Strategies for monitoring plant water stress

One of the main lines of research on the impact of climate change is the study of drought and its effects on agricultural production. The aim of this study is to determine the key parameter of plant expression in relation to water stress and soil hydrophysical properties, thereby more accurately determining the need for real-time soil profile water enhancement. The research was conducted from 2019 to 2021 at the Nove Zamky experimental site, with research on royal walnut (Juglans regia L.) During the study, we closely monitored changes in branch and stem diameters of the plants using DD-S dendrometers (Ecomatic), sap flow rate was monitored using the Dynagage Trunk Gages system (Dynamax), and leaf spectral response was measured using the ASD system (FieldSpec). The values obtained were then compared with soil moisture, rainfall and air temperature data for the two irrigation treatments. The effect of water stress in the nonirrigated variants is not only to change the intensity of biomass growth in stems and branches, but also to reduce the volume of existing tissue. This change is also closely linked to changes in sap flow rate, which was also statistically confirmed in this study. Water stress reduces water uptake by the roots and decreases the sap flow rate; the tissue in the stems and branches becomes insufficiently hydrated, leading to less diameter growth than in the case of irrigated plants.