EFFECT OF DIURNAL SAMPLING ON THE HEADSPACE COMPOSITION OF DETACHED NICOTIANA-SUAVEOLENS FLOWERS

Compounds emitted over a 24 hour sampling period by detached flowers o f Nicotiana suaveolens were examined after collecting flowers at 12.00 and 24:00 hours (dark period 24:00-08:00 hours), entraining volatiles in air and trapping on Tenax. The yields were approximately 640 ng g- 1 and 31 000 ng g-1 at 12:00 and 24:00 hours, respectively, and these differences were due largely to benzoic acid derivatives. This pattern of higher emission at ca 24:00 hours was consistent with the rhythms seen in an earlier study for in situ flowers. Several new compounds in cluding phenylpropanoid-derivatives and sesquiterpene hydrocarbons wer e identified in the headspace of flowers collected at 24:00 hours. A n umber of these phenylpropanoid-derived headspace components (e.g. E-ci nnamyl aldehyde, benzyl salicylate), had been found previously in glyc osidically-bound forms.