A Technique for Measurement of Volatile Organic Compound (VOC) Emission Rates from Small Salad Crops

An open system for collection of volatile organic compounds (VOC) was constructed to measure the emission rate of VOC from a whole plant of the small salad crops intended for use in NASA’s Advanced Life Support Systems (ALSS). The design of the system provides a controlled plant growth environment in order to maintain normal plant physiology during VOC sampling. The system air is re-circulated through a heat exchanger to control the plant chamber temperature and humidity. An inlet air stream of 20 cc/min is purged through the system to prevent build-up of VOC to levels that may have adverse effects and to maintain system pressure at 1 atm. CO₂ is added to maintain canopy concentration of 1000 μmole/mole and light is set at 250 μmol.m⁻².sec⁻¹ (photosynthetic photon flux, PPF). Overall, this system provides a nondestructive, steady state rate measurement of emitted plant VOC even at very low levels, regardless of plant age. Ethylene emission rates from USU-Apogee wheat (Triticum aestivum L.) are presented here.