A farmer in Central China's Hubei Province shows two big sweet potatoes grown on his farm, which weigh around 17 kilograms. This new kind of sweet potato, developed by the farmer himself, can increase production by 25 percent. Production per mu (0.067 hectares) can reach 6,000 kilograms. The new kind of sweet potato has also been introduced to other provinces such as Shaanxi and Hebei. Photo: CFP