Last year Maryland legislators toiled over how high they would raise the mortgage interest rate ceiling, but this year a major concern will be how low they will keep state spending.

As the General Assembly's doors open today, legislators will face more than picture taking and perfunctory resolutions for constituents. They must address bills curbing government spending and controlling budget surpluses as well as changes in the state's laws covering occupational disease, unemployment insurance, product liability and disposal of hazardous waste.

Other legislation which already has been filed ranges from bills encouraging employe stock ownership plans to those prohibiting foreigners from owning agricultural land or a large percentage of voting stock in a commerical bank. Other legislation would grant tax credits for energy-saving devices and stimulate development of alternative sources of energy such as coal liquefaction and gasohol.

In addition, the perennial sales tax reduction legislation has been prefiled as well as a request to study the possibility of a new state license plate.

One issue some legislators and lobbyists guarantee to be controversial this session concerns changes in the state's occupational disease laws. A commission studying the issue has made certain recommendations but "labor feels it was on the short side of that commission," said Senate Economic Affairs Committee Chairman Harry J. McGuirk (D-Baltimore).

What is most controversial is not what was included in the commission's recommendation, but what was omitted, namely the presumption that a disease contracted by a worker on the job was caused by conditions at the work place. Labor has pushed for inclusion of that presumption in legislation and is expected to do so again this year. Business groups such as the state Chamber of Commerce oppose such a presumption.

Labor groups also want to abolish the state medical board which hears occupational disease cases, but the commission has recommended expanding the board from three doctors who currently decide the cases.

Another expected controversial proposal changes in unemployment benefits from a flat 106-a-week payment to about two-thirds of the average weekly wage in the state, McGuirk said. The state Department of Human Resources is pushing the legislation to improve benefits to the state's unemployed workers. Many states already tie benefits to the average weekly salary.

The chamber, however, opposes such legislation because it would wrench control of unemployment benefits from the legislature and it could "lead to uncontrolled benefit costs," said Samuel W. Christine III, a chamber lobbyist.

Bankers will be watching legislation to raise the interest rates for demand, consumer and credit card loans to 18 percent.

Currently, the ceiling on demand loans is 12 percent. The interest rate on consumer loans cannot exceed 18 percent if the loan is less than $3,500 and 12 percent if the loan exceeds that amount.

The interest rate on credit card finance charges is limited to 18 percent on the first $500 and 12 percent on the excess, according to William K. Weaver, executive vice president of the Maryland Bankers Association.

The bankers back such a bill because they said money has become too expensive to lend at lower rates, Weaver said. But, he added, "It's an extremely difficult bill to get enacted because nobody wants to vote higher interest rates."

Other legislation would require a commission to review the whole spectrum of product liability while another would establish a special board to determine sites for the disposal of hazardous wastes.

Another bill would grant tax credits to manufacturers who install pollution-control devices. That proposal was suggested by the state Department of Economic and Community Development because pollution-control equipment is a necessary expenditure by industrial and commercial firms in the state, but adds nothing to their productivity.

Another proposal espoused by the state is changing its levy on interstate railroads from a 2 percent gross receipts tax to a corporate income tax on net profits. The proposal is intended to improve the financial condition of the railroads and encourage their investment in new equipment, state officials said.

A tax-increment financing bill would allow counties and incorporated municipalities to use revenues from urban or downtown redevelopment to pay bonds issued to finance the redevelopment.

One of the early concerns of the legislature, however, is expected to be proposed constitutional amendments to limit state spending and control revenue surpluses.

Other legislation already prefiled would:

Prohibit Sunday racing at Bowie race track.

Authorize $5 million to acquire a site for, and plan, design, construct and equip a coal liquefaction plant.

Require retail service stations to post price information, have an air pump, water and toilet facilities available and provide air and water free.

Broaden the definition of franchises and add certain record-keeping regulations for them.

Prohibit the state Public Service Commission from granting the telephone companies authority to charge rates based on the length of local calls.

Restrict evictions of senior citizens from buildings being converted into condominiums.

Establish a Maryland Research Park Authority near the University of Maryland College Park campus. The park would be geared toward research and high-technology industries, and would involve the government, private business and the university. It would be similar to the Research Triangle concept located between Durham, Chapel Hill and Raleigh, N.C.