W.G.VAN.DOORN at ATO.agro.nl wrote:
:: In our institute (of the Netherlands Department of Agriculture, located
: in Wageningen) we study both the fundamental and applied aspects of plant
: senescence.
: Plant senescence is now generally thought to be related to an increase
: in free radicals, due to a decrease in the activity of scavenging molecu-
: les. The free radicals then result in a decreased phospholipid content of
: membranes, which would explain why the cells show increased leakage of
: solutes.
: Would an increase in exposure to radiation, specifically ultra violet
wavelengths in the 300-400nm range inhibit selectively the molecules with
conjugated pi orbitals, be responsible for the decrease in activity of
the so-called scavaging molecules ? I have been contemplating similar
issues over the last month, which explains why I have such a hypothesis
to offer.
The organic chemistry text which i have open before me points out
that mono- and sesquiterpenes (resonance at shorter wavelengths), but
also longer chains of carbons in adjacent pi-bonds like beta-carotene
(lambda max = 455nm). It would seem that such molecules would be
disfavored under conditions of exposure to a modified spectrum. This
would be akin to moving a plant to latitudes where the wavelengths and
their respective intensities and durations caused the failure of
coordinated maturation processes as well as issues of repair (of which i
have never had a clear concept).
I have a posting to an agricultural discussion by an australian
whose cauliflower florets became necrotic this season. Furthermore, I
understand from a Japanese news broadcast that the hot pepper crop in
South Korea this last fall was so extremely spicy as to indicate that the
plant had matured in a substantially different fashion. The butterflies
have failed to arrive in Santa Cruz, CA this fall, as they do during
their seasonal migration.
I would like to continue this exchange, but it is rather early
where I am, and I need some sleep. You make think me mad for the above
collection of ideas; there certainly is a lot of confusion about. But I
have yet to find any other way to consider these events, and so i find it
necessary to ask your consideration and appraisal.
sincerely,
chris hartleben
