Morton's Department Stores opened its second new Prince George's County store in six weeks yesterday, providing evidence of suburban expansion by a retailer that has been closely indentified with the District since opening here in 1935.

Mortimer Lebowitz, the founder and president of Morton's, said yesterday he is interested in other Prince George's sites for continued growth. For now, there will be no more new stores in the District, he added.

Morton's stores, now numbering six, serve primarily lower-income shoppers with budget-type apparel and other merchandise being phased out by some more-affluent-oriented area retailers.

In the 1930s, Morton's became the first major retailer here to integrate fitting and rest rooms and was among the first to hire black sales personnel. The destruction of two inner city stores in 1968 rioting, followed by an exodus of many black families to Prince George's County, led Morton's to open its first unit in the suburbs in 1972 - when the company took over a former Woodward & Lothrop branch at Eastover Shopping Mall.

Morton's opened a major store on F Street in downtown Washington, in 1973, taking over the former Jelleff's flagship location. Morton's also operated brances at 7th and D streets NW and 2324 Pennsylvania Ave. SE.

The store opened yesterday is located at 6545 Annapolis Rd. across from Capital Plaza shopping center. Six weeks ago, a fifth store was opened on Silver Hill Road across from the Census Bureau.

Both of the new locations previously were branches of the now-defunct Robert Hall chain. With about 8,400 square feet of retail space, the new stores are much smaller than Morton's needs for its full range of merchandise, however.

Lebowitz said yesterday the two new stores will feature only those items - primarily apparel for men, women and children - that are "hot things" at the moment. "We'll be turning over (the merchandise) very fast, in a very, very efficient operation," he said.

With 100 new employes at the new stores, Morton's now has more than 400 workers on its payroll. Annual sales are estimated at more than $10 million.