In-Season Estimation of Japanese Squash Using High-Spatial-Resolution Time-Series Satellite Imagery

Yield maps and in-season forecasts help optimize agricultural practices. The traditional approaches to predicting yield during the growing season often rely on ground-based observations, which are time-consuming and labor-intensive. Remote sensing offers a promising alternative by providing frequent...

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Main Authors: Nan Li, Todd H. Skaggs, Elia Scudiero
Format: Article
Language:English
Published: MDPI AG 2025-03-01
Series:Sensors
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Online Access:https://www.mdpi.com/1424-8220/25/7/1999
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author Nan Li
Todd H. Skaggs
Elia Scudiero
author_facet Nan Li
Todd H. Skaggs
Elia Scudiero
author_sort Nan Li
collection DOAJ
description Yield maps and in-season forecasts help optimize agricultural practices. The traditional approaches to predicting yield during the growing season often rely on ground-based observations, which are time-consuming and labor-intensive. Remote sensing offers a promising alternative by providing frequent and spatially extensive information on crop development. In this study, we evaluated the feasibility of high-resolution satellite imagery for the early yield prediction of an under-investigated crop, Japanese squash (<i>Cucurbita maxima</i>), in a small farm in Hollister, California, over the growing seasons of 2022 and 2023 using vegetation indices, including the Normalized Difference Vegetation Index (NDVI) and the Soil-Adjusted Vegetation Index (SAVI). We identified the optimal time for yield prediction and compared the performances across satellite platforms (Sentinel-2: 10 m; PlanetScope: 3 m; SkySat: 0.5 m). Pearson’s correlation coefficient (<i>r</i>) was employed to determine the dependencies between the yield and vegetation indices measured at various stages throughout the squash growing season. The results showed that SkySat-derived vegetation indices outperformed those of Sentinel-2 and PlanetScope in explaining the squash yields (R<sup>2</sup> = 0.75–0.76; RMSE = 0.8–1.9 tons/ha). Remote sensing showed very strong correlations with yield as early as 29 days after planting in 2022 and 37 and 76 days in 2023 for the NDVI and the SAVI, respectively. These early dates corresponded with the vegetative stages when the crop canopy became denser before fruit development. These findings highlight the utility of high-resolution imagery for in-season yield estimation and within-field variability detection. Detecting yield variability early enables timely management interventions to optimize crop productivity and resource efficiency, a critical advantage for small-scale farms, where marginal yield changes impact economic outcomes.
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spelling doaj-art-869ff967af0c44609aefb3652b83891d2025-08-20T03:08:59ZengMDPI AGSensors1424-82202025-03-01257199910.3390/s25071999In-Season Estimation of Japanese Squash Using High-Spatial-Resolution Time-Series Satellite ImageryNan Li0Todd H. Skaggs1Elia Scudiero2Environmental Sciences, University of California, Riverside, CA 92521, USAUSDA-ARS U.S. Salinity Laboratory, Riverside, CA 92507, USAEnvironmental Sciences, University of California, Riverside, CA 92521, USAYield maps and in-season forecasts help optimize agricultural practices. The traditional approaches to predicting yield during the growing season often rely on ground-based observations, which are time-consuming and labor-intensive. Remote sensing offers a promising alternative by providing frequent and spatially extensive information on crop development. In this study, we evaluated the feasibility of high-resolution satellite imagery for the early yield prediction of an under-investigated crop, Japanese squash (<i>Cucurbita maxima</i>), in a small farm in Hollister, California, over the growing seasons of 2022 and 2023 using vegetation indices, including the Normalized Difference Vegetation Index (NDVI) and the Soil-Adjusted Vegetation Index (SAVI). We identified the optimal time for yield prediction and compared the performances across satellite platforms (Sentinel-2: 10 m; PlanetScope: 3 m; SkySat: 0.5 m). Pearson’s correlation coefficient (<i>r</i>) was employed to determine the dependencies between the yield and vegetation indices measured at various stages throughout the squash growing season. The results showed that SkySat-derived vegetation indices outperformed those of Sentinel-2 and PlanetScope in explaining the squash yields (R<sup>2</sup> = 0.75–0.76; RMSE = 0.8–1.9 tons/ha). Remote sensing showed very strong correlations with yield as early as 29 days after planting in 2022 and 37 and 76 days in 2023 for the NDVI and the SAVI, respectively. These early dates corresponded with the vegetative stages when the crop canopy became denser before fruit development. These findings highlight the utility of high-resolution imagery for in-season yield estimation and within-field variability detection. Detecting yield variability early enables timely management interventions to optimize crop productivity and resource efficiency, a critical advantage for small-scale farms, where marginal yield changes impact economic outcomes.https://www.mdpi.com/1424-8220/25/7/1999remote sensingyield estimationsatellite imageryNDVI
spellingShingle Nan Li
Todd H. Skaggs
Elia Scudiero
In-Season Estimation of Japanese Squash Using High-Spatial-Resolution Time-Series Satellite Imagery
Sensors
remote sensing
yield estimation
satellite imagery
NDVI
title In-Season Estimation of Japanese Squash Using High-Spatial-Resolution Time-Series Satellite Imagery
title_full In-Season Estimation of Japanese Squash Using High-Spatial-Resolution Time-Series Satellite Imagery
title_fullStr In-Season Estimation of Japanese Squash Using High-Spatial-Resolution Time-Series Satellite Imagery
title_full_unstemmed In-Season Estimation of Japanese Squash Using High-Spatial-Resolution Time-Series Satellite Imagery
title_short In-Season Estimation of Japanese Squash Using High-Spatial-Resolution Time-Series Satellite Imagery
title_sort in season estimation of japanese squash using high spatial resolution time series satellite imagery
topic remote sensing
yield estimation
satellite imagery
NDVI
url https://www.mdpi.com/1424-8220/25/7/1999
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