This should do the job:
<xsl:template match="*">
<xsl:copy><xsl:copy-of select="@*"/><xsl:apply-templates/></xsl:copy>
</xsl:template>
<xsl:template match="prdpho/text()[normalize-space()]">
<p><xsl:copy-of select="."/>
</xsl:template>
Michael Kay
http://www.saxonica.com/
Author, XSLT Programmer's Reference and XPath 2.0 Programmer's Reference