Saying, "this is a very sad occasion for all of us," Frank E. Taplin, president of the Metropolitan Opera Association, announced yesterday that the Met has canceled its entire season because of failure to reach agreement with striking musicians.

It was the first time in this century that the Met has canceled a season. The dramatic announcement was made at a press conference in the opera hall's List Hall.

"The executive committee has voted unanimously to cancel the '80-'81 season," Taplin said. "The committee acted upon the unanimous authorization of the board of directors."

"We are at the mediator's call," said the opera's executive drector, Anthony A. Bliss. "However, I do not see any possible resolution in time to operate this season. If such a resolution occurred within a few days, we would do our best. After Thursday, the singers in the company may take engagements elsewhere. At that point, directors and conductors and singers would have other dates and it would be a question of availability. But I do not see any such possibility."

Taplin said negotiations broke down over the orchestra's demands for a four-performance week. "They want pay for four performances per week this season equivalent to that which they were paid for five performances last season. We cannot negotiate on that issue. In addition, there are 17 unions with whom we must sign contracts. There is a ripple effect in the unions, and they would want percentage increases to match the orchestra's gains."

Noting that the cancellation will put some 1,200 to 1,500 Metropolitan employes out of work, Bliss said, "The most tragic effect of this will be for the chorus and the ballet and the others who are not in this fight. But we simply cannot afford to put on a patched-together season and expect to live up to the artistic standards our audiences and contributors rightly demand. We cannot put the Met back into red ink without losing our donors. . . "

"Nothing will happen unless the orchestra stops acting like lemmings."

Picketing union members were bitter at the news of the cancellation. One man said, "we have not had one negotiating session. We have had dictating sessions, all one-sided. But Bliss is walking the plank."

William Shuman, the famous American composer, said while walking across the great plaza in front of the opera house, "It is horrible to think that the Metropolitan might actually close down."

Texaco announced at noon yesterday, before formal word of the action was out, that in the event of a cancellation they would carry on with their weekly broadcast of operas as they have done for nearly 800 performances from the stage of the Metropolitan. There will be the usual intermission features, but the music will be heard via recordings. All of the operas scheduled for the season are available on records.