JS wrote:

Does anyone know if airport x-ray machines can damage either plants or
seeds? A web-search drew a blank, so if someone has the answer I would
be very grateful.

Airport Xray systems are pretty safe for plants or seeds. Hand baggage is
subject to a tiny Xray dose. Checked baggage may be given a larger hit -
especially if an operative spots something unusual. Even that is unlikely
to seriously affect seeds, but it may fog some fast photographic films.

The irradiation systems designed to sterilise anthrax spores in mail
destined for sensitive places are not. They also have the interesting
effect of turning addresses on thermal printed labels to black on black
and wrecking smart chip bank cards. Fortunately as yet very little mail is
subject to this level of abuse.

Regards,
Martin Brown