<?xml version="1.0" encoding="ISO-8859-1"?><article xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<front>
<journal-meta>
<journal-id>0187-5779</journal-id>
<journal-title><![CDATA[Terra Latinoamericana]]></journal-title>
<abbrev-journal-title><![CDATA[Terra Latinoam]]></abbrev-journal-title>
<issn>0187-5779</issn>
<publisher>
<publisher-name><![CDATA[Sociedad Mexicana de la Ciencia del Suelo A.C.]]></publisher-name>
</publisher>
</journal-meta>
<article-meta>
<article-id>S0187-57792021000100125</article-id>
<article-id pub-id-type="doi">10.28940/terra.v39i0.820</article-id>
<title-group>
<article-title xml:lang="en"><![CDATA[Field diagnostic techniques to determine nitrogen in maize]]></article-title>
<article-title xml:lang="es"><![CDATA[Técnicas de diagnóstico en campo para determinar nitrógeno en maíz]]></article-title>
</title-group>
<contrib-group>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Roacho-Cortés]]></surname>
<given-names><![CDATA[Eduhin]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Castellanos-Ramos]]></surname>
<given-names><![CDATA[Javier Z.]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Etchevers]]></surname>
<given-names><![CDATA[J. D.]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
</contrib-group>
<aff id="Af1">
<institution><![CDATA[,Colegio de Postgraduados Campus Montecill ]]></institution>
<addr-line><![CDATA[Texcoco Estado de México]]></addr-line>
<country>Mexico</country>
</aff>
<aff id="Af2">
<institution><![CDATA[,Fertilab  ]]></institution>
<addr-line><![CDATA[Celaya Guanajuato]]></addr-line>
<country>Mexico</country>
</aff>
<pub-date pub-type="pub">
<day>00</day>
<month>12</month>
<year>2021</year>
</pub-date>
<pub-date pub-type="epub">
<day>00</day>
<month>12</month>
<year>2021</year>
</pub-date>
<volume>39</volume>
<copyright-statement/>
<copyright-year/>
<self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_arttext&amp;pid=S0187-57792021000100125&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_abstract&amp;pid=S0187-57792021000100125&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_pdf&amp;pid=S0187-57792021000100125&amp;lng=en&amp;nrm=iso"></self-uri><abstract abstract-type="short" xml:lang="en"><p><![CDATA[Summary: Few technologies are available to quantify crop's nutritional status during their vegetative cycle, such as in maize. Semiquantitative alternatives could replace the laboratory foliar analysis's classical approach for measuring nitrogen (N) in maize (Zea mays L.) in the field, although they require regional calibration against standard laboratory tests. In this work, we have calibrated four semi quantitative and two quantitative methods for diagnosing maize nutritional status in the El Bajio region, Guanajuato, Mexico. An experiment to test the effect of increasing N rates application on plant sap (cell extract) N was set up during the 2019 agricultural cycle. Five N treatments (0, 120, 240, 360, and 480 kg of N·ha-1) were tested, and each treatment was replicated five times. We have tested the following semi quantitative N methods: plant sap nitrate concentration (N-NO3) of the central midrib of the recently mature leaf (RML), plant sap N-NO3 of the base stem (in both cases measured by the ion selective method, using the portable LAQUAtwin® model NO3-11 nitrate ion meter, single-photon avalanche diode (SPAD) unit record, and the Normalized Difference Vegetation Index (NDVI). Additionally, a quantitative laboratory method for determining N-NO3 in the lower part of the maize plant's stem and total N in the RML was used. Data were acquired at different plant phenological stages: V7, V12, R1, and N-NO3 in the dry matter of the stem's base at R5. These results were correlated with the relative grain yield and those with a correlation coefficient (r) greater than 0.7 were accepted. Later, a critical concentration (CC) was estimated using an arithmetic-graphic technique for the crop to reach a relative yield of 90% for each method. The proposed CC results require further validation before being used in a commercial application. In synthesis, this work proposes a procedure for diagnosing N nutrition of maize in the field that might improve the current methods used for this purpose.]]></p></abstract>
<abstract abstract-type="short" xml:lang="es"><p><![CDATA[Resumen: Existen pocas tecnologías, aparte del análisis foliar clásico de laboratorio, que pueden emplear los productores para dar seguimiento al estado nutrimental que guardan los cultivos a lo largo del ciclo vegetativo. Este es el caso particular del maíz. Sin embargo, se dispone de métodos alternativos, de carácter semicuantitativo para medir la situación del nitrógeno (N) en el maíz en campo, pero para que sean efectivos, deben ser calibrados regionalmente contra el procedimiento estándar de laboratorio. En este ensayo se calibraron cuatro métodos semicuantitativos y dos cuantitativos, para diagnosticar la condición nutrimental del nitrógeno (N) del maíz en el Bajío guanajuatense. Para ello se estableció un experimento en el ciclo agrícola 2019. Los tratamientos fueron dosis crecientes de N (0, 120, 240, 360, 480 kg de N·ha-1). Cada tratamiento se repitió cinco veces. Los métodos semicuantitativos calibrados fueron: concentración de nitrógeno nítrico (N-NO3) del extracto celular (EC) de la nervadura central (NC) de la hoja recientemente madura (HRM), N-NO3 del EC en la base del tallo (BT), observación