For India A, all-rounder Jalaj Saxena did the star turn with his off-breaks grabbing six for 106 in 22.4 overs, while left-arm spinner Rakesh Dhruve got two wickets.
At stumps, India A were six for one having lost Unmukt Chand (4) cheaply. Tomorrow is the last day of the first-class match.
New Zealand were in trouble at one point with the scoreboard reading 106 for six before Ronchi's swift counter-attacking knock of 125 off only 110 balls changed the course of the New Zealand A innings at the Port Trust Stadium.
When Ronchi, who had made his international debut for Australia before shifting to his native country, was finally trapped leg-before by seamer Dhawal Kulkarni's incoming delivery.
"There was a bit of help for the spinners but basically it was a flat track. I took my chances and I am happy that it paid off," Ronchi told reporters at the post-match conference.
"I am happy that I could execute my plan perfectly as I have worked on certain variations. The caught and bowled dismissal (Derek de Boorder) that I got was the best among the six," Saxena said.
