A funny thing is happening down on the South African platteland, that flat expanse of farmland and isolated small towns where white racial attitudes have always been at their hardest.

Last Tuesday white businessmen from half a dozen small towns decided at a meeting here to send a delegation to Pretoria to put the grievances of local blacks to President Pieter W. Botha.

A second delegation will call on Constitutional Affairs Minister Chris Heunis to ask him to let the little towns take over the administration of their adjoining black "locations" from the central government, because they believe they can give the blacks a better deal.

This sudden concern for black welfare in a traditional bastion of apartheid is the result of the latest campaign that blacks have launched in their rebellion against the country's system of segregation and white minority rule.

For the past three months, in one small town after another in the racially volatile eastern Cape Province, blacks have been refusing to buy goods in white-owned stores. They have been getting by with the few essentials they are able to purchase at the rudimentary stalls in their ghetto townships, which are called "locations" in the outback.

In some cases where there are not enough "location" stalls, the boycott organizers have exempted one or two general stores in the adjacent white town, usually those run by shopkeepers with less hard-line racial attitudes.

The results have been shattering for the white shopkeepers. Many had not realized until now how dependent they were on the "location" customers, whom they dealt with brusquely and sometimes compelled to use separate entrances. Many have gone bankrupt and all are suffering. According to some commercial leaders in the little towns, it has been a blow worse than the Great Depression of the 1930s.

The shopkeepers' reactions have varied. Some have tried, often with the security forces, to crush the boycotts. Others have become eager to meet and negotiate with local black leaders. This has resulted in the blacks presenting lists of grievances, some broadly political, some relating to their local living conditions, which these strangers to interracial negotiation are now pondering.

It was the problem of finding themselves thrust into the unaccustomed role of having to intercede for the aggrieved blacks that led to Tuesday's meeting here -- and the decision by the businessmen to send delegations to Botha and Heunis.

Two towns in particular represent the polarities of white reaction to the boycotts. One is Colesburg, in the sheep-farming Karroo region 150 miles northwest of Cradock, where local blacks contend that there has been an attempted countersiege to make them abandon their boycott.

The other is the resort town of Port Alfred, 200 miles to the southwest, where the whites became involved in negotiations with local black leaders that led to a lifting of the consumer boycott and some direct meetings between the blacks and government representatives.

Blacks in Colesburg say that local businessmen, backed by the police, tried to starve them into submission. They say there was an attempt to pressure two exempted stores into refusing them service, and that water supplies to the town's three "locations" were shut off twice.

Jaap de Ruiter, chairman of the Colesburg Sakekamer, an Afrikaner businessmen's organization, denies this. In a stormy interview in his office -- during which he telephoned police, who arrived presently and ordered me not to enter the "locations" -- de Ruiter said the only water stoppage had been due to a burst pipe and "because we have a drought here."

He implied that the exempted stores were reluctant to sell to blacks because too many wanted to buy on credit. "They are starving themselves out," he said, although he later admitted that it was "not totally incorrect" to say the Sakekamer had tried to pressure the exempted stores into closing.

One of the exempted shopkeepers, Wynies van Wyngaard, confirmed that there had been such an attempt but would not elaborate. The atmosphere in Colesburg is tense with aggression, fear and mutual suspicion.

Despite the attempted countersiege, the boycott is continuing and appears to be ruthlessly enforced. Blacks interviewed in the town Wednesday told how boycott pickets had stopped a woman who had bought meat at a local butcher shop that day and flung her purchase into the dirt. When she complained to police, black activists beat her unconscious, poured gasoline over her and set her on fire. She is now in a hospital in critical condition.

Port Alfred, by contrast, is relaxed. Two factors seem to have set it on a different course. One is that a former industrial psychologist named David Hanson decided to make the resort his retirement home, so that when the boycott began Port Alfred whites had someone to advise them on conflict management.

The other is the presence of an able and forceful black leader named Gugile Nkwinti, a former nurse now studying law at Rhodes University in nearby Grahamstown.

