A joyous desert jam

Indio —  Bill GRAHAM, the man who turned concert promotion into an art form, knew above all what it took to get people to buy tickets.

“You could announce that the proceeds from tonight’s concert will give us a cure for cancer and that tickets are only $10,” Graham once said. “But the first thing anyone will ask before putting down his money is, ‘Bill, who’s playing?’ ”

The remarkable thing about the annual Coachella Valley Music and Arts Festival is that it has built so much credibility in just the five years since it started in 1999 that alt-rock fans are most likely simply to ask the dates of next year’s festival.

Saturday’s opening half of the weekend festival at the Empire Polo Field here underscored the point.

Even though one of the greatest bands ever in rock, Radiohead, made its only U.S. appearance of the year Saturday night, fans probably will more remember the overall 12-hour parade of bands and DJs than the British quintet’s 90-minute set -- as stirring as it was.

In fact, the moment that most defined the warm, tasteful spirit of Coachella came hours earlier Saturday when Beck, who wasn’t even part of the festival bill when it was first announced, took the stage for an acoustic set so informal that he pretty much made it up as he went along.

Beck, who headlined the opening day of the first Coachella festival, simply called promoter Paul Tollett a few days ago and asked if he could join the lineup.

Interest in the pop auteur was so high that 3,000 fans packed the festival’s Gobi Tent, while maybe twice that number stood outside in blistering, 99-degree heat. Los Angeles’ favorite young pop son has a new album due this fall, but he didn’t share any of it Saturday. He just wanted to have fun, and it was good to see a musician of his caliber feel free enough in the festival atmosphere to simply let his hair down.

During his 40-minute solo stint, he played some old favorites, including “Lost Cause” from “Sea Change,” as well as a song so new that he forgot all the words.

For the finale, he set down the guitar and picked up some device that resembled a TV remote. As he pushed various buttons, he triggered electronic drum beats to back himself on a version of his “It’s All in Your Mind,” also from “Sea Change,” but nothing seemed just right.

So, he invited five fans up to play tambourine on a good-natured, bluesy-folk treatment of the Kinks’ “Nothin’ in the World Can Stop Me Worryin’ ‘Bout That Girl.”

Total surprise. Total delight.

“I wanted to be here for two reasons,” Beck said backstage later. “First, they always have a slew of bands I want to see at Coachella, and I know the people here are open to seeing something unvarnished and spontaneous and that’s what I love myself. I’ve been in the studio for the last six, seven months and I wanted to get out and shake off some of the studio dust and play before people.”

Saturday’s headliners, Radiohead, and the reunited Pixies took less experimental paths, but both generated exciting moments.

The Pixies were among the most influential alt-rock bands of the late ‘80s and early ‘90s, and their return to action after a decade drew a sizable crowd to the main stage. The Boston quartet’s mix of aggressive textures, tuneful melodies and deeply introspective lyrics had a profound impact on two ultimately more memorable bands, Nirvana and the Smashing Pumpkins.

As the band ran through some of its best-known tunes, however, you could see all the influences on the Pixies’ own music. In the deliciously poppy “Here Comes Your Man” alone, there were traces of everything from the Beach Boys’ bounce to the Jesus & Mary Chain’s tension. Whether singing on his own or with bassist Kim Deal, Pixies leader Frank Black exhibited the dedication and command of someone who is justly proud of his band’s legacy.

When Radiohead followed on the main stage, vocalist Thom Yorke wasted no time demonstrating that the throat problems that forced the band to cancel a concert last week in Australia weren’t going to hamper him here.

“Hi yaaaaa,” he growled good-naturedly into the microphone at the start of the 90-minute set. The crowd roared as Radiohead quickly moved into “There There,” the number from last year’s “Hail to the Thief” album that most reflected a return to the dynamic rock textures of its “OK Computer” CD after the more atmospheric undercurrents of collections that followed “OK.”

On that, other “Hail” numbers and earlier tunes, including a surprise inclusion of “Creep,” Yorke sang with all the power and character that have made Radiohead so acclaimed.

Radiohead detractors say the group’s approach is too cold, leaning more on artful textures than rock’s raw, more visceral side. Yet there is a sense of everyman in Yorke’s vocals and a bold ambition in the band’s lovely, often fragile arrangements that addresses cornerstone rock issues of self-affirmation and doubt with as much fervent emotion as almost anyone has brought to a stage.

Considering the band could easily sell 50,000 tickets on its own in Southern California, the willingness to play Coachella was both a sign of its own integrity and an endorsement of Coachella’s devotion to sidestepping rock flavors of the month in favor of bands that aim for something unique.

The group’s lure was so strong that it made the crowd size an issue. So many fans chose to watch Radiohead’s set rather than the competing shows Saturday that the normal Coachella intimacy was lost for many. The festival’s previous attendance high was 33,000 last year.

Tollett, president of Goldenvoice and the guiding force behind Coachella, was thrilled by the sellouts both Saturday and Sunday, but not enough to automatically strive for more fans next year, he said backstage. In fact, Tollett added, he’s prepared to cut back if he finds the 50,000 figure uncomfortable.

“It’s easy to keep the bands happy,” he said. “When they sign the contract, they give you a rider that tells you, ‘Here’s what we need.’ But the fans don’t give you a rider.

“You can get some idea of how people feel by reading websites, but the best thing is to experience the weekend through the fans’ eyes,” Tollett said. “I’ll spend most of the weekend walking around, using the restrooms, buying food, listening to lots of music. The worst thing you can do is assume everybody’s happy just because you sold 50,000 tickets.”

It’s that attitude that has made Coachella the premier pop music festival in the country and made artists like Radiohead eager to headline and artists such as Beck anxious to just stop by for the day.

Bill Graham would have been proud.