Red leaves when autumn comes to fight stress

Scientists already know why some leaves turn into yellow and orange in the fall, but they are still not clear why a tree turns red. A new study shows that red leaves help plants reduce stress when preparing for harsh winter.

(Photo: smugmug.com) The reduced temperature and short daytime time make the leaves stop producing chlorophyll that produces green leaves - helping them catch the sun and create energy. Chlorophyll is very sensitive to cold, so frost will prevent the production of that substance quickly.

The result is yellow and orange carotenoids that are visible when the leaves lose their green color.

"The yellow is still there during the summer, but you don't see it until the blue fades away. In trees like aspen and oak, it is a major discoloration, " real physiologist Paul Schaberg at the US Forest Service, said.

According to Schaberg, red comes from anthocyanin, and unlike carotenoids, is only produced in the fall. It is also the substance that gives red to strawberries, apples and plums.

In trees, red pigments act as glass panels to prevent harmful ultraviolet rays and cover leaves when there is too much light. They also prevent cells from freezing quickly. They also act as antioxidants.

Plants produce red leaves to react with stressors in the environment such as cold ice, ultraviolet rays, drought and mold.

But red leaves are also a sign of " depression ". If you see the leaves turn red early, right from the end of August, that tree may be sick or injured.

Why do leaves lose energy to produce red hung anthocyanin, when they are about to die?

" It has been suggested that this is because it helps the leaves to cope with stress. The creation of anthocyanins helps the leaves stay longer, helping the plants to absorb more beneficial things before the leaves fall out. use these resources for the next breeding season, " Schaberg said.

MT