Many Boston-area discount department stores will open their doors on four consecutive Sundays between Thanksgiving and Christmas if Governor Dukakis signs legislation amending the 200-year-old Massachusetts blue laws within two weeks, as is expected.

Spokesmen for department stores such as Filene's, Bradlees, Lechmere Sales and Zayres said they will definitely open on Sundays if the bill is signed into law, but Howard Davis, general manager of the Harvard Coop, said yesterday the Coop has no plans for Sunday hours at this time.

Davis said the Sunday hours option will be discussed at a Coop management meeting today, but he cited the desire to avoid undue strain on executive staff and regular personnel as the main reason why the Coop may not open on Sundays.

The Coop already extends its hours until 9 p.m. every night during the Christmas shopping season, a schedule that requires hiring part-time workers and putting a strain on regular personnel, Davis said.

He added that Sunday openings would inevitably require regular staff to work longer hours. "In order to give service we have to have personnel who know our merchandise. You can't run a store with just part-time workers," Davis said.

Other Harvard Square merchants contacted yesterday appear to be adopting a wait-and-see attitude toward Sunday openings.

"Personally I don't want it--six days is enough," the manager of J. August and Co., a clothing shop on Massachusetts Ave., said yesterday.