cooperative-market/beesdoo_purchase_manual_date_planned/report/report_purchaseorder.xml

<?xml version="1.0" encoding="utf-8"?>
<odoo>
<data>
    <template id="report_purchaseorder_document" inherit_id="purchase.report_purchaseorder_document" name="beesdoo purchaseorder">
        <div t-if="o.date_order" position="after">

            <div class="col-xs-3">
                <strong>Date Planned:</strong>
                <div t-field="o.date_planned" />
            </div>

        </div>
        <xpath expr="//span[@t-field='line.date_planned']/.." position="attributes">
            <attribute name="style">display:none;</attribute>
        </xpath>
    </template>
</data>
</odoo>