how plants know when autumn is? Or how they know know when to do seasonal things?
In: Biology
Light less light means that auxin (a hormone) in the plant isn’t being destroyed, more auxin in the plant the plant then goes into “winter mode”
Plants measure the duration of uninterrupted hours of darkness using phytochromes. Plants that flour in the summer (long day plants) need short nights and long days to trigger flowering. Plants that flower in winter/autumn need long nights and short days to flower.
There are 2 different phytochromes, Pr and Pfr. Pr, absorbs red light (r=red) and Pfr absorbs far red light (fr= far red). During day light Pr is converted into Pfr quickly and at night Pfr is converted back into Pr at a slowly.
Short day plants need consistently low levels of Pfr which is brought about by long nights. On the other hand long day plants need high levels of Pfr which is brought about with long days and short nights.
I hope this is a good explanation
There are a number of triggers. Temperature, amount of sunlight, and water availability are all variables that change with the seasons. Plants are attuned to these and change their growth patterns accordingly.
Certain plants go by temperature change. So, in the Southeast we have trees and bushes that will start to bloom if there enough days in a row of over a certain temperature.
Others use the angle of the sun to determine when to start budding. That same angle also indicates when to end photosynthesis in the leaves and that when they die and begin to lose leaves.
I’m sure someone can explain more technically, but that’s my understanding.
The length of the daylight is a primary key for seasonal behavior. The days get shorter, and that signals the plant to do different things.
Thank guys for the responses. I appreciate 🙂
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