Champa rice

In 1012, after a severe drought on the lower Yangtze and Huai rivers, Emperor Zhenzong of the Song dynasty (pictured) ordered thirty thousand bushels of a fast-ripening rice from the kingdom of Champa shipped to the stricken region. It ripened in under a hundred days, needed less water than earlier varieties and could be relied on even on higher ground and hillsides, so farmers were able to grow two crops a year instead of one. Intensive rice farming of this kind is credited with letting China's population keep growing until it became the most populous country in the world. It is also an early case of a state, not a lone inventor, putting a better seed into farmers' hands.