Ozone induced emissions of biogenic VOC from tobacco: relationships between ozone uptake and emission of LOX products
Volatile organic compound (VOC) emissions from tobacco ( Nicotiana tabacum L. var. Bel W3) plants exposed to ozone (O 3 ) were investigated using proton-transfer- reaction mass-spectrometry (PTR-MS) and gas chromatog- raphy mass-spectrometry (GC-MS) to find a quantitative reference for plants' responses to O 3 stress. O 3 exposures to illuminated plants induced post-exposure VOC emission bursts. The lag time for the onset of volatile C 6 emissions produced within the octadecanoid pathway was found to be inversely proportional to O 3 uptake, or more precisely, to the O 3 flux density into the plants. In cases of short O 3 pulses of identical duration the total amount of these emit- ted C 6 VOC was related to the O 3 flux density into the plants, and not to ozone concentrations or dose-response relationships such as AOT 40 values. Approximately one C 6 product was emitted per five O 3 molecules taken up by the plant. A threshold flux density of O 3 inducing emissions of C 6 products was found to be (1.6 ± 0.7) ¥ 10 - 8 mol m - 2 s - 1 .