The Field and the Fridge

The same leaf wants opposite air on the two sides of a knife. Alive it wants a little dryness — VPD around 0.8–1.2 kPa — because transpiration is pulling water and calcium up to its tips; too still and wet and the tips starve. Cut, it wants saturation and cold, because it is still losing water and no longer replacing it. Harvest does not change the leaf's water physics. It removes the root, which is the return path — and a reversible flux becomes an accumulating loss. Why a field and a fridge are two rooms, read as the moment a return path is cut.