Abstract
Crop lodging assessment is essential for evaluating yield damage and informing crop management decisions for sustainable agricultural production. While a few studies have demonstrated the potential of optical and SAR data for crop lodging assessment, large-scale crop lodging assessment has been hampered by the unavailability of dense satellite time series data. The unprecedented availability of free Sentinel-1 and Sentinel-2 data may provide a basis for operational detection and monitoring of crop lodging. In this context, this study aims to understand the effect of lodging on backscatter/coherence and spectral reflectance derived from Sentinel-1 and Sentinel-2 data and to detect lodging incidence in wheat using time-series analysis. Crop biophysical parameters were measured in the field for both healthy and lodged plots from March to June 2018 in a study site in Ferrara, Italy, and the corresponding Sentinel images were downloaded and processed. The lodged plots were further categorised into different lodging severity classes (moderate, severe and very severe). Temporal profiles of backscatter, coherence, reflectance and continuum removed spectra were studied for healthy and lodging severity classes throughout the stem elongation to ripening growth stages. The Kruskal Wallis and posthoc Tukey tests were used to test for significant differences between different classes. Our results for Sentinel-2 showed that red edge (740 nm) and NIR (865 nm) bands could best distinguish healthy from lodged wheat (particularly healthy and very severe). For Sentinel-1, the analysis revealed the potential of VH backscatter and the complementarity of VV and VH/VV backscatter in distinguishing a maximum number of classes. Our findings demonstrate the potential of Sentinel data for near real-time detection of the incidence and severity of lodging in wheat. To the best of our knowledge, there is no study that has contributed to this application.
Highlights
Lodging, defined as the permanent displacement of plant shoots from their upright position or destruction of the root anchorage, is a major yield-limiting factor in cereal crops, including wheat (Zhang et al, 2017)
The lowest reflectance values in the NIR spectral region were observed in the early vegetative stage, where leaf area index (LAI) (2.2) and FB were low (1.69 t/ha), and soil had a dominant effect on the reflectance
We assessed the potential of Sentinel-1 and Sentinel-2 time-series data for detecting lodging incidence in wheat and understanding the effect of lodging on the backscatter/coherence and spectral response
Summary
Lodging, defined as the permanent displacement of plant shoots from their upright position (stem lodging) or destruction of the root anchorage (root lodging), is a major yield-limiting factor in cereal crops, including wheat (Zhang et al, 2017). Accurate and timely detection of crop lodging can help farmers improve crop yield forecasts, guide harvest operations and contribute to loss assessments for crop insurance (Ceballos et al, 2019; Shah et al, 2017). Field-based approaches – that use visual inspection- are the most common methods to assess lodging and detect its incidence (Chauhan et al, 2019a), but are infeasible for areas larger than a few hundred hectares and depend on the skill, experience and consistency of the observer (Bock et al, 2010). A few studies have explored the use of optical and synthetic aperture radar (SAR) remote sensing data for crop lodging assessment. There have been no studies that have utilised satellite-based optical timeseries data for detecting lodging incidence and its severity
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
