The Montgomery County Board of Education voted early today to further reduce the minority enrollment at Rosemary Hills Elementary in Silver Spring, the school at the heart of a controversial desegregation plan that the board reinstated last week.

The reinstated plan involves pairing students from the largely affluent and white Chevy Chase community with students from the high minority Rosemary Hills area. The previous board attempted to dismantle the program a year ago.

The reinstatement drew highly charged reactions from the communities involved, and this morning's actions were an attempt to mollify those concerns. The board also was operating under a deadline from the State Board of Education to return with a plan for the area by today.

Members of the Rosemary Hill community were concerned that an exemption from the plan for all students now attending Chevy Chase Elementary would so boost their school's already high minority enrollment while reducing the size of the student body that new parents required to send their students to Rosemary Hills would opt not to do so.

Under the plan approved last week, students from Chevy Chase Elementary and North Chevy Chase Elementary would attend Rosemary Hills for preschool classes through second grade and return to their neighborhood schools for the remaining grades. Students living in the Rosemary Hills area would attend that school for their primary grades and then attend either Chevy Chase or North Chevy Chase for the remaining grades.

Students currently attending Chevy Chase Elementary, however, were allowed to remain at their neighborhood school for the full term of their grade school education.

Board member Odessa Shannon asked for a partial reversal of that decision by requiring kindergarten pupils this year at Chevy Chase to attend Rosemary Hills next year.

Without the Chevy Chase students, board members were told, minority enrollment at Rosemary Hills would be 54.3 percent next year, far above the countywide average of 25.4 percent. A number of board members said they felt the Chevy Chase community had undergone enough turmoil and that it would only be fair to allow students to remain there.

Instead, the board voted to send pupils from the former Lynnbrook Elementary area, another largely white community, to Rosemary Hills, beginning with kindergarten next year. The board also voted to send for one year the second-grade students at Rosemary Hills to North Chevy Chase. Those two actions, officials said, would reduce the minority enrollment at Rosemary Hills to 48.9 percent.