Delta Air Lines Inc. said it expects its first-quarter results through Sept. 30 will be significantly worse than the equivalent period last year.

The airline cited the sharp rise in jet fuel prices and the current condition of the economy as reasons for the decline.Delta said it now pays about 94 cents a gallon for fuel, compared with 57 cents a gallon on July 31.

Delta has previously announced a 5.3 percent domestic fare increase effective Aug. 30, and a further 4.2 percent effective Oct. 1.

The increases are designed to offset the increase in fuel costs. But neither increase will have a significant impact on first-quarter 1990 revenue.