Tough filly Melody Belle has surprised even her co-trainer Jamie Richards to become the first New Zealand-trained horse in 31 years to win the Group Two BRC Sires' Produce Stakes.

To the cheers of 15 of her 32 owners who made the trip across the Tasman, Melody Belle ($5) raced away in the straight to beat Taking Aim ($8.50) by 4-3/4 lengths in Saturday's 1400m-race.

She was the first kiwi to win since the Bruce Marsh-trained Mr Shannon in 1986.

Richards said he believed there was some improvement in the filly as she heads to the Group One J J Atkins Stakes on June 10.

"She is a strong filly by Commands so I am confident she can run a strong 1600 metres in the Atkins," Richards said.

"I was mindful of the fact she had not started since April 1 when she won the (Group One) Sires at Awapuni. But she had a trial and that set her up for today.

"She was a cheap buy ($57,500) at the Karaka sales but she has now won a Karaka Million and a BRC Sires."

Richards believes Melody Belle, who was promoted to $2.80 favourite for the J J Atkins, can develop into a spring filly with races like the Thousand Guineas and the Caulfield Guineas in mind.

Richards and training partner Stephen Autridge have a big team in Brisbane and have already won a Group race with Shocking Luck in the Rough Habit Plate.

Winning jockey Opie Bosson believes there is improvement in Melody Belle.

"She has taken a lot of confidence since she won the Karaka Million in January. She put herself into the race and finished hard," Bosson said.

Hugh Bowman, who rode Taking Aim, said the colt had tried hard after getting into a reasonable position from a wide barrier.

"The winner was too good but he fought on well," Bowman said.

Pierata ($16) finished third, beaten 1-1/4 lengths, and jockey Corey Brown said she might need blinkers.