Senate Minority Leader Howard Baker, Jr. (R. Tenn.), who may have the single most important vote in the Senate on the controversial Panama Canal treaties, today cautiously adopted a position in favor of Senate approval.

At the same time, Baker told Gen. Omar Torrijos, Panama's leader, that he saw "no chance" that the treaties could win the required two-thirds approval in the Senate if submitted as presently written. There will have to be some modifications, Baker said, both to satisfy him, and to win over two-thirds of his colleagues.

Baker described his position to reporters late last night in his Panama City hotel, then repeated it briefly today at Torrijos' seaside home northwest of here. Associates said Baker had only made up his mind in the last few days.

Torrijos told reporters he was "very satisfied" with his talks with Bakers.

The Tennessee Republican - regarded as a likely presidential candidate in 1980 - did not specify exactly what modifications he would demand in the treaties, but he indicated they would not be extensive. At the least, he said, the Senate would have to "act on" the assurances Torrijos gave in an unsigned communique with President Carter in October.

The communique said the treaties should be interpreted to say that the United States retains the right to protect the neutrality of the Panama Canal, though military intervention if necessary, and that U.S. warship would have priority rights to pass through the canal in an emergency. ad2 Panamaf-F - nicholson

These points concern numerous Senators, and it already appeared likely that a reservation or an amendment incorporating them would be adopted in the Senate,

[TEXT OMITTED FROM SOURCE] modifications "to guarantee certain rights in (certain) situations," he could approve the treaties, and they could win Senate approval.

Baker told Gen. Torrijos of the need for formal modification of the treaties during a one-hour meeting this afternoon. Earlier, the general led a tour of Panama by helicopter, airplane, bus and foot for Baker, Republican Senators John Chaffee of Rhode Island and Jake Garn (of Utah), White House lobbyist Frank Moore, and a crowd of wives, aides and reporters.

After their private meeting, Torrijos declined to discuss Baker's statements in any detail. He told reporters he was "very satisfied" with their talk and added:

"We have an open mind; we are not dogmatic; we do not feel that the truth is only within the limits of what we say."

Whether that was a signal that the Panamanian strong man would accept some additons to the treaties was not clear. Torrijos presumably is not prepared to discuss that question openly now, before the Senate debate has evern begun. There is a vocal, nationalistic element here that accuses Torrijos of already yielding too much to the United States.

Baker and Chaffee both said after their talk with the general that they were favorably impressed by Torrijos' flexibility.

"My general impression is there is a possibility" of finding a jointly acceptable way to win approval for the treaties, Baker said.

Even Sen. Garn, who has come out against the treaties, noted Torrijos' "willingness to be conciliatory" after the meeting. Garn said changes in the treaties could also persuade him to vote for it, but did not specify what changes.

Chaffee has already said he would vote for the treaties without any modifications, but he said today he would rather see some changes if they would enable the treaties to sail through the Senate instead of squeaking by.

In his relaxed conversation with reporters late night - his remarks were embargoed for publication Thursday morning - Baker acknowledged that the Panama issue is "loaded with dynamite" for him, both because of his leadership role in the Senate, and because he is perceived as a presidential candidate.

Baker has been probably the principal target of anti-treaty pressure groups, and has received thousands of letters urging him to vote no. He has hired two consultants on the issue -one who favors the treaties, and one who opposes them.

Baker said he did not think the Panama issue would split the GOP irreparably or linger as a major issue until 1980, but he said it was a very emotional question.

When Torrijos first invited Baker to Panama a month ago, associates of the senator said he was inclined to refuse the invitation. Baker's view of the panama issue has changed substantially since then, these sources said. Last night, Baker said he though he would vote to report the treaties from the Senate Foreign Relations Committee of which he is a member.

Baker said he expects Majority Leader Robert C. Byrd (D.W.V.), to bring the Panama treaties up for Senate consideration in February, perhaps right after the Feb. 10-20 recess.

It took a flotilla of 11 U.S. and Panamanian air force helicopters and one two-engine passenger plane to carry Torrijos, Baker and their party on a hopscotch tour of Panama today.

During the trip, the American senators saw Torrijos mingle freely and joke with his people, and elicit views contrary to his own from Panamanian citizens.

The three Senators will continue to meet the Panamanians and American officials here for the rest of the week, and will see Torrijos again Saturday morning before leaving the country.