Three physiological parameters capture variation in leaf respiration of Eucalyptus grandis, as elicited by short-term changes in ambient temperature, and differing nitrogen supply.
We used instantaneous temperature responses of CO2 -respiration to explore temperature acclimation dynamics for Eucalyptus grandis grown with differing nitrogen supply. A reduction in ambient temperature from 23 to 19 °C reduced light-saturated photosynthesis by 25% but increased respiratory capacity by 30%. Changes in respiratory capacity were not reversed after temperatures were subsequently increased to 27 °C. Temperature sensitivity of respiration measured at prevalent ambient temperature varied little between temperature treatments but was significantly reduced from ~105 kJ mol-1 when supply of N was weak, to ~70 kJ mol-1 when it was strong. Temperature sensitivity of respiration measured across a broader temperature range (20-40 °C) could be fully described by 2 exponent parameters of an Arrhenius-type model (i.e., activation energy of respiration at low reference temperature and a parameter describing the temperature dependence of activation energy). These 2 parameters were strongly correlated, statistically explaining 74% of observed variation. Residual variation was linked to treatment-induced changes in respiration at low reference temperature or respiratory capacity. Leaf contents of starch and soluble sugars suggest that respiratory capacity varies with source-sink imbalances in carbohydrate utilization, which in combination with shifts in carbon-flux mode, serve to maintain homeostasis of respiratory temperature sensitivity at prevalent growth temperature.
['Kruse|Jörg|J|0000-0002-1614-8128', 'Rennenberg|Heinz|H|', 'Adams|Mark A|MA|']
D000704:Analysis of Variance D002245:Carbon Dioxide D019069:Cell Respiration D005052:Eucalyptus D016014:Linear Models D009584:Nitrogen D010788:Photosynthesis D018515:Plant Leaves D025341:Principal Component Analysis D012995:Solubility D013213:Starch D000073893:Sugars D013696:Temperature D013997:Time Factors
Eucalyptus grandis temperature response acclimation homeostasis C/N-balance flux regulation