Question

how do you demostrate that root pressure is necessary for transportation of water in plants​

Answer 1

Root pressure, in plants, force that helps to drive fluids upward into the water-conducting vessels (xylem). It is primarily generated by osmotic pressure in the cells of the roots and can be demonstrated by exudation of fluid when the stem is cut off just above ground.

Importance: Root pressure can transport water and dissolved mineral nutrients from roots through the xylem to the tops of relatively short plants when transpiration is low or zero. Xylem vessels sometimes empty over winter. Root pressure may be important in refilling the xylem vessels.