<?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>2007-9028</journal-id>
<journal-title><![CDATA[Ecosistemas y recursos agropecuarios]]></journal-title>
<abbrev-journal-title><![CDATA[Ecosistemas y recur. agropecuarios]]></abbrev-journal-title>
<issn>2007-9028</issn>
<publisher>
<publisher-name><![CDATA[Universidad Juárez Autónoma de Tabasco, Dirección de Investigación y Posgrado]]></publisher-name>
</publisher>
</journal-meta>
<article-meta>
<article-id>S2007-90282021000100011</article-id>
<article-id pub-id-type="doi">10.19136/era.a8n1.2580</article-id>
<title-group>
<article-title xml:lang="en"><![CDATA[Influence of P-Ca on cytokinins in xylem sap and on stomatal resistance in apple]]></article-title>
<article-title xml:lang="es"><![CDATA[Influencia del P-Ca sobre citocininas en savia de xilema y en resistencia estomática en manzano]]></article-title>
</title-group>
<contrib-group>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Ramírez]]></surname>
<given-names><![CDATA[Homero]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Melendres-Alvarez]]></surname>
<given-names><![CDATA[Aarón Isain]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Zermeño-González]]></surname>
<given-names><![CDATA[Alejandro]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Jasso-Cantú]]></surname>
<given-names><![CDATA[Diana]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
<contrib contrib-type="author">
<name>
<surname><![CDATA[Villarreal-Quintanilla]]></surname>
<given-names><![CDATA[José Ángel]]></given-names>
</name>
<xref ref-type="aff" rid="Aff"/>
</contrib>
</contrib-group>
<aff id="Af1">
<institution><![CDATA[,Universidad Autónoma Agraria Antonio Narro Departamento de Horticultura ]]></institution>
<addr-line><![CDATA[Saltillo Coahuila]]></addr-line>
<country>Mexico</country>
</aff>
<aff id="Af2">
<institution><![CDATA[,Universidad, Autónoma Agraria Antonio Narro  ]]></institution>
<addr-line><![CDATA[Saltillo Coahuila]]></addr-line>
<country>Mexico</country>
</aff>
<aff id="Af3">
<institution><![CDATA[,Universidad Autónoma Agraria Antonio Narro  ]]></institution>
<addr-line><![CDATA[Saltillo Coahuila]]></addr-line>
<country>Mexico</country>
</aff>
<aff id="Af4">
<institution><![CDATA[,Universidad Autónoma, Agraria Antonio Narro  ]]></institution>
<addr-line><![CDATA[Saltillo Coahuila]]></addr-line>
<country>Mexico</country>
</aff>
<pub-date pub-type="pub">
<day>00</day>
<month>00</month>
<year>2021</year>
</pub-date>
<pub-date pub-type="epub">
<day>00</day>
<month>00</month>
<year>2021</year>
</pub-date>
<volume>8</volume>
<numero>1</numero>
<copyright-statement/>
<copyright-year/>
<self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_arttext&amp;pid=S2007-90282021000100011&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_abstract&amp;pid=S2007-90282021000100011&amp;lng=en&amp;nrm=iso"></self-uri><self-uri xlink:href="http://www.scielo.org.mx/scielo.php?script=sci_pdf&amp;pid=S2007-90282021000100011&amp;lng=en&amp;nrm=iso"></self-uri><abstract abstract-type="short" xml:lang="en"><p><![CDATA[ABSTRACT. With the purpose to search upon the cytokinins origin, a study was conducted on the effects of prohexadione-ca (P-Ca) on cytokinins in xylem sap and on stomatal resistance in apple. Golden Delicious seedlings were sprayed with 100 ppm P-Ca. Stomatal leaf resistance was measured at intervals between 1 and 4 hours of spraying and 15 days after the treatment. Golden Delicious trees were sprayed with 200 ppm P-Ca two weeks after full bloom. At intervals between 1 and two weeks after P-Ca treatment, the main de-shooted stem was removed from root system and xylem sap was collected for cytokinins analysis using the suction technique. Prohexadione- ca significantly increased stomatal resistance (range 2.74-4.35 s/cm&#8722;1) when compared to control (range 2.12-3.44 s/cm&#8722;1); however, P-Ca did not modify the level of cytokinins in xylem sap since range values were between 0.10 to 0.20 µg kinetin equivalents/20 ml xylem sap for both, cytokinin and control.]]></p></abstract>
<abstract abstract-type="short" xml:lang="es"><p><![CDATA[RESUMEN. Para investigar el origen de las citocininas, se estudió los efectos de prohexadiona de calcio (P-Ca) sobre citocininas en savia de xilema y en la resistencia de estomas en manzano. Plantas Golden Delicious fueron asperjadas con 100 ppm P-Ca y la resistencia de estomas en sus hojas fue medida a intervalos de 1 a 4 horas y 15 días posteriores. Arboles Golden Delicious fueron asperjados dos semanas después de floración con 200 ppm P-Ca. Entre una y dos semanas después del tratamiento, el tallo fue removido del sistema radicular; y, la savia de xilema extraída con la técnica de succión para analizar citocininas. P-Ca aumentó significativamente la resistencia de estomas (rango 2.74-4.35 s/cm&#8722;1) al compararse con el testigo (rango 2.12-3.44 s/cm&#8722;1); sin embargo, no modificó citocininas en savia del xilema. El nivel entre testigo y P-Ca siempre fluctuó en los rangos de 0.10 a 0.20 µg kinetin equivalentes/20 ml xilema.]]></p></abstract>
<kwd-group>
<kwd lng="en"><![CDATA[Deciduous fruit]]></kwd>
<kwd lng="en"><![CDATA[growth retardant]]></kwd>
<kwd lng="en"><![CDATA[hormone translocation]]></kwd>
<kwd lng="en"><![CDATA[leaf approach]]></kwd>
<kwd lng="es"><![CDATA[Frutal templado]]></kwd>
<kwd lng="es"><![CDATA[perfil foliar]]></kwd>
<kwd lng="es"><![CDATA[retardante del crecimiento]]></kwd>
<kwd lng="es"><![CDATA[translocación hormonal]]></kwd>
</kwd-group>
</article-meta>
</front><back>
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