An automated system for use in collecting volatile chemicals released from plants

Abstract

A system is described for the collection of volatiles produced by plants that minimizes stress on the plant in an environment that is free from chemical impurities. Air entering a volatile collection chamber containing a plant is purified using a nonwoven fabric media infused with charcoal. A multitasking, computer-automated system is described that can simultaneously collect volatilized chemicals from plants as well as monitor and record environmental conditions associated with those collections. Collection of up to 16 samples can be made in varying sampling order, flow rates, and user-specified time periods, without disturbing the sampling environment. During the same time period, this system is capable of simultaneously monitoring up to eight environmental parameters using any type of sensor with electrical signal outputs. A multiport base assembly was designed to fit around the base of the plant permitting air samples to be collected at the bottom of the chamber. The chamber can pass ambient light so the plant may follow its natural photocycles. The entire system can be configured for continuous laboratory duty or portable field use by utilizing components that run on DC voltages. For the purpose of testing the system's performance, we determined the periodicity of the release of volatiles from red and yellow flowering four o'clock plants,Mirabilis jalaba (Nyctaginaceae). The major chemical released from four o'clocks was identified as ocimene. The onset of release occurred between 1400 and 1600 hr and increased with time with maximum amount of ocimene released during 1800–2000 hr, followed by a decrease in emission. No ocimene was detected after 2400 hr. Determination of the amount of ocimene released per flower was calculated for the 1800- to 2000-hr time period. Based on the number of open flowers during the 1800- to 2000-hr period, yellow four o'clock's released 80.9 (±7.3 SD) ng/hr/flower, while the red flowers released 51.9 (±7.0 SD) ng/hr/flower.