Päiväkirja-arkisto kohteelle joulukuu 2020

23. joulukuuta 2020

Autumn Foliage / Colors of Leaves – explanation(s) contributed by somebody

Carotenoids

Carotenoids gives an orange-yellow color in leaves, but are usually masked by chlorophyll. As autumn approaches, chlorophyll in leaves (of certain types of trees) is replaced at a slower rate than they are being used up. During this period, with the total supply of chlorophyll gradually dwindling, the "masking" effect slowly fades away. These carotenoids, along with the chlorophyll, provide colors of yellow, brown, orange, and the many hues in between.

Anthocyanins[1][2]

Another group of pigments in the cells called anthocyanins - which give red, purple, and their blended colors, decorates the forest of trees as the autumn foliage. Unlike the carotenoids, anthocyanins are not present in the leaf throughout the growing season, but are actively produced towards the end of summer. During the summer growing season, phosphate is at a high level. It has a vital role in the breakdown of the sugars manufactured in photosynthesis, but in the fall, phosphate, along with the other chemicals and nutrients, moves out of the leaf into the stem of the plant. When this happens - the sugar-breakdown, leading to the production of anthocyanin pigments.

The formation of anthocyanins depends on the storage and breakdown of sugars on leaves as the level of phosphate in the leaf is reduced. The brighter the light during this period, the greater the production of anthocyanins and the more brilliant the resulting autumn foliage.

Anthocyanins can be found in the maples, oaks, sourwood, sweetgums, dogwoods, tupelos, cherry trees and persimmons. These pigments often combine with the carotenoids' colors to create the deeper orange, fiery reds, and bronzes typical of many hardwood species.


Remarks:

  1. Anthocyanins: anthos (Greek) = flower, kyanous = dark blue
    are water-soluble vacuolar pigments that, depending on their pH, may appear red, purple, blue or black.
    Anthocyanidins is the sugar-free counterparts of anthocyanins. i.e. anthocyanidins + sugar = anthocyanins

  2. Anthocyanins occurs in all tissues of higher plants, including leaves, stems, roots, flowers and fruits, but predominantly in outer cell layers such as epidermis and peripheral mesophyll cells.

Lähetetty 23. joulukuuta 2020 03:29 käyttäjältä lunababy22 lunababy22 | 1 havainto | 0 kommenttia | Jätä kommentti