Present address: Departamento de Ciencias Ambientales, Universidad de Castilla-La Mancha, Toledo 45071, Spain.
Diurnal and seasonal variation in the carbon isotope composition of leaf dark-respired CO2 in velvet mesquite (Prosopis velutina)
Article first published online: 10 JUN 2009
© 2009 Blackwell Publishing Ltd
Plant, Cell & Environment
Volume 32, Issue 10, pages 1390–1400, October 2009
How to Cite
SUN, W., RESCO, V. and WILLIAMS, D. G. (2009), Diurnal and seasonal variation in the carbon isotope composition of leaf dark-respired CO2 in velvet mesquite (Prosopis velutina). Plant, Cell & Environment, 32: 1390–1400. doi: 10.1111/j.1365-3040.2009.02006.x
- Issue published online: 7 SEP 2009
- Article first published online: 10 JUN 2009
- Received 11 February 2009; received in revised form 3 April 2009; accepted for publication 9 May 2009
- dark respiration;
- photosynthetic 13C discrimination;
- respiratory apparent 13C/12C fractionation;
- water stress
We evaluated diurnal and seasonal patterns of carbon isotope composition of leaf dark-respired CO2 (δ13Cl) in the C3 perennial shrub velvet mesquite (Prosopis velutina) across flood plain and upland savanna ecosystems in the south-western USA. δ13Cl of darkened leaves increased to maximum values late during daytime periods and declined gradually over night-time periods to minimum values at pre-dawn. The magnitude of the diurnal shift in δ13Cl was strongly influenced by seasonal and habitat-related differences in soil water availability and leaf surface vapour pressure deficit. δ13Cl and the cumulative flux-weighted δ13C value of photosynthates were positively correlated, suggesting that progressive 13C enrichment of the CO2 evolved by darkened leaves during the daytime mainly resulted from short-term changes in photosynthetic 13C discrimination and associated shifts in the δ13C signature of primary respiratory substrates. The 13C enrichment of dark-respired CO2 relative to photosynthates across habitats and seasons was 4 to 6‰ at the end of the daytime period (1800 h), but progressively declined to 0‰ by pre-dawn (0300 h). The origin of night-time and daytime variations in δ13Cl is discussed in terms of the carbon source(s) feeding respiration and the drought-induced changes in carbon metabolism.