Emission of volatiles from flowers and leaves of Brassica napus in situ

Separate headspace samplings of Brassica napus flowers and leaves in situ showed that six volatiles were emitted from the flowers only, 12 compounds were common to both flowers and leaves, and 11 compounds were emitted from the leaves only. The average emission of floral volatiles was 45 ng per flower per hr. Floral rhythmic emission was shown for sabinene and limonene, both emitted from flowers and leaves. In contrast, no rhythm of emission was detected for the major compounds emitted from the flowers only, i.e. α-farnesene, linalool and 3-carene. A rhythmic nature of emission could not be discerned after transfer to constant environmental conditions. The significance of the floral volatiles in plant-insect relationships is discussed.