An account of the evolution and principles involved in breeding crops grown in the tropics. This book developed from a symposium held in New Delhi in 1970 at the Indian Agricultural Research Institute. It begins with a consideration of the history of agriculture. Recent techniques make is possible to set crop plant evolution against the time scale of agricultural development, enabling the rate of evolution to be determined with some precision. Throughout the account the studies stress the range of material and changes and improvements in crops, with special reference to their importance not only in the tropics, but also to world agriculture. This book brings to the notice of geneticists and breeders in western countries the work undertaken in India in elucidating the evolution and recent improvement of crop plants of world wide importance. It is also an authoritative account for students of plant breeding in the tropics taking courses in universities, in institutes and colleges of agriculture who need to have within the covers of one book a comprehensive, yet concise text that clearly sets out the principles involved in the breeding of crops grown in the tropics.