According to Official Guinness Records,
The lowest score to par after 72 holes in a major golf tournament is - 32 (32 under par) and was achieved by Chapchai Nirat (Thailand) at the 2009 SAIL Open at the Classic Golf Resort, Gurgaon, India, on 21 March 2009. The SAIL Open is part of the Asian Tour which is one of the six full members of the International Federation of PGA Tours. This defines the tournament as a "major" tournament.
For a complete list of 2009 records, please visit 2009 Guinness Records in India.