Superabsorbent hydrogels: A new tool for vineyard water management?

New superabsorbent hydrogels (SH) could be groundbreaking technologies for the adaptation of agriculture to climate change, but knowledge about their physio-chemical traits, their effects on soil hydrology, and their efficacy on tree crop physiology is very limited. In this work, two potassium polyacrylate SH (SH1 and SH2) and an organic material derived SH (SH3) were tested for their water holding capacity and the capability to improve soil hydrology according to the water demands of cultivated grapevine, one of the most relevant rainfed tree crops. All SH absorbed a significant amount of water as compared to their relative weight (from 9.19 g H2O/g polymer of SH3, to 369.64 g H2O/g polymer of SH2) and made it available at water potential (Psi) levels compatible with grapevine root system uptake. When incorporated to the soil, all SH successfully increased soil field capacity, affecting also wilting point, and increasing maximum plant available water (from +43 % of SH2 to +84 % of SH1). All SH increased stem Psi of potted vines subjected to a progressive water deficit, as compared to controls (+0.25 MPa at four days from irrigation suspension, +0.2 MPa at eight days from water suspension, when Control vines showed a stem Psi of -1.63 MPa).Our work demonstrated for the first time the potentialities of three different SH and their positive effects on soil water relations. Both synthetic and organic-derived SH could improve vine water status under limited water supply. While other studies are needed to clarify effects according to different rootstocks and soils, the results pave the way for the integration of SH in vineyard water management.