Quantitative headspace analyses of rose¯ow-ers showed no signi®cant dierences in composition of emitted volatile compounds between¯owers on the intact plant and cut¯owers placed in vase water containing sucrose at 0, 15 or 30 g á l A1 . Volatile components emitted were geraniol, nerol, citronellol, E-citral, Z-citral, methylgeranylate, trans-caryophyllene, b-cubebene, dihydro-b-ionone, 2-phenylethanol, 2-phenylethylacetate, 3,5-dimethoxytoluene and hexylacetate. When exposed to a 12-h photoperiod these components showed maximum emission during the light period and a rhythmicity which diered for the individual compounds. The circadian nature of the rhythmicity was con®rmed by the continuation of rhythmicity during continued darkness or light, and was characterized bỳ transient' and`free running' periods of 27 and 24 h, respectively, and a phase shift of 12 h in rhythmicity when a 24-h period of continuous darkness was followed by re-exposure to a 12-h photoperiod. Rhythmicity in emission was not observed when¯owers were kept in darkness before¯ower bud opening, but started immediately upon exposure to a 12-h photoperiod.

No abstract

No abstract

No abstract