This book is based to a great extent on the biochemical and molecular mechanisms of tolerance of commonly encountered abiotic stresses in nature. This book will deal with increasing temperature, water, salinity, and heavy metals and ozone, and how these abiotic stresses can be managed by microbes through their alleviation mechanisms. Water stress includes both drought and flooding. The first section outlines the relevance of abiotic stresses in present day environmental conditions. The second section deals with three major stresses—temperature, water and salinity and the metabolic changes and protective adjustments in plants for withstanding these stresses. The third section deals with the role of heavy metals and ozone. The final section is devoted to general abiotic stresses and their alleviation by microbes. These offer a cost-effective and eco-friendly means of combating different stresses.