The present multi-volume treatise has been planned to discuss important aspects of the crop-plant physiological aspects, viz., hormones, nutrients, cell membranes, and induced proteins, as related to different types of stresses each in separate volumes. Another type of stress which can be classed under biotic, environmental (sil) or chemical, viz., the stress of allelochemicals which has not been discussed before as a stress factor, will be discussed in a separate volume emphasizing its practical/ ap-plied aspects, rather than mentioning only the allelopathic effects. In this volume on Hormone Relations, different stresses have been arranged in order of their importance and work done.