Wiltpunt

Wiltpunt, or wilting point, is a term used in soil science and plant physiology to describe the soil water status at which a plant can no longer extract enough water to maintain turgor, and the leaves begin to wilt. It represents a threshold of available soil moisture below which a plant cannot recover its turgor even if moisture is temporarily restored. Closely related is the permanent wilting point, the condition from which recovery is unlikely after rehydration.

Measurement and variability: The wilting point is commonly expressed as soil matric potential (negative pressure, in kilopascals) or as volumetric water content. Values depend on plant species, root system, and soil texture and structure. Coarser soils typically reach wilting at higher water contents than fine-textured soils, and drought-tolerant species may tolerate lower water availability before wilting. Field conditions such as salinity and temperature can modify the effective wilting threshold.

Applications: In agriculture and irrigation planning, the wilting point helps determine when to irrigate to prevent stress. It is used in soil water balance models, crop water use studies, and irrigation scheduling tools. It also serves as a contrast to field capacity (the moisture level after gravitational drainage) and to the hygroscopic point (water bound too tightly for plant extraction).

Terminology and usage: The term wiltpunt is common in Dutch-language agronomy and soil science; English-language references use wilting point or permanent wilting point. While the precise threshold varies, the concept remains the same: it marks the limit of readily available water for plants.