DuPont Co. said it can address antitrust regulators' concerns that its merger with Dow Chemical Co. could limit discovery of new agricultural pesticides, boosting investor confidence that the $72 billion deal will be approved.

Regulators are mostly concerned that the combination could hurt innovation in crop-protection chemicals, Chief Executive Ed Breen said Tuesday on a conference call to discuss fourth-quarter results. The remedy will involve products as well as related research and development resources.

The merger of the two biggest U.S. chemical makers will close in June, three months later than previously anticipated, Wilmington, Del.-based DuPont said. The tie-up — along with Bayer's agreement to buy Monsanto and China National Chemical Corp.'s deal to buy Syngenta — could reshape the industry.

The European Union, which has questioned whether the DuPont-Dow combination would slow development of new pesticides, on Monday granted a 10-day extension to March 14 as the deadline for review. The companies requested the delay to fine-tune a package of concessions.

"My gut is we are in the second quarter" to complete the merger, Breen said.

Breen's comments helped reassure investors that DuPont can satisfy regulators, said Matt Arnold, an analyst at Edward Jones & Co. "Their conversations with regulators seem to be going well."