CONTINUOUS DETERMINATION OF ETHYLENE FROM ROOTS VIA LASER PHOTOACOUSTIC-SPECTROSCOPY

A CE cabinet was constructed to detect root ethylene emission via a la ser photoacoustic detector. This cabinet was 1) non-destructive with r espect to plants, 2) ethylene-free, 3) under controlled atmospheric co nditions, 4) suitable for a continuous determination of ethylene produ ction of intact roots and 5) simple and removable. A constant gas flow passing through the cabinet resulted in a rapid indication of change of the ethylene concentration in root space at ppb level. Using this c abinet, the influences of wounding and drought stress on ethylene emis sion of roots of strawberry (Fragaria x ananassa Duch.) and the effect of light on ethylene production of roots of citrus (Citrus madurensis Lour.), were investigated. The ethylene production of strawberry root s showed two peaks around 8 nl C2H4 g(-1) dw h(-1) within the first tw o ours after treatment. With intact citrus roots an increase of ethyle ne production of 25% (0.6 nl C2H4 g(-1) dw h(-1)) was observed when th e plant was placed from darkness in light conditions.