In the country's agricultural heartland, old

ingrained fears tinge the debate over the referendum next month on Gen. Augusto Pinochet's presidency.

For prosperous landowners, frightening memories of farm seizures by leftist peasants in the early 1970s has helped push them solidly into the pro-Pinochet camp.

"This is the fear we have, of returning to the past," said Francisco Olea, owner of a 100-acre spread here in the country's fertile Central Valley.

But for struggling farm workers, the prospect of reprisal by their bosses or local officials is keeping many from openly voicing dissent. Some say resentment with Pinochet's authoritarian rule, and with a hand-to-mouth existence, will find expression in the ballot box.

"At least before there was work, and the worker had the right to express his opinion," said laborer Ramon Arias, as he painted a tractor by the roadside. Two farmhands with him made similar comments, but refused to give their names.

Chileans will decide Oct. 5 in a yes or no ballot on a new term for Pinochet, the right-wing army commander who seized power in a bloody 1973 coup and has already ruled longer than any previous president.

If a majority vote for him, he will remain as president until 1997, but the military junta that he has headed as the governing body since 1973 will be disbanded. If he loses, open elections will be held in a year and he must hand over power in 1990, when a new Congress, two-thirds elected and one-third appointed, will go into place.

Farmowner Olea and others like him have benefited from an export-oriented, free-market economic program carried out by Pinochet's administration. Foreign sales of grapes and other fruit, much of it grown in the Central Valley, have been booming. With government credits and technological assistance, many farm owners are expanding production and making solid profits.

But they have not forgotten the chaotic, radical reform programs launched by President Salvador Allende, a self-declared Marxist elected in 1970 and toppled in the coup led by Pinochet three years later.

Olea's home and land were illegally seized by peasants. He negotiated with them so he could live in his house, which also had been taken over, while they worked his land as they liked.

"We lived through a savage lack of order," said Luis Aullet. "There was no respect for your home, your land."