Why yellow leaves in autumn?

The molecule is yellow and orange trees instead causes the receiver to dress, but what makes the brilliant red of many plants is still a mystery. Leaf color is revealed to us thatthe level of plant stress.

Leaves in response to temperature drop and the sun low and less of the fall by ceasingproduction of chlorophyll - a substance facilitating tree caught the light and produce energy. Because chlorophyll is sensitive to cold conditions, so in these cases to theearly frost, the leaves will change color rapidly.


As the green chlorophyll gradually go down, the red and yellow pigments - carotenoidsare usually present in the store carrots or pumpkin - the dominant leaf surface.

"Yellow and red colorings are still ever present in the leaves all summer, but have pale blue go until we see," said Paul Schaberg, a research botanist for the U.S. Agency forForestry said. 

 

However, the brilliant red color of some species is still a mystery to scientists. When autumn, maple and ash that become red because of quality pigments (anthocyanins), appears only in the fall. They also give color to red for ripe berries, red apples and plums.
In plants, the red coloring of this act as a shield sunlight, preventing the harmful rays and to ensure that the leaves from the light intensity is too strong. It also acts as antifreeze, protecting cells from freezing plant, and also as antioxidants.
Plants produce these substances in response to extreme conditions such as freezing cold, UV rays, dry and mold.
In addition, the red leaves are also a sign of illness and fatigue. If we find one or more leaves of trees turn red very early - around August - most likely it is to fight fungus or a driver who crashed into it.
But why take the effort to trees dying leaves only a few days then they fall off?
"Some people speculate that it leaves to help cope with stress," Schaberg told LiveScience. "If the leaf pigment helps plants survive on little more days, the leaves may help plants obtain what is good for the trees before falling. Tree will hoarding living resources that grow next season."
If viewed from the link between the red of the leaves with the level of pollution, the changing leaves of autumn as to be not just beautiful. Scientists hope that studying the pigmentation of leaves will help understand the level of "stress" that plants suffer and consequently know the impact of the environment. One day, the leaves will tell us what trees are found.