New information keeps on expanding and enriching every sphere of knowledge. Plant Physiology is more like a rule of this dictum. The primary motivation for preparing this text was our own need for organising a document on the subject that presents the current scenario of advancements in fundamental concepts and the perspectives of application. Amidst our endeavour, we came across a quotation of Albert Einstein. It conveyed the need of equal emphasis on fundamentals and applied aspects. Further, it projected a new dimension that possibly, concerns for mankind and fate of mankind are located at temporally segregated scales. A common set of priorities may not serve the man and his fate at the same time. Consequently, references to green revolution and sustainability have appeared in descriptions pertaining to role of plant physiology in agriculture  (Chapter 1 and 35).