Assessing the extent of citrus trees root apparatus under deficit irrigation via multi-method geo-electrical imaging

Abstract

Tree rooting strategies are driven by external and internal factors such as climate conditions (rain frequency, wind direction), soil structure and crop type. In order to ensure water efficiency for irrigated crops, it is essential to know how each crop adapts its rooting strategy. We couple Mise-a-la-masse (MALM) with Electrical Resistivity Tomography (ERT) for investigating orange tree roots undergoing different irrigation strategies (Partial Root-zone Drying – or PRD - versus Full Irrigation). This is a totally novel approach giving an overall picture of roots structure and functioning in the subsoil. Our results show clear differences of rooting extent between different irrigation strategies, and identify privileged direction of root development due to distinct RWU patterns. These results are corroborated also by seasonal monitoring of evapotranspiration (ET) and soil water content (SWC), which exhibit very large differences in the soil water distribution in space and time for the trees undergoing different irrigation schedules.

Imaging of plant current pathways for non-invasive root Phenotyping using a newly developed electrical current source density approach

“…This study describes the first direct and concurrent characterization of the root-soil current pathway and root architecture. Intrinsic differences in the root electrical properties of maize, cotton, grapevines, and orange trees emerge from the combined interpretation of our results with those presented by Mary et al (2018Mary et al ( , 2019, and Mary et al 2020).…”

“…In their study on field grapevines, Mary et al (2018Mary et al ( , 2019Mary et al ( , 2020 concluded that the CSD could be used to infer the root depth distribution. Because of the significant suberization of major roots in grapevines and orange trees, the electric current could penetrate deep into the root system before significant leakage occured.…”

“…Thus far, only indirect information obtained from invasive and time-consuming experiments have been available to address this issue (e.g., excavation and trimming). Mary et al (2018Mary et al ( , 2019, and Mary et al 2020) tested the combined use of ERT and Mise A La Masse (MALM) methods for imaging grapevine and citrus roots in the field. An approach hereafter called inversion of Current Source Density (iCSD) was used to invert the acquired data.…”

Time-lapse monitoring of root water uptake using electrical resistivity tomography and mise-à-la-masse: a vineyard infiltration experiment

“…These models also lend themselves more naturally to calibration against field evidence, as they focus on the functioning of roots, especially in terms of RWU (e.g. Volpe et al, 2013;Manoli et al, 2014). However, calibration requires that suitable data such as root density and soil water content evolution are available in a form comparable with the model to be calibrated.…”

Electrical resistivity imaging for monitoring soil water motion patterns under different drip irrigation scenarios

“…9 Mean electrical resistivity (ER) change (%) observed during the irrigation phases (t 1 -t 5 ) and after the irrigation event (shaded area; t 6 -t 7 ) in comparison to the initial condition (t 0 , no irrigation period) for the ERI monitoring period (June, July and September, 2019). T1-T4 refer to full irrigation, sustained deficit irrigation, regulated deficit irrigation and partial root-zone drying strategies, respectively previous studies (Mary et al 2019). In fact, following the homogeneous structure of the soil and the climatic conditions at the field site (Fig.…”