Gov.-elect Charles S. Robb, in a break with Virginia tradition, named six newcomers to his cabinet today and pledged they would play key roles in maintaining adequate programs in education, health and welfare despite massive reductions in federal aid.

Robb, who said he was "enormously proud" of the appointees, said, "In many cases we have made potentially controversial, perhaps, but exciting choices." But, he said, "We're going to look beyond the traditional response to any challenge that confronts us."

Robb's selections broke several longstanding practices. There were no holdovers from past administrations in the cabinet selection. Only one of the appointees, Secretary of Education John T. Casteen III, is a native Virginian and half of the cabinet choices have spent most of their professional careers in other states. Former Rep. Joseph L. Fisher of Arlington, named as secretary of human resources, is the only activist Democrat on the list.

For the first time, the cabinet will include three members--Fisher, Franklin E. White of Silver Spring, named as secretary of public safety, and Secretary of Administration and Finance Wayne F. Anderson of Alexandria--who are strongly identified with the federal government. White served a three-year stint on the domestic policy staff of the Carter White House, while Anderson spent seven years as executive director of the federal Advisory Commission on Intergovernmental Relations.

Fisher, who served in Congress six years and spent l0 years on the Arlington County Board, will be the first liberal ever to serve in a Virginia cabinet. White, an attorney who once worked for the NAACP Legal Defense Fund, will be the cabinet's first black male and will oversee a prison system and state police organization that for decades constituted a whites-only preserve. Washington native Betty J. Diener, the new Secretary of Commerce, will be the first female in a post previously reserved for males.

"It's non-traditional and it's the type of thing that Chuck Robb is committed to," said L. Douglas Wilder of Richmond, the state's only black senator, who said he was pleased with the appointees. "I think it's saying that Chuck is not afraid to go against the past when he chooses a man like Frank White to run agencies where blacks were once not allowed."

Robb, the first Democrat elected governor in Virginia in 16 years, won his smashing victory in November by putting together a broad-based coalition of blacks, labor union members, liberals, conservative businessmen and suburbanites disenchanted with Republican opponent J. Marshall Coleman. That coalition still seemed intact today after his cabinet appointments, announced at a news conference this morning. Black community leaders, conservatives in the General Assembly, members of the business community and the Virginia Education Association all expressed pleasure with the nominees.

"It's a very impressive group," said W. Roy Smith, a former legislator and Richmond pharmaceutical executive who has served as Robb's key liaison to the state's business establishment. "Of course you like to have people in government who always agree with you, but I'd rather see people who are able and well-qualified and that's what he's succeeded in doing."

While Robb made a clean sweep of outgoing Republican Gov. John N. Dalton's cabinet appointees, he said two key members of Dalton's budgetary team would remain in his administration. Andrew B. Fogarty, a Dalton cabinet assistant secretary and former legislative aide, will serve as secretary of transportation, a last-minute selection made after a search failed to come up with a qualified candidate from outside the state. Stuart W. Connock, Dalton's secretary of administration and finance, will return to his old post as state budget and planning director but will sit in on cabinet meetings.

Reflecting the personality of their new boss, most of the cabinet nominees gave low-key appraisals of their posts, offering no specifics on the direction they expect to provide the agencies they oversee.

Robb said Fisher, 67, a Harvard-trained economist and educator, would have the toughest role in overseeing the state's troubled mental health system and deficit-ridden Medicaid program and in coping with federal budget cuts in social welfare programs. He said Fisher would bring "the federal perspective and a sense of compassion" to the post.

"The challenges for human resources in Virginia are staggering," Fisher said. "Certainly we will do everything possible to sustain and improve the human resources programs that really are needed."

White, 40, described his own post as "a hot spot" because it includes the state's overcrowded and increasingly costly prisons system. The former civil rights lawyer refused to discuss his views on the penal system but is expected to emphasize less-costly alternatives to incarceration for nonviolent offenders.

Diener, 41, the first woman to receive a doctorate in marketing and public policy from Harvard, may prove to be the most controversial appointee. More than two-thirds of the faculty of Old Dominion University's School of Business in Norfolk, where she served as dean for two years, called for her ouster last month. Robb also was warned against her appointment by several Tidewater legislators who were promoting Norfolk Sen. Peter Babalas for the post.

Robb said he was aware of the criticism of Diener from faculty members, but added, "She has an extraordinary reputation in the business community."

Casteen, 38, dean of admissions at the University of Virginia, who in the past has been critical of state high school graduates, once said, "It's astounding the number of college applicants who can't write a literate essay." He had nothing but praise for the state school system today, but faces the immediate challenge of deciding whether to support School Supt. S. John Davis' attempt to toughen standards for teachers.

Fogarty, 36, will oversee the state's troubled highway department, whose leaders are contending they need a major increase in the state's 11-cent-per-gallon gasoline tax to finance a bare-bones roads program. He would make no commitment about such an increase today, nor would he discuss the fate of Highway Commissioner Harold C. King, whom many legislators would like to see removed.

Anderson, 57, will be both Robb's top finance aide and cabinet chief of staff. The man who held that post for most of the Dalton years, Charles B. Walker, dominated the cabinet and often dictated policies and programs to fellow secretaries.

Anderson said he did not expect to play a similar role in the new cabinet. "I couldn't be less concerned about whether in four years someone will rank me third or fifth or first," he said, adding that his chief concern will be holding the line on budget expenditures without crippling state programs. "All innovations don't cost money," he said.