Oscillatory Transpiration May Complicate Stomatal Conductance and Gas-exchange Measurements
in HortScienceA closed-loop photosynthesis system and a heat-balance sap-flow gauge independently confirmed oscillatory transpiration in a greenhouse-grown Rosa hybrids L. Repetitive sampling revealed 60-minute synchronized oscillations in CO2-exchange rate, stomatal conductance, and whole-plant sap-flow rate. To avoid confusing cyclical plant responses with random noise in measurement, we suggest that gas-exchange protocols begin with frequent, repetitive measurements to determine whether transpiration is stable or oscillating. Single measurements of individual plants would be justified only when transpiration is steady state.
