Short-and long-term challenges in crop breeding

Agriculture provides the primary energy source and nutrients for humans,and is the key factor determining worldwide population and its basic health status.In the history of agriculture,desirable traits beneficial for farming rather than natural growth have been artificially selected through breeding of new elite varieties.Each successful step in crop breeding,e.g.wild plant domestication,crop introduction and the ’Green Revolution’,led to a period of rapid population growth.In the last seven decades after the Second World War,the world population has grown from 2.5 to7 billion.Driven by rapid advances in science and technology,the rate of generating crop varieties is accelerating.T aking China as an example,the annual production of its major staple crop,rice,has increased from～57 million tons in 1950 to more than 200 million tons at present.More importantly,in the past two decades,