November 21, 1984

Economic growth slumped to a 1.9 percent annual rate in the July-September quarter, the Commerce Department reported today. It was the poorest performance since the current expansion began in late 1982. The revised calculation of the gross national product - the nation's total output of goods and services - was significantly lower than the 2.7 percent estimated a month ago and confirmed the view of an growing number of analysts that the country may already be in a ''growth recession.'' Such a recession is characterized not by an actual decline in output but by growth so skimpy that the economy cannot absorb increases in the labor force, and by a consequent rise in unemployment.

An experimental plan to reduce the costs and ticket prices of Broadway plays - a plan that has excited interest and curiosity in the theater industry - will go into effect Friday when the drama ''Dancing in the End Zone'' begins rehearsals. Morton Gottlieb, the play's producer, has won a series of unusual financial concessions from the artists, labor unions and theater owner that reduce the cost of the production. In return, Mr. Gottlieb has agreed to use only 499 seats in the 954-seat Ritz Theater, thus putting the Ritz in a special ''small theater'' category, and to keep his top ticket price below $30. The play opens Jan. 3. The plan, in effect, allows a play the cachet of playing in a Broadway theater while holding prices closer to the Off Broadway level. As a result of the concessions, Mr. Gottlieb said, it will cost $450,000 rather than $800,000 to produce ''Dancing in the End Zone,'' and the top ticket price will be $29.50, compared with the high of $37.50 for dramas on Broadway.

An article in Business Day yesterday about Monday's stock market trading misstated an earnings prediction by John Blair & Company. The forecast was for reduced earnings in the fourth quarter.

After a 10-year battle with the Securities and Exchange Commission, Robert E. Brennan, the president of First Jersey Securities Inc., signed a consent decree last night in which he and his brokerage firm accepted a permanent injunction not to bid for stock in a company at the same time he was selling it to the public. The 40-year-old executive, famous for nationwide television commercials in which he steps from a helicopter to deliver a personal message to investors, called the decree ''a great day for me and First Jersey. We've been fighting for 10 years to get this.''

The International Business Machines Corporation yesterday agreed to sell the military computer division of the Rolm Corporation within six months, in order to get Federal approval to acquire the rest of the company. The agreement came in a consent decree with the Justice Department. The move leaves intact the bulk of Rolm, the Silicon Valley company for which I.B.M. made a $1.25 billion offer seven weeks ago. Although Rolm started in 1969 as a military computer company, the military specification division now accounts for only one- eighth of the company's business. The company's main attraction for I.B.M. is believed to be the telecommunications operation that it began in 1975.