Change of color of the sheets

During the months of Fall, much of Arbre S Feuillu S know a change of color of the sheets before they fall. This change of color which exists at many trees is often called autumnal colors.

Chlorophyl and green color

A sheet is green because of the presence of a group of Pigment S called Chlorophylle S. When chlorophyl is abundant in the cells, as it is the case for the period of growth of the plants, the green of the chlorophyl molecules dominates and masks the color of any other pigment which could be present in the sheet. Thus the sheets in summer are generally green.

Chlorophyl occupies the vital function to absorb the solar rays and to use energy resulting from this absorption in the development of the “food” of the plant - the simple sugar S which are produced starting from Eau and from Carbon dioxide. These sugars are the base of the food of the plant - the single source of Glucide necessary for its growth and its development. In this manufacturing process of food, chlorophyl itself dissociates and thus it is continuously " consommée". However, during the period of growth, the chlorophyl level remains high owing to the fact that the chlorophyl loss is compensated by the plant and thus the sheets remain green.

At the end of the summer, the veins which ensure the transport of fluids towards the interior and the outside of the sheet are gradually blocked by a stopper of cork at the base of the sheets at the precise place where the petiole will break. Whereas this layer of cork develops, the surge of water and Minéraux is reduced more and more quickly. It is during this period that the chlorophyl level starts to decrease.

Pigments which contribute to the other colors

Carotenoids

When the Fall approach, certain at the same time internal and external factors with the plant cause a deceleration of the chlorophyllian renewal more important than the speed of dissociation of chlorophyl. For this period, the chlorophyl synthesis decreasing gradually, the effect of mask attenuates slowly. Then the other pigments which were present in the cells during all the life of the sheet start to appear. In fact the Caroténoïde S emit in colors yellow, brown, and oranges.

The carotenoids are, at the side of the chlorophyllian pigments, in Organite S called Plaste S, tiny structures inside the cells of the sheets. Sometimes they are so abundant in the sheet which they give to the plant a color green-yellow, even in summer. However, in the majority of the cases, the carotenoids become apparent for the first time in autumn, when the sheets start to lose their chlorophyl.

The carotenoids, which are usually found in the world of alive the, are responsible for the color characteristic of the Carotte, of the Maïs, the canary, the Jonquille S, like that of the Egg yolk and the Banane.

Their yellow and their orange tint the sheets of the species of trees with hard wood such as the Frêne, the maple, the tulipier, the Peuplier, the Tremble, the Bouleau, the Merisier, the Platane, the Sassafras, and the Aulne.

Anthocyanes

Reds, crimsons, and their combinations which relative the foliage of autumn come from another family of pigments called anthocyanes. With the difference of carotenoids, these pigments are generally not present in the sheet during the period of growth. These molecules appear at the end of the summer. Indeed, while the crude sap continues to flow into the sheet, the elaborate sap charged with sugar, is blocked by the cork stopper, causing a forced accumulation of sugar in foliar fabrics.

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