The scene in the basement of Bucky's Bar was like nothing the solid, prosperous farmers of this politically conservative area had ever encountered before.

Nearly 100 farmers and their wives crowded into the cave-like basement of the road-house tavern here to listen attentively as seven long-haired outsiders, veterans of past environmental and antiwar confrontations, demonstrated how to use the tactics of nonviolent protest.

The long-haired instructors, some from as far way as Philadelphia, were invited by the farmers to come out to this rural area last week for help in a bitter struggle that has pitted more than 1,000 angry western Minnesota farmers against the United Power Association and the Cooperative Power Association, two large rural power cooperatives seeking to construct the nation's biggest high-voltage power line through here.

Clashes over construction of the line, scheduled to run from a strip mine and power plant complex in Underwood, N.D., to the outskirts of Minneapolis, are expected to flare this week. Construction crews are scheduled to resume surveying work here Monday after a delay of nearly a year prompted by a series of violent confrontations over the line between farmers and construction workers.

Uneasiness over the safety of ultrahigh voltage lines, which carry twice the power of all but a handful of existing electric transmission line, recently has raised concern over possible health hazards among farmers and other rural residents in New York, Iowa, North Dakota, Montana, Ohio and California.

Jittery officials in several counties here have requested a call-up of units of the Minnesota National Guard to meet what farm leaders have pledged will be widespread resistance to the line from members of nine different groups organized across western Minnesota to oppose the project.

Minnesota Gov. Rudy Perpich has declined to say whether the guard would be used to protect construction workers but has announced the state would sanction peaceful protests by the farmers. Perpich rejected a similar request for the guard during last year's clashes. The governor has been touring the area alone by car the last two weeks and telephoning farmers urging calm.

Perpich has also offered to form a "science court" to help mediate the dispute. So far farmers have rejected the idea because construction would continue during the science court's deliberations.

The 410-mile project would leapfrog across the rich black dirt farmland here in 1,400-foot jumps between towers that would, at up to 185 feet in height, literally tower over the flat Great Plains landscape. Farmers opposing the line say they fear the line's total power load of over 800,000 volts of direct current could create hazards to humans or livestock in its path.

Last month the New York State Public Service Commission, which is embroiled in a similar dispute with farmers there over a 765-000-volt line now under construction, ordered power companies to maintain a 550-foot protective zone under the line. The commission's staff warned that preliminary research indicated ultrahigh voltage lines could cause possible but unspecified "biological effects" on humans living nearby.

Researches in New York have said they have found that the heavy electric field generated by the high-voltage lines has caused blood and growth disorders in laboratory animals. A University of Minnesota researcher siad recently that the unusually high voltages of the lines could produce toxic gases in the atmosphere around them.

Utility officials say, however that it is too early to tell whether the line are hazardous to health, but that research is continuing.

In Western Minnesota, where uncommonly rich soil and regularly bountiful harvests have not encouraged political activism, there is an even deeper chord that seems to have been struck by the transmission line controversy.

Farmers give varying reasons for opposing the line but a common theme appears to be that it has become symbolic of what some farmers see as a continuing erosion of concern for independent farmers and rural areas in favor of the needs and desires of cities and big business.

Ironically the electric co-ops sponsoring the lines are owned by farmers and supply the critical electric power that is needed to operate heavy, farm machinery. But farmers here say the co-ops have outgrown their original purpose. "This is not a cooperative venture anymore," said Verlyn Marth, a farm owner from Grant County who has been a spokesman in the past for protesters of the line. "It's a billion dollar energy cartel and it has nothing to do with us anymore."

"We're being tramped on constantly and used by these people and that is what this whole thing is all about," said Virgil Fuchs, another protest leader here.

Fuchs, 35, achieved local hero status last year when he flatened the equipment of a survey crew with his tractor and then rammed the crew's pick-up truck as workers attempted to lay out a right-of-way for the line across his land.

Farmers here contend that the lower cooperatives ignored their objections and laid the course of the line straight through their fields rather than along "section lines" that are generally not farmed and mark the boundaries of fields.

When several counties, whose local governments are dominated by farmers, either rejected permits for the line or laid down stringent conditions for its construction, the power cooperatives went to the State Envoirnmental Quality Board which granted the permits.

Late last month the Minnesota Supreme Court rejected the farmers' legal appeal, setting the stage for a resumption of work on the line. The farmers have indicated they plan to sue in federal court in Washington on environmental grounds.

The Minnesota protest centers on Pope, Meekers, Sterns and Grant counties, which stretch in a line along the route of the project almost to the North Dakota border. Farmers here have established a tight communications network of citizen's band radios and party line telephones to warn of the approach of a survey crew for the line.

Last year, when a crew attempted to work across a Pope County farmer's land, more than 50 farmers showed up within a few minutes and encircled the survey crew. In the ensuring struggle, eight farmers and power line workers were arrested and one farmer was hospitalized. Farmers here now refer proudly to the site of the battle as "Constitution Hill."

Roving crews of protesters have also adopted a type of guerrilla warfare hit-and-run strategy against the surveyors; waving protest signs in the fields to block the survey crews' line of sight, and barreling along nearby unpaved roads in pickup trucks raising clouds of dust also to obstruct sight of survey crews.

Here in Stearns County, Bucky's Bar has become a de facto - if somewhat unlikely - headquarters for the local guerrilla movement. Farmers hunker for hours under a wall lined with softball trophies and stuffed ducks discussing which strategies to use against the power line crews.

At the training session last week, instructors from the Minneapolis-based environmentalist group. Movement for a Better Society, worked with farmers to draw up a long list of harassment tactics. The ideas ranged from inviting construction crew members into the bar and drinking them under the table to filling their construction holes with liquid fertilizer.

The movement has also drawn sympathy from local law enforcement leaders. One lawman quietly suggested last week that if enough farmers turn out at the construction sites the projects will have to be halted while police write citations, for civil disobedience for each protester - a 10 minutes process.

Despite the emphasis on nonviolence, there is uneasiness that more serious trouble could break out if the confrontations multiply and get out of control. Tempers are stretched taut and many farmers - and construction workers - carry shotguns or rifles racked in the rear windows of their pick up trucks.

"No one is going to do it in front of a television camera, but if they try to put that line through here it's going to be blown out or shot up some night," said Marth, the Grant County farmer leader.

"Farmers are putting out the message here to the power companies," he said. "If you come out here, you're facing nearly 500 miles of hostile territory and if you want our land you're going to have to take it away by force."