Ever since his first inaugural address in 1979, Gov. Harry Hughes has pledged to respect the independence of the Maryland General Assembly, but he probably did not have in mind the kind of independence the legislature will exercise on April 10.

That is the night that Hughes, a candidate for the U.S. Senate, has scheduled a fund-raiser at a Baltimore hotel. As it turns out, on the same night the legislature will hold its quadrennial black tie dinner marking the end of its term.

The legislative affair could keep many lawmakers from attending the salute to Hughes. But at least one Baltimore legislator, Del. Samuel I. (Sandy) Rosenberg, sees no conflict at all.

"That's the date of the Orioles' first night game," said Rosenberg, a Democrat. "I'll be at Memorial Stadium." Funds for Pet Projects

When Sen. William H. Amoss took the Senate floor yesterday to try to protect a $419,000 grant for improvements at Susquehanna State Park, the Harford County Democrat knew he was in trouble.

It is pork barrel time again in the General Assembly, but Gov. Harry Hughes has not left any pork, to speak of, for legislators to pass around.

That means the Senate Budget and Taxation Committee is looking for some projects that it can cut out of the governor's capital budget so there will be a little money left for senators and delegates to spend on their pet projects.

And that explains why the $419,000 was cut from the budget and why Amoss was unable to persuade fellow senators to put it back even though he said the money was needed to halt the deterioration of the historic Manor House at the park.

Sen. Charles H. Smelser (D-Carroll), who handles the capital budget in the Senate, set forth the problem at the outset.

He noted that the governor and the legislature have an agreement to limit spending to $220 million in the capital budget, which provides money to buy land, build buildings and make improvements all over the state. Hughes used all but $15,000 of that amount in the budget he submitted to the General Assembly.

"We're attempting to find a few million here and there for the legislature," Smelser said.

The Senate processed about half of the capital budget yesterday and approved cuts of $11.7 million. More will be taken out as the rest of the program is processed next week. Lobbyist Disclosure Voted

A bill that supporters say would give Marylanders a better look at how lobbyists spend their money in Annapolis was approved yesterday without dissent by the Senate.

The bill would tighten the current law, which requires lobbyists to disclose the names of public officials to whom they give gifts valued at more than $75 during any year.

The chief sponsor of the bill, Sen. Julian L. Lapides (D-Baltimore), said that lobbyists with more than one client can evade the limit by splitting the value of gifts among several clients.

Lapides' bill increases the limit to $100 but specifies that the amounts charged off by a lobbyist to various clients must be added together and a report filed if the cumulative total is $100.