{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,7]],"date-time":"2026-09-07T06:08:22Z","timestamp":1788761302373,"version":"build-2803163510"},"reference-count":38,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2026,9,7]],"date-time":"2026-09-07T00:00:00Z","timestamp":1788739200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Plant Sci."],"abstract":"<jats:p>Rapid and non-destructive monitoring of maize SPAD is important for precision water and nitrogen management in arid irrigation areas. This study developed a UAV\u2013smartphone cross-device calibration framework for SPAD estimation using UAV multispectral imagery, smartphone RGB images, and ground-measured SPAD data collected at the jointing, tasseling, and grain-filling stages. Spectral and texture features were integrated for UAV-based modeling, and regularized least-squares calibration was used to map smartphone-derived features into the UAV feature space. The random forest model using combined spectral and texture features achieved the best UAV-based performance, with validation R\u00b2 values of 0.81, 0.79, and 0.75 across the three growth stages, representing an improvement of more than 9% over single-feature models. After cross-device calibration, smartphone-based SPAD estimation achieved R\u00b2 values of 0.80, 0.86, and 0.82, respectively. These results demonstrate that cross-device feature calibration can effectively bridge UAV multispectral and smartphone RGB observations, providing a low-cost and accurate approach for field-scale maize SPAD monitoring and precision water\u2013nitrogen management.<\/jats:p>","DOI":"10.3389\/fpls.2026.1922896","type":"journal-article","created":{"date-parts":[[2026,9,7]],"date-time":"2026-09-07T05:34:44Z","timestamp":1788759284000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":0,"title":["A camera calibration method driven by unmanned aerial vehicles and high-precision estimation of maize SPAD values under adverse conditions"],"prefix":"10.3389","volume":"17","author":[{"given":"Jianwen","family":"Yan","sequence":"first","affiliation":[{"name":"National Key Laboratory of Ecological Environment for Soil and Water Engineering in Arid Areas, Inner Mongolia Agricultural University","place":["Hohhot, China"]},{"name":"Inner Mongolia Autonomous Region Engineering Research Center for High-Efficiency Water-Saving Technology Equipment and Water and Soil Environmental Effects","place":["Hohhot, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Shilong","family":"Miao","sequence":"additional","affiliation":[{"name":"National Key Laboratory of Ecological Environment for Soil and Water Engineering in Arid Areas, Inner Mongolia Agricultural University","place":["Hohhot, China"]},{"name":"Inner Mongolia Autonomous Region Engineering Research Center for High-Efficiency Water-Saving Technology Equipment and Water and Soil Environmental Effects","place":["Hohhot, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Xianyue","family":"Li","sequence":"additional","affiliation":[{"name":"National Key Laboratory of Ecological Environment for Soil and Water Engineering in Arid Areas, Inner Mongolia Agricultural University","place":["Hohhot, China"]},{"name":"Inner Mongolia Autonomous Region Engineering Research Center for High-Efficiency Water-Saving Technology Equipment and Water and Soil Environmental Effects","place":["Hohhot, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Haibin","family":"Shi","sequence":"additional","affiliation":[{"name":"National Key Laboratory of Ecological Environment for Soil and Water Engineering in Arid Areas, Inner Mongolia Agricultural University","place":["Hohhot, China"]},{"name":"Inner Mongolia Autonomous Region Engineering Research Center for High-Efficiency Water-Saving Technology Equipment and Water and Soil Environmental Effects","place":["Hohhot, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Shijie","family":"Ding","sequence":"additional","affiliation":[{"name":"National Key Laboratory of Ecological Environment for Soil and Water Engineering in Arid Areas, Inner Mongolia Agricultural University","place":["Hohhot, China"]},{"name":"Inner Mongolia Autonomous Region Engineering Research Center for High-Efficiency Water-Saving Technology Equipment and Water and Soil Environmental Effects","place":["Hohhot, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Zhen","family":"Li","sequence":"additional","affiliation":[{"name":"National Key Laboratory of Ecological Environment for Soil and Water Engineering in Arid Areas, Inner Mongolia Agricultural University","place":["Hohhot, China"]},{"name":"Inner Mongolia Autonomous Region Engineering Research Center for High-Efficiency Water-Saving Technology Equipment and Water and Soil Environmental Effects","place":["Hohhot, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ning","family":"Wang","sequence":"additional","affiliation":[{"name":"Inner Mongolia Autonomous Region Water Resources Research Institute","place":["Hohhot, China"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1965","published-online":{"date-parts":[[2026,9,7]]},"reference":[{"key":"B1","doi-asserted-by":"publisher","DOI":"10.3389\/fpls.2023.1253536","article-title":"Prediction of vertical distribution of SPAD values within maize canopy based on unmanned aerial vehicles multispectral imagery","volume":"14","author":"Chen","year":"2023","journal-title":"Front. 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