ibclogo XVI International Botanical Congess


Abstract Number: 4765
Poster No. = 2073


CHLOROPHYLL FLUORESCENCE FOR PLANTS EXPOSED TO ELEVATED CO2 IN THE MOJAVE DESERT


Michael E. Loik1, Travis E. Huxman2, and Stanley D. Smith2. 1Environmental Studies Dept., University of California, Santa Cruz, CA 95064 and 2Biological Sciences Dept., University of Nevada, Las Vegas, NV 89154


Desert plant responses to drought may be altered by elevated CO2 in the future. We examined seasonal patterns of water relations and chlorophyll fluorescence for plants exposed to ambient (360 ?mol per mol) or elevated (550 ?mol per mol) CO2 in the Mojave Desert. We tested the hypotheses that elevated CO2 increases the efficiency of Photosystem II (PSII), and alters the responses of PSII to drought. The effects of CO2 and drought were very species-specific. When water potential was relatively high, non-photochemical energy quenching was decreased under elevated CO2, yet the quantum yield of PSII was not affected. As plant water potential decreased, these responses to elevated CO2 were reversed. The results suggest that, for certain times of the year when water potential is suitable for stomatal opening, elevated CO2 may alter photosynthetic light processing for desert plants.


HTML-Version made 7. July 1999 by Kurt Stüber