"Falstaff" -- the name of the single monumental character that is also the name of Giuseppe Verdi's last and finest opera -- can easily lead an audience to expect a one-man show. This is particularly true in a production like the one that opened last night at Wolf Trap, when the cast is composed of Donald Gramm and nobody else in particular.

Such expectations were only partly fulfilled last night. Gramm's performance as the corpulent Romeo was, in fact, worth the price of admission all by itself. He is internationally famous in the role, and in this production he clearly showed why, with a voice that ranged from indignant basso as he thundered against a "world of villains" to a thin, piping treble as he imitated the amorous sighs of the ladies he intended to conquer.

But "Falstaff" is, above all else, and ensemble opera, a collective effort that cannot be carried or held together by a single star. The Wolf Trap production worked, on the whole, very well despite a few rough edges, and the reason is that the nobodies surrounding the superstar turned out to include quite a few somebodies.

Except for Gramm, the production was cast with members of the Wolf Trap Opera Training Program -- young singers who have spent the summer here for final polishing of their talents and the kind of exposure that may help to launch them on major careers. Several of them demonstrated that they are ready to start such careers.

There is a special excitement in this kind of production, the excitement of discovery. Some Washingtonians have an air of satisfaction when they say that they saw stars being born at Wolf Trap in earlier years -- for example, in the pioneering production of "Treemonisha" in the early 1970s.It is likely that someday people who were at the opening night of this production will show the same kind of satisfaction when they say they saw Jennifer Barron and Peter Lightfoot singing "Falstaff" with Donald Gramm at Wolf Trap in 1980. These were the two who made the strongest impression in a cast that had many good performances and few notable weaknesses.

In the role of Alice Ford, Barron's statuesque physical presence and rich agile voice were put at the service of a carefully developed comic talent. As her husband, Lightfoot showed a need for some further training in dramatic movement and gestures before he will be ready to meet the most stringent acting requirements of major opera companies today -- but his acting was quite good enough by operatic standards of the recent past, and his singing was glorious, not only as music but as dramatic music. He is very precise in timing, appropriately varied in dramatic nuance, crystal-clear in diction (an important point since this production uses Andrew Porters's excellent English translation) and emotionally powerful.

Hardly less noteworthy, though they were cast in parts of secondary importance, were Stephen Owen and Neil Nease singing the comic roles of Pistol and Bardolph. Their antic acting somewhat overshadowed their singing, simply because the script required them to do more of it, but their voices were excellent when called upon, either solo or in their frequent comic harmonizations.

Marsha Henderson, in the role of Mistress Quickly, gave a satisfactory performance both vocally and dramatically, but with further experience and some final polishing, she should be able to develop it even more. The same was true of Stephen Schnurman, in the role of Dr. Caius. Kathryn Karassik and Rodney Miller, who sang the young lovers, Nanetta and Fenton, both have fine voices which missed on one or two notes in last night's performance; neither had a role that seriously tested dramatic ability.

Eric Caldwell, who had been scheduled to conduct, suffered what was announced as a "slight indisposition" last night, and so the young singers found themselves unexpectedly facing a young conductor, Caldwell's assistant, Fred Scott.He is, despite his youth, already a seasoned conductor, and his expert knowledge of the score was shown in a myriad of fine touches, once he had established full control after a slightly uneven beginning. There were occasional problems of balance between the orchestra and the singers, but for the most part, these were minor.

The sets and costumes, the charming children's ballet in the final scene and the stage direction, all gave the aspiring singers a showcase of high professional quality. There were occasional problems of vocal ensemble, particularly in the light, quick passages, and the diction was not always as clear as the excellent text deserved. On opening night, the first act seemed less well organized musically and dramatically than the second, which was almost flawless.

On the whole, this production did justice to Verdi's masterpiece. And the people who shared the stage with Donald Gramm demonstrated their right to such an honor.