Tax code default based on purchasing Group

Hi,

I have two questions.Can some body guide me for these,please.

1.Is it possible to make default Tax code based on purchasing group in PO screen. Taxcode at item level.

2.Based on material text(no mateial) can we default Taxcode in PO screen? I know how to default Taxcode with mateial using Inforecord.

With Regards,

Jaheer.