Use of a Laser-Driven Photoacoustic Detection System for Measurement of Ethylene Production in Cymbidium Flowers

Abstract

A laser-based photoacoustic method was used for determination of ethylene (C2H4) production of emasculated orchid (Cymbidium) flowers in a flow-through system. The laser photoacoustic equipment consisted of a line-tuneable CO2 laser in conjunction with a single-pass resonant acoustic cell. The minimum detection limit of the system for C2H4 in air was 0.03 nanoliter per liter. C2H4 production of intact Cymbidium (cv Mary Pinchess ''Del Rey'') flowers was very low (0.015 nanoliter per gram per hour) and showed an increase within 3 hours following emasculation (removal of pollinia plus anthercap). Production peaked (0.14 nanoliter per gram per hour) 8 hours after emasculation and decreased therafter. Production again increased 45 hours after emasculation. Coloration of the labellum appeared shortly after the first peak; wilting of the petals and sepals appeared during the second rise in ethylene production. The use of the laser photoacoustic technique in plant physiological studies is discussed.