There is a formula for how fast a population can change:

Genetic diversity of starting population

x

intensity of selection pressure

x

size of population.

However, the intensity factor has something like a bell curve– if you get too intense without a big enough population size, you’ll lose genetic diversity and set things back.

High diversity + intense selection + large population = fast adaptation (2-3 years?)

That’s from a book called Darwinian agriculture, I adapted it somewhat into a formula. So the answer would on specific circumstances. BUT this is a probably too simplistic… factor in endophytes, specific conditions etc etc, that is one of those ‘wicked problems’. There is a group of people talking about things like this you might enjoy.. https://landracegardening.discourse.group/