Prince George's County Executive-elect Parris Glendening named a black to a vacancy on the county school board yesterday, saying it was time for the nine-member board to have a more than one black member.

Sarah Johnson, 42, an administrator with the D. C. school system, will be the second black on the nine-member board, which has never had more than one black voting member. She was picked from a large number of competing candidates, most of whom were black.

Johnson said yesterday she would work closely with county government officials to maintain quality education in the face of continuing budget troubles facing the schools.

Johnson will fill the remaining two years of board member JoAnn Bell's term, representing the 56 percent black Suitland area district. Bell was elected to the County Council earlier this month.

Johnson said she hoped to be a qualified representative to the board for all the citizens of Prince George's County, not just the black community.

"I don't know that the fact that a child is black or white should determine the kind of education they get," said Johnson, who has had two sons in the school system. "I'm not saying there are not special needs, but the fact that the child is black or white does not necessarily affect those needs."

Glendening said that despite low morale among schoolteachers facing a possibility of a second year of layoffs, the announcement of early retirements of a few senior school administrators and the rejection by voters of a property tax measure aimed at relieving the crisis in school funding, the school system is not a "sinking ship."

"I don't believe that the characterization is fair. I as county executive and the school board are absoulutely committed to the schools," said Glendening, a government professor at the University of Maryland. "If people want to see how committed we are just watch how the elected officials behave," he added.

At the same time, Glendening said that if additional revenue sources cannot be found he would distribute service reductions "as fairly and painlessly as possible" throughout the county. The schools receive about 60 percent of the county budget.