科研之友
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摘要
Climate change is resulting in increasing atmospheric [CO2], rising growth temperature (T), and greater frequency/severity of drought, with each factor having the potential to alter the respiratory metabolism of leaves. Here, the effects of elevated atmospheric [CO2], sustained warming, and drought on leaf dark respiration (R-dark), and the short-term T response of R-dark were examined in Eucalyptus globulus. Comparisons were made using seedlings grown under different [CO2], T, and drought treatments. Using high resolution T-response curves of R-dark measured over the 15-65 degrees C range, it was found that elevated [CO2], elevated growth T, and drought had little effect on rates of R-dark measured at T <35 degrees C and that there was no interactive effect of [CO2], growth T, and drought on T response of R-dark. However, drought increased R-dark at high leaf T typical of heatwave events (35-45 degrees C), and increased the measuring T at which maximal rates of R-dark occurred (T-max) by 8 degrees C (from 52 degrees C in well-watered plants to 60 degrees C in drought-treated plants). Leaf starch and soluble sugars decreased under drought and elevated growth T, respectively, but no effect was found under elevated [CO2]. Elevated [CO2] increased the Q(10) of R-dark (i.e. proportional rise in R-dark per 10 degrees C) over the 15-35 degrees C range, while drought increased Q(10) values between 35 degrees C and 45 degrees C. Collectively, the study highlights the dynamic nature of the T dependence of R-dark in plants experiencing future climate change scenarios, particularly with respect to drought and elevated [CO2].
