Amanda Rasmussen1 and Susanne Schmidt,2
1Centre for Plant Integrative Biology, University of Nottingham, UK; 2School of Agriculture and Food Science, University of Queensland
Plants require at least 14 essential elements called ‘mineral nutrients’ to sustain life function and complete their life cycle, in addition to carbon (in the form of CO2), oxygen, and hydrogen (in the form of water). Some plants have specific requirements for additional elements. The acquisition via the roots and use of these elements are the topic of plant nutrition.
Nutrients are taken up by roots via active or passive transport across membranes, and travel from the bulk soil to the roots via diffusion or mass flow. However, in order to access all the available nutrients, plants have evolved dynamic and plastic root systems that explore the soil for maximum nutrient uptake. In monocots, lateral roots grow into the volume of soil between seminal roots, as shown by in situ CT imaging (Figure 4.1).
By responding to signals and gradients in the soil, the root system can maximise growth in local nutrient patches while minimising growth in areas of deficiency. This is extremely important for plant survival particularly in deficient or marginal soils. Efficient root growth is also an important factor in maximising yield with lower fertiliser applications because ‘wasted’ root growth costs energy that could otherwise be invested in the crop of interest (whether seeds, leaves, stems or tubers). For this reason understanding the root environmental responses and breeding crops with efficient root systems for the conditions of interest are currently highly active areas of agronomic research.
This section covers the different nutrients required for plant growth, and the different root architectures and structures which help the plants maintain sufficient nutrient uptake to support the above ground biomass.