© 2004 Heron Publishing—Victoria, Canada
Exposure to elevated carbon dioxide concentration in the dark lowers the respiration quotient of Vitis cane wood
David R. Smart
Department of Viticulture and Enology, University of California, One Shields Avenue, Davis, CA 95616-8749 (drsmart@ucdavis.edu) / Received December 11, 2002; accepted April 27, 2003; published online December 1, 2003
Summary
Cane cuttings of the grapevine rootstock Vitis rupestris Scheele × V. riparia Michx. cv. 3309 Couderc were brought out of endodormancy by warming at 30 °C. Cane pieces (12 to 13 cm long) with nodes containing
a primary bud were placed in a gas exchange system and monitored for net respiratory fluxes of CO2 and O2. Grapevine respiration rates expressed on a wood volume basis were 1.4 to 3.4 mmol CO2 or O2 m–3 s–1, which is higher than stem respiration rates reported for many other woody taxa but similar to rates measured for ecodormant
buds of other Vitis species. Passive water loss from canes was 0.7 to 1.2 mmol H2O m–3 s–1. During a 7-day period, nonstructural carbohydrate concentrations in cane wood declined only slightly, whereas sucrose was
nearly completely consumed. When ambient CO2 concentration ([CO2]) was raised from 300 to 750 µmol mol–1 and then 2000 µmol mol–1, net CO2 exchange rates declined by 5.9 ± 0.6 and then 11.0 ± 0.6%, whereas net O2 consumption rates remained about constant. The mean respiration quotient (net CO2/O2 flux) for canes with intact ecodormant buds was 0.99 ± 0.03 when the [CO2] was 300 µmol mol–1, and decreased to 0.87 ± 0.03 and 0.088 ± 0.02 when the [CO2] was increased to 750 and 2000 µmol mol–1, respectively. The results support the hypothesis that, in Vitis canes, inhibition of respiratory CO2 efflux in response to high [CO2] is an indirect consequence of non-photosynthetic carboxylation reactions, and not a result of inhibition of respiratory
metabolism.
Keywords:
oxygen, stem respiration.
