Willie Nelson looked like a natural in his brief appearance in "The Electric Horseman." In fact, his disembodied baritone remained the most satisfying, evocative element in the show.

The somewhat embarrassing revelation of "Honeysuckle Rose," opening today at area theaters, is that Willie Nelson doesn't appear ready to carry a leading role. He looks faintly preposterous as the bone of contention in this flimsily contrived romantic triangle about country-western show folk.

Nelson appears too withdrawn or inexperienced to come out of his grizzled shell and articulate the passionate impulses or sheer vanity that lead the character he portrays -- country singer/bandleader Buck Bonham -- into romantic folly. As a result, the acting load shifts to the women devoted to Buck. As his admirable wife Viv, Dyan Cannon shoulders the burden so deftly that she may save the movie from sappy collapse. As Lily, the adorning young thing who coaxes Buck into a brief affair, Amy Irving is such a quivery love-smitten doe that Cannon's performance seems heroically magnified. Irving's tremulous exertions keep threatening to nudge the movie over that sappy brink.

The plot of "Honeysuckle Rose" is borrowed from "Intermezzo" the 1939 tear-jerker in which David O. Selznick introduced Ingrid Bergman to American audiences by remaking one of her Swedish films. Nelson and Irving play country-western adaptations of the classical musicians originally portrayed by Leslie Howard and Bergman.

Buck Bonham is presented as a celebrated love object. He makes no romantic overtures. Lily already idolizes him, confessing that she's been going to sleep since girlhood with his songs in her heart. The hero doesn't have to lift a finger to get this ingenue into bed; Buck evidently does it all with his haunting lyrics.

There's a messy intramural aspect to the affair, and it aggravates the weaknesses in Nelson's characterization. Lily is the daughter of Buck's grand old sideman and crony Garland (played by Slim Pickens, mellowing into a more imposing and invaluable comic institution with every passing year and role). As the story begins, the band is coming off a tour. Buck rejoins Viv and their little boy. During this break Garland decides to retire. At Viv's suggestion, Lily is hired to replace her father temporarily for the ensuing tour.

The affair blossoms as soon as the band hits the road again. Viv, a former vocalist who looks after the Bonham ranch and business arrangements, gets wind of things and forces a crisis by turning up for a surprise look-see. What she discovers provokes a sensation at a concert: She walks on stage after Buck and Lily have finished a cozy duet and announces that the marriage is finished. "Isn't that the kinda thing country songs are all about?" Viv asks ironically in the shocked aftermath.

Leslie Howard satisfied popular notions of a melancholy, painfully sensitive gentleman. Nelson's resembles one of the favorite codgers of my boyhood, Gabby Hayes, incongruously disguised as a squaw man. The connotations ain't the same.

Nelson needs to demonstrate an active attraction to Amy Irving if one is to make sufficient sense of Buck's betrayal of wife and friend. His passivity makes the affair look rather insignificant to Buck, who appears to indulge a show-biz form of droit de seigneur by taking advantage of Lily's infatuation. Given his longstanding relationships with Viv and Garland, there would appear to be more compelling reasons for him to avoid getting entangld with this particular young admirer.

Was the script always underwritten or did the filmmakers shy away from testing Nelson's acting range? Obvisously, it was hoped that the songs would be suggestive enough to camouflage the dramatic holes. Whenever a decisive dramatic confrontation is needed, the remedy is "Sing, Willie, sing!"

With "The Seduction of Joe Tynan" and "Honeysuckle Rose," Jerry Schatzberg has demonstrated considerable improvement as a director. But he overindulges one particular editing device in "Honeysuckle Rose" -- cutting from the performance of a song in public to little illustrative details of the band traveling and socializing that occur perhaps before and perhaps after the performance itself. The most annoying affectation of this kind occurs when Emmylou Harris appears briefly for a duet with Nelson.

Schatzberg's technique remains too slack and wayward for my taste, but it's no longer detached to the point of inertia. In addition, "Joe Tynan" and "Honeysuckle Rose" suggest that Schatzberg may help to bring out the best in certain actresses. Barbara Harris and Meryl Streep were wonderful in the former. Dyan Cannon does wonders for the latter.

She seems to have gotten a second wind, beginning with her delightful supporting bits in "Heaven Can Wait" and "Revenge of the Pink Panther." Now more attractive and resourceful than ever, she endows Vic Bonham with a subtle but always comprehensible play of emotions.

The concluding sequence, in which Viv must decide whether to forgive Buck's infidelity, would be dead without Cannon's ability to suggest the ambivalence felt by this proud, affectionate and ultimately wise show-business spouse. In the closing number, Cannon's acting is far more eloquent than Nelson's crooning. The leading lady rescues a vehicle meant to enhance the image of her leading man.