Merger talks between Dow Chemical Co and DuPont to create a chemicals titan with a $130 billion market value lifted Dow shares to a record on Wednesday and put DuPont on track for its biggest daily gain in more than six years. A potential deal could ease shareholder pressure on the two companies, strengthen their position amid weak demand for farm chemicals, but attract regulatory scrutiny in major markets including China. Dow shares rallied 11.7 percent to a record high of $56.82.