Nitrogen forms and their availability-dependent root developmental adaptation in plants

Nitrogen (N) is one of the crucial nutrients required for the growth and development of plants. The two predominant forms of N acquired by terrestrial plants are nitrate (NO3−) and ammonium (NH4+). Due to the leaching behavior of these forms, N often ends up being the limiting nutrient for crop plants. Postgreen revolution strategies of accelerated crop production necessitated the heavy application of N fertilizers, a large portion of which succumbs to air and water. To adapt to varying levels of NO3− and NH4+ and under their low availability, plants have inherent mechanisms of altering their root system architecture (RSA), a phenomenon termed as N foraging response. Knowledge about the biochemical mechanisms and genetic aspects behind N source preference and root plasticity is vast but scattered. In this chapter, we attempt to put forward the coordination of primary root (PR) and lateral root (LR) development by intrinsic factors such as growth regulators and N metabolites in an N-form-specific manner. The influence of N interaction with other nutrients on root development has also been featured.