de las unidades SPAD, Índice de Vegetación de Diferencia Normalizada (NDVI) y dos métodos cuantitativos de laboratorio: N-NO3 en la materia seca (MS) de la BT y N total foliar. Estas mediciones se realizaron en las etapas fenológicas V7, V12, R1 del maíz, y en R5 cuando se evaluó el N-NO3 en la BT. Los resultados de las mediciones realizadas con cada método, fueron correlacionados con el rendimiento relativo de grano (RR). Se aceptaron aquellas asociaciones que tuvieron un coeficiente de correlación (r) superior a 0.70. Para cada método se estimó mediante una combinación de técnicas aritmética y gráfica, una concentración crítica (CC), definida como la concentración suficiente para que el cultivo alcanzase un rendimiento relativo (RR) de 90%. El trabajo constituye un modelo de cómo abordar el problema del diagnóstico de la nutrición nitrogenada en campo. Las CC propuestas en este trabajo para diferentes estados fenológicos, se deben entender como preliminares y requieren ser validadas a nivel de lotes comerciales en campo.]]></p></abstract>
<kwd-group>
<kwd lng="en"><![CDATA[ion selective method]]></kwd>
<kwd lng="en"><![CDATA[nitrate-nitrogen]]></kwd>
<kwd lng="en"><![CDATA[NDVI]]></kwd>
<kwd lng="en"><![CDATA[plant sap]]></kwd>
<kwd lng="en"><![CDATA[SPAD]]></kwd>
<kwd lng="en"><![CDATA[total nitrogen]]></kwd>
<kwd lng="en"><![CDATA[Zea mays]]></kwd>
<kwd lng="es"><![CDATA[método selectivo de iones]]></kwd>
<kwd lng="es"><![CDATA[nitrógeno-nitrato]]></kwd>
<kwd lng="es"><![CDATA[NDVI]]></kwd>
<kwd lng="es"><![CDATA[savia vegetal]]></kwd>
<kwd lng="es"><![CDATA[SPAD]]></kwd>
<kwd lng="es"><![CDATA[nitrógeno total]]></kwd>
<kwd lng="es"><![CDATA[Zea mays]]></kwd>
</kwd-group>
</article-meta>
</front><back>
<ref-list>
<ref id="B1">
<nlm-citation citation-type="book">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Alcántar-González]]></surname>
<given-names><![CDATA[G.]]></given-names>
</name>
<name>
<surname><![CDATA[Sandoval-Villa]]></surname>
<given-names><![CDATA[M.]]></given-names>
</name>
</person-group>
<article-title xml:lang=""><![CDATA[Interpretación resultados del análisis]]></article-title>
<person-group person-group-type="editor">
<name>
<surname><![CDATA[Alcántar-González]]></surname>
<given-names><![CDATA[G.]]></given-names>
</name>
<name>
<surname><![CDATA[Sandoval-Villa]]></surname>
<given-names><![CDATA[M.]]></given-names>
</name>
</person-group>
<source><![CDATA[Manual de análisis químico de tejido vegetal]]></source>
<year>1999</year>
<page-range>107-38</page-range><publisher-loc><![CDATA[México ]]></publisher-loc>
<publisher-name><![CDATA[Sociedad Mexicana de la Ciencia del Suelo, A.C. Chapingo]]></publisher-name>
</nlm-citation>
</ref>
<ref id="B2">
<nlm-citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Ali]]></surname>
<given-names><![CDATA[M. M.]]></given-names>
</name>
<name>
<surname><![CDATA[Al-Ani]]></surname>
<given-names><![CDATA[A.]]></given-names>
</name>
<name>
<surname><![CDATA[Eamus]]></surname>
<given-names><![CDATA[D.]]></given-names>
</name>
<name>
<surname><![CDATA[Tan]]></surname>
<given-names><![CDATA[D. K. Y.]]></given-names>
</name>
</person-group>
<article-title xml:lang=""><![CDATA[Leaf nitrogen determination using non-destructive techniques-A review]]></article-title>
<source><![CDATA[Journal of Plant Nutrition]]></source>
<year>2017</year>
<volume>40</volume>
<numero>7</numero>
<issue>7</issue>
<page-range>928-53</page-range></nlm-citation>
</ref>
<ref id="B3">
<nlm-citation citation-type="">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Campbell]]></surname>
<given-names><![CDATA[C. R.]]></given-names>
</name>
</person-group>
<source><![CDATA[Reference Sufficiency Ranges for Plant Analysis in the Southern Region of the United States]]></source>
<year>2013</year>
<volume>1040</volume>
<publisher-loc><![CDATA[North Carolina ]]></publisher-loc>
</nlm-citation>
</ref>
<ref id="B4">
<nlm-citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Beegle]]></surname>
<given-names><![CDATA[D.]]></given-names>
</name>
<name>
<surname><![CDATA[Rotz]]></surname>
<given-names><![CDATA[J.]]></given-names>
</name>
</person-group>
<article-title xml:lang=""><![CDATA[Late season cornstalk nitrate test]]></article-title>
<source><![CDATA[Agronomy Facts 70]]></source>
<year>2009</year>
<publisher-loc><![CDATA[Pennsylvania State Univ. ]]></publisher-loc>
<publisher-name><![CDATA[University Park]]></publisher-name>
</nlm-citation>
</ref>
<ref id="B5">
<nlm-citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Binford]]></surname>
<given-names><![CDATA[G. D.]]></given-names>
</name>
<name>
<surname><![CDATA[Blackmer]]></surname>
<given-names><![CDATA[A. M.]]></given-names>
</name>
<name>
<surname><![CDATA[El-Hout]]></surname>
<given-names><![CDATA[N. M.]]></given-names>
</name>
</person-group>
<article-title xml:lang=""><![CDATA[Tissue test for excess nitrogen during corn production]]></article-title>
<source><![CDATA[Agronomy Journal]]></source>
<year>1990</year>
<volume>82</volume>
<numero>1</numero>
<issue>1</issue>
<page-range>124-9</page-range></nlm-citation>
</ref>
<ref id="B6">
<nlm-citation citation-type="confpro">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Blackmer]]></surname>
<given-names><![CDATA[A. M.]]></given-names>
</name>
<name>
<surname><![CDATA[Mallarino]]></surname>
<given-names><![CDATA[A. P.]]></given-names>
</name>
</person-group>
