The Commerce Department petitioned the Federal Communications Commission yesterday to increase minority participation in broadcasting in expensive major media markets by waiving rules limiting radio and television ownership.

In that petition, the National Telecommunications and Information Administration asked the FCC to exempt companies with at least 25 percent minority ownership and substantial minority participation from national limits on radio stations and limits on television stations in the top 50 markets that an individual or group may own.

Commerce Secretary Juanita M. Kreps said that favorable FCC action on the petition would encourage the broadcasting industry to involve minorities in ventures in markets "where tremendous capital is required to purchase a station."

Kreps announced the move at a meeting of the National Minority Purchasing Council shortly before the petition was filed.

She pointed to a number of initiatives by the Carter administration which she said had increased minority involvement in broadcasting. "In less than two years. we've been able to increase the number of minority-owned broadcast outlets by two-thirds," she said.

Even with that increase, from approximately 62 commercial broadcast stations in January 1978 to about 134 stations, minority ownership accounts for only about 1.5 percent of the nation's commercial broadcast outlets, Henry Geller noted in a letter prefacing the petition. Geller is assistant secretary of Commerce for communications and information.

Most growth in minority participation has been in small and rural markets, the petition pointed out.

According to figures from the Commerce Department, no VHF stations in the 50 top television markets and only one UHF station -- WGPR in Detroit -- are minority-owned.

In filing the petition, the Commerce Department took note of recent FCC actions aimed at broadening minority participation in broadcasting. The changes suggested in the petition might accelerate this process, however Geller noted.

The strongest of the measures requested by the petition is a policy statement by the FCC that at least 25 percent minority participation in radio station ownership be considered a compelling reason for waiving the commission's seven-station limit on AM and FM station ownership. That limit is one of the most-firmly-held FCC policies limiting broadcast station ownership, one Commerce Department official noted.

The 25 percent ownership figure, which Commerce used as a suggested benchmark in various proposals, doesn't represent legal control, the petition conceded. "But it does introduce substantial minority ownership, and thus influence and diversity in this area," according to the petition.

Minorities also should be involved in the operations of firms seeking an exemption, the Commerce Department said. Other arreas where minority involvement should be considered a reason for exemption are on the number of television stations in the top 50 markets that any broadcasters may own, and bans on television and radio cross-ownership in a single market.

The FCC already has the authority to make an exception to rules limiting ownership and has done so in some cases. What the Commerce Department proposes is to make explicit that minority involvement in a project is a factor that may lead to favorable consdideration.

The National Telecommunications and Information Administration also asked the FCC to expand the time period during which minority groups may purpose stations at distress-sale prices from broadcasting groups whose licenses are under scrutiny.