Functions of the root system

This chapter deals with the root system of the plant, focusing on its functions. The root is the first organ to emerge from the germinating seed. Root elongation is a continuous process that is essential for healthy plant growth. It allows the plant to explore new soil volumes for water and nutrients and as a support for the growing plant. Any reduction in the rate of root elongation negatively affects the growth and function of aerial organs which, eventually, is translated into restricted plant development. Continuous root elongation is needed for mechanical anchoring, water uptake, nutrient uptake, and the avoidance of drought conditions. This chapter presents early observations on the importance of root growth and elongation as well as recent work that has unveiled the reasons underlying the field observations. Furthermore, it highlights that knowledge of all the hurdles to root growth is an important tool for increasing world food production. Following this, it discusses the depth of the root system, which has important biological and agronomic consequences: the deeper the roots, the better the plant's ability to withstand environmental extremes such as long periods of drought and short frost events, and to access nutrients. The phenomena of water uptake and the response of root growth to local nutrient concentrations are also explained. Finally, it provides an understanding of the interactions between environmental conditions and form of nitrogen nutrition and describes the role of roots as source and sink for organic compounds and plant hormones.