guttatie

Guttation is the exudation of liquid water from the edges or tips of plant leaves through specialized structures called hydathodes. It occurs mainly at night or in the early morning when soil moisture is high and transpiration is low, allowing root pressure to push water up through the xylem to the leaf margins.

The process involves root pressure driven by osmotic uptake of water by the roots. When stomata are closed or not actively transpiring, the generated pressure forces water and dissolved minerals to exude through hydathodes, creating visible droplets at leaf tips or along the edges. The droplets are mostly water with dissolved minerals and other small compounds from the plant.

Guttation is often mistaken for dew, but it is plant-driven rather than a result of atmospheric condensation. It is commonly observed in many herbaceous plants and seedlings, and is especially noticeable after heavy irrigation, on young leaves, or in species with efficient hydathodes. Examples of plants where guttation is frequently observed include grasses, beans, peas, tomatoes, cucumbers, strawberry plants, and other moisture-rich crops.

In general, guttation is a normal physiological process and not an indication of disease. It can reflect high soil moisture and active root pressure; in some cases the minerals carried by guttation droplets can leave residues on leaf surfaces.