TUNICA, Miss. (AP) _ A restaurant owner whose business is off 30 percent quit making doughnuts because nobody buys them. The same news about dried up business is repeated at the liquor store, tire shop, grocery and appliance store.

The worst drought in 50 years is a double whammy for Tunica County, one of the poorest counties in the nation. Farmers who grow cotton, soybeans and wheat in the upper Mississippi Delta are afraid their crops will burn up, and a lake that used to lure tourist dollars is so low that few fishermen and boaters bother to go out.

''Boy, it hurts. There's not a business in town that's not affected,'' said Jim Fowler, sitting behind the counter of the customerless Brown Bag Liquors. ''It's a real bad situation all the way around.''

Tunica County is 64 percent farmland. It ranks 78th among Mississippi's 82 counties in per capita income, with a yearly average of $6,800, according to the state economist's office. Other than the recreation business from the lake, it has no industry. The population is 9,652, down from 16,826 in 1960.

Cotton is still king here, accounting for 40 percent of the crop value. But there also are long, straight rows of soybeans, wheat, rice and other crops in flat fields of sandy loam and buckshot black clay.

They're all struggling to grow. There hasn't been a decent rain since April.

'It hasn't got to the point where we're going to abandon the crop and throw the towel in. But we're hurting,'' said county agriculture agent Dwayne Wheeler.

''The drought affects everybody. When the farmer's not spending money, there's not a whole lot of money being spent,'' Wheeler said.

''It's killing my business,'' said Wiley Chambers, owner of the Blue and White Restaurant, where the glazed cake doughnuts are a thing of the past. ''These farmers won't spend any money when it looks bad, and it looks bad.''

Jim Sturgill, owner of Delta Tire and Alignment, had nary a car or tractor in his garage.

''Look in the shop, there's nothing. We haven't done any business,'' Sturgill said.

On a 100-plus degree day, the pavement seems to melt in the distance under a blistering sun, and dogs nap in what shade they can find. Tractors pulling discs kick up clouds of dust that hang in the air and assault the throat.

Owen Bibb, 55, has 4,000 acres of land, some of which hasn't been planted while he waits for rain. On Friday, he laid off 15 farmhands.

''We're scared of what may be facing us,'' Bibb said. ''We're in no position to stand a sorry crop. We can't survive a complete bust. All we can do is put our faith in the good Lord. Worrying don't help.''

If it's too dry to plow, the fish surely aren't biting at the Tunica Cut- off. The 20-mile-long lake was once part of the Mississippi River, which made a meandering loop.

In 1942, the U.S. Army Corps of Engineers eliminated the loop by plowing a new channel, leaving a lake fed by the river. With the river at its lowest level since records were first kept in 1872, the lake is emptying.

The county is losing an estimated $20,000 each week on gas, groceries, bait, hardware and other goods the fishermen aren't buying, according to the Tunica Cut-off Lake Development Association. The estimate is based on a Corps of Engineers study last year on the lake's economic benefits.

''It's pitiful. It's killing us,'' said Tait Selden, 33, owner of one of four fishing camps on the lake.

Fishermen normally come from Arkansas, Missouri, Tennessee and Ohio for the lake's bounty of bass, brim, sauger, crappie and catfish. But Selden said his business is off 80 percent. Parking lots that hold 200 cars on a good weekend are barren.

''If this lake wasn't here, this town would have dried up and blown away a long time ago,'' Selden said.

Selden and his associates want the government to build a dam to keep the lake at an acceptable level.

For now, there's nothing but shrinking businesses that match the shrinking lake. Marvin Daughtry, who raises bugs for bait, says his business is off 40 percent overall and 70 percent on the lake.

''It absolutely scares me to death the future implications of this,'' said the owner of Daughtry's Cricket Ranch. ''Nobody knows how deep this is going to go.''