HERMOSILLO, Mexico -- The temperature was climbing past 100 degrees, humidity not far behind. Mexican actor Diego Luna, in the director’s chair for a change, was trying to re-create 1960s California on a set in this industrial city in Mexico’s northern Sonora state.

The performers’ wigs were wilting, their brows brilliant with sweaty shine. Vintage suits in unbreathable polyester double-knit didn’t help. Yet tempers remained surprisingly calm as scenes were shot over and over.

Luna is directing what is being billed as the first feature film about Cesar Chavez, the Mexican-American union leader who organized farm workers in California and across the southwestern United States and led two historic grape boycotts aimed at drawing attention to harsh conditions in the fields.

It is only Luna’s second outing as a feature director and his first on a primarily English-language film. Michael Pena ( Crash, Million Dollar Baby) stars as Chavez, and America Ferrera ( Ugly Betty) plays his wife, Helen. Rosario Dawson takes on the role of Chavez’s longtime organizing partner, Dolores Huerta.

“It’s a struggle,” Luna said of the language, speaking during a break in Hermosillo’s downtown plaza, where the Art Deco-ish public library was doubling as one of the fruit companies that Chavez targeted. “Directing means choosing the right words. I don’t like those directors who act the part for you, and that’s the temptation when you don’t speak the language.”

But Luna, who spends roughly half his time in Los Angeles these days, was holding his own on the set one day last month, speaking in English to the American actors, switching to Spanish for the extras and much of the crew. He went back and forth between shouting “Action!” and “Accion!” at the start of each take.

Although Chavez, who died in 1993, was an American and did most of his work in the United States, it has taken a Mexican company, Luna’s Canana Films, to make the picture, most of which is also being shot in Mexico. The filmmakers make no bones about choosing the positive aspects of Chavez’s life and not the darker side, such as his authoritarian tendencies, but they insist the film is not simplistic hagiography. Pablo Cruz, one of Luna’s producing partners, acknowledged that some Mexican-American filmmakers have been rankled by the idea of a Mexican production company telling the story of a Chicano hero.

“It was very hard — and it’s a little sad — in this day and age in the United States to find money for this type of film,” said Keir Pearson, who penned the screenplay for Chavez.

Pearson, a 2005 Oscar nominee for his Hotel Rwanda script, said he spent two years negotiating with Chavez’s heirs and acquired the life rights about a year ago, succeeding where a number of others before him had failed. Luna and his fellow producers were able to secure funding, much of it from Mexican sources, Pearson said. (A spokeswoman for the production company said the film had a budget of $10 million. It is scheduled for release in 2013.)

The decision to film in Mexico was not just a matter of lower production costs and because the producers lived in Mexico. There was a critical visual element — it’s impossible to find the 1960s style of vineyards in today’s California. But in Sonora, home to nearly all of Mexico’s production of table grapes, the old system of draping vines on wooden crosses remains common.