The question is what signal initiates plant response to drought 1. Y w or some component of it or 2. In this case, the water relations of the shoot respond to moist soil, but the overall growth rate of the plant still declines, as would be expected from dry soil. Recently, this was addressed in a cool experiment. Therefore, there is still some sort of signal from roots to the leaves that signals stomate guard cells to close.
Cells lose turgor and begin to shrink away from their cell walls.
Increase cell wall elasticity . In this case, high elasticity allows the cell wall to shrink around the shrinking cytoplasm. The squeezing of the cell wall around the cytoplasm maintains greater turgor at a particular tissue water content. This is a good thing for a rapidly transpiring plant when H2O avail. Note that it's surprising here that turgor pressure isn't responsible for decreased growth with drought.