When Diana Ross left the Supremes, it was the beginning of the end - not just for the Supremes as a consistent hit-making organization but for "girl groups" as a whole. Ever since, the soul scene has been increasingly dominated by solo artists and self-contained groups.

So the ideas that a trio of female singers could suddenly become the hottest thing on the soul circuit seems a little out of date. After all, it is 1977, and we are in the era of P-Funk. But look at the top of the soul albums and singles charts, and there they are the Emotions.

Success did not exactly come overnight to these three sisters from Chicago. Though "Rejoice" (Columbia PC 34762) is only the second record the Emotions have done for Columbia, the group has been performing together for years. As the Hutchinson Sunbeams, they appeared on Jerry Van Dyke's television show in 1958, and they spent a good part of the 60s with Stax-Volt Records, where they were under the tutelage of the songwriting and production team of Isaac Hayes and David Porter.

Nowadays, Sheila, Wanda and Pamela Hutchinson are closest to Maurice White of Earth, Wind & Fire. He signed them to his Kalimba Productions when Stax-Volt folded, and he's the one who co-produced their hit single, "Best of My Love." If you believe in the "starmaker" theory, you might even want to say that White has made the Emotions what they are, just as he's had much to do with the rapid rise of singer Deniece Williams.

But that would be to ignore the contribitionss of the individual Hutchinsons. Sheila in particular has emerged on "Rejoice" as a brilliant vocalist and skilled songwriter. Backed by the Earth, Wind & Fire rhythm section on "Love's What's Happenin" and by a group of prominent West Coast session musicians on "A Feeling Is," she creates with her vocals and her writing a bright, happy, carefree mood.

The titile tune, written by Wanda Hutchinson, has the same feeling. As a group, the Emotions favor breezy, upbeat numbers, though "Key to My Heart," which EWF bassist Verdine White wrote and on which Maurice White sings, is a sweet and splendid ballad with a strong horn introduction.Many of these are love songs, of course, but "A Long Way To Go" and especially "Blessed" indicate that the trio is capable of tackling weightier subjects.

So though the Emotions are in some respects a throwback to the days when groups like the Vandellas, Shirelles, Marvelettes and Crystals were major forces in pop music, their music has a distinctly 70s character. The Supremes never wrote their own songs, and when they sang about love, they didn't mean universal or spiritual love. As much because of their material as they vocal style, the Emotions have been able to inject some life and excitement into a soul format that badly needed it.

Other new release on the soul front include:

Aretha Franklin: Sweet Passion (Atlantic SD 19102). Her career began in the church, and though she's moved on to sing jazz, pop and anything else that catches her fancy, Aretha Franklin still may be one of the finest gospel singers around. "Sweet Passion" is essentially a middle-of-the-road effort - there are two songs written by Marvin Hamlisch here, including the hit single "Break It to Me Gently" - Lady Soul is at her best singing and playing piano on the intense and fervent "Touch Me Up," written for her by producer Lamont Dozier. Equally impressive are here multitracked vocals on "When I Think About You," where she sings both parts of a call-and'response chorus.

Earl Klugh: Finger Paintings (Blue Note BN-LA737-H). Like George Benson, in whose band he used to play, guitarist Earl Klugh has crossed over from jazz to pop - and quite pleasantly, too. He plays acoustic guitar almost exclusively these days, so his instrumental versions of proven pop hits such as James Taylor's "Long Ago and Far Away" and Orleans' "Dance With Me" have a gentle, soothing sound. Two Brazilian-style numbers in which Klugh plays in the manner of Joao Gilberto, "Dr. Macumba" and "Cabo Frio" have a funkier, loping beat, but that's due more to the heat generated by an all-star rhythm section than Klugh himself.

Al Jarreau: Look to the Rainbow (Warner Bros. 2BZ3052). Here in America, Jarreau has only a cult following, but in Europe, where this live, double record set was recorded earlier this year, he's enormously popular. What seems to draw the strongest audience response on this album, Jarreau's third, are the tines featuring wordless bursts of pure vocalese - scat singing, in other words.