U.S. antitrust authorities are poised to approve plans by biotech crop developer Monsanto Co. to buy Delta and Pine Land Co. on the condition that the companies divest some key assets, a source familiar with the deal said on Thursday. Antitrust officials at the Justice Department are working out final details of a settlement deal that would require the companies to sell some genetic material owned by Delta and Pine that is used to develop new cotton seed varieties, the source said. The genetic material, known as germplasm, would be sold to a rival company in the business, the source said.