Rice is the most widely grown and consumed cereal across the world, where Asian countries are the topmost with 80%, since it meets half of the worldwide dietary. Rice is an extensive freshwater user through conventional puddled cultivation. However, as a result of changing climate, water scarcity is increasing, threatening rice cultivation. Therefore, it is imperative for genetic improvement of rice cultivars suitable to grow under water deficit conditions. While the significance of root traits in water uptake is unambiguously putative which is significantly correlated with higher water use efficiency. Besides water, plants need balanced mineral nutrients in each stage of its development to attain maximum yield. Among the essential nutrients, nitrogen (N) is one of the most important; with its deficiency, plants have limited growth, yield, and quality. Plants obtain N from the soil solution in two forms: NO3− and NH4+. Since plants mainly uptake N as NO3− form root-specific transporters, but 1/3 of the applied N is leaching as NO3−. However, earlier findings found that N use efficiency (NUE) may be enhanced through genetic improvement. There are two-gene (NRT1 and NRT2) families of nitrate transporters encoding NO3− uptake proteins. Among them, NRT2 gene encodes the high-affinity transporters under low nitrate concentration, while NRT1 gene facilitates the root low-affinity transporters. In the chapter, we discussed various techniques/strategies in improving NUE and WUE in rice through phenotypic architecture particularly root and shoot, genetic engineering and molecular strategies in a range of plant species aimed at enhancing uptake, translocation, and remobilization of N as a sustainable way to increase rice productivity and quality and also and to incorporate into rice improvement programs through modern breeding and molecular approaches.
