The book furnishes information on how we can augment nitrogen use efficiency (NUE) and yield in rice crop under varying water regimes in situ. It also explains the extent of feasibility to determine the optimum rate of nitrogen for maximizing NUE and productivity of rice crop under physiological drought condition. The SPAD (Soil Plant Analytical Development) values are the mainstay for modulating the doses of nitrogen required by the crop at real time of adverse physiological drought against the normal set of condition for keeping abreast the key physiological parameters attributing to the economically sound biomass productivity in relevant situation elsewhere. The book although is the reflection of some outcome of limited research, which is based on the academic work as a part of requirements of Master program in the discipline of Crop Physiology, Assam Agricultural University (India), delves into the problem of physiological drought in upland rice crop, and its management over a period of crop growth and development. Therefore, its comparative to consider the publication as a resourceful manual for students and beginners in the theme of N-Nutrition & Rice Physiology.