<source><![CDATA[Cornstalk testing to evaluate nitrogen management]]></source>
<year>2000</year>
<conf-name><![CDATA[ Proceedings of the Integrated Crop Management Conference. Proceedings of the 14th Annual Integrated Crop Management Conference]]></conf-name>
<conf-loc> </conf-loc>
<publisher-loc><![CDATA[Iowa State University ]]></publisher-loc>
<publisher-name><![CDATA[University Extension. Ames]]></publisher-name>
</nlm-citation>
</ref>
<ref id="B7">
<nlm-citation citation-type="book">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Cadahía-López]]></surname>
<given-names><![CDATA[C.]]></given-names>
</name>
</person-group>
<article-title xml:lang=""><![CDATA[Procesamiento de muestras]]></article-title>
<person-group person-group-type="editor">
<name>
<surname><![CDATA[Cadahia-López]]></surname>
<given-names><![CDATA[C.]]></given-names>
</name>
</person-group>
<source><![CDATA[La savia como índice de fertlización]]></source>
<year>2008</year>
<page-range>40-5</page-range><publisher-loc><![CDATA[Barcelona, España ]]></publisher-loc>
<publisher-name><![CDATA[Mundi-Prensa]]></publisher-name>
</nlm-citation>
</ref>
<ref id="B8">
<nlm-citation citation-type="book">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Castellanos]]></surname>
<given-names><![CDATA[Z. J.]]></given-names>
</name>
<name>
<surname><![CDATA[Etchevers-Barra]]></surname>
<given-names><![CDATA[J. D.]]></given-names>
</name>
<name>
<surname><![CDATA[Peña-Datoli]]></surname>
<given-names><![CDATA[M.]]></given-names>
</name>
<name>
<surname><![CDATA[Huerta-Garcia]]></surname>
<given-names><![CDATA[S.]]></given-names>
</name>
<name>
<surname><![CDATA[Ortiz-Monasterio]]></surname>
<given-names><![CDATA[I.]]></given-names>
</name>
<name>
<surname><![CDATA[Arango-González]]></surname>
<given-names><![CDATA[A.]]></given-names>
</name>
<name>
<surname><![CDATA[Macías-Cervantes]]></surname>
<given-names><![CDATA[J.]]></given-names>
</name>
<name>
<surname><![CDATA[Venegas-Villaroel]]></surname>
<given-names><![CDATA[C.]]></given-names>
</name>
</person-group>
<source><![CDATA[¿Cómo crece y se nutre una planta de maíz?]]></source>
<year>2019</year>
<edition>1er</edition>
<publisher-loc><![CDATA[Celaya, Gto., México ]]></publisher-loc>
<publisher-name><![CDATA[Fertilab]]></publisher-name>
</nlm-citation>
</ref>
<ref id="B9">
<nlm-citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Cataldo]]></surname>
<given-names><![CDATA[D. A.]]></given-names>
</name>
<name>
<surname><![CDATA[Maroon]]></surname>
<given-names><![CDATA[M.]]></given-names>
</name>
<name>
<surname><![CDATA[Schrader]]></surname>
<given-names><![CDATA[L. E.]]></given-names>
</name>
<name>
<surname><![CDATA[Youngs]]></surname>
<given-names><![CDATA[V. L.]]></given-names>
</name>
</person-group>
<article-title xml:lang=""><![CDATA[Rapid colorimetric determination of nitrate in plant tissue by nitration of salicylic acid]]></article-title>
<source><![CDATA[Communications in Soil Science and Plant Analysis]]></source>
<year>1975</year>
<volume>6</volume>
<numero>1</numero>
<issue>1</issue>
<page-range>71-80</page-range></nlm-citation>
</ref>
<ref id="B10">
<nlm-citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Cate]]></surname>
<given-names><![CDATA[R. B.]]></given-names>
</name>
<name>
<surname><![CDATA[Nelson]]></surname>
<given-names><![CDATA[L. A.]]></given-names>
</name>
</person-group>
<article-title xml:lang=""><![CDATA[A simple statistical procedure for partitioning soil test correlation data into two classes]]></article-title>
<source><![CDATA[Soil Science Society of America Journal]]></source>
<year>1971</year>
<volume>35</volume>
<page-range>658-60</page-range></nlm-citation>
</ref>
<ref id="B11">
<nlm-citation citation-type="book">
<collab>CIMMYT (Centro Internacional de Mejoramientode Maíz y Trigo)</collab>
<source><![CDATA[Manual de determinación de rendimiento]]></source>
<year>2012</year>
<publisher-loc><![CDATA[México, D. F. ]]></publisher-loc>
<publisher-name><![CDATA[CIMMYT]]></publisher-name>
</nlm-citation>
</ref>
<ref id="B12">
<nlm-citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Colaço]]></surname>
<given-names><![CDATA[A. F.]]></given-names>
</name>
<name>
<surname><![CDATA[Bramley]]></surname>
<given-names><![CDATA[R. G. V.]]></given-names>
</name>
</person-group>
<article-title xml:lang=""><![CDATA[Do crop sensors promote improved nitrogen management in grain crops?]]></article-title>
<source><![CDATA[Field Crops Research]]></source>
<year>2018</year>
<volume>218</volume>
<page-range>126-40</page-range></nlm-citation>
</ref>
<ref id="B13">
<nlm-citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Dechorgnat]]></surname>
<given-names><![CDATA[J.]]></given-names>
</name>
<name>
<surname><![CDATA[Francis]]></surname>
<given-names><![CDATA[K. L.]]></given-names>
</name>
<name>
<surname><![CDATA[Dhugga]]></surname>
<given-names><![CDATA[K. S.]]></given-names>
</name>
<name>
<surname><![CDATA[Rafalski]]></surname>
<given-names><![CDATA[J. A.]]></given-names>
</name>
<name>
<surname><![CDATA[Tyerman]]></surname>
<given-names><![CDATA[S. D.]]></given-names>
</name>
<name>
<surname><![CDATA[Kaiser]]></surname>
<given-names><![CDATA[B. N.]]></given-names>
</name>
</person-group>
<article-title xml:lang=""><![CDATA[Root ideotype influences nitrogen transport and assimilation in maize]]></article-title>
<source><![CDATA[Frontiers in Plant Science]]></source>
<year>2018</year>
<volume>9</volume>
<numero>531</numero>
