2018 ASHS Annual Conference

Oxygen consumption, measured by galvanic cell oxygen sensors (Apogee Instruments, Logan UT) connected to an automated data acquisition system were used to quantify post-harvest root respiration in multiple closed chambers. Individual sensors were mounted in sealed glass jars (240 cm³) containing roots and media harvested from plants grown in ‘128-plug trays’ (individual cell volume = 22 cm³). Separate sensors were mounted in jars containing media only (empty cells adjacent to those with plants) to quantify background microbial respiration. After stabilizing for 15 minutes, oxygen depletion was measured from 15 to 30 minutes (data collected every second) after closure and the root respiration rate was calculated from linear regression. Respiration per unit mass was calculated by dividing CO₂ evolution rate by root fresh and dry mass (after washing media from roots). This technique was used to quantify differences between ornamental and vegetable species root respiration rate, and in a separate experiment, conduct temperature response curves on several tomato cultivars that vary in heat tolerance. The benefits and limitations of this technique for rapid quantification of root respiration rate resulting from our experimentation will be discussed.