The first half of this week's National Smphony subscription concerts at the Kennedy Center is relatively unfamiliar to today's concertgoers. Mstislav Rostropovich opened the program last night with Dvorak's "In Nature's Realm." This was a first performance by the orchestra in spite of the fact the lovely overture has been played in this country since Dvorak introduced it here in 1892.

There is a strong suggestion that nature in this particular case is in an autumnal mood. You hear little of the festive feeling of the familiar Carnival Overture the composer wrote to follow it. The lyrical character is relaxed and everything is lovely -- no storms, no thunderclouds. There are moments in the work where a more emphatic approach would benefit the whole. a

Bloch's Concerto Grosso No. 1 was played in honor of the 100th anniversary of the composer's birth. This is the first of two he wrote in this form, and the only one that is at all well-known. And even it had not been heard at a National Symphony concert in far too long. There are exquisite textures achieved through superb manipulation of string choirs heard against and in dialogue with the piano. The performance was strong throughout, gaining a wonderful hue in the pastorale and a kind of invincible vigor in the closing fugue. Hugh Wolff was properly applauded long and loud, along with the entire string orchestra, for the sheer joy of his musicianly pianism.

The final half of the evening went to the Pathetique Symphony of Tchaikovsky, which Rostropovich read with his customary affection, taking the first two movements with restraint, an approach that gave the whirlwind march an electrifying impact, bringing entirely appropriate applause from the audience. The orchestra played it with dazzling brilliance, and then offered up the final tragic threnody in overwhelming manner. It was a first-rate concert.