<issue>531</issue>
<page-range>1-16</page-range></nlm-citation>
</ref>
<ref id="B14">
<nlm-citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Di Gioia]]></surname>
<given-names><![CDATA[F.]]></given-names>
</name>
<name>
<surname><![CDATA[Simonne]]></surname>
<given-names><![CDATA[E. H.]]></given-names>
</name>
<name>
<surname><![CDATA[Gonnella]]></surname>
<given-names><![CDATA[M.]]></given-names>
</name>
<name>
<surname><![CDATA[Santamaria]]></surname>
<given-names><![CDATA[P.]]></given-names>
</name>
<name>
<surname><![CDATA[Gazula]]></surname>
<given-names><![CDATA[A.]]></given-names>
</name>
<name>
<surname><![CDATA[Sheppard]]></surname>
<given-names><![CDATA[Z.]]></given-names>
</name>
</person-group>
<article-title xml:lang=""><![CDATA[Assessment of ionic interferences to nitrate and potassium analyses with ion-selective electrodes]]></article-title>
<source><![CDATA[Communications in Soil Science and Plant Analysis]]></source>
<year>2010</year>
<volume>41</volume>
<numero>14</numero>
<issue>14</issue>
<page-range>1750-68</page-range></nlm-citation>
</ref>
<ref id="B15">
<nlm-citation citation-type="">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Dobermann]]></surname>
<given-names><![CDATA[A. R.]]></given-names>
</name>
</person-group>
<source><![CDATA[Nitrogen use efficiency - state of the art]]></source>
<year>2005</year>
<publisher-loc><![CDATA[Frankfurt, Germany ]]></publisher-loc>
</nlm-citation>
</ref>
<ref id="B16">
<nlm-citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Edalat]]></surname>
<given-names><![CDATA[M.]]></given-names>
</name>
<name>
<surname><![CDATA[Naderi]]></surname>
<given-names><![CDATA[R.]]></given-names>
</name>
<name>
<surname><![CDATA[Egan]]></surname>
<given-names><![CDATA[T. P.]]></given-names>
</name>
</person-group>
<article-title xml:lang=""><![CDATA[Corn nitrogen management using NDVI and SPAD sensor-based data under conventional vs. reduced tillage systems]]></article-title>
<source><![CDATA[Journal of Plant Nutrition]]></source>
<year>2019</year>
<volume>42</volume>
<numero>18</numero>
<issue>18</issue>
<page-range>2310-22</page-range></nlm-citation>
</ref>
<ref id="B17">
<nlm-citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Etchevers]]></surname>
<given-names><![CDATA[J.-D.]]></given-names>
</name>
</person-group>
<article-title xml:lang=""><![CDATA[Técnicas de diagnóstico útiles en la medición de la fertilidad del suelo y el estado nutrimental de los cultivos]]></article-title>
<source><![CDATA[Terra Latinoamericana]]></source>
<year>1999</year>
<volume>17</volume>
<numero>3</numero>
<issue>3</issue>
<page-range>209-2019</page-range></nlm-citation>
</ref>
<ref id="B18">
<nlm-citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Fox]]></surname>
<given-names><![CDATA[R. H.]]></given-names>
</name>
<name>
<surname><![CDATA[Roth]]></surname>
<given-names><![CDATA[G. W.]]></given-names>
</name>
<name>
<surname><![CDATA[Iversen]]></surname>
<given-names><![CDATA[K. V.]]></given-names>
</name>
<name>
<surname><![CDATA[Piekielek]]></surname>
<given-names><![CDATA[W. P.]]></given-names>
</name>
</person-group>
<article-title xml:lang=""><![CDATA[Soil and tissue nitrate tests compared for predicting soil nitrogen availability to corn]]></article-title>
<source><![CDATA[Agronomy Journal]]></source>
<year>1989</year>
<volume>81</volume>
<numero>6</numero>
<issue>6</issue>
<page-range>971&#8209;974</page-range></nlm-citation>
</ref>
<ref id="B19">
<nlm-citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Fox]]></surname>
<given-names><![CDATA[R. H.]]></given-names>
</name>
<name>
<surname><![CDATA[Piekielek]]></surname>
<given-names><![CDATA[W. P.]]></given-names>
</name>
<name>
<surname><![CDATA[Macneal]]></surname>
<given-names><![CDATA[K. E.]]></given-names>
</name>
</person-group>
<article-title xml:lang=""><![CDATA[Comparison of late-season diagnostic tests for predicting nitrogen status of corn]]></article-title>
<source><![CDATA[Agronomy Journal]]></source>
<year>2001</year>
<volume>93</volume>
<numero>3</numero>
<issue>3</issue>
<page-range>590-7</page-range></nlm-citation>
</ref>
<ref id="B20">
<nlm-citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Hatfield]]></surname>
<given-names><![CDATA[J. L.]]></given-names>
</name>
<name>
<surname><![CDATA[Gitelson]]></surname>
<given-names><![CDATA[A. A.]]></given-names>
</name>
<name>
<surname><![CDATA[Schepers]]></surname>
<given-names><![CDATA[J. S.]]></given-names>
</name>
<name>
<surname><![CDATA[Walthall]]></surname>
<given-names><![CDATA[C. L.]]></given-names>
</name>
</person-group>
<article-title xml:lang=""><![CDATA[Application of spectral remote sensing for agronomic decisions]]></article-title>
<source><![CDATA[Agronomy Journal]]></source>
<year>2008</year>
<volume>100</volume>
<numero>S3</numero>
<issue>S3</issue>
<page-range>117-31</page-range></nlm-citation>
</ref>
<ref id="B21">
<nlm-citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Heckman]]></surname>
<given-names><![CDATA[J. R.]]></given-names>
</name>
<name>
<surname><![CDATA[Samulis]]></surname>
<given-names><![CDATA[R.]]></given-names>
</name>
<name>
<surname><![CDATA[Nitzsche]]></surname>
<given-names><![CDATA[P.]]></given-names>
</name>
</person-group>
<article-title xml:lang=""><![CDATA[Sweet corn crop nitrogen status evaluation by stalk testing]]></article-title>
<source><![CDATA[HortScience]]></source>
<year>2002</year>
<volume>37</volume>
