should senescence bit looked at differently if comparing Soil/Coco/Hydro..etc grows.
In which way do you mean? It happens in all of them.
As said genetics play a role. think of it this way its a natural process. A large majority of trees do this in the northern climates to as the temp drops and growth slows due to climate.
Most plants respond to ethylene in the same manner. Plants have many adaptations to provide the most successful chance at survival of their species.
In cannabis a lot depends on the nutrient supply. It will be more pronounced if the nutrients are low and the plant is in late flower putting all its energy into buds for reproduction it will pull what it can from elsewhere in the plant.
Ever notice after a certain point in a life cycle they stop throwing out fans almost completely and only the buds grow?
Also its a natural aging process so in most strains leaves getting past the 60 day mark you may see start to show this as they are larger older and less efficient at photosynthesis, cell division slows and then stops… the leaves aren’t dead but they start to turn yellow and eventually die and fall off. This is why i explain in my defol thread that removing the largest oldest leaves is a better option than new growing fans
many get concerned when they see this but its just natural aging