Modern agriculture has been providing food, feed, fiber and morerecently biofuel to meet the World ́s demand. One of the bases of this modernagriculture is the improved cultivars, which are much higher yielder than ancientones. The scientific literature documents the significant contribution of plantbreeding to agriculture and finally food production worldwide. Now-a-days,agriculture has new and huge challenges, due to population growth, the pressure onagriculture liability on the environmental conservation, and climate change. Tocope with these new challenges, many plant breeding programs have reorientedtheir breeding scope to stress tolerance in the last years. So, in this book, expertson plant physiology and on plant breeding presents the most recent advances anddiscoveries applied to abiotic stresses, discussing the new physiological concepts,breeding methods, and modern molecular biological approaches to developimproved cultivars tolerant to most sorts of abiotic stress.