In plant physiology, the 'Root pressure' is a positive pressure that develops in the roots due to the active absorption of minerals and the subsequent osmotic entry of water. It is most evident during: MCQ with Answer and Explanation

Root pressure is a positive hydrostatic pressure generated in the xylem of roots due to the active secretion of ions into the xylem, which lowers the water potential and causes water to enter osmotically from the soil. This pressure can push water up the stem. Root pressure is most evident and measurable during the early morning or at night, when the rate of transpiration from the leaves is very low (or zero) and the soil moisture is high, allowing for maximum water absorption. It is responsible for phenomena like guttation and the exudation of sap from cut stems.