Many people talk to plants to encourage them to grow, but scientists at Lancaster University have discovered that plants talk to themselves using chemical signals. Professor Bill Davies reveals more about the discovery and how it has lead to partial root drying - a way of manipulating water use and crop growth without genetic manipulation. Given that 70 percent of the world's water goes to feeding crops. Quentin Cooper looks at what affect the technique will have on global agriculture. Producer Ros Smith. Email: [email address removed]