THE "DECONCINI RESERVATION," which the Senate attached to the first Panama Canal treaty, is a ratty thing to behold.Imposed on a desperate (and careless) White House by Sen. Dennis DeConcini (D-Ariz.) as the price of his vote, it authorizes the United States on its own to use military force "in Panama" to keep the canal open and operating after the year 2000, when ostensibly Panama would be in full control. The "reservation" is arrogant. It mocks the intent to replace the dangerously obsolete terms of the 1903 treaty with a relationship respectful of a small country's sovereignty and pride. And it could yet kill the two Panama treaties.

Here is why: From the moment it was enacted, Mr. DeConcini's handiwork galled all Panamanians, regardless of their attitude toward the government or the new treaties. All other Latins, too, instantly understood that the language trod grossly on Latin America's traditional resentment and fear of American intervention. It can be argued that, regardless of treaty language, this country has the power to intervene in Panama, and would. But to state that, to rub Panama's nose publicly in the dirt, is intolerable. So it is no surprise that the Panamanians, passing beyond their initial, relatively subdued criticism of the reservation at home, are now soliciting international sympathy for their objections to it. Once international support for their position solidifies, as almost certainly it will - and why not? - they may openly reject the reservation and hope to face the United States down.

Now, perhaps Gen. Omar Torrijos, the Panamanian leader, is feinting, or trying to win an international moral victory to cover Panama's humiliation. Or perhaps he is merely gathering international support to deter further hurtful amendments that the Senate may impose on the second treaty (covering the period up to 2000). It may yet turn out that Panama's crushing need for the new revenues promised by the treaties will induce the general to swallow his pride, brush aside his opposition and accept the administration's worried assurances that the reservation does not really alter the substance of the first treaty. It is not inconceivable that he will bow to the threats of Sen. Howard Baker (R-Tenn.), who, incredibly, takes the position that since he, Howard Baker, has "really gone out on a limb for these treaties . . . our friends in Panama ought to know that just the twitch of an eyelid, just the slightest provocation or expression that these treaties, or this treaty in this form, is not acceptable to Panama, and this whole thing could go down the tube." By jingo, Mr. Baker, how could Panama dare to inconvenience your presidential aspirations?

Such are the stakes for both countries, however, that anyone wishing both countries well is reduced to foisting upon Panama an additional burden of compromise. We say with genuine regret that we do not see that the Panamanian government has a good alternative to learning to live with the DeConcini reservation. To carry its anger to the point of giving the Senate the pretext to turn tail on the treaties would be a disaster. In a fairer world, it would not be this way. The fact is that the United States lacks the maturity, and the administration the political prowess, to make things come out otherwise.

The shame of this approach is evident. If, however, Panama finally balks at accepting the American revision of the first treaty, or if the Senate poles more equally egregious amendments on the second, then it is clear where the principal responsibility for the resultant diplomatic catastrophe will lie. It will lie on uninformed, insensitive, posturing ligislators like Dennis DeConcini and Howard Baker - men demonstrably blind to the requirements of treaty other nations, even a small, close, friendly and strategically vital nation like Panama, with decency and respect.