The use of biotechnology in incorporating abiotic stress tolerance in crop species depends on a better understanding of the physiology of stress tolerance, and the identification of specific genes determining tolerance to a specific stress. The complex in heritance of stress tolerance hinders the immediate impact of biotechnologists introducing any novel genes. However, molecular markers may well serve in manipulating quantitatively inherited traits of stress tolerance physiological processes such as source sink relationships, translocation, and interrelations between plant parts, water status, hormonal levels and balance are crucial in determining how a plant responses to stress. It is important to know the extent to which stress tolerance genes enhance the breath of adoption to stress, and whether they increase or decrease tolerance to stress. Understanding abiotic stress factors such as temperature and drought tolerance and abiotic stress tolerance traits are important factors on the crop productivity of crops. The present volume is an assemblage of scientific knowledge information which is written by eminent researchers in their respective fields. It describes related methods for the creation, selection and fixation of superior plants in the development of improved cultivars suited to the needs of growers and consumers. The present volumes will be highly useful for the researchers, agronomists, plant physiologists, biotechnologists and agriculturists to sustain the crop production. "