Host Tree Drought Responses in Mediterranean Black Truffle Orchards: Linking Atmospheric Demand, Soil Water Availability and Canopy Conductance

The cultivation of black truffle (Tuber melanosporum) has expanded in Mediterranean areas, where rising drought frequency and atmospheric aridity pose increasing risks for both host tree performance and truffle productivity. Since truffle development depends on the physiological activity of the host tree, understanding how trees use water under dry conditions is essential to improve orchard management and promote resilience to climate change.

This study assessed the response of tree conductance to varying edaphic and atmospheric drought conditions in irrigated black truffle orchards through continuous ecophysiological monitoring. The study was conducted in three productive truffle orchards called Mora, Cella and Maials, all located in northeastern Spain and distributed along an atmospheric dryness gradient. Infrared canopy temperature was monitored in three trees per site together with soil water potential (SWP), vapor pressure deficit (VPD), and other meteorological conditions. Canopy total conductance was modelled based on the infrared thermometry observations in order to analyse plant–atmosphere interactions under different environmental conditions.

The results revealed a close relationship between atmospheric water demand and canopy temperature regulation, with higher VPD generally associated with reduced canopy conductance. Additionally, clear differences among sites were found. Trees located in Mora site (lower VPD conditions) showed the highest canopy conductance even under lower SWP values compared to Cella and Maials, indicating a partial decoupling between soil water availability and gas exchange. In contrast, trees in Cella and Maials displayed stronger stomatal regulation as atmospheric demand increased.

These findings show the value of thermal-based indicators for monitoring tree transpiration in truffle orchards and offer new insights of drought responses of host trees in truffle plantations. This information will serve to improve irrigation optimization and support adaptive management strategies to sustain black truffle production under increasingly arid climatic conditions.