Hello,
In transaction OPG9 Select SAP010, SAP011, SAP012 and go to fields and change filed name MATXT from PLNUM.
So in transaction OPG9 change the structure MARA and field name MAKTX for SAP010, SAP011 and SAP012. Then material description will be appearing in planning board against planned order.
Best Regards,
R.Brahmankar