Rice (Oryza sativa L.) plays a major role as a staple food supporting more than three billion people, and it comprises 50% to 80% of their daily calorie intake (Khush, 2005). Water is a highly limited resource (Wang et.al, 2012) which is important for yield and productivity of rice crop. Water deficit stress affects rice at morphological (reduced germination, plant height, plant biomass, number of tillers, various root and leaf traits), physiological (reduced photosynthesis, transpiration, stomatal conductance, water use efficiency, relative water content, chlorophyll content, photo system II activity, membrane stability, carbon isotope discrimination and abscise acid content), biochemical (accumulation of osmoprotectant like proline, sugars, polyamines and antioxidants), at molecular levels. A thorough understanding of these characters that govern the yield of rice under water stress condition is a prerequisite (Pandey & Shukla 2015). Excess water is a natural disturbance affecting crop and forage production worldwide, and it provokes on most terrestrial plants. Adaptive traits of plants enable survival under soil water logging or partial submergence. It leads to oxygenation of submerged tissues (i.e. parts of shoots and entire root system), while leaves above water continue with carbon fixation. Thus, a better comprehension of plant functioning under water excess would help to assist breeding programs as well as to define better management decisions for cultivation of crops and forage species in lands prone to flooding. The present paper attempts to focus light on the physiological responses of rice crop to both the water stress conditions in a mini reviewed form.

Keywords: Water stress; Drought; Submergence; Morphology; Physiology; Anatomy; Biochemical traits;Stress hormones; Tolerance mechanisms.