What is a key indicator of soil moisture stress in crops?

Wilting of leaves and reduced leaf turgor serve as significant indicators of soil moisture stress in crops due to their direct physiological effects on plant health. When a plant experiences insufficient water, it loses turgor pressure, which is the pressure of the cell contents against the cell wall. This loss of pressure results in wilting, as the cells can no longer maintain their firm shape. The leaves, which require adequate moisture for both hydration and nutrient transport, respond to this stress by drooping or wilting, signaling that the plant is unable to absorb enough water from the soil.

In contrast, other indicators like yellowing of leaves and stunted growth might suggest nutrient deficiencies or disease rather than a direct response to water stress. Increased pest activity and crop damage typically relate to a broader range of agronomic issues, not specifically tied to moisture levels. Uneven crop maturity across the field could indicate variability in planting, soil types, or other factors but is not a direct sign of soil moisture stress. Therefore, the wilting of leaves and reduced leaf turgor directly reflect the immediate and critical impact of insufficient water availability on plant physiology.