Would Warm roots during winter help to still grow succesful ?

I used to have a grow buddy that would dump trays of ice cubes in his reservoir. He swore by cold water in the root zone. He would pull 2lb per plant indoors. Cooler water will help to reduce certain harmful risk factors, but i think that given the heaps of data that we now have about weed growing conditions and what they seem to respond best to, is room temperature. My water is usually around 71F and I haven't had any issues with that.

hmmmm temp is directly linked to photosynthesis, 87 is optimal for the chemical process, providing the correct ppfd with temps at 60 will drastically reduce the chlorophyll's ability to capture light. bud production will slow but trichome preservation will be much better. cold water holds much more oxygen, which is more important for roots that don't care about CO2

Cannabis roots in hydroponics, thrive in cool water, as cool water holds much more dissolved oxygen

Keeping the roots the right temp will be the best option before worrying about the rest. Warmer air holds higher amounts of co2 for plant to breath.

It will be fine. It may not be "optimal" but it will get the job done. The temps your talking aren't low enough to seriously stunt a plant, you'd have to dip around/under 10 for that. You'll want to run your humidity a little extra dry but that's about it.

The best temps are 19~22°C for water and 24~29°C for air.