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A whole-plant cuvette system to measure short-term responses of conifer seedlings to environmental change

Summary

Published in Tree Physiology 14: 759-768

A computer-controlled whole-plant cuvette system is described that allows precise and independent control of temperature (± 0.05 °C), vapor pressure (± 0.02 kPa), CO2 concentration (± 2 mmol mol-1) and photosynthetic photon flux density (± 5 mmol m-2 s-1), and allows the continuous measurement of net photosynthesis and transpiration rates. Vapor pressure is controlled by circulating chamber air through a CaSO4 desiccant column supported on a digital balance. Transpiration rate is calculated from the change in desiccant mass with time. Photosynthesis rate is measured by integrating the output of a mass flow controller used to inject CO2 into the chamber to compensate for that assimilated by the plant.

The control system can be driven by set points that can be varied, for example, as a function of time, or held constant. We were able to simulate weather data obtained from climate stations and accurately follow, in real time, the output of sensors measuring outside conditions.

Experiments on well-watered one- and two-year-old nursery-raised western red cedar (Thuja plicata Donn.) and white spruce (Picea glauca (Moench) Voss) seedlings showed that if the mean daily temperature was increased from 20 to 22 °C with vapor pressure remaining constant at 1 kPa, CO2 concentrations must almost double to compensate for the decrease in net photosynthesis rate.

Sector(s): 

Forests

Categorie(s): 

Scientific Article

Theme(s): 

Forestry Research, Forests, Silviculture

Author(s)

LIVINGSTON, Nigel J., Gordon J. DAVIES, B.M. EBY, Greg FILEK, Edgar E. FUCHS, Steeve PEPIN and Robin E. PERCY

Year of publication :

1994

Format :

Paper

Keywords :

photosynthesis, temperature, transpiration, vapor pressure, sylviculture des forêts naturelles résineuses, silviculture and yield of natural forests - softwood stands, sylviculture et rendement des forêts naturelles - peuplements résineux

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