{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,22]],"date-time":"2026-03-22T00:37:12Z","timestamp":1774139832902,"version":"3.50.1"},"reference-count":64,"publisher":"MDPI AG","issue":"6","license":[{"start":{"date-parts":[[2023,3,15]],"date-time":"2023-03-15T00:00:00Z","timestamp":1678838400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Water Research Commission of South Africa (WRC)","award":["K5\/2971\/\/4"],"award-info":[{"award-number":["K5\/2971\/\/4"]}]},{"name":"Water Research Commission of South Africa (WRC)","award":["84157"],"award-info":[{"award-number":["84157"]}]},{"name":"National Research Foundation of South Africa (NRF) Research Chair in Land Use Planning and Management","award":["K5\/2971\/\/4"],"award-info":[{"award-number":["K5\/2971\/\/4"]}]},{"name":"National Research Foundation of South Africa (NRF) Research Chair in Land Use Planning and Management","award":["84157"],"award-info":[{"award-number":["84157"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Remote Sensing"],"abstract":"<jats:p>Maize (Zea Mays) is one of the most valuable food crops in sub-Saharan Africa and is a critical component of local, national and regional economies. Whereas over 50% of maize production in the region is produced by smallholder farmers, spatially explicit information on smallholder farm maize production, which is necessary for optimizing productivity, remains scarce due to a lack of appropriate technologies. Maize leaf area index (LAI) is closely related to and influences its canopy physiological processes, which closely relate to its productivity. Hence, understanding maize LAI is critical in assessing maize crop productivity. Unmanned Aerial Vehicle (UAV) imagery in concert with vegetation indices (VIs) obtained at high spatial resolution provides appropriate technologies for determining maize LAI at a farm scale. Five DJI Matrice 300 UAV images were acquired during the maize growing season, and 57 vegetation indices (VIs) were generated from the derived images. Maize LAI samples were collected across the growing season, a Random Forest (RF) regression ensemble based on UAV spectral data and the collected maize LAI samples was used to estimate maize LAI. The results showed that the optimal stage for estimating maize LAI using UAV-derived VIs in concert with the RF ensemble was during the vegetative stage (V8\u2013V10) with an RMSE of 0.15 and an R2 of 0.91 (RRMSE = 8%). The findings also showed that UAV-derived traditional, red edge-based and new VIs could reliably predict maize LAI across the growing season with an R2 of 0.89\u20130.93, an RMSE of 0.15\u20130.65 m2\/m2 and an RRMSE of 8.13\u201319.61%. The blue, red edge and NIR sections of the electromagnetic spectrum were critical in predicting maize LAI. Furthermore, combining traditional, red edge-based and new VIs was useful in attaining high LAI estimation accuracies. These results are a step towards achieving robust, efficient and spatially explicit monitoring frameworks for sub-Saharan African smallholder farm productivity.<\/jats:p>","DOI":"10.3390\/rs15061597","type":"journal-article","created":{"date-parts":[[2023,3,15]],"date-time":"2023-03-15T04:39:45Z","timestamp":1678855185000},"page":"1597","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":28,"title":["Assessing the Prospects of Remote Sensing Maize Leaf Area Index Using UAV-Derived Multi-Spectral Data in Smallholder Farms across the Growing Season"],"prefix":"10.3390","volume":"15","author":[{"given":"Siphiwokuhle","family":"Buthelezi","sequence":"first","affiliation":[{"name":"Discipline of Geography and Environmental Science, School of Agricultural Earth and Environmental Sciences, University of KwaZulu-Natal, Private Bag X01, Pietermaritzburg 3209, South Africa"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7358-8111","authenticated-orcid":false,"given":"Onisimo","family":"Mutanga","sequence":"additional","affiliation":[{"name":"Discipline of Geography and Environmental Science, School of Agricultural Earth and Environmental Sciences, University of KwaZulu-Natal, Private Bag X01, Pietermaritzburg 3209, South Africa"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-4589-7099","authenticated-orcid":false,"given":"Mbulisi","family":"Sibanda","sequence":"additional","affiliation":[{"name":"Discipline of Geography, Environmental Studies & Tourism, Faculty of Arts, University of the Western Cape, Bellville 7535, South Africa"}]},{"given":"John","family":"Odindi","sequence":"additional","affiliation":[{"name":"Discipline of Geography and Environmental Science, School of Agricultural Earth and Environmental Sciences, University of KwaZulu-Natal, Private Bag X01, Pietermaritzburg 3209, South Africa"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8803-8780","authenticated-orcid":false,"given":"Alistair D.","family":"Clulow","sequence":"additional","affiliation":[{"name":"Discipline of Agrometeorology, School of Agricultural, Earth and Environmental Sciences, University of KwaZulu-Natal, Pietermaritzburg 3209, South Africa"}]},{"given":"Vimbayi G. P.","family":"Chimonyo","sequence":"additional","affiliation":[{"name":"Centre for Transformative Agricultural and Food Systems, School of Agricultural, Earth & Environmental Sciences, University of KwaZulu-Natal, Private Bag X01, Pietermaritzburg 3209, South Africa"},{"name":"International Maize and Wheat Improvement Center (CIMMYT)-Zimbabwe, Mt Pleasant, Harare P.O. Box 163, Zimbabwe"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-9323-8127","authenticated-orcid":false,"given":"Tafadzwanashe","family":"Mabhaudhi","sequence":"additional","affiliation":[{"name":"Centre for Transformative Agricultural and Food Systems, School of Agricultural, Earth & Environmental Sciences, University of KwaZulu-Natal, Private Bag X01, Pietermaritzburg 3209, South Africa"},{"name":"International Water Management Institute (IWMI-SA), Southern Africa Office, Pretoria 0184, South Africa"}]}],"member":"1968","published-online":{"date-parts":[[2023,3,15]]},"reference":[{"key":"ref_1","unstructured":"Gollin, D. 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