I have been following the anthocyanin/red colouration discussion, and have
read with interest many of the ideas/hypotheses advanced to date. However, I
have consistently wondered whether anthocyanin synthesis in the fall is
simply a mechanism to reduce the effective light intensity (PFR), i.e. that
anthocyanin functions as a sun screen (cytosolic carotenoids have been
postulated to function in the same manner in the green alga Haematococcus).
Why would a maple turn red in the fall? Is it simply to decrease the degree
of photoinhibition induced by low temperature? That is, as temperatures
decrease proportionally more than PFR in the fall, synthesis of anthocyanins
would serve to screen the photosynthetic apparatus, and thus minimize the
degree of photoinhibition. I don't know if there are experiments or data
that support this idea, but it should be easy enough to test using a
chlorophyll a fluorescence measurements. Does anyone know of such experiments?
Harold Weger
Harold G. Weger tel: 306-585-4479
Department of Biology fax: 306-585-4894
University of Regina e-mail: Harold.Weger at uregina.ca
3737 Wascana Parkway
Regina, Saskatchewan
S4S 0A2
Canada
