Soil incorporation of Superabsorbent Hydrogels to counteract water scarcity: modelling tree physiological and biochemical response

Superabsorbent Hydrogels are materials capable of absorbing significant amounts of water as compared to their mass. In view of climate change constraints, the use of new Hydrogels is gaining interest, but little is known about their effects on tree physiology when incorporated at transplanting. The goal of the work was to determine the effects of the incorporation of a potassium polyacrylate based Hydrogel to the soil (SH) of potted grapevines, modeling their physiological answer as compared to untreated Controls (CON). We aimed to understand if their use could benefit plant water status and physiological performances before, during, and after a progressive water deficit. The application of Hydrogel significantly affected soil hydrology, increasing field capacity, wilting point and maximum available content (from 23 % to 42 % of total soil moisture). When irrigation was reduced, soil water potential (Ψ) and vine midday stem Ψ decline were postponed in SH (by about two days). In SH vines, the biosynthesis of leaf proline and hydrogen peroxide was reduced or prevented as compared to CON, and at re-watering SH vines had significantly higher photosynthetic rates (+8.95 μmol m-2 s-1) and Fv/Fm (+34 %). As a result, at the end of the experiment SH vines marked a significantly higher vine leaf area (+8.2 %) and third internode diameter (+29.8 %). Overall, Hydrogels were effective in changing vine water status and physiological performances either under full irrigation or under reduced water availability. The results pave the way for the implementation of their use at transplanting to reduce orchard and vineyard water footprint and increase their resilience to drought.