Salinity stress is one of the most detrimental abiotic factors affecting plant development, harming vast swaths of agricultural land worldwide. Silicon is one element that is obviously crucial for the production and health of plants. With the advent of nanotechnology in agricultural sciences, the application of silicon oxide nanoparticles (SiO-NPs) presents a viable strategy to enhance sustainable crop production. The aim of this study was to assess the beneficial effects of SiO-NPs on the morpho-physio-biochemical parameters of rice (Oryza sativa L., variety: DRR Dhan 73) under both normal and saline conditions. To create salt stress during transplanting, 50 mM NaCl was injected through the soil. 200 mM SiO-NPs were sprayed on the leaves 25 days after sowing (DAS). It was evident that salt stress significantly hindered rice growth because of the reductions in shot length (41 %), root length (38 %), shot fresh mass (40 %), root fresh mass (47 %), shoot dry mass (48 %), and root dry mass (39 %), when compared to controls. Together with this growth inhibition, elevated oxidative stress markers including a 78 % increase in malondialdehyde (MDA) and a 67 % increase in hydrogen peroxide (H2O2) indicating enhanced lipid peroxidation were noted. Increasing the chlorophyll content (14 %), photosynthetic rate (11 %), protein levels, total free amino acids (TFAA; 13 %), and total soluble sugars (TSS; 11 %), all help to boost nitrogen (N; 16 %), phosphorous (P; 14 %), potassium (K; 12 %), and vital nutrients. The adverse effects of salt stress were significantly reduced by exogenous application of SiO-NPs. Additionally; SiO-NPs dramatically raised the activity of important antioxidant enzymes such as superoxide dismutase (SOD), peroxidase (POX), and catalase (CAT), improving the plant's ability to scavenge reactive oxygen species (ROS) and thereby lowering oxidative damage brought on by salt. This study highlights SiO-NPs' potential to develop sustainable farming practices and provides significant new insights into how they enhance plant resilience to salinity, particularly in salt-affected regions worldwide.

Seasonal freezing and thawing significantly influence the migration and distribution of soil hydrothermal salts. Understanding the dynamics of hydrothermal salt forces in canal foundation soils is crucial for effective canal disease control and optimization. However, the impact on rectangular canals remains poorly understood. Therefore, field-scale studies on water-heat-salt-force-displacement monitoring were conducted for the canal. The study analyzed the changes and interaction mechanisms of water-heat-salt-force in the soil beneath the canal, along with the damage mechanisms and preventive measures. The results indicate that the most rapid changes in temperature, moisture, and salt occur in the subsoil on the canal side, with the greatest depth of freezing. Heat transfer efficiency provides an intuitive explanation for the sensitivity of ground temperature at the junction of the canal wall and subsoil to air temperature fluctuations, as well as the minimal moisture migration in this region under the subcooling effect. The temperature-moisture curve suggests that current waterheat-force and water-heat-salt-force models exhibit a delay in accurately predicting water migration within the subsoil. Rectangular canals are more susceptible to damage under peak freezing conditions, requiring a combined approach of freezing restraint and frost-heaving force to mitigate damage. These findings offer valuable insights for canal design, maintenance, and further research.

Moderate nitrogen addition can enhance plant growth performance under salt stress. However, the regulatory effects of nitrogen addition on the growth of the leguminous halophyte medicinal plant, Sophora alopecuroides, under salt stress remain unclear. In this study, a two-factor pot experiment with different NaCl levels (1 g/kg, 2 g/kg, 4 g/kg) and NH4NO3 levels (0 mg/kg, 32 mg/kg, 64 mg/kg, 128 mg/kg) was set up to systematically study the response of S. alopecuroides plant phenotype, nodulation and nitrogen fixation characteristics, nitrogen (N), phosphorus (P), potassium (K) nutrient absorption and utilization efficiency, plant biomass and nutrient accumulation to nitrogen addition under salt stress. The results demonstrated that under mild (1 g/kg NaCl) and moderate (2 g/kg NaCl) salt stress, S. alopecuroides exhibited a relatively low nitrogen demand. Specifically, low (32 mg/kg N) and medium (64 mg/kg N) nitrogen levels significantly enhanced nodule nitrogenase activity and nitrogen fixation capacity. Furthermore, the uptake of essential nutrients, including N, P, and K, in the aboveground biomass was markedly increased, which in turn promoted the accumulation of major nutrients such as crude protein, crude fat, and alkaloids, as well as overall biomass production. However, under severe (4 g/kg NaCl) salt stress, S. alopecuroides exhibited a preference for low nitrogen levels (32 mg/kg N). Under S3 conditions, excessive nitrogen application (e.g., 64 mg/kg and 128 mg/kg N) exacerbated the damage caused by salt stress, leading to significant inhibition of nitrogen fixation and nutrient uptake. Consequently, this resulted in a substantial reduction in biomass. This study provides a theoretical basis for nitrogen nutrition management of S. alopecuroides under salt stress conditions and offers valuable insights for optimizing fertilization and nutrient management strategies in saline-alkali agricultural production.