<numero>5</numero>
<issue>5</issue>
<page-range>783-6</page-range></nlm-citation>
</ref>
<ref id="B22">
<nlm-citation citation-type="book">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Horwitz]]></surname>
<given-names><![CDATA[W.]]></given-names>
</name>
<name>
<surname><![CDATA[Latimer]]></surname>
<given-names><![CDATA[G. W.]]></given-names>
</name>
</person-group>
<source><![CDATA[Official Methods of Analysis of AOAC International]]></source>
<year>2005</year>
<edition>18th</edition>
<publisher-loc><![CDATA[Gaithersburg, MD, USA ]]></publisher-loc>
<publisher-name><![CDATA[The Association of Official Agricultural Chemists]]></publisher-name>
</nlm-citation>
</ref>
<ref id="B23">
<nlm-citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Huang]]></surname>
<given-names><![CDATA[G.]]></given-names>
</name>
</person-group>
<article-title xml:lang=""><![CDATA[Validation of late season cornstalk nitrate test under different natural and social environments for better fertilizer management in China]]></article-title>
<source><![CDATA[Oriental Journal of Chemistry]]></source>
<year>2013</year>
<volume>29</volume>
<numero>4</numero>
<issue>4</issue>
<page-range>1381-9</page-range></nlm-citation>
</ref>
<ref id="B24">
<nlm-citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Inman]]></surname>
<given-names><![CDATA[D.]]></given-names>
</name>
<name>
<surname><![CDATA[Khosla]]></surname>
<given-names><![CDATA[R.]]></given-names>
</name>
<name>
<surname><![CDATA[Reich]]></surname>
<given-names><![CDATA[R. M.]]></given-names>
</name>
<name>
<surname><![CDATA[Westfall]]></surname>
<given-names><![CDATA[D. G.]]></given-names>
</name>
</person-group>
<article-title xml:lang=""><![CDATA[Active remote sensing and grain yield in irrigated maize]]></article-title>
<source><![CDATA[Precision Agriculture]]></source>
<year>2007</year>
<volume>8</volume>
<numero>4-5</numero>
<issue>4-5</issue>
<page-range>241-52</page-range></nlm-citation>
</ref>
<ref id="B25">
<nlm-citation citation-type="">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Bruulsema]]></surname>
<given-names><![CDATA[T. W.]]></given-names>
</name>
<name>
<surname><![CDATA[Fixen]]></surname>
<given-names><![CDATA[P. E.]]></given-names>
</name>
<name>
<surname><![CDATA[Sulewski]]></surname>
<given-names><![CDATA[G. D.]]></given-names>
</name>
</person-group>
<collab>IPNI (International Plant Nutrition Institute)</collab>
<source><![CDATA[4R - Manual de Nutrición de Plantas: Un Manual Para Mejorar el Manejo de la Nutrición de Plantas]]></source>
<year>2013</year>
<edition>1st</edition>
<publisher-loc><![CDATA[International Plant Nutrition Institute Peachtree Corners ]]></publisher-loc>
</nlm-citation>
</ref>
<ref id="B26">
<nlm-citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Isla]]></surname>
<given-names><![CDATA[R.]]></given-names>
</name>
<name>
<surname><![CDATA[Blackmer]]></surname>
<given-names><![CDATA[A. M.]]></given-names>
</name>
</person-group>
<article-title xml:lang=""><![CDATA[A simplified test of cornstalk nitrate for better N management]]></article-title>
<source><![CDATA[Agronomy for Sustainable Development]]></source>
<year>2007</year>
<volume>27</volume>
<numero>3</numero>
<issue>3</issue>
<page-range>237-41</page-range></nlm-citation>
</ref>
<ref id="B27">
<nlm-citation citation-type="book">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Justes]]></surname>
<given-names><![CDATA[E.]]></given-names>
</name>
<name>
<surname><![CDATA[Meynard]]></surname>
<given-names><![CDATA[J. M.]]></given-names>
</name>
<name>
<surname><![CDATA[Mary]]></surname>
<given-names><![CDATA[B.]]></given-names>
</name>
<name>
<surname><![CDATA[Plénet]]></surname>
<given-names><![CDATA[D.]]></given-names>
</name>
</person-group>
<article-title xml:lang=""><![CDATA[Diagnosis using stem base extract: JUBIL method]]></article-title>
<person-group person-group-type="editor">
<name>
<surname><![CDATA[Lemaire]]></surname>
<given-names><![CDATA[G.]]></given-names>
</name>
</person-group>
<source><![CDATA[Diagnosis of the nitrogen status in crops]]></source>
<year>1997</year>
<page-range>163-87</page-range><publisher-loc><![CDATA[Berlin, Heidelberg ]]></publisher-loc>
<publisher-name><![CDATA[Springer Berlin Heidelberg]]></publisher-name>
</nlm-citation>
</ref>
<ref id="B28">
<nlm-citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Lemaire]]></surname>
<given-names><![CDATA[Gilles]]></given-names>
</name>
<name>
<surname><![CDATA[Jeuffroy]]></surname>
<given-names><![CDATA[M.-H.]]></given-names>
</name>
<name>
<surname><![CDATA[Gastal]]></surname>
<given-names><![CDATA[F.]]></given-names>
</name>
</person-group>
<article-title xml:lang=""><![CDATA[Diagnosis tool for plant and crop N status in vegetative stage]]></article-title>
<source><![CDATA[European Journal of Agronomy]]></source>
<year>2008</year>
<volume>28</volume>
<numero>4</numero>
<issue>4</issue>
<page-range>614-24</page-range></nlm-citation>
</ref>
<ref id="B29">
<nlm-citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Maddonni]]></surname>
<given-names><![CDATA[G. A.]]></given-names>
</name>
<name>
<surname><![CDATA[Otegui]]></surname>
<given-names><![CDATA[M. E.]]></given-names>
</name>
<name>
<surname><![CDATA[Cirilo]]></surname>
<given-names><![CDATA[A. G.]]></given-names>
</name>
</person-group>
<article-title xml:lang=""><![CDATA[Plant population density, row spacing and hybrid effects on maize canopy architecture and light attenuation]]></article-title>
