The administration of Maryland Gov. Harry Hughes put the finishing touches today on a $37 million supplemental budget for the coming fiscal year that includes an additional $2 million for the magnet school desegregation plan in Prince George's County.

County Executive Parris Glendening, who had pledged to finance the magnet program from county sources if necessary, said the additional funds will allow the county to spend $2 million on "other crucial needs." He would not specify where the money would be spent.

With $3.5 million promised for the magnet program in Hughes' original budget for fiscal 1987, the money in the supplemental budget will increase the state's contribution to the program to $5.5 million.

"We are very, very pleased," said Glendening. "This governor and this state legislature have been significant in their support for education."

The magnet plan, which the county launched last fall, is expected to cost $12.9 million in the 1986-87 school year. Glendening announced this winter he would make unspecified "internal adjustments" to cover that cost and a $40 million increase in the fiscal 1987 education budget, approved by the Board of Education at $389 million.

School officials had asked the state to fund the entire cost of the magnet program next year and reimburse the county for $9 million spent on it this school year.

"Any increased support by the state government for desegregation is greatly appreciated," said school spokesman Brian J. Porter, "although certainly more could be done."

The supplemental budget adds $15 million to a reserve fund established in the wake of the state's savings and loan crisis. It also provides $9.5 million to improve Maryland's helicopter evacuation service for medical emergencies, contingent on legislative passage of a tax amnesty program that could generate millions of dollars in new income for the state government.

Other supplemental funds include $980,000 for the state's legal expenses in the thrift crisis; $500,000 to fight acquired immune deficiency syndrome (AIDS); $600,000 for family planning, and $60,000 for a program to prevent youth suicide.