This book is intended to cover all known abiotic stresses and their effects on the various aspects physiological processes in plants. The first chapter deals with introduction and the introductory remarks on abiotic stress and overall effects of different factors on crop. Second chapter deals with aspects of seed germination, seedling growth and root development under stressful condition for different factors of abiotic stress. Third chapter is a contributory chapter and deals with different aspects of biological nitrogen fixation under abiotic stress. Fourth chapter deals with growth, development and phenology of crop plants under environmental stress condition. Various aspects of photosynthesis under abiotic stress have been discussed in the fifth chapter. Mineral nutrition under abiotic stress condition and roles of different nutrient to overcome abiotic stress has been discussed in Sixth chapter. Seventh chapter discussions have been provided regarding transgenic approach to enhance drought tolerance and it is a contributory chapter. Eighth chapter is about the effects of different factors of abiotic stress on respiration processes of plant have been discussed. These review chapters addresses how knowledge of the physiological mechanisms of crops can improve crop yield. The study of crop physiology can assist cereal breeding by: i) improving our understanding of the factors that determine crop yield and adaptation through the syncretic concept of ideotype and, consequently, improve crop simulation models; ii) defining particular ?secondary? traits to select (analytical breeding) when choosing: iii) indicating the kind of genetically modified organisms (GMOs) with potential for development and how to test them; and iv) phenotyping associated with marker-assisted