A field experiment was conducted during kharif season of 2017-18 on the topic entitled “Effect of growing environment on growth and development of rice (Oryza sativa L.) cultivars.” in sandy loam soil of . University of Agriculture and Technology, Kumarganj, Faizabad (.). The experiment consisted of nine treatment combinations comprised of three transplanting dates viz. July 5th, July 15th and July 25th and three varieties viz., NDR-97, NDR-3112 and BPT-5204. Results reveal that different phenophases of rice markedly varied with only dates of transplanting but also different weather variables which ultimately create the different crop growing environment to harvest the yield accordingly. Highest Growing Degree days (GDD) was recorded in growing environment of July 5th due to occurrence of long duration. Highest heliothermal and photothermal unit was recorded in Ist date of transplanting on July 5th at vegetative stage. | Study of phenophasic climatic requirement for maximum yield of rice in the prevailing weather conditions