SEASONAL COLOR

SEASONAL COLOR Contrary to the wxlely held belief that leaf axx change is produced by earty tal frosts, a combination of bnght days and cod night sets the chain of events m motion that results ip the brilliant shades of autumn By September there are approximately three hours less of sunlight than during the height of summer, and light rays strike leaves at more of an angle and are reflected rather than absorbed Thus, photosynthesis steady decreases, ana there is a proportional reduction of chiorophyl synthesis Within a short time the unstable green pigment already present breaks down, and the underlying yellow pigments are revealed

At the sane time, the combination of shorter days and coder temperatures tngger the termatior- of a thin wa# of cells where the real is attacneo to the twig, effectively shutting off the flow of water and bringing to a halt further sugar and chlorophyll production Unless anthocyarnns are present, the leaf will apoear yellow Brilliant shades of red will predominate in some species, however if the days have been suffaenity onght to produce large quantities of sugar and the nights sufficiently cod to trap it within the lea! Intermediate hues between yellow and red represent a derxing of carotene, xanthophytl. and the anthocyamns m which the latter pigment s not present in sufficient concentration to obscure completely the termer two. OTHER FACTORS that play a rote in the development and intensity of tall coloration are the trees exposure and elevation, genetic makeup, and the prevailing soil conditions Soil conditions such as pH and relative fertility determine cdor to some degree If you have any questions or comments regarding this artide or any other questions please contact me at jwood@bartlett.com or 1-877-BARTLETT.

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