It is hardly a matter of doubt anymore: America's ability to immorate just isn't what it used to be. And a panel of distinguished researchers and professionals says America herself is to blame.

In a somber forum Tuesday night sponsored by the National Academy of Sciences, six representatives of business, government and academia added their concern to that expressed by others in recent months over the disturbing realization that something's happened to Yankee ingenity.

Signs of America's innovative spirit on the wame are everywhere, the panelists noted. Among the evidence cited was:

The declining growth rate of the U.S. economy and only minimal gains in productivity.

The worsening U.S. balance of trade, caused in part by increasing imports of foreign-manufactured goods.

The decreasing number of U.S. patents issued to U.S. inventors and an increase in patents issued to foreign inventors.

The declining amount of real dollars spent on research and development by industry and the high degree of concentration of the R&D that is done in a few industries and a few companies.

These indicators are distressing," said Elmer B. Staats, U.S. comptroller general. Stressing the historical importance of technology innovation in powering America's economic growth, Staats warned that unless specific steps are taken to stimulate innovation, Americans can expect their standard of living to stagnate and their competive ranking in the world to weaken.

How has the U.S. which once placed a premium on inventiveness and made national heroes out of its pioneers, reached this state of affairs. Although on one could offer a complex explanation, the panelists generally agreed that government actions were largely to blame - specifically, restrictive tax and regulatory policies, along with complex and confused antitrust and patent laws, that together have eliminated financial incentives for industrial innovation and have discouraged investment in R&D.

"Innovations affect the economy, but the reverse is also true," declared Ivar Giaever, a Nobel Laureate who supervises R&D for General Electric and the panel moderator. "The economic climate affects the amount of innovation, and the climate recently has not been encouraging."

In addition to legal impediments and financial discincentives, the warning of U.S. innovation also has been attributed to business managers' defeatist attitude and lessened inclination to take risks.

Business leaders on the panel conceded that U.S. companies are focusing more on short-term results in their planning, preferring to concentrate on innovations that will improve existing processes and reduce costs rather than yield a major break-through. But they said this is simply the result of having to cope with a more uncertain marketplace.

"As much as anything, it is uncertainty that effects industry's inclination to invest in connovations," stated N. Bruce Hanay, vice president of Bell Telephone Laboratories.

President Carter appointed a 28-agency task force last spring to spend a year studying the innovation dilemma, and a spokesman for the National Academy said a report on Tuesday's panel would be forwarded to the study group. The panel left no doubt what its major recommendation would be.

"We must restore incentives, or remove disincentives, for entrepeneurs to take risks," concluded Ralph Landzu, chairman of Halcon International "Our industry is good at invention and entrepreneurship if you give it a chance."