cellular uptake of a vital stain, which occurs in living cells only, was halved at -6+/-1 degrees C for the cultivated CAM species Agave salmiana, Opuntia ficus indica and Stenocereus queretaroensis growing at day/night air temperatures of 30 degrees C/20 degrees C compared with -12 degrees C for the wild species Opuntia humifusa. When plants were grown at reduced temperatures of 10 degrees C/0 degrees C, stain uptake was halved at about -8 degrees C for the cultivated species but at -24 degrees C for O. humifusa. The greater low-temperature sensitivity and the lesser low-temperature acclimation of the cultivated species severely limit the regions where they can presently be grown, but such regions will expand as air temperatures rise accompanying global climate change. When the atmospheric CO2 concentration was doubled from the current ambient value of 360 mu mol mol(-1) to 7201 mu mol mol(-1), net CO2 uptake over 24-h periods increased 36% for A. salmiana and S. queretaroensis; about one-third of the increase resulted from higher net CO2 uptake rates in the last 4 h of daytime and two-thirds from higher rates during the first 8 h of the night. The doubled atmospheric CO, concentration predicted to occur before the end of the twenty-first century will increase CO2 uptake and hence biomass productivity of such CAM species, further expanding the regions where they may be profitably cultivated. (C) 1996 Academic Press Limited.