The Institute of Agricultural Research was started as an offshoot of Botany, BHU. in 1931 under the leadership of Dr. B.N.Singh. In the very beginning the Institute of Agricultural Sciences was imparting an integrated course with Plant Physiology as a base, and was awarding M.Sc.(Ag.) degree in Agricultural Botany. The Department of Plant Physiology came into existence in 1969. Dr. Bhola Nath Singh built up a very active research group. Despite inadequate facilities, contributions were made initially in terms of modern and sophisticated instruments. The Department at present has a resourceful pool of basic and advanced equipments fulfilling the need of students and research personnel. The faculty members have been recipient of awards, fellowship and other recognition for their contribution in their respective fields. The research data are being published and their usefulness is recognized world-wide. So far the Department has awarded more than 200 Ph.D. and more than 500 M.Sc. (Ag) degree in Plant Physiology including D.Sc. to a fairly a good number of scientists.
The Department has contributed immensely in the fields of irradiation biology, photoperiodism, vernalization, mineral nutrition, plant water relation, chemical weed control and plant growth substances. Intensive researches in field of photosynthesis led to the development of new methodologies and valuable techniques, and ultimately led to modification of the Blackman’s law of limiting factors in photosynthesis. Report on mango malformation, researches on sugarcane and cotton physiology and investigation on permeability of protoplasm – a probable factor in transpiration in respect to plant water relations – were all established initially from this department. Studies on plant micronutrients started in fourth decade and studies on macro- and micronutrients are going on in current years. Work on chemical weed control was pioneered in this department with the understandings of uses and effects of a number of herbicides for various field crops. Researches on foliar nutrition of crop plants in India were started in fifth decade. Advance studies in field of tree physiology were started in the seventh decade and useful findings drawn have been utilized for better seed germination, growth and flowering as well as on rooting in cuttings of ornamental plants and fruit tress. At present faculty members in the department are engaged in the field of abiotic stresses, plant mineral nutrition, plant metabolism, photosynthesis and respiration, plant growth development seed physiology, plant tissue culture and plant growth regulators. The research data are being presented in national and international seminars/conferences, and research papers published in national and international journals of repute. The faculty members have also authored and edited a good number of books on the subject.