{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,1,19]],"date-time":"2026-01-19T06:00:17Z","timestamp":1768802417640,"version":"3.49.0"},"reference-count":37,"publisher":"MDPI AG","issue":"6","license":[{"start":{"date-parts":[[2011,6,16]],"date-time":"2011-06-16T00:00:00Z","timestamp":1308182400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/3.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Sensors"],"abstract":"<jats:p>Nitrogen concentration in plants is normally determined by expensive and time consuming chemical analyses. As an alternative, chlorophyll meter readings and N-NO3 concentration determination in petiole sap were proposed, but these assays are not always satisfactory. Spectral reflectance values of tomato leaves obtained by visible-near infrared spectrophotometry are reported to be a powerful tool for the diagnosis of plant nutritional status. The aim of the study was to evaluate the possibility and the accuracy of the estimation of tomato leaf nitrogen concentration performed through a rapid, portable and non-destructive system, in comparison with chemical standard analyses, chlorophyll meter readings and N-NO3 concentration in petiole sap. Mean reflectance leaf values were compared to each reference chemical value by partial least squares chemometric multivariate methods. The correlation between predicted values from spectral reflectance analysis and the observed chemical values showed in the independent test highly significant correlation coefficient (r = 0.94). The utilization of the proposed system, increasing efficiency, allows better knowledge of nutritional status of tomato plants, with more detailed and sharp information and on wider areas. More detailed information both in space and time is an essential tool to increase and stabilize crop quality levels and to optimize the nutrient use efficiency.<\/jats:p>","DOI":"10.3390\/s110606411","type":"journal-article","created":{"date-parts":[[2011,6,17]],"date-time":"2011-06-17T13:56:03Z","timestamp":1308318963000},"page":"6411-6424","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":78,"title":["Nitrogen Concentration Estimation in Tomato Leaves by VIS-NIR Non-Destructive Spectroscopy"],"prefix":"10.3390","volume":"11","author":[{"given":"Valentina","family":"Ulissi","sequence":"first","affiliation":[{"name":"Department of Agricultural and Environmental Sciences, University of Perugia, Borgo XX Giugno 74, 06121, Perugia, Italy"}]},{"given":"Francesca","family":"Antonucci","sequence":"additional","affiliation":[{"name":"Agricultural Engineering Research Unit of the Agricultural Research Council (CRA-ING), Via della Pascolare 16, 00015, Monterotondo scalo (Rome), Italy"}]},{"given":"Paolo","family":"Benincasa","sequence":"additional","affiliation":[{"name":"Department of Agricultural and Environmental Sciences, University of Perugia, Borgo XX Giugno 74, 06121, Perugia, Italy"}]},{"given":"Michela","family":"Farneselli","sequence":"additional","affiliation":[{"name":"Department of Agricultural and Environmental Sciences, University of Perugia, Borgo XX Giugno 74, 06121, Perugia, Italy"}]},{"given":"Giacomo","family":"Tosti","sequence":"additional","affiliation":[{"name":"Department of Agricultural and Environmental Sciences, University of Perugia, Borgo XX Giugno 74, 06121, Perugia, Italy"}]},{"given":"Marcello","family":"Guiducci","sequence":"additional","affiliation":[{"name":"Department of Agricultural and Environmental Sciences, University of Perugia, Borgo XX Giugno 74, 06121, Perugia, Italy"}]},{"given":"Francesco","family":"Tei","sequence":"additional","affiliation":[{"name":"Department of Agricultural and Environmental Sciences, University of Perugia, Borgo XX Giugno 74, 06121, Perugia, Italy"}]},{"given":"Corrado","family":"Costa","sequence":"additional","affiliation":[{"name":"Agricultural Engineering Research Unit of the Agricultural Research Council (CRA-ING), Via della Pascolare 16, 00015, Monterotondo scalo (Rome), Italy"}]},{"given":"Federico","family":"Pallottino","sequence":"additional","affiliation":[{"name":"Agricultural Engineering Research Unit of the Agricultural Research Council (CRA-ING), Via della Pascolare 16, 00015, Monterotondo scalo (Rome), Italy"}]},{"given":"Luigi","family":"Pari","sequence":"additional","affiliation":[{"name":"Agricultural Engineering Research Unit of the Agricultural Research Council (CRA-ING), Via della Pascolare 16, 00015, Monterotondo scalo (Rome), Italy"}]},{"given":"Paolo","family":"Menesatti","sequence":"additional","affiliation":[{"name":"Agricultural Engineering Research Unit of the Agricultural Research Council (CRA-ING), Via della Pascolare 16, 00015, Monterotondo scalo (Rome), Italy"}]}],"member":"1968","published-online":{"date-parts":[[2011,6,16]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","unstructured":"Lichtfouse, E (2010). Genetic Engineering, Biofertilisation, Soil Quality and Organic Farming, Springer-Verlag. Series of Sustainable Agriculture Reviews 4;.","DOI":"10.1007\/978-90-481-8741-6"},{"key":"ref_2","unstructured":"Farneselli, M, Benincasa, P, and Tei, F (2008, January 22\u201325). Validation of N nutritional status tools for processing tomato. Malmo, Sweden."