Growth in personal income slowed in most states during the first three months of 1988, the government reported Wednesday.

The Commerce Department also said the timing of farm subsidy payments depressed income in the corn-growing states of Nebraska and Iowa and boosted income in the wheat-growing states of Montana, North Dakota and Oklahoma.Growth in the 50 states slowed to 0.8 percent in the January-March period, compared with growth of 2.8 percent in the final quarter of 1987. Income dropped in six states, edged up in 42 and showed no growth in two.

In all but three states - Oklahoma, Idaho and Montana - income either fell or its growth slowed from the fourth quarter.

Residents of Montana saw their incomes shoot up by 6 percent over the last three months of 1987, the biggest increase of any state. Income in North Dakota jumped 4.1 percent while income in Oklahoma rose 2.4 percent.

All three increases were attributed to advance subsidy payments on the 1988 wheat and barley crops.

Nebraska had the biggest decline, 6.0 percent, followed by Iowa, 4.2 percent, and South Dakota, 2.6 percent. Incomes fell there in the January-March period following large fourth-quarter corn subsidy payments.

Other states suffering declines or no growth were Minnesota, down 0.8 percent; Colorado, down 0.4 percent, and Texas and Utah, both with no change.

The report noted that the effects of subsidy payments can vary substantially from state to state and quarter to quarter because the assistance is not paid out evenly over the year and each eligible crop is under a different subsidy program.

Excluding farm income, Nevada showed the strongest growth, 2 percent, followed by Vermont and Virginia, 1.7 percent each.

Alaska, the only state where incomes declined when farm income was excluded, slipped 1.0 percent. Oklahoma showed no growth, while Texas and Colorado edged up only 0.1 percent. Weak oil prices were blamed for the poor performance of incomes in those states, which are heavily dependent on oil drilling and mining.

Overall, personal income excluding farm payments rose 1.0 percent in the 50 states.

The report also noted profit sharing and bonus payments by auto companies boosted income in Michigan, which had a 0.9 percent rise, and Ohio, where income advanced 1.0 percent.