A crowd of more than 6,000 gathered at Wolf Trap last night for the National Symphony's all-Tchaikovsky extravaganza. At the close, cheers mixed with the second of cannons and enthusiams ran high.

THE NSO is a beautiful instrument, and its colors shone brightly in Tchaikovsky's Symphony No. 4. The authoritative brass in its opening was nicely foiled by the dreamy winds. The unruly bowing in the cellos in the first movement was refreshing, the fast and fragile pizzicato ostinato was briskly plucked, and the sheer power of the finale was staggering.

In a curiously selected suite from "The Sleeping Beauty," the music that accompanies Prince Desire toward the vision of Aurora brought lush and serene strings. The "1812" Overture had lovely cello singing.

If even the freshest memories of this concert are of individual musical moments rather than of whole works, it is because of Mstislav Bostropovich's erratic conducting of Tchaikovsky. The Fourth Symphony fell apart rhythmically, except for the finale; and where there was passion it was often neither attractive nor welcome.

It is unfair and perhaps unnecessary to expect a dance tempo in ballet music played in concert, but it at least ought to make sense. The Rose Adagio was played andante, or faster, Carabosse's theme stumbled over its own speed, and yet the sublime Lilac Fairy music suggested only heavy feet. As with the symphony, this suite had lovely, stirring moments; but there was no evidence that the music had been thought through, and the results were often shallow.

The "1812," on the other hand, is almost impossible to misinterpret and was also lavished with fine playing. The program, cannons and all, is repeated tomorrow at 8.