Satellite multispectral indices to estimate canopy parameters and within‑feld management zones in super‑intensive almond orchards
2022
Sandonís Pozo, Leire | Llorens Calveras, Jordi | Escolà i Agustí, Alexandre | Arnó Satorra, Jaume | Pascual Roca, Miquel | Martínez Casasnovas, José Antonio
Continuous canopy status monitoring is an essential factor to support and precisely apply orchard management actions such as pruning, pesticide and foliar treatment applications, or fertirrigation, among others. For that, this work proposes the use of multispectral vegetation indices to estimate geometric and structural orchard parameters from remote sensing images (high temporal and spatial resolution) as an alternative to more time-consuming processing techniques, such as LiDAR surveys or UAV photogrammetry. A super-intensive almond (Prunus dulcis) orchard was scanned using a mobile terrestrial laser (LiDAR) in two diferent vegetative stages (after spring pruning and before harvesting). From the LiDAR point cloud, canopy orchard parameters, including maximum height and width, cross-sectional area and porosity, were summarized every 0.5 m along the rows and interpolated using block kriging to the pixel centroids of PlanetScope (3×3 m) and Sentinel-2 (10×10 m) image grids. To study the association between the LiDAR-derived parameters and 4 diferent vegetation indices. A canonical correlation analysis was carried out, showing the normalized diference vegetation index (NDVI) and the green normalized difference vegetation index (GNDVI) to have the best correlations. A cluster analysis was also performed. Results can be considered optimistic both for PlanetScope and Sentinel-2 images to delimit within-feld management zones, being supported by signifcant diferences in LiDAR-derived canopy parameters.
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