Remote Sensing for Plant Water Content Monitoring: A Review

This paper reviews the different remote sensing techniques found in literature to monitor plant water status, allowing farmers control irrigation management and avoid unnecessary periods of shortage a needless waste valuable water. The scope this covers broad range 77 references published between years 1981 2021 collected from search web sites, especially Scopus. Among them, 74 are research papers remaining three review papers. approaches have been categorized according part subjected measurement, that is, soil (12.2%), canopy (33.8%), leaves (35.1%) or trunk (18.9%). In addition brief summary each study, main monitoring technologies analyzed review. Concerning presentation data, results obtained. According year publication, number has increased exponentially over time, mainly due technological development last decades. most common sensor is radiometer, which employed 15 (20.3%), followed by continuous-wave (CW) spectroscopy camera (10.8%) THz time-domain (TDS) (10.8%). Excluding two studies, minimum coefficient determination (R2) obtained 0.64. indicates high degree correlation estimated measured data for methods. five frequent indicators study are: normalized difference vegetation index (NDVI) backscattering coefficients (10.8%), spectral reflectance (8.1%), reflection (8.1%) dielectric constant (8.1%).