Recent advances in the study of nitric oxide (NO) biology, biochemistry, molecular biology and physiology in plants are presented in this book, providing an overview of current understanding of the NO actions involved in adaptive responses of plant fitness to environmental constraints. The special emphasis is on NO-dependent signalling, molecular adjustments and targets as key elements in plant growth, development and stress physiology. The first part of the book is devoted to the description of key features related to NO biochemistry, synthesis and metabolism and the modes of action involved. The second part covers the functionality of NO in three central nodes of the plant life cycle: growth, development and stress physiology. Finally, a detailed analysis of the advantages and disadvantages of the use of fluorometric detection of NO in plant research brings to light information necessary for understanding the limitations of the method.