RE: How do trees 'know' when to shed their leaves?
Hey there,
the leaf fall is triggered by the phytohormone ethylene.
For ethylene production, the enzyme ACC synthase is needed.
According to this publication here, UV-B triggers ACC synthase expression and thus ethylene synthesis. But in autumn or winter, there is not that much sunlight present anymore.
Other stimulants are toxins, wounding, and pathogens.
Therefore, I assume that the leaf fall in autumn is caused by a multiple setting where stress, high nutrient load, and other factors (indicators of mature plants or fruits), promote the synthesis of ethylene.
The change of color is because the trees take all the "good" elements out of the leaves. These are for instance ions. In the center of chlorophyll, there is magnesium.
Probably the tree knows that a high ethylene concentration is associated with leaf fall and therefore quickly evacuating the ions (and other good things) and thus changing the color of the leaves before they are gone.
Regards
Chapper
Fantastic, would you consider writing this in a separate Answer post?
Simply click the "Answer This Question" button.
Thanks!
Hey there,
I'm terribly sorry! I tried to answer but I don't understand the tool!
Anytime when I hit the answer button I fill out that form and paste my answer in one of these lines but can't submit.
See scrennshot:
I have no chance to do something else except hitting the cancel button.
That's why I wrote comments all the time.
What can I do?
Regards
Chapper
Hi @chappertron,
Your main text should be in the Description field, not the tag.
The tags are there to allow you to specify tags such as steemstem, science, etc. Just like on steemit.
Also I recommend that you out a nice picture in your text as it will make the answer stand out on the home page.
Let me know if you are having any more difficulty.
Hey,
I haven't see it!
Very cool platform!
Will come across more often.
Regards
Chapper