After a reopening night during which two reports of threats against nonboycotting horsemen were confirmed, a breakthrough was reported in contract talks between horsemen and the Charles Town Turf Club.

Alvin Trenk, vice chairman of the Kenton Corp., which owns the thoroughbred track, predicted that the horsemen's boycott will be lifted Saturday morning. He said that after a late-night meeting with Fendall Clagett of the Horsemen's Benevolent and Protective Association, which represents 1,800 owners and trainers.

"That could be more optimistic than I am at the present time," said Clagett. "But I'm hopeful."

Trenk's proposals will be presented to the horsemen at a 10:30 a.m. Saturday meeting that already had been scheduled to brief the HBPA members.

According to both sides, the horsemen would be asked to accept straw instead of sawdust and wood chips as stall bedding -- the major issue for horsemen because they say it would cost them at least $600,000 annually -- in return for a share of profits from manure sales and for other concessions in a new contract.

"It would be a contract which should be an attractive incentive to horsemen," said Clagett.

The horsemen here have been without a contract for two years. They have claimed that the new management, which took over in September 1977, has been trying to take away rights the horsemen had in the old contract.

While both Trenk and Clagett said the reported threats of violence -- which Clagett disclaims -- drew the two sides together tonight, they also said the main reason for getting a solution now involves proposed legislation that would be beneficial to this city's biggest industry.

Hearings are scheduled Tuesday in Charleston, the state capital, on a bill that would permit a local referendum on Sunday racing. Kenton Corp. announced last month it would close the track permanently because of a reported $250,000 in losses last year and a projected deficit of $750,000 this year.

Tonight's reopening was scheduled after Gov. Jay Rockefeller intervened and helped get the Sunday racing bill introduced. Trenk has maintained that only Sunday racing will permit the track to prosper and remain open.

Clagett said the horsemen also will ask the statehouse for 1 percent more of the weekday handle for purses.

Trenk is hopeful that contract negotiations can be completed in a few days while the horsemen enter their steeds so the track can race with full fields.

However, one horseman said tonight that the general membership had decided previously that it would not race without a signed contract. He is unsure whether the horsemen will change their minds about that Saturday.

Tonight's opening program drew a crowd of 2,873 which wagered $215,524 on a nine-race card that had 59 horses, including one four-horse field.

There were three scratches among tonight's entries, including McMurdo, the favorite in the fourth race.

Early in the evening Trenk reported that Arthur J. Smith Jr., the horse's trainer, had been threatened with violence as he approached the track entrance.

"A car with three men in it pulled up beside him and they threatened him with a shotgun," Trenk said. "They told him if he went into the track, they'd get him going home."

Smith then drove to a local store, called the track and was advised by Trenk to return to his Laurel, Md., home. Smith could not be reached for comment. The Martinsburg state police barracks verified that a report was made.

Another horseman, William S. Berry, said his wife received a phone call from a woman who threatened to burn their trailer if his horse raced tonight. It apparently was a case of mistaken identity; the real trainer of the horse in the first race was William C. Barry.

Trenk said that he had received calls from horsemen reporting a dozen threats. He said they all involved phone calls. Of the 16 jockeys who chose to ride tonight, including three from Waterford Park, only one reported a threat.

"I wasn't threatened to my face," said jockey Mary Ellen Longan, winner of the first race, "but behind my back."

Clagett issued a statement imploring horsemen not to make threats. He said he knew personally of no threats and added, "The two sides are getting polarized and I don't want to see it develop into any kind of physical violence. I don't see any threat of it. But management does."

Another scratch tonight was Gov. Rockefeller. His office phoned its regrets earlier today, because of the weather. But both sides, however, said he did not attend because of the lack of a contract settlement.

He missed about 30 pickets outside the entrances to the track. They carried such slogans as "This is The Final Straw," "No Contract, No Entries" and "Straw is Going to Break Our Backs."

Other no-shows were enough entries for Tuesday's program (Monday is a dark day this month). Racing Secretary William Dick reported late tonight that only 32 entries had been received for Tuesday.

A low-field card of nine races is scheduled Saturday night.

At lunchtime today, George Vickers, president of the local Chamber of Commerce, said local businessmen appeared to be in their best mood since the Kenton Corp. announced its shutdown last month.

"My business drops off almost 100 percent when the track's closed," said Phil Perks, owner of the Sportsman's Motor Lodge, facing the track across Rte. 340. "We hope the track keeps going for a long time. At 7 p.m. on Dec. 17 (the night after the 1978 closing) up to this time, Charles Town looked like a real ghost town. Believe me, no one was on the street."