Wilting refers to the loss of rigidity of non-woody parts of plants. This occurs when the turgor pressure in non-woody plant cells falls towards zero, as a result of diminished water in the cells. Lower water availability may result from:
- drought conditions, where the soil moisture drops below conditions most favorable for plant functioning;
- high salinity, which causes water to diffuse from the plant cells and induce shrinkage;
- saturated soil conditions, where roots are unable to obtain sufficient oxygen for cellular respiration, and so are unable to transport water into the plant; or
- bacteria, fungi, or other microorganisms that clog the plant's vascular system.
Wilting diminishes the plant's ability to transpire and grow. Permanent wilting leads to plant death. Symptoms of wilting and blights resemble one another.
In woody plants, reduced water availability leads to cavitation of the xylem.