Question

what will happen if xylem is blocked in a plant?

Answer 1

Essentially the leaf needs water from xylem to remain hydrated because it needs to transpire water to the atmosphere as part of the photosynthesis process. If the water from xylem is cut off then the leaf begins losing water from its cells as photosynthesis occurs (water is part of the process--it supplies hydrogen ions to the process and oxygen is given off) so the cells first shut down their stomata (the spot where transpiration occurs to the atmosphere) and then as water continues to be used the amount of water in the leaf is no longer enough to keep the cells fully hydrated and they begin to shrink allowing for wilt to occur.