Deep-rooted maize plants utilize water and nutrients more effectively, particularly in compacted soil. However, the mechanisms by which different maize genotypes adjust root angles in response to compaction remain underexplored. We conducted a two-year study (2021-2022) on silty loam soils in the North China Plain. We tested two genotypes of maize [one with naturally deep roots (DR) and another with shallow roots (SR)] in compacted (C) and non-compacted (NC) soil. Soil compaction impeded shoot growth in both genotypes; however, DR exhibited better growth than SR. Under compacted conditions, DR maintained steeper root angles and demonstrated superior mechanical strength with larger root cortex areas (increased by 60 %) and stele (increased by 92 %), as well as higher cellulose concentration (up to 146 %). Notably, PIEZO1 gene expression increased significantly (up to 242 %) in DR under compaction, suggesting its role in root structural enhancement, unlike in SR where it remained unchanged. These findings underscore the importance of genetic, anatomical, and biochemical adaptations in maize roots, facilitating their resilience to soil compaction. Such insights could inform the breeding of maize genotypes that are better adapted to diverse soil conditions, potentially boosting agricultural productivity.

Grassland degradation and reduced yields are often linked to the root soil composite of perennial alfalfa roots. This study introduces a novel modeling approach to accurately characterize root biomechanical properties, assist in the design of soil-loosening and root-cutting tools. Our model conceptualizes the root as a composite structure of cortex and stele, applying transversely isotropic properties to the stele and isotropic properties to the cortex. Material parameters were derived from longitudinal tension, longitudinal compression, transverse compression, and shear tests. The constitutive model of stele was Hashin failure criteria, accounting for differences in tensile and compressive strengths. Results reveal that root tensile strength mainly depends on the stele, with its tensile properties exceeding compressive and transverse strengths by 4-10 times. In non-longitudinal tensile stress scenarios, like shear and transverse compression tests, the new model demonstrated superior accuracy over conventional models. Results of shear tests were further validated using non-parametric statistical analysis. This study provides a finite element method (FEM) modeling approach that, by integrating root anatomical features and biomechanical properties, significantly enhances simulation accuracy. This provides a tool for designing low-energy consumption components in grassland degradation restoration and conservation tillage.

Soil salinization has become one of the major problems that threaten the ecological environment. The aim of this study is to explore the mechanism of salt tolerance of hybrid walnuts (Juglans major x Juglans regia) under long-term salt stress through the dynamic changes of growth, physiological and biochemical characteristics, and anatomical structure. Our findings indicate that (1) salt stress inhibited seedling height and ground diameter increase, and (2) with increasing salt concentration, relative water content (RWC) decreased, and proline (Pro) and soluble sugar (SS) content increased. The Pro content reached a maximum of 549.64 mu g/g on the 42nd day. The increase in superoxide dismutase (SOD) activity (46.80-117.16%), ascorbate peroxidase (APX) activity, total flavonoid content (TFC), and total phenol content (TPC) under salt stress reduced the accumulation of malondialdehyde (MDA). (3) Increasing salt concentration led to increases and subsequent decreases in the thickness of palisade tissues, spongy tissues, leaves, and leaf vascular bundle diameter. Upper and lower skin thickness, root periderm thickness, root diameter, root cortex thickness, and root vascular bundle diameter showed different patterns of change at varying stress concentrations and durations. Overall, the study concluded that salt stress enhanced the antireactive oxygen system, increased levels of osmotic regulators, and low salt concentrations promoted leaf and root anatomy, but that under long-term exposure to high salt levels, leaf anatomy was severely damaged. For the first time, this study combined the anatomical structure of the vegetative organ of hybrid walnut with physiology and biochemistry, which is of great significance for addressing the challenge of walnut salt stress and expanding the planting area.

The morphology of a plant's root is strongly affected by the compaction of the growth medium, the size of its particles, or the presence of non -movable obstacles. However, little is known about the effect of these characteristics on root anatomy and mechanical properties of the root tissues. Anatomical features of maize roots grown in media that varied in density and/or structure (soil, glass beads, vermiculite) were analyzed on cross -sections through the elongation and maturation zones of the roots of 14 -day -old seedlings. The sections were stained for lignin and suberin to recognize the developmental stages of exodermis and endodermis. Cortex thickness, number of cortical cell layers, and diameter of the vascular cylinder (stele) were measured in both zones. The Young's modulus of the roots was determined using mechanical tensile tests. Assuming that the root can be considered a composite material, a model was used that allowed, for the first time, the estimation of the mechanical properties of the stele and cortex. While the cell arrangement of roots grown in a medium with high density and fine movable particles (soil) was regular, roots grown in a medium with low density and light particles (vermiculite) and a medium with high density and large unmovable particles (glass beads) showed early damage of the rhizodermis and impaired cell arrangement in the cortex and vascular cylinder. In these roots, the exodermis and endodermis matured closer to the root tip than in roots from the soil. The vermiculite roots were the most outliers in terms of morphometric parameters and mechanical properties. The Young's modulus of the stele was many times greater than the Young's modulus of the cortex in the roots of all variants. Of the media used in the experiment, the soil appears to be most favorable for the maize root growth and development.