ABSTRACT
Water is the most important component of all living cells. The continuous absorption of water is essential for the growth and survival of plants. Water always moves from a region of higher water potential to the region of lower water potential. Plants absorb water by their roots from the soil through osmosis, and the increased water content inside the protoplasm exerts a turgor pressure on the cell wall. Factors controlling the absorption of water include root system, soil temperature, and soil water. Plants lose water by evaporation through their leaves to the atmosphere. The loss is made good use by water flowing from the soil into the roots, and thence within the xylem to the leaves. Water can move across the root via different pathways: the apoplast, symplast, transmembrane, and vacuolar symplast. During transpiration, the column of water is being pulled out of the plant by evaporation at the leaf cell surface. Plants combine different forces to overcome the pull of gravity. These combined forces culminate in a process called transpiration stream. Since most of the water is lost through stomata, plants regulate the degree of stomatal opening and closing to regulate water loss.
