In the face of highly expanding knowledge in the area of Plant Physiology and curriculum modularization, there is a growing need for a reference book that deals with essential concepts, for an undergraduate as well as graduate students and teachers, researchers in the area of plant Sciences, environmental Sciences and related field of studies. The intention is to bridge the knowledge gap which is crucial for understanding the rapid advances made currently in these fields of studies. The book has three parts. Part I: Plant Cell, Water and Solute Transport. Part II: Metabolism. Part III: Regulation of Growth and Developmental Processes. Part IV: Special topics such as the effect of water deficit stress, flooding, extreme temperatures, salinity stresses on plants and their acclimation strategies. The book has 12 chapters covering Plant cell, Water and Solute Transport, Enzymes, Photosynthesis, Respiration, Signal Transduction, Phytohormones and Stress Physiology. This book is written in simple and lucid manner with numerous illustrations. I wish to express my sincere gratitude to my colleague and co-author S.N. Paipuru and my long time mentor P.Sundine as well as my colleagues at JJU.