Drought and salt stress are two major abiotic factors significantly impacting crop growth and yield. Climate change leads to increasing drought and soil salinization issues, rising significant challenges to agricultural production. Amylases play a crucial role in enhancing the tolerance of crops to these stresses by regulating physiological and enzymatic activities. Previous study identified MeAMY1 and MeBAM3 as key genes involved in cassava starch metabolism under drought stress. To investigate their functions under drought and salt stress, MeAMY1 and MeBAM3 genes were cloned and over-expressed in Arabidopsis thaliana in the current study. Overexpression of MeAMY1 in Arabidopsis enhances amylase activities, promotes starch hydrolysis, releases soluble sugar and thus enhances osmotic balance in transgenic Arabidopsis. In the mean while, expression of BAM1 and SEX1 were depressed by MeAMY1 to maintain the protects cells closed under stress and preserved starch for adapting the stressful environments. Overexpression of the MeBAM3 in Arabidopsis can increase the expression levels of AMY3 and RVE1, promotes starch hydrolysis, releases soluble sugar from the chloroplasts to the cytoplasm and thus enhances osmoregulatory substance content, reducing stress-induced damage to antioxidant enzymes and cell membranes and improving stress tolerance. The principal component analysis further indicated that MeAMY1 and MeBAM3 overexpression lines responded similarly to drought stress, while MeBAM3 overexpression provided greater resilience to salt stress.

In the northwestern saline soils and coastal areas, cement soil (CS) materials are inevitably subjected to various factors including salt erosion, dry-wet cycle (DWC), temperature fluctuations and dynamic loading during its service life, which the coupling effect of these unfavourable factors seriously threatened the durability and engineering reliability of CS materials. Additionally, combined with the substantially extensive application prospects of rubber cementitious material, as a resource-efficient civil engineering material and fibre-reinforced composites, consequently, in order to address aforementioned issues, this investigation proposed to consider the incorporation of rubber particles composite basalt fiber (BF) to CS materials as an innovative engineering solution to effectively enhance the mechanical and durability properties of CS materials for prolonging its service life. In this study, sulphate ions were utilized to simulate external erosive environment and basalt fibre rubber cement soil (BFRCS) specimens were subjected to various DWC numbers (0, 1, 4, 7, 11 and 15) in diverse concentrations (0 g/L, 6 g/L and 18 g/L) of Na2SO4 solution, and specimens that had completed the corresponding DWC number were then conducted both unconfined and dynamic compressive strength tests simultaneously to analyze static and dynamic stress-strain curves, static and dynamic compressive strength, apparent morphological deterioration characteristics and energy absorption properties of BFRCS specimens. Furthermore, further qualitative and quantitative damage assessments of pore distribution and microscopic morphology of BFRCS specimens under various DWC sulphate erosion environments were carried out from the fine and microscopic perspectives through pore structure test and scanning electron microscopy (SEM) test, respectively. The test results indicated that the static, dynamic compressive strength and specific energy absorption (SEA) of BFRCS specimens exhibited a slight increase followed by a progressive decline as DWC number increased. Additionally, compared to 4 mm BFRCS specimens, those with 0.106 mm rubber particle size demonstrated more favorable resistance to DWC sulphate erosion. The air content, bubble spacing coefficient and average bubble chord length of BFRCS specimens all progressively grew as DWC number increased, while the specific surface area of pores gradually decreased. The effective combination of BF with CS matrix significantly diminished pores and weak areas within specimen, and its synergistic interaction with rubber particles efficiently mitigated the stresses associated with expansive, contraction, crystallization and osmosis subjected by specimen. Simultaneously, more ettringite (AFt) had been observed within BFRCS specimens in 18 g/L sulphate erosive environments. These findings will facilitate the design and construction of CS subgrade engineering in northwestern saline soils and coastal regions, promoting sustainable and durable solutions while reducing the detrimental environmental impact of waste rubber.

A novel thermo-hydro-mechanical-chemical (THMC) coupling model grounded in thermodynamic dissipation theory was established to unravel the intricate behavior of unsaturated sulfate-saline soils during cooling crystallization. The model quantifies energy transfer and dissipation during crystallization and introduces a method to calculate the amount of sulfate crystallization. It intricately captures the interdependencies between crystallization, pore water pressure, crystallization pressure and volumetric expansion, while also accounting for the dynamic feedback of latent heat from phase transitions on heat conduction. The reliability of the model was validated through experimental data. Numerical simulations explored the effects of cooling paths, thermal conductivity, initial salt content and initial porosity on the crystallization behavior and mechanical properties. The model provides theoretical support for optimizing the engineering design and facility maintenance of sulfatesaline soils.

