Impacts of drought on leaf respiration in darkness and light in Eucalyptus saligna exposed to industrial-age atmospheric CO2 and growth temperature
Author for correspondence:
Tel: +61 (0)2 6125 5046
- •Our study assessed the impact of a wide range of industrial-age climate scenarios on leaf respiration (R) in Eucalyptus saligna.
- •Well-watered or sustained drought-treated plants were grown in glasshouses differing in atmospheric CO2 concentration ([CO2]) (280, 400 and 640 μl l−1) and temperature (26 and 30°C). Rates of R in darkness (Rdark) and light (Rlight), photosynthesis (A) and related leaf traits (mass : area relationships, and nitrogen, phosphorus, starch and sugar concentrations) were measured.
- •Light inhibited R in all cases (Rlight < Rdark) (well-watered: 40%; drought-treated: 73%). Growth [CO2] and temperature had little impact on area-based rates of Rdark or Rlight, with Rlight exhibiting minimal thermal acclimation. By contrast, sustained drought resulted in reduced Rdark, Rlight and A, with the inhibitory effect of drought on A and Rlight (c. 50–70%) greater than that on Rdark (c. 15%). Drought effects were fully reversible after watering. Variability in Rlight appeared to be dependent on the underlying rate of Rdark and associated Rubisco activity.
- •Collectively, our data suggest that there is an asynchronous response of leaf carbon metabolism to drought, and a tighter coupling between Rlight and A than between Rdark and A, under both past and future climate scenarios. These findings have important implications for ecosystem/global models seeking to predict carbon cycling.