When Natalie Dessay opens the Metropolitan Opera season in a new production of Donizetti’s “Lucia di Lammermoor” tonight, audiences will listen for a portion of the opera many regard as a fixture: the cadenza with flute that Lucia sings at the end of her Mad Scene. But they will listen in vain. As Ms. Dessay pointed out in a recent phone call, there is a good reason she won’t sing it: “It’s not by Donizetti. I prefer to sing my own cadenza.”

Old traditions die hard, especially those involving the so-called bel canto operas of the early 19th century. And it makes little difference that many of those traditions don’t date from the time of the operas involved. According to a 2004 article in the Cambridge Opera Journal by Romana Margherita Pugliese, the cadenza does not even date from the early 19th century, as was commonly supposed, but was most likely composed for the soprano Nellie Melba by her teacher Mathilde Marchesi for performances at the Paris Opéra in 1889 — more than half a century after the opera’s 1835 premiere.

Opera singers, though, typically cling to tradition for fear of giving performances that run counter to audience expectations.

But not Ms. Dessay, whose artistic scruples are just as rigorous as her dazzling vocal skills and compelling gifts as an actor.

For those who have followed Ms. Dessay’s portrayals of Lucia in previous productions, her rejection of the flute cadenza will come as no surprise. The Metropolitan’s will be her third Italian-language “Lucia,” but when she first sang the role, in 2001 in Lyon, it was in her native French.

“I was not so confident then, and thought I would feel more comfortable singing Luciain French. It was a bad idea. Italian suits the music and the story so much better. It is much easier to sing in Italian than French,” she said, in a startling comment from the leading French soprano, whose peerless singing in her native language is universally acclaimed. “I love my own language and am proud to sing in it, but French is so difficult.”

The Lyon production was one of several in recent years to use a version of the opera Donizetti prepared for the Théâtre de la Renaissance in 1839, even though his revisions were made not out of artistic concerns, but rather simply for the practical purpose of adapting the opera for performance in Paris with a French cast.

She was noncommittal when asked if the new production would bring out another side to the character of Lucia, but said with a laugh, “It isn’t going to be Regie theater [radical director’s theater], which I happen to like by the way. It will be very beautiful — it will look wonderful on stage.”

One reason “Lucia” retains its popularity may be its treatment of the heroine’s madness. Where previous operas depicted female madness as a fleeting thing, easily cured by proximity to the tenor and reassurances of his love, Lucia’s madness is irreversible and triggers violence. “She has a fragility from the beginning. She is strange — she sees ghosts and she has hallucinations. But she does not really travel from the beginning to the Mad Scene,” Ms. Dessay said, referring to the lack of character development.

“All the men use her in a certain way — her brother, of course, but even her lover through his jealousy. I try to explore the suffering and to where it can drive someone.”

Ms. Dessay also said that a glass harmonica — the instrument specified by Donizetti — rather than a flute, will accompany her in the Mad Scene, and that she will perform her role uncut.

Surprisingly, Lucia will be the first Italian role at the Met for Ms.

Dessay, who made her debut there in 1994 as Fiakermilli in Richard Strauss’s “Arabella.”

“It really is very strange, but I basically sang only in French and German for the first 10 years of my career.” Fully recovered from recent operations on her vocal chords, she looks forward to singing both Italian bel canto and French roles in the years ahead. Indeed, this season at the Met she returns in the spring for a new production of another Donizetti opera, but one in French: “La Fille du Régiment.” Baroque aficionados will be delighted to know that she plans to sing Cleopatra in Handel’s “Giulio Cesare” in 2011. And she is also toying with playing Donna Anna in “Don Giovanni.” “It’s the highest of the three [women’s] roles, but I am not quite sure about it.” Mozarteans will be hoping for a positive resolution of her doubts.