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Article

Leaf Nitrogen Concentration and Plant Height Prediction for Maize Using UAV-Based Multispectral Imagery and Machine Learning Techniques

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Faculty of Engineering and Architecture and Urbanism, University of Western São Paulo (UNOESTE), Rodovia Raposo Tavares, km 572 - Limoeiro, Pres. Prudente, SP 19067-175, Brazil
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Faculty of Engineering, Architecture and Urbanism and Geography, Federal University of Mato Grosso do Sul (UFMS), Cidade Universitária, Av. Costa e Silva, Pioneiros, MS 79070-900, Brazil
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Post-Graduate Program of Environment and Regional Development, University of Western São Paulo (UNOESTE), Rodovia Raposo Tavares, km 572 - Limoeiro, Pres. Prudente, SP 19067-175, Brazil
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Programa de Pós-Graduação em Agronomia - Área de Concentração: Produção Vegetal, da UEMS, Unidade Universitária de Aquidauana, Aquidauana, MS 79200-000, Brazil
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Department of Agronomy, Federal University of Mato Grosso do Sul (UFMS), Rodovia MS 306, km. 305 Caixa Postal 112, Chapadão do Sul, MS 79560000, Brazil
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Faculty of Computing, Federal University of Mato Grosso do Sul (UFMS), Cidade Universitária, Av. Costa e Silva, Pioneiros, MS 79070-900, Brazil
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Inovisão, Universidade Católica Dom Bosco, Av. Tamandaré, 6000, Campo Grande, MS 79117-900, Brazil
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Department of Geography, State University of Mato Grosso (UNEMAT), Av. dos Ingas, 3001 - Jardim Imperial, Sinop, MT 78555-000, Brazil
*
Author to whom correspondence should be addressed.
Remote Sens. 2020, 12(19), 3237; https://doi.org/10.3390/rs12193237
Received: 14 September 2020 / Revised: 2 October 2020 / Accepted: 3 October 2020 / Published: 5 October 2020
(This article belongs to the Special Issue Remote Sensing for Precision Nitrogen Management)
Under ideal conditions of nitrogen (N), maize (Zea mays L.) can grow to its full potential, reaching maximum plant height (PH). As a rapid and nondestructive approach, the analysis of unmanned aerial vehicles (UAV)-based imagery may be of assistance to estimate N and height. The main objective of this study is to present an approach to predict leaf nitrogen concentration (LNC, g kg−1) and PH (m) with machine learning techniques and UAV-based multispectral imagery in maize plants. An experiment with 11 maize cultivars under two rates of N fertilization was carried during the 2017/2018 and 2018/2019 crop seasons. The spectral vegetation indices (VI) normalized difference vegetation index (NDVI), normalized difference red-edge index (NDRE), green normalized difference vegetation (GNDVI), and the soil adjusted vegetation index (SAVI) were extracted from the images and, in a computational system, used alongside the spectral bands as input parameters for different machine learning models. A randomized 10-fold cross-validation strategy, with a total of 100 replicates, was used to evaluate the performance of 9 supervised machine learning (ML) models using the Pearson’s correlation coefficient (r), mean absolute error (MAE), coefficient of regression (R²), and root mean square error (RMSE) metrics. The results indicated that the random forest (RF) algorithm performed better, with r and RMSE, respectively, of 0.91 and 1.9 g.kg¹ for LNC, and 0.86 and 0.17 m for PH. It was also demonstrated that VIs contributed more to the algorithm’s performances than individual spectral bands. This study concludes that the RF model is appropriate to predict both agronomic variables in maize and may help farmers to monitor their plants based upon their LNC and PH diagnosis and use this knowledge to improve their production rates in the subsequent seasons. View Full-Text
Keywords: UAV; random forest; nitrogen; maize UAV; random forest; nitrogen; maize
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MDPI and ACS Style

Osco, L.P.; Junior, J.M.; Ramos, A.P.M.; Furuya, D.E.G.; Santana, D.C.; Teodoro, L.P.R.; Gonçalves, W.N.; Baio, F.H.R.; Pistori, H.; Junior, C.A.d.S.; Teodoro, P.E. Leaf Nitrogen Concentration and Plant Height Prediction for Maize Using UAV-Based Multispectral Imagery and Machine Learning Techniques. Remote Sens. 2020, 12, 3237. https://doi.org/10.3390/rs12193237

AMA Style

Osco LP, Junior JM, Ramos APM, Furuya DEG, Santana DC, Teodoro LPR, Gonçalves WN, Baio FHR, Pistori H, Junior CAdS, Teodoro PE. Leaf Nitrogen Concentration and Plant Height Prediction for Maize Using UAV-Based Multispectral Imagery and Machine Learning Techniques. Remote Sensing. 2020; 12(19):3237. https://doi.org/10.3390/rs12193237

Chicago/Turabian Style

Osco, Lucas P., José M. Junior, Ana P.M. Ramos, Danielle E.G. Furuya, Dthenifer C. Santana, Larissa P.R. Teodoro, Wesley N. Gonçalves, Fábio H.R. Baio, Hemerson Pistori, Carlos A.d.S. Junior, and Paulo E. Teodoro 2020. "Leaf Nitrogen Concentration and Plant Height Prediction for Maize Using UAV-Based Multispectral Imagery and Machine Learning Techniques" Remote Sensing 12, no. 19: 3237. https://doi.org/10.3390/rs12193237

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