The confirmation Friday of Rose Bird as California's first woman chief justice of the state supreme court produced a special bonus for the man who appointed her, Gov. Edmund G. Brown Jr.

Not only did Brown one of his closest advisers on the high bench and fulfill a pledge to women's groups, but he also put his frontrunning rival in the 1978 gubernatorial race here, Attorney General Evelle Younger, on a very uncomfortable spot.

Younger, a 58-year-old Republican, cast the deciding vote Friday which got Bird's nomination through the three-member Commission on Judicial Appointments. His vote could very well cost him important conservative support in his drive next year for the Republican gubernatorial nomination.

Younger said he cast his vote "reluctantly" but felt, after hearing witnesses for two days, that there was no reason to oppose Bird's nomination. "My limited responsibility requires only that I determine if Rose Bird is qualified," Younger said. "Absent any significant evidence to the contrary, I am compelled to find that she is."

Despite the luke-warm nature of his endorsement, Younger will have a difficult time explaining his vote to conservatives who dominate California's Republican Party. Bird, 40, has aroused intense opposition from key conservatives here who object to her liberal judicial views and her role last year in setting up the state's agriculture labor relations board. Conservatives and their grower allies accused Bird of stacking the farm labor board with members favorable to Cesar Chavez' United Farm Workers Union.

Since Brown's nomination of Bird last month, Younger has been under intense pressure from within his own party to quash her nomination. With the two state judges on the appointments panel split, Younger held the swing vote and thus received the most public attention.

All this month Younger, according to top aides, has been huddling with political advisers trying to figure out waht to do about the Bird nomination. "It's been pretty heavy," one high-ranking official at the attorney general's Sacramento office said this week. "People who hardly knew where he was were suddenly writing him and finding him. Everybody's been up here trying to put pressure on him."

Most of the advice Younger got from within his own party was to oppose the Brd appointment. Shortly after Brown named Bird, now his secretary of agriculture, for chief justice, 19 out of the 23 members of the Republican caucus in the state assembly sent a letter to Younger urging him to oppose the nomination.

The state assemblyman Jene Chappie, charman of the caucus, sad the assembly move was the result of deep disenchantment over Bird's performance on the farm labor issue and what seen as her permissive attitude on crime. Chappie added that Younger's support of Bird could cost him the Republican gubernatorial nomination.

". . . when damn near all the Republican caucus is saying vote against the old gal, well, you know he'd better not support her," Chappie said before Friday's vote. "I won't support him if he comes out for her. She represents everything we're opposed to."

Other threatening noises have come from grassroots conservative groups who were already turned off by Younger's support of President Ford in last year's Republican presidential primary here. Two prominent rightwing organizations, the United Republicans of California, and the Oakland Citizens for Law and Order, have pledged to oppose Younger next year because of the Bird issue.

From the other side Younger was heavily lobbied by women's groups, who threatened to oppose him if he helped defeat Bird. But aides to the attorney general, whose record has been generally praised by California feminists, said pressure from women activists had little to do with Younger's decision.

A more important factor, aides insist, seems to have been warnings from Younger's legal assistants that opposing Bird would be highly inconsistent with his previous record on the appointments board. They recalled that in 1973 Younger supported William Clark, a Reagan nominee to the Supreme Court, whose qualifications were in doubt because he had failed the bar examination once and never graduated from law school.

"Younger in the past has been very strong on his role not (one) being to decide if there's another person more qualified," a top aide explained. "All we're concerned with is that they're minimally qualified which Bird obviously is."

So Younger in achieving consistency has also reaped a tremendous amount of resentment from the conservatives who have won virtually every Republican statewide primary race here over the past decade. The situation for the attorney general is so uncomfortable now that some local political columnists have suggested that Brown nominated Bird at this time purely for the reason of embarrassing his potentially leading opponent.

But Gray Davis, Brown's chief of staff, said politics had nothing to do with the Bird appointment. "We're not trying to embarrass the attorney general," Davis said. "If Younger's in a difficult spot, he put himself there."