AN EXPERIMENTAL SYSTEM FOR THE QUANTITATIVE C-14 LABELING OF WHOLE TREES IN-SITU

The first part of this paper provides a brief review of the requiremen ts that apply to C-14-labelling chamber technology, particularly for t ree labelling, and of the means that can be used to meet them. Two mai n points are considered: the quality of the plant chamber environment - the necessity of thermal and hygrometric regulations is discussed - and the possibility of determining the exact amount of (CO2)-C-14 assi milated by the plant. The authors then describe a simple system allowi ng the quantitative labelling of entire trees, without temperature- or hygrometry-regulating devices which can be used in the morning. The C O2 concentration is maintained at its natural level throughout the lab elling procedure through an injection of cold CO2 operated by an IRGA- driven computer. This system was successfully used for the labelling o f grafted walnut trees.