Poor ratings could mean last roundup for 'Seven Brides'

Seven Brides for Seven Brothers is scheduled for a divorce from television . . . unless more city folk tune in. That's the word from CBS headquarters, where Nielsen numbers - spelled m-o-n-e-y - often are the only gauge for series longevity.

''Seven Brides for Seven Brothers'' (Wednesday, 8-9 p.m., check changed listings for following weeksm) has been a popular show in small-town America but a failure in the big cities. That's why this innovative singing-dancing-action show, which concentrates on old-fashioned family relationships and takes place on a ranch, is airing its last new show of the season next Wednesday and after that retires into reruns for the rest of the season.

The crucial status of the show and a need to promote it in urban America are what instigated a last-ditch publicity campaign by producers David Gerber and MGM/UA Television. That's why the star of the series, Richard Dean Anderson, has come acallin', western style.

Dressed cowboy style in jeans and workshirt, Mr. Anderson, who played the role of Jeff Webber on ABC's soap opera ''General Hospital'' for five years, is anxious to prolong the life of ''Seven Brides.'' He's tall, brown-haired, brown-eyed, and as straightforwardly honest a person as the character he plays in the struggling series.

''There's a pure aura about the show,'' he says earnestly. ''The value of the close-knit family unit is always there. And there's an honesty that's obvious in the relationship between the family members. It's probably the basis for what transpires in a lot of families throughout America, in rural and urban areas.''

Richard admits that the song-and-dance routines within the framework of the show were difficult for some audiences to accept. ''You'd walk off the ranch, scrape the mud off your boots and say, 'Hey, that reminds me of a song' and break into a dance. For lots of people that's a little hard to fathom. So, the singing and dancing have been downplayed in the last few shows and there is more of an emphasis on action-adventure.''

''Seven Brides'' is unique in series TV this season in that all of its episodes are shot on location. Instead of the eastern Montana locale of the original film on which the series is loosely based, the stories now concern the area where the series is filmed - the one-time gold-mining town of Murphys (pop. 1,183) in the Mother Lode country of northern California, in the foothills of the Sierra Nevada.

Aside from lots more viewers, what would Richard Dean Anderson like to see the show accomplish?

''I don't want to take a pompous attitude,'' he says with embarrassment, ''but I think the show has a lot to say to all Americans about the value of close family ties. I think it is an honest reflection of a family unit scrapping , bickering some, but always loving and doing what it can to survive. If it can establish its own morality and remain true to itself, then I'd be ecstatic.''

After Richard loped off, I spoke to CBS Entertainment president Donald (Bud) Grant in Hollywood. ''It's up to audiences now,'' he said ominously. ''We won't really know if it is going to survive until the new schedule is announced (sometime in April).

''It's one of those shows which needs just a little more in the way of viewers to make it. Sure 'Seven Brides' has become a fine show, well executed, with a sense of what America is all about. But it just has to get better numbers.''

Wednesday is your last chance to see an original ''Seven Brides for Seven Brothers,'' one of network TV's few family-oriented shows. Unless there's an upswing in viewership, you can count on the ''Seven Brides'' wedding march turning into ''Olde Acquaintances.'' The stars glitter on PBS

This weekend PBS has captured two glorious programs to suit the nation's varied music lovers.

In the midst of WNET/NY's struggle to survive as the major originator of PBS prime-time programming, it is presenting its public broadcasting partners with two of the season's most impressive musical shows, one featuring pop music, the other, mainly classical: Jukebox Saturday Night (PBS, Saturday, 8-11 p.m., check local listings) and Gala of Stars 1983 (PBS, Sunday, 8-11 p.m.).

I have not only screened both completed shows, but I was present earlier at the tapings. And I can report that the opportunity to see all the performers close-up on TV makes up in great part for the thrill of being present at the live performances. Especially if the shows are being stereo simulcast in your area (check local listings).

The 1930s and 1940s nostalgia for swing, jazz, and Dixieland is given free rein in Saturday's ''Jukebox.'' Perhaps just a bit too much free rein. All of the performers from the past are amazingly spry, their talent amazingly intact. But, just about all of them are on too long - the show would have benefited from tightening.

Who's on ''Jukebox?'' Well, there's Margaret Whiting, Helen Forrest, Helen O'Connell, Bea Wain, Jack Leonard, Herb Jeffries, Keely Smith, and Bob Crosby, all introduced by Eddie Albert. And, most impressively, there is Betty Hutton, a woman whose successful personal comeback brings the audience to its feet in tears. There's a fine house band and even some of the original members of the Bobcats. The audience gets up and dances, enjoying every moment of this one-night revival of the swing era.

''Gala of Stars 1983'' doesn't skimp on stars, either. Besides host Beverly Sills, there is Garrick Ohlsson, Grace Bumbry, Mirella Freni, Carlo Bergonzi, Sherrill Milnes, Patricia McBride, Suzanne Farrell, Lynn Harrell, scenes from New York City Opera's production of ''Candide,'' Cleo Laine (yes, Cleo Laine), and a surprise visit from one of the entertainment world's top superstars today - Placido Domingo. If all of that talent doesn't lure you, there is also the inimitable Miss Piggy.

Of course, the exquisite pleasure of being at a live performance is missing, but this peerless (if a bit wearing because of its length) version directed by Kirk Browning is the next best thing. Both specials provide resounding evidence that PBS viewers everywhere - throughout America as well as in New York - must support WNET financially so that it can continue to bring such consummate fare to public broadcasting.

As a member of the on-camera live audience of both of these shows, I was especially eager to see the taped versions. My verdict? Well, the music was great but the hair on top of my head seems to be thinning.