Question

Explain how "osmotic adjustment" can be used to maintain turgor pressure as soil water content decreases.

Answer 1

Osmotic adjustment is a mechanism in plants to tolerate osmotic stress by lowering the osmotic potential by the accumulation of solutes, and to maintain the volume of protoplast and turgor pressure. Osmotic adjustment occurs in leaves, hypocots, roots, floral apex and spikelets under osmotic stress conditions. Osmotic adjustment in the root has a different role from that in the shoot. The role of osmotic adjustment in root elongating zone is to maintain turgor pressure to continue root elongation and root growth in drying soils, which enable the plant to maintain its
transpiration by exploiting a greater volume of soil or utilize available water in a given soil volume more efficiently. The signifi cance of osmotic adjustment in the elongated zone of the root is to promote desiccation tolerance and to initiate lateral roots that are responsible for effi cient absorption and transport of water.