Molecular Soil Biology 2025, Vol.16, No.5, 241-254 http://bioscipublisher.com/index.php/msb 242 2 Root System Architecture of Maize 2.1 General features of maize root morphology (primary, seminal, nodal, and lateral roots) The root system of corn is composed of various types of roots, including primary roots, embryonic roots (also known as secondary roots), node roots (crown roots and supporting roots), and lateral roots. The primary roots and embryonic roots belong to the embryonic root system. They are formed after the seeds germinate and provide support for the early water and nutrient absorption of the seedlings. The node root develops from the base of the stem during the growth of the plant and is the main source of the biomass of the root system of mature plants. Lateral roots grow out from the primary roots, embryonic roots and node roots, greatly increasing the surface area of the roots and facilitating more efficient absorption of water and nutrients. Different types of roots have obvious differences in structure and function. Together, they constitute the complex Root System Architecture (RSA), providing a basis for corn to adapt to the variable soil environment (Hochholdinger et al., 2018; Rivas et al., 2022; Guo et al., 2025). 2.2 Plasticity of root growth under variable soil conditions The root system of corn has strong plasticity and can adjust its growth pattern according to conditions such as soil moisture, nutrients and density. In the case of high-density planting or water shortage, corn will reduce the number and length of jointed roots and lateral roots, but maintain the extension of the main root to expand the soil exploration range and reduce rhizosphere competition. In areas with more nitrogen or phosphorus in the soil, roots will increase branching, and different types of roots (such as primary roots, embryonic roots, crown roots, and supporting roots) respond differently to nutrient distribution. This indicates that the root system can adapt to the spatial differences of soil resources. In addition, different genotypes have differences in the hydraulic structure and anatomical characteristics of roots, which will affect their ability to absorb water and resist drought (Rishmawi et al., 2023; Protto et al., 2024). 2.3 Root exudation and its role in modifying the soil environment Corn roots secrete organic acids, enzymes and secondary metabolites, etc. These secretions can significantly alter the physical, chemical and biological properties of the rhizosphere soil. They can regulate soil pH, promote the release of insoluble nutrients (such as phosphorus), and also influence the composition of microbial communities, enhance the activity of beneficial microorganisms, and help with nutrient cycling and stress resistance. Under adverse conditions such as drought or nutrient deficiency, the composition and release amount of secretions will change, thereby regulating the enzyme activity and microbial diversity in the rhitrosphere and improving the adaptability of corn (Hu et al., 2018; Hao et al., 2022; Adeniji et al., 2024). In addition, root hairs and secretions can also work in synergy to expand the influence range of the rhizosphere, enhance soil enzyme activity, and accelerate the decomposition of organic matter (Bilyera et al., 2021; Zhang et al., 2022). 3 Soil Physical Properties and Root Interactions 3.1 Influence of soil texture, structure, and compaction on root penetration The texture and structure of the soil can affect the resistance encountered by the root system and the distribution of rhizosphere volume density. Phalempin et al. (2021) conducted a series of comparative studies. In homogeneous soil, corn roots need to rely on their own growth to push soil particles and gradually form pores. In soils with significant structural differences, the roots of corn tend to grow along the existing pores, reducing soil compaction. If the compaction of the soil increases (such as compaction caused by mechanical tillage or tire rolling), the bulk density and penetration resistance of the soil will also increase, which will limit the downward and outward expansion of corn roots, resulting in reduced root length, root surface area and root dry weight, and ultimately affecting the absorption of water and nutrients (Rut et al., 2021; Nawaz et al., 2023; Nassir et al., 2024; Zhu et al., 2024; Gao et al., 2025). When the penetration resistance exceeds 2 200 kPa, the growth of corn roots almost stops. Although the diameter of the fine roots of corn will increase in this case to enhance the penetration power, the overall distribution of the root system will still be limited. 3.2 Role of soil moisture availability and aeration in root growth Soil moisture and aeration can jointly affect root growth. Appropriate amounts of water can reduce mechanical resistance and promote root extension and branching (Jaswal and Sandal, 2024). Drought or excessive dryness
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