Effects of organic mulching and regulated deficit irrigation on crop water status, soil and yield features in an orange orchard under Mediterranean climate

The adoption of soil and water conservation measures (SWCM) is essential for improving the use of natural resources and making the agro-systems more resilient to climate change. In this context, a three-years trial was carried-out in an orange orchard characterized by different soil management (SM, i.e., bare and organic mulched soils) and water regimes (WR, i.e., full irrigation, FI, and regulated deficit irrigation, RDI). In response to the applied SWCM, crop water status (CWS), soil and yield main features were explored using multiple soil-plant-atmosphere continuum (SPAC) monitoring approaches. Overall average water saving of 24 % was achieved under RDI in comparison to FI. The stem water potential revealed a year-dependent behaviour in accordance to the patterns of the main ancillary physiological indicators. The adoption of additional plant-based measurements provided continuous information on the CWS, both in terms of trunk water potential (TWP) and sap flow fluxes, resulting in higher absolute values of TWP (-0.93 ± 0.01 MPa versus -0.83 ± 0.00 MPa) and lower transpiration rates (0.64 ± 0.00 mm d^-1 versus 0.88 ± 0.01 mm d^-1) in mulched compared to bare soils. The soil water content showed higher rates under mulched soils than in bare soil condition, both in FI (up to 15 %) and RDI (up to 27 %) at 0.75 m from the tree trunk to the inter-row. Soil temperature was lower in mulched soils under RDI. However, a great time-variability was observed for most of the soil physical-chemical variables under study. Nevertheless, the application of SWCM improved the yield over the years, resulting in higher fruit weights under mulched FI conditions. Finally, the study suggests that the adoption of SWCM can serve as an efficient strategy to enhance soil and yield features, highlighting the critical role of using SPAC methodological tools for monitoring the CWS at the field level.