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"327","DOI":"10.1016\/S1161-0301(02)00077-1","article-title":"Fertigation studies and irrigation scheduling in drip irrigation system in tomato crop (Lycopersicon esculentum L.)","volume":"19","author":"Singandhupe","year":"2003","journal-title":"Eur. J. Agron"},{"key":"ref_4","doi-asserted-by":"crossref","unstructured":"Lemaire, G (2007, January 28\u201330). Diagnostic Tool (s) for Plant and Crop N Status. Theory and Practice for Crop N Management. Lleida, Spain.","DOI":"10.1016\/j.eja.2008.01.005"},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"2129","DOI":"10.1081\/PLN-120014065","article-title":"Tomato leaf chlorophyll meter readings as affected by variety, nitrogen form, and nighttime nutrient solution strength","volume":"25","author":"Wood","year":"2002","journal-title":"J. Plant Nutr"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"159","DOI":"10.17660\/ActaHortic.2006.700.26","article-title":"Determination of SPAD threshold values in order to optimise the nitrogen supply in processing tomato","volume":"700","author":"Gianquinto","year":"2006","journal-title":"Acta Hort"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"69","DOI":"10.21273\/HORTSCI.27.1.69","article-title":"Inherent limitations of nondestructive chlorophyll meters: A comparison of two types of meters","volume":"27","author":"Monje","year":"1992","journal-title":"HortScience"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"147","DOI":"10.17660\/ActaHortic.1999.506.20","article-title":"Evaluation of soil and petiole sap nitrate quick tests for broccoli in Quebec","volume":"506","author":"Coulombe","year":"1999","journal-title":"Acta Hort"},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"45","DOI":"10.1016\/S1161-0301(02)00096-5","article-title":"Critical nitrogen concentration in processing tomato","volume":"18","author":"Tei","year":"2002","journal-title":"Eur. J. Agron"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"2461","DOI":"10.1080\/00103620600820154","article-title":"Evaluation of nitrate quick tests to improve fertigation management","volume":"37","author":"Jimenez","year":"2006","journal-title":"Commun. Soil Sci. Plant Anal"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"231","DOI":"10.17660\/ActaHortic.2003.627.30","article-title":"The assessment of soil and crop nutrient status in the development of efficient fertilizer recommendations","volume":"627","author":"Hartz","year":"2003","journal-title":"Acta Hort"},{"key":"ref_12","doi-asserted-by":"crossref","unstructured":"Lemaire, G (1997). Diagnosis of Nitrogen Status in Crops, Springer-Verlag.","DOI":"10.1007\/978-3-642-60684-7"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"448","DOI":"10.1016\/j.biosystemseng.2010.01.003","article-title":"Estimation of plant nutritional status by Vis-NIR spectrophotometric analysis on orange leaves [Citrus sinensis (L) Osbeck cv Tarocco]","volume":"105","author":"Menesatti","year":"2010","journal-title":"Biosyst. Eng"},{"key":"ref_14","unstructured":"Benincasa, P, Tosti, G, Boldrini, A, Tei, F, and Guiducci, M (2008, January 18\u201320). Poliannual Results on Soil N Management and Maize N Nutrition by Green Manuring. Modena, Italy."},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"705","DOI":"10.1080\/10440046.2010.507452","article-title":"Actual N availability from winter catch crops used for green manuring in maize cultivation","volume":"34","author":"Benincasa","year":"2010","journal-title":"J. Sustain. Agr"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"98","DOI":"10.1093\/jaoac\/59.1.98","article-title":"Determination of total nitrogen in plant tissue, using a block digestor","volume":"59","author":"Isaac","year":"1976","journal-title":"J. AOAC"},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"736","DOI":"10.1016\/j.talanta.2005.03.025","article-title":"A method for calibration and validation subset partitioning","volume":"67","year":"2005","journal-title":"Talanta"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"109","DOI":"10.1016\/S0169-7439(01)00155-1","article-title":"PLS-regression: A basic tool of chemometrics","volume":"58","author":"Wold","year":"2001","journal-title":"Chemometr. Intell. Lab. Syst"},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"1442","DOI":"10.2134\/agronj2003.1442","article-title":"Model evaluation by comparison of model-based predictions and measured values","volume":"95","author":"Gauch","year":"2003","journal-title":"Agron. J"},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"545","DOI":"10.1080\/00103629609369576","article-title":"Monitoring nitrogen status of corn with a portable chlorophyll meter","volume":"27","author":"Waskon","year":"1996","journal-title":"Commun. Soil Sci. Plant Anal"},{"key":"ref_21","first-page":"88","article-title":"An\u00e1lise de NO3_ na mat\u00e9ria seca e determina\u00e7\u00e3o r\u00e1pida de NO3_ na seiva do pec\u00edolo