Nitrogen is a vital element for plants, as it is a component of many molecules and structures that are essential for plant growth and development. Plants can absorb nitrogen from the soil in two forms: nitrate (NO3-) and ammonium (NH4+). However, these forms of nitrogen are often scarce in natural and agricultural ecosystems, and plants have to cope with various abiotic stresses that affect their nitrogen uptake and metabolism. Some of these stresses include nutrient deficiencies, unfavorable pH, salinity, drought, and heavy metal toxicity. Plants have evolved different strategies to manage nitrogen and adapt to these stressors, such as regulating the expression and activity of nitrogen transporters, modifying the root architecture, and altering the nitrogen assimilation pathways. Nitrogen is therefore not only a key nutrient for plant productivity, but also a modulator of plant responses to abiotic stress.