Antal Dorati introduced a vibrant work to the National Symphony audience last night when he led the orchestra's first performance of Zoltan Kodaly's Peacock Variations. Kodaly, who died in 1967, was one of Hungary's symbols of freedom during much of his long life.

The variations, written in 1939, grow out of one of the composer's favorite folk songs, which is richly elaborated in varying moods during the relatively brief work. The brilliant scoring is as individual in sound as the chromatic harmonies and rhythmic figures are familiar-and yet it would be hard to ascribe the music to any other man.

The wonderful performance, stamped with Dorati's authentic command, reached an ecstatic peak in Oshio Kohno's improvisatory flute solo, supported by whispering harp and tremulant strings.

The fiery spirit of the whole is vividly embodied in the blazing coda. This is music we have waited too long to hear.

It was preceded by Beethoven: The second Leonore Overture, least often heard of the four written for "Fidelio," and the Violin Concerto. The overture, with more use of minor keys than its companions, and its unfamiliar trumpet call in place of the one in the opera, was played unusually deliberately, and with strong effect.

Henryk Szeryng was the soloist in the concerto, probing its beauties with exquisite tone, and handling the bristling Joachim cadenzas as if they were not really all that difficult. Dorati and the orchestra gave him ideal support that had, however, a certain detachment. The program will be repeated nightly through Friday.