Scholarly record
POTENTIAL OF SAP FLOW FOR IDENTIFYING STRESS IN HORTICULTURAL CROPS
Abstract
Climate change represents one of the major environmental problems of our time (IPCC, 2021), significantly affecting plant water regimes and agricultural production. Increased temperatures, prolonged droughts, and unpredictable rainfall patterns lead to reduced soil water availability (Allen et al., 1998), increasing the urgency for efficient and precise irrigation management. As traditional methods based on soil moisture or empirical models become less effective under variable climatic conditions (Jones, 2004), the use of advanced technologies to monitor real-time plant water status is gaining relevance. This study evaluates the potential of sap flow measurement using Dynagage Trunk Gages sensors (Dynamax Inc., 2007; 2020) to manage irrigation in horticultural crops, focusing on royal walnut (Juglans regia L.). These sensors work on the heat balance principle, utilizing a constant heat source and differential thermocouples to measure heat dissipation, thereby determining sap flow in units of g-h?- (Granier, 1987; Lu et al., 2004). The system allows for non-invasive, continuous monitoring without harming the plant, making it a practical tool for field applications. The experiment was conducted in 2024 in the Danube Plain region of Slovakia, one of the driest and warmest areas in the country (Atlas of the Slovak Landscape, 2020; Climate Atlas of Slovakia, 2020). Sap flow was monitored in irrigated and non-irrigated trees during two critical phenological phases: budding and flowering. Results showed that sap flow rates closely followed air temperature trends and significantly decreased under water stress, particularly in the non-irrigated variant. This supports earlier findings (Fernandez et al., 2008; Cermak et al., 2004) and confirms sap flow as a sensitive indicator of plant water stress. However, as the data reflect past rather than real-time stress responses, this method has limitations in triggering immediate irrigation decisions. Despite its temporal limitation, sap flow monitoring offers a cost-effective, scalable approach to understanding plant-water interactions. Compared to more complex systems such as transpiration modeling based on leaf area indices or remote sensing, which require extensive microclimatic data and technical resources (Fernandez et al., 2008), the sap flow method is accessible and efficient. Its integration into automated irrigation systems has the potential to improve water use efficiency and reduce ecological impacts of over-irrigation (Dynamax Inc., 2020). Furthermore, the method holds promise for adaptation to other crops and agro-ecological zones, aligning with global goals for climate-resilient and sustainable agriculture (Shao et al., 2008; Silva et al., 2009).
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References19
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