com microeletrodo port\u00e1til na avalia\u00e7\u00e3o do status nitrogenado do tomateiro","volume":"14","author":"Fontes","year":"1996","journal-title":"Hortic. Brasil"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1016\/0034-4257(77)90015-3","article-title":"Reflectance of leaf components","volume":"6","author":"Gausman","year":"1977","journal-title":"Remote Sens. Environ"},{"key":"ref_23","first-page":"44","article-title":"Development of a visible spectroscopic method for determining chlorophyll a and b in vivo in leaf samples","volume":"5","author":"Yoder","year":"1989","journal-title":"Spectroscopy"},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"162","DOI":"10.21273\/HORTSCI.41.1.162","article-title":"Nondestructive detection of nitrogen in chinese cabbage leaves using VIS-NIR spectroscopy","volume":"41","author":"Min","year":"2006","journal-title":"HortScience"},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"1287","DOI":"10.1081\/PLN-120020371","article-title":"Assessment of nitrogenized nutrition of citrus rootstocks using chlorophyll concentrations in the leaf","volume":"26","author":"Esposti","year":"2003","journal-title":"J. Plant Nutr"},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"926","DOI":"10.2134\/agronj1991.00021962008300050029x","article-title":"Chlorophyll meter to predict nitrogen top-dress requirement for semi dwarf rice","volume":"83","author":"Turner","year":"1991","journal-title":"Agron. J"},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"487","DOI":"10.1080\/01904169209364335","article-title":"Field chlorophyll measurements for evaluation of corn nitrogen status","volume":"15","author":"Wood","year":"1992","journal-title":"J. Plant Nutr"},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"1435","DOI":"10.1080\/01904169209364409","article-title":"Determination of cotton nitrogen status with a hand-held chlorophyll meter","volume":"15","author":"Wood","year":"1992","journal-title":"J. Plant Nutr"},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"971","DOI":"10.1080\/01904169009364129","article-title":"Determination of the nitrogen status of irrigated potato crops. I. Critical nutrient ranges for nitrate-nitrogen in petioles","volume":"13","author":"Williams","year":"1990","journal-title":"J. Plant Nutr"},{"key":"ref_30","first-page":"37","article-title":"Field diagnostic test for nitrate in tomato petiole SAP","volume":"44","author":"Lyons","year":"1987","journal-title":"Qld. J. Agr. Anim. Sci"},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"761","DOI":"10.1080\/00103628309367406","article-title":"Monitoring sap nitrate in vegetable crops: Comparison of test strips with electrode methods, and effects of time of day and leaf position","volume":"14","author":"Scaife","year":"1983","journal-title":"Commun. Soil Sci. Plant Anal"},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"934","DOI":"10.21273\/HORTSCI.31.6.934","article-title":"A petiole SAP nitrate test for cauliflower","volume":"31","author":"Kubota","year":"1996","journal-title":"HortScience"},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"835","DOI":"10.1071\/EA9940835","article-title":"Petiole SAP nitrate is better than total nitrogen in dried leaf for indicating nitrogen status and yield responsiveness of capsicum in subtropical Australia","volume":"34","author":"Olsen","year":"1994","journal-title":"Aust. J. Exp. Agr"},{"key":"ref_34","doi-asserted-by":"crossref","first-page":"32","DOI":"10.21273\/HORTSCI.8.1.33b","article-title":"Diurnal variation in nitrate concentrations in beets","volume":"8","author":"Minotti","year":"1973","journal-title":"HortScience"},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"922","DOI":"10.21273\/JASHS.112.6.922","article-title":"Sampling consideration for nitrate quick test for green house grown tomatoes","volume":"112","author":"Coltman","year":"1987","journal-title":"J. Am. Soc. Hort. Sci"},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1016\/j.eja.2006.10.001","article-title":"Elaboration of a nitrogen nutrition indicator for winter wheat based on leaf area index and chlorophyll content for making nitrogen recommendations","volume":"27","author":"Mary","year":"2007","journal-title":"Eur. J. Agron"},{"key":"ref_37","doi-asserted-by":"crossref","unstructured":"Lemaire, G (1997). Diagnosis of the Nitrogen Status in Crop, Springer-Verlag.","DOI":"10.1007\/978-3-642-60684-7"}],"container-title":["Sensors"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1424-8220\/11\/6\/6411\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T21:56:27Z","timestamp":1760219787000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1424-8220\/11\/6\/6411"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2011,6,16]]},"references-count":37,"journal-issue":{"issue":"6","published-online":{"date-parts":[[2011,6]]}},"alternative-id":["s110606411"],"URL":"https:\/\/doi.org\/10.3390\/s110606411","relation":{},"ISSN":["1424-8220"],"issn-type":[{"value":"1424-8220","type":"electronic"}],"subject":[],"published":{"date-parts":[[2011,6,16]]}}}