A man checks the quality of rice grains for a rice buying agent in Tay Mo village, outside Hanoi November 27, 2012. China, the world's top rice producer and consumer, aims to improve its super-hybrid rice yield by a further 11 percent by 2015 as part of its efforts to maintain food self-sufficiency, the official Xinhua news agency reported on Tuesday. Last year, China became a net rice importer for the first time in 15 years and imports in the first ten months of 2012 rose nearly three-fold to 1.98 million tonnes, the majority of which was from Vietnam. REUTERS/Kham (VIETNAM - Tags: BUSINESS FOOD COMMODITIES AGRICULTURE)