Hundreds of D.C. senior citizens crowded into the Metro board meeting room yesterday to protest proposals to raise special discount fares for the elderly and handicapped as part of a general increase in April.

"For some elderly people, the Metro system means the difference between an active and interesting life and one of loneliness and boredom," said Virginia Keith of the United Planning Organization, a private agency that administers many city social service programs.

Applauded by elderly men and women sitting in board members' chairs and on the carpeted floor, speakers told a panel of Metro officials that the proposed increase would place transit beyond the reach of many senior citizens.

"I come with a plea," said Arletta P. Shorter. " . . . Please do not raise the fare on us widowed women living in Southeast on a fixed income."

The gathering was one of eight hearings on the proposed Metro increase. The heavy turnout, organized by agencies that provide social services to the elderly, contrasted markedly with low-key responses at hearings elsewhere in the area in recent days.

The Metro board will make a ruling on the proposed increase next month. Under the proposal, most base fares would increase from 65 to 75 cents, with mileage fees that rail riders pay at rush hour and some bus-zone fees also facing boosts.

Elderly and handicapped riders, who now pay 20 cents for bus rides in D.C., would pay 30 cents under the proposal. In the suburbs, their current 30-cent bus fares would go up to 35 cents. On Metrorail, they now pay between 30 cents and 60 cents, depending on how far they ride. Under the proposal, they would pay between 35 and 75 cents.

In another development yesterday, Metro General Manager Richard S. Page released a report by the American Public Transit Association listing 33 recommendations for improved safety at Metro. Metro had requested the study, officials said.

The report said Metro is working hard to improve safety, but "these efforts tend to be fragmented and lacking in direction." Training deficiencies were found, it said, which "cast doubt upon the authority's ability to respond" to an emergency.

Among its recommendations were: creation of specific safety objectives, better coordination of safety programs, improved investigation of dangerous incidents, clarification of ambiguous safety procedures and better training and retraining of personnel.

Metro officials said many of these steps have already been implemented as part of a reappraisal following the Jan. 13, 1982, Orange Line accident that killed three subway passengers.

Newly released federal statistics for 1981 indicate Metro remains among the safest U.S. transit systems, Metro officials said. Even if the accident had occurred in 1981, Metro's rates of fatalities and injuries would have remained well below the average of 11 major U.S. rail systems, Metro said.

In other developments yesterday:

* The Metro board voted to continue an experiment to reduce train lengths to free up cars for the reserve fleet and possibly to open new Yellow Line track between Gallery Place and National Airport as early as April.

* The board voted to begin soliciting bids for about 80 new buses. The board opted to buy "advanced design buses," rather than older-style vehicles that make up most of the fleet.