Abstract
An assimilation chamber for simultaneous measurement of photosynthesis, respiration and transpiration of intact plant was set up, and its function was examined especially inmeasuring root respiration and estimating dry matter increase by measured CO_2 exchange rate. Rice seedlings grown at different nutrient conditions were used as plant materials. Well-controlled pH and temperature of nutrient solution made possible a stable and continuous measurement of root respiration using an infrared gas analyzer. Dry matter increase calculated by CO_2 exchange rate was a good estimate of the measured value. There was positive correlation between top dry matter partitioning ratio and relative value of top respiration rate, and between top-root dry matter partitioning ratio and top-root respiration ratio. Therefore, the assimilation chamber was evaluated to be of help for the analysis of physiological dynamics in the growing plant.