<source><![CDATA[Field Crops Research]]></source>
<year>2001</year>
<volume>71</volume>
<numero>3</numero>
<issue>3</issue>
<page-range>183-93</page-range></nlm-citation>
</ref>
<ref id="B30">
<nlm-citation citation-type="book">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Mills]]></surname>
<given-names><![CDATA[H. A.]]></given-names>
</name>
<name>
<surname><![CDATA[Jones Jr.]]></surname>
<given-names><![CDATA[J. B.]]></given-names>
</name>
</person-group>
<source><![CDATA[Plant Analysis Handbook II. A Practical Sampling, Preparation, Analysis, and Interpretation Guide]]></source>
<year>1996</year>
<publisher-loc><![CDATA[Athens, Georgia ]]></publisher-loc>
<publisher-name><![CDATA[MicroMacro]]></publisher-name>
</nlm-citation>
</ref>
<ref id="B31">
<nlm-citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Muñoz-Huerta]]></surname>
<given-names><![CDATA[R. F.]]></given-names>
</name>
<name>
<surname><![CDATA[Guevara-Gonzalez]]></surname>
<given-names><![CDATA[R. G.]]></given-names>
</name>
<name>
<surname><![CDATA[Contreras-Medina]]></surname>
<given-names><![CDATA[L. M.]]></given-names>
</name>
<name>
<surname><![CDATA[Torres-Pacheco]]></surname>
<given-names><![CDATA[I.]]></given-names>
</name>
<name>
<surname><![CDATA[Prado-Olivarez]]></surname>
<given-names><![CDATA[J.]]></given-names>
</name>
<name>
<surname><![CDATA[Ocampo-Velazquez]]></surname>
<given-names><![CDATA[R. V.]]></given-names>
</name>
</person-group>
<article-title xml:lang=""><![CDATA[A review of methods for sensing the nitrogen status in plants: Advantages, disadvantages and recent advances]]></article-title>
<source><![CDATA[Sensors (Switzerland)]]></source>
<year>2013</year>
<volume>13</volume>
<numero>8</numero>
<issue>8</issue>
<page-range>10823-43</page-range></nlm-citation>
</ref>
<ref id="B32">
<nlm-citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Plénet]]></surname>
<given-names><![CDATA[D.]]></given-names>
</name>
<name>
<surname><![CDATA[Lemaire]]></surname>
<given-names><![CDATA[G.]]></given-names>
</name>
</person-group>
<article-title xml:lang=""><![CDATA[Relationships between dynamics of nitrogen uptake and dry matter accumulation in maize crops. Determination of critical N concentration]]></article-title>
<source><![CDATA[Plant and Soil]]></source>
<year>1999</year>
<volume>216</volume>
<numero>1-2</numero>
<issue>1-2</issue>
<page-range>65-82</page-range></nlm-citation>
</ref>
<ref id="B33">
<nlm-citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Raun]]></surname>
<given-names><![CDATA[W. R.]]></given-names>
</name>
<name>
<surname><![CDATA[Solie]]></surname>
<given-names><![CDATA[J. B.]]></given-names>
</name>
<name>
<surname><![CDATA[Johnson]]></surname>
<given-names><![CDATA[G. V.]]></given-names>
</name>
<name>
<surname><![CDATA[Stone]]></surname>
<given-names><![CDATA[M. L.]]></given-names>
</name>
<name>
<surname><![CDATA[Lukina]]></surname>
<given-names><![CDATA[E. V.]]></given-names>
</name>
<name>
<surname><![CDATA[Thomason]]></surname>
<given-names><![CDATA[W. E.]]></given-names>
</name>
<name>
<surname><![CDATA[Schepers]]></surname>
<given-names><![CDATA[J. S.]]></given-names>
</name>
</person-group>
<article-title xml:lang=""><![CDATA[In-season prediction of potential grain yield in winter wheat using canopy reflectance]]></article-title>
<source><![CDATA[Agronomy Journal]]></source>
<year>2001</year>
<volume>93</volume>
<numero>1</numero>
<issue>1</issue>
<page-range>131-8</page-range></nlm-citation>
</ref>
<ref id="B34">
<nlm-citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Rauschkolb]]></surname>
<given-names><![CDATA[R. S.]]></given-names>
</name>
<name>
<surname><![CDATA[Brown]]></surname>
<given-names><![CDATA[A. L.]]></given-names>
</name>
<name>
<surname><![CDATA[Prato]]></surname>
<given-names><![CDATA[J. D.]]></given-names>
</name>
<name>
<surname><![CDATA[Kegel]]></surname>
<given-names><![CDATA[F. R.]]></given-names>
</name>
</person-group>
<article-title xml:lang=""><![CDATA[Rapid tissue testing for evaluating nitrogen nutritional status of Corn and Sorghum]]></article-title>
<source><![CDATA[California Agriculture]]></source>
<year>1974</year>
<volume>28</volume>
<numero>6</numero>
<issue>6</issue>
<page-range>10-2</page-range></nlm-citation>
</ref>
<ref id="B35">
<nlm-citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Reed]]></surname>
<given-names><![CDATA[A. J.]]></given-names>
</name>
<name>
<surname><![CDATA[Hageman]]></surname>
<given-names><![CDATA[R. H.]]></given-names>
</name>
</person-group>
<article-title xml:lang=""><![CDATA[Relationship between nitrate uptake, flux, and reduction and the accumulation of reduced nitrogen in maize ( Zea mays L.)]]></article-title>
<source><![CDATA[Plant Physiology]]></source>
<year>1980</year>
<volume>66</volume>
<numero>6</numero>
<issue>6</issue>
<page-range>1184-9</page-range></nlm-citation>
</ref>
<ref id="B36">
<nlm-citation citation-type="book">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Reisenauer]]></surname>
<given-names><![CDATA[H. M.]]></given-names>
</name>
</person-group>
<source><![CDATA[Soil and plant-tissue testing in California]]></source>
<year>1978</year>
<publisher-loc><![CDATA[Berkeley, CA, USA ]]></publisher-loc>
<publisher-name><![CDATA[University of California]]></publisher-name>
</nlm-citation>
</ref>
<ref id="B37">
