We live in critical times for the world's diversity of plants and animals. It is universally agreed that a catastrophic loss of biological diversity is occurring at the moment, with species, and equally importantly, genes being lost forever. However, the signing of the Biodiversity Convention at the Earth Summit in 1992 drew attention to the need to conserve and equitably utilize biological diversity for the benefit of all humankind. The convention placed emphasis on the need for a complementary approach to conservation that employed both emex situ/em and emin situ/em techniques. br/ Though much conservation and genetic research has focused on emex situ/em techniques, where the biological diversity is moved from its original location for safe storage, relatively little progress has been made in developing strategies appropriate for the genetic conservation of biological diversity emin situ/em, in its native environment. The time is right for a definitive assessment of the principles required to conserve the genetic diversity of crops, their wild relatives and wild species within natural habitats. br/ This book therefore provides a practical and theoretical introduction to the techniques of emin situ/em conservation of plant genetic resources. It includes methodologies, case studies and in-depth discussion of on-farm and genetic reserve conservation, written by acknowledged international experts on the subject.