Of music and maestros: NYC's Mehta to stay; San Francisco's de Waart to leave

When an orchestra feels good about its music director, it is bound to play better than when rancor riddles the ranks. And better playing was most noticeable at the New York Philharmonic last week , just after it had been announced that Zubin Mehta had renewed his contract as music director through 1990.

It put an end to the ridiculous speculation that he might leave New York to return to his old home, the Los Angeles Philharmonic. It evidently was just what the Philharmonic players wanted to hear.

Many of them had been dismayed when reports of in-house dissatisfaction with Mehta began circulating in the press this past summer. Evidently, they wanted everyone to know the orchestra is behind its music director. Unexpectedly, in Richard Strauss's technically demanding ''Sinfonia Domestica,'' the Philharmonic was playing carefully and attentively.

It was not just that Mr. Mehta was back in town, after having spent the opening weeks of the season with the Israel Philharmonic. In fact, Rafael Kubelik had opened the Philharmonic year in September and led the opening-weeks concerts. The orchestra had played in a routine fashion for him. And Mr. Kubelik is not a routine conductor; his reading of Beethoven's ''Eroica'' symphony was clear, precise, dramatic, stirring. His account of William Schuman's 10th Symphony (''American Muse'') was equally trenchant. (How nice to find a European conductor of Kubelik's esteem conducting American music.) Schuman's symphony is a pretty, affecting work, which Kubelik unfolded affectionately.

I first heard Mr. Mehta this season in a pension fund benefit concert that featured Mstislav Rostropovich. The opening work on that program had been Stravinsky's ''Petrushka'' and had been marked by particularly raucous, unruly playing. At a later concert, Debussy's ''Jeux,'' the playing all but fell apart for the technical indifference.

Hence the genuine surprise in hearing the Strauss performed so well. ''Domestica'' is not one of the most popular of Strauss's tone poems, and critics have deplored the family-life ideas incorporated into the score - such things as his wife, his crying baby, and other nursery scenes, a chiming clock, and so forth.

The music intrigues and entertains with passionate, tender, and rich tunes. Mehta let the piece unfold effortlessly, with a sure sense of the Strauss line. It was a happy performance of a happy work, and that happiness - rare at the Philharmonic - suffused the afternoon. San Francisco Symphony

Another orchestra that is clearly happy with its music director is the San Francisco Symphony. The two concerts offered in Carnegie Hall under Edo de Waart were on a far higher level than a concert the orchestra offered here last year (not to mention a concert I heard in San Francisco during the same season). These were also two deeply satisfying concerts in matters of programming and execution.

The first night featured Liadov's charming tone poem ''Kikimora,'' followed by Saint-Saens' now-rarely encountered Fourth Piano Concerto (Horacio Gutierrez the animated soloist), and Elgar's First Symphony. The second program began with Mozart's ''Nozze di Figaro'' overture and then the composer's Oboe Concerto - with the astounding Heinz Holliger as seamless soloist. The evening followed with Roger Sessions' Sixth Symphony and concluded with Rachmaninoff's Symphonic Dances.

The Mozart items are the only works encountered with any regularity these days. The concerto is more often heard in its flute version. The orchestra plays Mozart very well indeed, not always the case with US groups.

It plays Rachmaninoff even better - subtle shadings, superb rich sound, wonderful, evocative blends. The Sessions was performed as if the demanding music were second nature. And fortunate is the composer who can get such an accomplished performance of his or her symphony anywhere today!

The Elgar may have lacked a requisite, burnished Edwardian resonance. But the orchestra played the long arching phrases and the often ultrademanding virtuoso passages with commitment and understanding.

De Waart's versatility was constantly impressive. He is an accomplished accompanist, as he proved in the Saint-Saens, giving elegant underpinning to the excessively enthusiastic Gutierrez; in the Mozart, he followed Holliger's astoundingly long phrases with ease.

The Elgar hung together magnificently - no easy task for a Dutchman in music that generally only Englishmen manage to understand down to the last note. The Rachmaninoff surpassed just about anything in either concert. The composer's melancholia suffused the score, and the drama unfolded with thrust but no overripe bluster. It was the sort of performance one would wish to hear again and again, and Philips Records - who has the orchestra under contract - could do no better than to commit it to disc at the soonest possible opportunity.

De Waart leaves the orchestra at the end of next season. It may be too soon, but he leaves behind an ensemble of uncommon elegance and pliancy. The successor will inherit an exceptional group and it will be up to them to continue de Waart's superior efforts at building the orchestra into a front-ranking US ensemble. Esteemed maestro

Eugen Jochum is a revered, even esteemed, maestro, especially noted for his Bruckner. Thus the chance to witness his direction of Bruckner's Eighth Symphony with the Bamberg Symphony in Carnegie Hall was not to be passed up.

As it turned out, the performance was noteworthy more for intentions than actuality. Jochum's inexorable way with the score highlighted the majesty and power of the piece. But the Bamberg brass, in particular, performed so poorly it might have sounded like sabotage if one suspected the ensemble did not like the maestro. Yet the skeleton of Jochum's eloquent interpretation was secure, even moving. When the Bambergers played adequately, the maestro was given the respect his age and reputation so richly deserve.