Plant Hydrological Responses to Dust: A Case Study from a Citrus Orchard in Cyprus

Dust influences plant hydrological functioning in several ways. Dust (or particulate matter) can block or reduce stomatal activity, which regulates gas exchange between the plant and the atmosphere, thereby affecting both transpiration and stomatal conductance. In addition, during dust events, the reduction in solar radiation reaching the plant surface directly influences transpiration rates.
This study aims to examine the effects of dust on plant hydrological responses through systematic monitoring of stomatal conductance and transpiration (using sap flow methods). Two neighbouring plots (east and west) of Citrus (Mandora) trees, located in the Fasouri area (Limassol, Cyprus), were selected for monitoring. In each plot, three representative trees were chosen. Sap flow sensors were installed on each tree, and soil moisture sensors were placed at different depths around the selected trees. Furthermore, weekly measurements of stomatal resistance were taken from six leaves per tree. At the east plot, additional stomatal resistance measurements were obtained from six extra leaves per tree after removing dust from their surface using a microfibre cloth. Meteorological conditions were recorded by a meteorological station within the farm, while particulate matter (PM) data were provided by an air quality station managed by the Department of Labour Inspection of Cyprus. The experiment began in April 2025 and is ongoing. 
Preliminary results show similar average stomatal resistance between untreated leaves in the east plot (311 s m⁻¹) and the west plot (303 s m⁻¹). However, treated (dust-free) leaves in the east plot exhibited 19% lower stomatal resistance (255 s m⁻¹) compared to untreated leaves in the same plot, indicating a clear effect of dust on stomatal functioning. Periods during which stomatal resistance was similar between treated and untreated leaves were observed following rainfall events, highlighting the importance of rainfall in maintaining healthy plant hydrological functioning.