Several of the performers who participated in the University of Maryland's four-day workshop called "The Business of Singing" capped off the event last night by getting together at the Tawes Theater and practicing their business. The concert was about as ad hoc as you can get--to the point that there was not even a printed program because the singers did not choose their repertoire until the last moment. Fortunately, there were no duplications.

The participants: soprano Lucine Amara, mezzo Betty Allen, baritone Gene Boucher, mezzo Louise McClelland and tenors Barry Morell and George Shirley.

There were spectacular moments, like Amara and Shirley in the final duet from Puccini's "Turandot," as well Calaf's gorgeous aria "Nessun dorma" from earlier in the opera, sung quite well by Shirley.

There were also fine low-key moments, like Allen's versions of the songs "Praises and Prayers" written for her by Virgil Thomson. One of the appealing parts of the program was that singers introduced their own material. Allen said that Thomson had first sent her some rather passionate love poems that he proposed to set. She sat on them for three weeks, because she wasn't too happy with the choices. Finally, she said, Thomson called her and said he supposed he could read the handwriting on the wall, and that maybe religious verses would be better. The resulting songs are full of the typical Thomson cross between the plain and the very sophisticated. They are delightful and should be sung more.

Amara sang heavyweight opera, "Suicidio" from Ponchielli's "La Gioconda," "Ecco la vita" from Verdi's "A Masked Ball" and "Pace, pace mio Dio" from Verdi's "La Forza del Destino." She remains something of a wonder. This is a woman who made her Met debut 32 years ago. Though her voice was never the most opulent one, it has remarkable staying power. Except for the final note of "Pace, pace," there was no sign of diminishment. The sound she poured into Turandot, especially, was potent.

Barry Morell was a stand-in for Jan Peerce. He sang Cavaradossi's two arias from "Tosca" with real passion.

McClelland did Viennese operetta material: two arias from Zeller's "Der Vogelhander," "Come Gypsy" from Kalman's "Countess Martiza" and that great song that isn't from an operetta but sounds like it is, "Vienna, City of My Dreams." We don't hear this delectable music enough these days; McClelland sounded lovely and idiomatic.

To begin the evening there was something special with Gene Boucher. He sang four droll songs by Milton Rosenstock set to masterful verses by Ogden Nash. One hilarious one was Nash's reaction to a government report commssioned in the 1950s to address an urgent problem of "wild geese eating up the Mall." Boucher added, "No one knows what ever came of that report."