<nlm-citation citation-type="book">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Reuter]]></surname>
<given-names><![CDATA[D. J.]]></given-names>
</name>
<name>
<surname><![CDATA[Edwards]]></surname>
<given-names><![CDATA[D. G.]]></given-names>
</name>
<name>
<surname><![CDATA[Wilhelm]]></surname>
<given-names><![CDATA[N. S.]]></given-names>
</name>
</person-group>
<article-title xml:lang=""><![CDATA[Temperate and tropical crops]]></article-title>
<person-group person-group-type="editor">
<name>
<surname><![CDATA[Reuter]]></surname>
<given-names><![CDATA[D. J.]]></given-names>
</name>
<name>
<surname><![CDATA[Robison]]></surname>
<given-names><![CDATA[J. B.]]></given-names>
</name>
</person-group>
<source><![CDATA[Plant analysis: An interpretation manual]]></source>
<year>1997</year>
<page-range>83-284</page-range><publisher-loc><![CDATA[Collingwood, Australia ]]></publisher-loc>
<publisher-name><![CDATA[CSIRO Publishing]]></publisher-name>
</nlm-citation>
</ref>
<ref id="B38">
<nlm-citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Rhezali]]></surname>
<given-names><![CDATA[A.]]></given-names>
</name>
<name>
<surname><![CDATA[Lahlali]]></surname>
<given-names><![CDATA[R.]]></given-names>
</name>
</person-group>
<article-title xml:lang=""><![CDATA[Nitrogen (N) mineral nutrition and imaging sensors for determining N status and requirements of maize]]></article-title>
<source><![CDATA[Journal of Imaging]]></source>
<year>2017</year>
<volume>3</volume>
<numero>4</numero>
<issue>4</issue>
<page-range>1-10</page-range></nlm-citation>
</ref>
<ref id="B39">
<nlm-citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Sainz Rozas]]></surname>
<given-names><![CDATA[H. R.]]></given-names>
</name>
<name>
<surname><![CDATA[Echeverria]]></surname>
<given-names><![CDATA[H. E.]]></given-names>
</name>
<name>
<surname><![CDATA[Herfurth]]></surname>
<given-names><![CDATA[E.]]></given-names>
</name>
<name>
<surname><![CDATA[Studdert]]></surname>
<given-names><![CDATA[G. A.]]></given-names>
</name>
</person-group>
<article-title xml:lang=""><![CDATA[Basal stalk nitrate of maize. II diagnosis of nitrogen nutrition]]></article-title>
<source><![CDATA[Ciencia del Suelo]]></source>
<year>2001</year>
<volume>19</volume>
<numero>2</numero>
<issue>2</issue>
<page-range>125-35</page-range></nlm-citation>
</ref>
<ref id="B40">
<nlm-citation citation-type="">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Sánchez-García]]></surname>
<given-names><![CDATA[P.]]></given-names>
</name>
<name>
<surname><![CDATA[Molinos-da-Silva]]></surname>
<given-names><![CDATA[C.]]></given-names>
</name>
<name>
<surname><![CDATA[Alcántar-González]]></surname>
<given-names><![CDATA[G.]]></given-names>
</name>
<name>
<surname><![CDATA[Sandoval-Villa]]></surname>
<given-names><![CDATA[M.]]></given-names>
</name>
</person-group>
<article-title xml:lang=""><![CDATA[Diagnóstico nutrimental en plantas]]></article-title>
<person-group person-group-type="editor">
<name>
<surname><![CDATA[Alcantar-Gonzáles]]></surname>
<given-names><![CDATA[G.]]></given-names>
</name>
<name>
<surname><![CDATA[Trejo-Téllez]]></surname>
<given-names><![CDATA[L. I.]]></given-names>
</name>
<name>
<surname><![CDATA[Gómez-Marino]]></surname>
<given-names><![CDATA[F. C.]]></given-names>
</name>
</person-group>
<source><![CDATA[Nutrición de cultivos]]></source>
<year>2016</year>
<page-range>185-216</page-range><publisher-loc><![CDATA[Texcoco, Estado de México ]]></publisher-loc>
</nlm-citation>
</ref>
<ref id="B41">
<nlm-citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Santillano-Cázares]]></surname>
<given-names><![CDATA[J.]]></given-names>
</name>
<name>
<surname><![CDATA[López-López]]></surname>
<given-names><![CDATA[Á.]]></given-names>
</name>
<name>
<surname><![CDATA[Ortiz-Monasterio]]></surname>
<given-names><![CDATA[I.]]></given-names>
</name>
<name>
<surname><![CDATA[Raun]]></surname>
<given-names><![CDATA[W. R.]]></given-names>
</name>
</person-group>
<article-title xml:lang=""><![CDATA[Uso de sensores ópticos para la fertilización de trigo (Triticum aestivum L.)]]></article-title>
<source><![CDATA[Terra Latinoamericana]]></source>
<year>2013</year>
<volume>31</volume>
<page-range>95-103</page-range></nlm-citation>
</ref>
<ref id="B42">
<nlm-citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Schepers]]></surname>
<given-names><![CDATA[J. S.]]></given-names>
</name>
<name>
<surname><![CDATA[Francis]]></surname>
<given-names><![CDATA[D. D.]]></given-names>
</name>
<name>
<surname><![CDATA[Vigil]]></surname>
<given-names><![CDATA[M.]]></given-names>
</name>
<name>
<surname><![CDATA[Below]]></surname>
<given-names><![CDATA[F. E.]]></given-names>
</name>
</person-group>
<article-title xml:lang=""><![CDATA[Comparison of corn leaf nitrogen concentration and chlorophyll meter readings]]></article-title>
<source><![CDATA[Communications in Soil Science and Plant Analysi]]></source>
<year>1992</year>
<volume>23</volume>
<numero>17-20</numero>
<issue>17-20</issue>
<page-range>2173-87</page-range></nlm-citation>
</ref>
<ref id="B43">
<nlm-citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Shapiro]]></surname>
<given-names><![CDATA[C.]]></given-names>
</name>
<name>
<surname><![CDATA[Attia]]></surname>
<given-names><![CDATA[A.]]></given-names>
</name>
<name>
<surname><![CDATA[Ulloa]]></surname>
<given-names><![CDATA[S.]]></given-names>
</name>
<name>
<surname><![CDATA[Mainz]]></surname>
<given-names><![CDATA[M.]]></given-names>
</name>
