Taiwanese buyer the Great Wall Group has issued a tender to purchase between 50,000 to 65,000 tonnes of corn to be sourced from the United States, Brazil or Argentina, European traders said on Monday. The tender closes on Tuesday, May 5, they said. The corn is sought in two consignments, one with shipment between June 1-20 and one for shipment between June 21 to July 10, they said.