Biological changes occurring in plants due to a change in external environmental conditions are referred to as stress. These external changes can trigger a wide array of plant responses such as altered gene expression, as well as changes in growth rates and crop yields. Plant stresses are classified into abiotic and biotic stress. Abiotic stresses cause major loss of crops worldwide. These include drought, floods, salinity and extreme temperatures. Shortage of water and increasing desertification are further increasing abiotic plant stress. Biotic stresses include infestation by nematodes, fungi, bacteria and herbivores. These stress causing agents deprive nutrients from the host plants and are responsible for major pre and post-harvest losses. To combat these stresses, plants have developed various mechanisms. This book unravels the recent studies in the field of abiotic and biotic stress in plants. It includes some of the vital pieces of work being conducted across the world, on various topics related to abiotic and biotic stresses in plants. This book will serve as a valuable source of reference for graduate and post graduate students.