</person-group>
<article-title xml:lang=""><![CDATA[Use of five nitrogen source and placement systems for improved nitrogen management of irrigated corn]]></article-title>
<source><![CDATA[Soil Science Society of America Journal]]></source>
<year>2016</year>
<volume>80</volume>
<numero>6</numero>
<issue>6</issue>
<page-range>1663-74</page-range></nlm-citation>
</ref>
<ref id="B44">
<nlm-citation citation-type="book">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Smith]]></surname>
<given-names><![CDATA[F. W.]]></given-names>
</name>
<name>
<surname><![CDATA[Loneragan]]></surname>
<given-names><![CDATA[J. F.]]></given-names>
</name>
</person-group>
<article-title xml:lang=""><![CDATA[Interpretation of plant analysis: Concepts and principles]]></article-title>
<person-group person-group-type="editor">
<name>
<surname><![CDATA[Reuters]]></surname>
<given-names><![CDATA[D. J.]]></given-names>
</name>
<name>
<surname><![CDATA[Robison]]></surname>
<given-names><![CDATA[J. B.]]></given-names>
</name>
<name>
<surname><![CDATA[Dutkiewicz]]></surname>
<given-names><![CDATA[C.]]></given-names>
</name>
</person-group>
<source><![CDATA[Plant analysis: An interpretation manual]]></source>
<year>1997</year>
<page-range>3-33</page-range><publisher-loc><![CDATA[Collingwood, VIC, Australia ]]></publisher-loc>
<publisher-name><![CDATA[CSIRO Publishing]]></publisher-name>
</nlm-citation>
</ref>
<ref id="B45">
<nlm-citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Sprent]]></surname>
<given-names><![CDATA[P.]]></given-names>
</name>
</person-group>
<article-title xml:lang=""><![CDATA[Some hypotheses concerning two phase regression lines]]></article-title>
<source><![CDATA[Biometrics]]></source>
<year>1961</year>
<volume>17</volume>
<numero>4</numero>
<issue>4</issue>
<page-range>634-45</page-range></nlm-citation>
</ref>
<ref id="B46">
<nlm-citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Ta]]></surname>
<given-names><![CDATA[C. T.]]></given-names>
</name>
</person-group>
<article-title xml:lang=""><![CDATA[Nitrogen metabolism in the stalk tissue of maize]]></article-title>
<source><![CDATA[Plant Physiology]]></source>
<year>1991</year>
<volume>97</volume>
<numero>4</numero>
<issue>4</issue>
<page-range>1375-80</page-range></nlm-citation>
</ref>
<ref id="B47">
<nlm-citation citation-type="">
<source><![CDATA[The R Foundation for Statistical Computing]]></source>
<year>2018</year>
</nlm-citation>
</ref>
<ref id="B48">
<nlm-citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Withe]]></surname>
<given-names><![CDATA[J. M.]]></given-names>
</name>
<name>
<surname><![CDATA[Tyson]]></surname>
<given-names><![CDATA[R. V.]]></given-names>
</name>
<name>
<surname><![CDATA[Hanlon]]></surname>
<given-names><![CDATA[E. A.]]></given-names>
</name>
<name>
<surname><![CDATA[Hochmuth]]></surname>
<given-names><![CDATA[G. J.]]></given-names>
</name>
<name>
<surname><![CDATA[Neal]]></surname>
<given-names><![CDATA[C. A.]]></given-names>
</name>
</person-group>
<article-title xml:lang=""><![CDATA[Plant petiole sap testing for nitrogen and potassium in sweet corn grown on mineral soil]]></article-title>
<source><![CDATA[Proceedings of the Florida State Horticultural Society]]></source>
<year>1996</year>
<volume>109</volume>
<page-range>149-51</page-range></nlm-citation>
</ref>
<ref id="B49">
<nlm-citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Withers]]></surname>
<given-names><![CDATA[N. J.]]></given-names>
</name>
</person-group>
<article-title xml:lang=""><![CDATA[SAP tests for measuring nitrogen status of cereals]]></article-title>
<source><![CDATA[Proceedings Agronomy Society of N.Z.]]></source>
<year>1982</year>
<volume>12</volume>
<page-range>41-4</page-range></nlm-citation>
</ref>
<ref id="B50">
<nlm-citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Xiong]]></surname>
<given-names><![CDATA[D.]]></given-names>
</name>
<name>
<surname><![CDATA[Chen]]></surname>
<given-names><![CDATA[J.]]></given-names>
</name>
<name>
<surname><![CDATA[Yu]]></surname>
<given-names><![CDATA[T.]]></given-names>
</name>
<name>
<surname><![CDATA[Gao]]></surname>
<given-names><![CDATA[W.]]></given-names>
</name>
<name>
<surname><![CDATA[Ling]]></surname>
<given-names><![CDATA[X.]]></given-names>
</name>
<name>
<surname><![CDATA[Li]]></surname>
<given-names><![CDATA[Y.]]></given-names>
</name>
<name>
<surname><![CDATA[&#8230; Huang]]></surname>
<given-names><![CDATA[J.]]></given-names>
</name>
</person-group>
<article-title xml:lang=""><![CDATA[SPAD-based leaf nitrogen estimation is impacted by environmental factors and crop leaf characteristics]]></article-title>
<source><![CDATA[Scientific Reports]]></source>
<year>2015</year>
<volume>5</volume>
<numero>1</numero>
<issue>1</issue>
</nlm-citation>
</ref>
<ref id="B51">
<nlm-citation citation-type="journal">
<person-group person-group-type="author">
<name>
<surname><![CDATA[Yin]]></surname>
<given-names><![CDATA[X.]]></given-names>
</name>
<name>
<surname><![CDATA[McClure]]></surname>
<given-names><![CDATA[A.]]></given-names>
</name>
</person-group>
<article-title xml:lang=""><![CDATA[Relationship of corn yield, biomass, and leaf nitrogen with normalized difference vegetation index and plant height]]></article-title>
<source><![CDATA[Agronomy Journal]]></source>
<year>2013</year>
<volume>105</volume>
<numero>4</numero>
<issue>4</issue>
<page-range>1005-16</page-range></nlm-citation>
</ref>
</ref-list>
</back>
</article>
