CHICAGO — U.S. farmers said they would push ahead with plantings planned before U.S.-China trade tensions eased and, now that the two countries have resumed talks, take a wait-and-see approach to President Donald Trump’s promises for more sales to China.Over the weekend, the world’s two largest economies pledged to keep talking about how China could import more energy and agricultural commodities from the United States to narrow a $335 billion annual U.S.