On Hanson's advice, local whites formed an employers' federation that opened negotiations with a group of black community organizations headed by Nkwinti. The employers' body, headed by Charles de Bruin, chairman of the local Chamber of Commerce, pledged its support for the blacks in trying to get redress for their grievances.

"We made it clear we wanted to become involved," de Bruin said. "We told them we were not in a position to discuss government strategies, but we could comment on local problems and we offered to use our channels of communication so that they could get to government to present their grievances."

Within two weeks, the boycott was called off. Meetings were organized with the chairman of the government body that administers black affairs in the region and with the local provincial counselor who represents the ruling National Party.

The influence of both Colesburg and Port Alfred has spread to other towns. Emulating the hard-liners, the Chamber of Commerce in Queenstown, west of here, has advised its members to cut the pay of their black employes in retaliation for the consumer boycott there.

It also has circulated a pamphlet advising housewives to keep their black domestic servants from taking food and other provisions home to the "location," saying that is "only feeding the intimidators."

Port Alfred's de Bruin, on the other hand, has become a roving adviser to towns that want to negotiate. He visited Cradock recently, and now the white traders here also have formed an employers' federation and begun negotiating with representatives from the "location."

Most people in the region believe the advocates of negotiation are gaining ground. "I would say most of the towns in the eastern Cape are swinging the way of Port Alfred rather than Colesburg," said Frank Collett, who was chairman of the Cradock meeting. "People who think long-term can see that negotiation is the only way to solve the problem."

Tony Gilson, director of the Port Elizabeth Chamber of Commerce, whose members are suffering the most effective boycott of all in that major eastern Cape Province city, agrees.

"Some who favored counteraction have come around to the view that that is not the right way," Gilson said in an interview. "They are beginning to realize that it would not only be ineffective but in the long run will make the real solutions much harder to achieve."

Gilson confirms an impression that the boycotts have jolted the whites into a sharper appreciation that their country is in crisis.

For more than a year the black townships have been imploding with revolutionary violence, but this made little impact on the whites living in their tranquil separate suburbs. Only when the boycotts began to hit them where it hurts did they become more aware of black grievances.

"Obviously our members are not happy about the boycott," Gilson said, "but it has awakened an awareness that the causes are a manifestation of genuine aspirations. Many businessmen now realize that there has got to be genuine reform."

In some towns there seem to have been major conversions. Johan van Rooyen, who represented the businessmen of backwater Steynsburg at Tuesday's meeting, said the first reaction of some whites in his town to the boycott was to arm themselves and form a vigilante group.

But the "Skiet Piets" (Afrikaans for "Shooting Peters"), as he called them, changed their minds as others began negotiating with local blacks. They found that whites considered to have a bad racial record suffered most from the boycotters.

"We've got one guy who beat up a black 15 years ago and they remember that. He's having a helluva time," van Rooyen said.

The result, according to van Rooyen, is that some supporters of extreme right-wing political parties are now among Steynsburg's most enthusiastic negotiators.

"We have built up a fantastic mutual trust in Steynsburg," van Rooyen enthused. "I really think we can work out something that can suit us and build up good will, peace and prosperity. If all of us can start at this basic level and build up trust, then I think we can solve our problem nationally as well."

Several others at the meeting exuded this kind of enthusiasm. It is as though the discovery of contact across the color line has released a latent moral energy in this unlikely environment.

There could be disillusionment ahead. Many blacks express a skepticism verging on cynicism about this new-found white concern. They also have discovered a weapon to use against the whites nationally, but one that could override local agreements made by local black leaders.

Another factor in many towns is the intervention of the security police, whose arbitrary arrests often disrupt the negotiations. The businessmen of Port Elizabeth cannot begin negotiations because all the city's major black leaders have been detained. "We keep appealing to the police to release them, but we get a flat no," Gilson said.

Even the Port Alfred accord is in danger of collapsing because Nkwinti was detained two weeks ago. This has sown suspicion among the local blacks. "I'll never let Gugile negotiate with the whites again. I don't trust them," his tearful wife, Koleka, said.