NEW YORK, APRIL 16 -- The New York Daily News, the nation's largest general-circulation newspaper, discriminated against four black reporters and editors in promotions, salaries and assignments, a federal jury found Wednesday night.

The case was the first one of racial bias involving black editorial employes and a major news organization to go to trial in the United States, and black journalists predicted today that it would affect newsrooms nationwide.

In a work force of 57,700 editors, reporters and photographers on daily newspapers, 6.6 percent are black, Hispanic, Asian or Native American. About half of those minority professionals are black. Of the country's 1,650 daily newspapers, 56 percent have no minority staff members.

The four-man, two-woman jury, which included one black woman, is to meet next week to set damages. In negotiations with The News, the plaintiffs reportedly had asked as much as $1 million each.

Jack Dunleavy, a News spokesman, said the paper would appeal and "ultimately be vindicated." Its case "was hampered by the trial judge's highly prejudicial rulings which excluded key witnesses and evidence," he said, adding that The News "will continue to pay, promote and assign on merit. The paper will also continue the ag- gressive affirmative action pro- gram . . . . "

F. Gilman Spencer, the News' editor, said 57 of its 445 editorial staff are minorities, including 42 blacks. The News has a circulation of 1.3 million, and about one-third of its New York readership is black.

The nine-week trial was marked by acrimonious personal charges on both sides. The lead plaintiff, reporter David Hardy, called The News, a tabloid known for its knock-'em-sock-'em headlines, "a little bit of South Africa on 42d Street." A News attorney called Hardy "a monumental ego" who used his stories for "vendettas."

The plaintiffs, who filed the suit in 1982, charged that racial epithets were used regularly in the newsroom. Plaintiff Joan Shepard testified that a white editor called her "streetwalker" after she had covered a walking tour of the city.

The jury concluded that Shepard, now a $48,800-a-year cultural affairs editor, was not considered for four job openings in the 1970s and 1980s. "This is another chapter in the struggle for racial equality in the United States," she said. " . . . Only those in the inner circle would find out about job openings. One friend tapped another friend on the shoulder and said, 'This is opening up in a couple of months.' "

Hardy testified he was removed from covering the 1980 Abscam scandal, although he had broken a story about one of the major figures involved. A "racist star system" determined assignments, he said.

Lawyers for the newspaper portrayed the defendants as mediocre journalists and, in the case of Hardy and copy editor Causewell Vaughan, ethically careless. The fourth plaintiff is assistant news editor Steven Duncan.

Trial testimony revealed that Vaughan was disciplined for asking a former U.S. representative to cosign a $2,400 loan in 1979. Vaughan later defaulted and the legislator had to pay it off.

The News also introduced evidence in pretrial motions that Hardy had written stories linking his landlords to the Mafia while he was involved in a tenant dispute with them and had not told his editors about the conflict. The landlords sued and The News was held liable for a reported $200,000 in damages. But Manhattan District Court Judge Miriam Goldman Cedarbaum ruled that the incident was inadmissible as evidence. Similar bias suits have been filed against major news organizations, including The Washington Post, The New York Times and The Associated Press in recent years, but all have been dropped or settled out of court.

Albert Fitzpatrick, president of the National Association of Black Journalists, said the verdict would "have a tremendous impact in the industry in that it will make newspapers and other entities in the media take a look at how they are treating minorities."

Kay Fanning, president of the American Society of Newspaper Editors, said, "We are trying to attract minorities to our newspapers. This whole case has been very counterproductive. I'm concerned it might influence minorities to feel unwelcome on newspapers."