As Maryland's new gasoline tax to finance highway repairs went into effect today, Robert A. Pascal, seeking the Republican nomination for governor, called a press conference at a Forestville service station to make a political issue of it.

Sweating under a broiling sun, Pascal, the Anne Arundel County executive, denounced the tax increase -- two cents this year, 2 1/2 cents next year, with automatic one-cent increases after that if the retail price of a gallon of gasoline exceeds $1.35. He declared that if Maryland's roads are in poor condition, the man most responsible is Gov. Harry Hughes.

"These roads and bridges did not get into this condition overnight," said Pascal, who repeated his routine later at another gasoline station in Baltimore. "They are in this condition because of systematic neglect and now the taxpayers are being asked to pay the piper because of it."

Pascal pledged that, if elected, he will see to it that the automatic one-cent rises based on the price of gas are eliminated from the law. "It is wrong to make it easy for a government to tax," Pascal said. "It should be grueling. The man who is responsible for the roads and bridges is the governor. I promise to repeal the last part of the bill, strictly for philosophical reasons."

Several hours later, after signing 432 new bills into law and vetoing 125 others during the final bill-signing ceremony of his first term as governor, Democrat Hughes fired back at Pascal.

"I don't know where Mr. Pascal's been these past months and years," Hughes said. "For years in the legislature, graduated taxes have been proposed this way. His own adviser, Mr. Herman Intemann, testified for that kind of taxation before the Ways and Means Committee." (Pascal said later he disagrees with Intemann's stand.)

"Until today," Hughes continued, "I never knew that Mr. Pascal had any opposition to this kind of tax because he's never said a word about it. I guess it's just more political rhetoric."

Responding to Pascal's charge that he, more than anyone, was responsible for the condition of the state's roads because of, "systematic neglect," Hughes said, "Our budget for road maintenance was overspent in 1979 and 1980. To say that (neglect of roads) is simply not true. That's just more irresponsible political rhetoric not based in fact."

He had one final slap at his opponent: "This is all very interesting for me to hear since, if you check the Anne Arundel County budget for this year, you will find that the amount budgeted for fixing roads is zero, absolutely zero." Pascal said later this is so because his county is seeking state bond funds for road repair.

Hughes' response to Pascal's charges came after he signed into law another controversial piece of legislation, a bill raising interest rate ceilings on most types of consumer loans from 18 percent to 24 percent.

To its critics, the interest rate bill came to symbolize the lending industry's increasing power in the State House. Hughes and his consumer-oriented attorney general, Stephen H. Sachs, had opposed interest rate deregulation in the past, but this year became tenuous allies of the banking lobby and prodded the legislature, with the result being huge legislative successes for the lending industry.

Spurred by the Maryland Bankers' Association, the lenders recently announced that the controversial compromise adopted by the legislature was not enough. The banking lobby hired a Baltimore law firm to review the bill's consumer protections, particularly those restricting variable interest rates, which had been worked out after tortuous negotiations with the attorney general's office.

The lawyers produced a 66-page opinion that said the bill was so vague that it would be an administrative nightmare for lending institutions that were forced to comply with its rules.

Some officials in the attorney general's office were noticeably piqued last week when they learned of the bankers' legal opinion.

Hughes, too, whose support of the bill placed him at odds with some consumer advocates but bolstered his stature with the business community, sent a veiled message to the bankers to live and let live.

"The state needs this bill; I support it, that's why I signed it," Hughes said. "I'm disappointed that they bankers are saying the bill is not enough. This is an election year. By all odds we normally wouldn't have gotten to first base with a bill like this."

Asked if he thought the bankers were wrong to push for more, Hughes said, "Sure I do. At this point they should let this work a while and see what happens."

The Teamsters' Union submitted a petition to the state Board of Elections today calling for a referendum on the ballot in November to allow voters to decide the fate of the interest rate bill Hughes signed today. But elections administrator Willard Morris said the petition, which had about 11,000 signatures, "looks suspicious.

"We've got a signature on here from Anchorage, Alaska," Morris said. "They're from all over the country, apparently any place a truck could stop." The teamsters need 30,000 valid signatures of Maryland voters (10,120 of them on the petition submitted today) to have a referendum scheduled.