Before a jubilant crowd, Panama's triumphant leader Omar Torrijos handed over the newly signed Panama Canal treaties to his government as he arrived here from Washington this afternoon.

Dressed in a white uniform, Torrijos raised his fist in victory and told a crowd of almost 200,000, "Never in the political history of this country could a leader have felt happier and prouder than I am. We replaced the treaty forced on us with bayonets in 1903. I feel I have not defrauded your note of confidence. Ancon Hill," a famous landmark in the U.S!-controlled Canal Zone, "now belongs to you."

Torrijos set Oct. 23 as the date for a plebiscite to ratify the treaty. "Not to vote that day means committing a sin aginist the country," he added.

Despite the sweltering heat, the Fifth of May Plaza just a few hundred yards from the Canal Zone had turned into a giant festival of banners, choirs and dancers with marimba bands. Planes and helicopters flew overhead.

"Seventy years of dialogue with the deaf have ended," Torrijos said. "Panama was not heard . . . until the moral figure of President Carter emerged."

Accompanied by loud applause and cheers, Torrijos read a message from Carter saying, "You, the people of Panama, have been very patient and understanding during this long process. We are fully conscious of what this has meant. We Americans look toward coming here when we will be working together with you in understanding and friendship."

Many in the crowd were government employees, who were told to sign in at gathering points all over town. According to a high-school teacher, those not showing would lose a day's salary. Offices and factories received instructions to close at 2 p.m. to enable employees to attend.

Torrijos concluded his speech with an appeal to avoid violence and asked for "consideration for the poor, ignorant residents of the Zone who have really believed that this territory was theirs. The error they have committed does not justify a similar error by us."

After the hour-long public ceremony concluded with the crowd's singing the national anthem, a Panamanian National Guardsman's symbolically parachuted into the Canal Zone.

Despite fears by authorities on both sides that militant students might try to enter the Zone, no such incident were reported. About 50 heavily armed American military police walked in the Scared Heart Catholic Church of Zone police were seem patrolling residential areas in a bakery truck.

American authorities had recommended that Zonians not cross the line into Panama today. Department of Defense employees and school children living in Panama were sent home at noon.

American resident's appeared more apprehensive today than they usually are during Panama's nationalist demonstrations, and many rumors circulated among Zonians.

"It's self-preservation day," said the wife of one policeman. "My husband told me to stay inside and lock the doors." Like many of her friends, she was listening to the police radio.

A key official who has lived in the Zone for only two years explained that there was a mentality among the Zone's 35,000 residents, who often feel that violence and invasions are imminent. He said uncertainty about the future had built up tension here over the past three years.

"You might say the situation almost borders on a collective neurosis. The slightest rumor tiggers people off. And as a result of the strain there have been many divorces here lately," he said.

A young woman at the Balboa Yacht Club told a group of friends last night that in Panama "Helicopters are dropping leaflets telling people to go to into the Zone adropping leaflets telling people to go to into the Zone and choose which house they want.