Continuous monitoring of trunk water potential by microtensiometers as a tool to assess kiwifruit plant water status under different irrigation systems

The increasing water scarcity and the misuse of this resource which occurred over the years require immediate actions to improve irrigation management, since approximately 72% of freshwater is used for irrigation at global level. Equipping the field with specific sensors, which help the understanding of the actual plant water status, allows to optimize irrigation management, thus playing a pivotal role in waterdemanding crops, such as kiwifruit. In this scenario, microtensiometers monitoring in a continuous way trunk water potential (TWP), provide useful information about plant water status, that can be used as support for irrigation decision. The research work aimed to evaluate plant microtensiometers (FloraPulse, Davis, CA, USA) during 2021 on a yellow-fleshed kiwifruit (Actinidia chinensis var. chinensis) orchard located in Metaponto (southern Italy). Plants were irrigated using two different irrigation systems (drip and microsprinkler) and the daily irrigation volume based on soil water content, crop coefficients and meteorological data was fractionated into several irrigation events. The effectiveness of the sensors was analysed through the daily TWP trends recorded on plants. The prompt sensor response to environmental conditions and management factors, such as VPD variation and soil water content changes, induced by rainfall and irrigation scheduling, was considered. Before harvest, daily fluctuations of TWP between -0.02 and -0.2 MPa were observed, underlining the potential of the irrigation strategy applied (several irrigation events per day) to prevent the excessive lowering of midday plant water potential values, as often happens when the irrigation scheduling is inappropriate, and the sensitivity of the sensor to register changes in the plant water status after each irrigation event. The preliminary results reveal that the microtensiometers are a promising tool to assess plant water status and therefore to support the growers’ irrigation decision making. Further research is needed to validate the sensor on kiwifruit.