A two-lift gradient design for airport pavements has been proposed to mitigate the functional degradation, especially the salt-frost (S-F) damage induced by deicing slat fluids. Herein, this study focuses on elucidating the mechanism and improvement of incorporating mineral admixtures in the development of a novel S-F resistant surface concrete material, which is of great significance for delaying the functional deterioration of pavement surface in northern China. The results indicated that the filling effect and secondary hydration reaction between the fly ash (FA) and silica fume (SF) and cement hydration products results in a dense spatial network structure, effectively reducing porosity and optimizing pore structure. It was found that SF can effectively improve the frost resistance and salt corrosion resistance of cement mortar, while the influence of FA depends on its content and environmental conditions. The incorporation of FA and SF significantly enhanced the structural density of cement concrete and reduced chloride ion permeability. The improvement in impermeability is most pronounced when both FA and SF are used in combination. In addition, a fitting equation between the admixture content and chloride ion permeability has been established, demonstrating good fitting results. In non-frozen saline soil areas, a large amount of FA or SF could be incorporated; in seasonally frozen areas, the priority should be given to SF to ensure salt corrosion resistance and frost resistance. The findings of this study provide a scientific basis for sustainable airport pavement construction in northern China.

This study investigates salt weathering in the indoor, humid environment of China's Jinsha earthen site. Methods such as digital microscope, scanning electron microscopy (SEM), ion chromatography (IC), energy dispersive spectroscopy (EDS), and laser particle size analysis were employed to collect and analyze samples from four heavily weathered walls. The sampling approach took into account differences in depth and height and prioritized the extraction from various weathering layers to unveil the attributes, causes, and mechanisms of salt weathering. The findings indicate that the Jinsha site's eastern segment suffered salt-induced damage, such as powdering, salt crusts, and blistering, due to the presence of gypsum and magnesium sulfate. These salts were primarily sourced from groundwater. Groundwater ions ascended to the site's surface via capillary action, instigating various forms of salt damage. Salt damage severity has a direct link to salt and moisture content. The degradation patterns can be categorized into powder and multi-layered composite deterioration, both seems related to soil particle composition. Powder deterioration tends to occur when the sand content exceeds 40%. This research proposes preservation strategies that focus on managing groundwater and conducting environmental surveillance. These measures are designed to effectively address and mitigate the risks associated with salt damage.

The fundamental cause of frost heave and salt expansion of saline soil is the water condensation and salt crystallization during the freezing process. Therefore, controlling the water and salt content is crucial to inhibit the expansion behaviors of saline soil. Recently, electroosmosis has been demonstrated to accelerate soil dewatering by driving hydrated cations. However, its efficiency in mitigating the salt-induced freezing damages of saline soil requires further improvement. In this study, a series of comparative experiments were conducted to investigate the synergistic effects of electroosmosis and calcium chloride (CaCl2) on inhibiting the deformation of sodium sulfate saline soil. The results demonstrated that electroosmosis combined with CaCl2 dramatically increased the cumulative drainage volume by improving soil conductivity. Under the external electric field, excess Na+ and SO42- ions migrated towards the cathode and anode, respectively, with a portion being removed from the soil via electroosmotic flow. These processes collectively contributed to a significant reduction in the crystallization-induced deformation of saline soil. Additionally, abundant Ca2+ ions migrated to cathode under the electric force and reacted with OH- ions or soluble silicate to form cementing substances, significantly improving the mechanical strength and freeze-thaw resistance of the soil. Among all electrochemical treatment groups, the soil sample treated with 10 % CaCl2 exhibited optimal performance, with a 71 % increase in drainage volume, a 180 similar to 443 % enhancement in shear strength, and a 65.1 % reduction in freezing deformation. However, excessive addition of CaCl2 resulted in the degradation of soil strength, microstructure, and freeze-thaw resistance.

In this study, ground granulated blast-furnace slag (GGBS) and fly ash (FA) were used as binders, while NaOH (NH) and Na2SiO3 (NS) served as alkali activators. Seawater (SW) was used instead of freshwater (FW) to develop a SW-GGBS-FA geopolymer for solidifying sandy soils. Geopolymer mortar specimens were tested for unconfined compressive strength (UCS) after being curing at room temperature. The results showed that the early strength of the seawater group specimens increased slowly less than that of the freshwater group specimens, while the late strength was 1.16 times higher than that of the freshwater group specimens. Factors including seawater salinity (SS), the GGBS/FA ratio, curing agent (CA) content, and the NH/ NS ratio were examined in this experiment. The results showed that the strength of the specimens was higher for SS of 1.2 %, G90:F10, CA content of 15 %, activator content was 15 %, and NH: NS of 50:50. The pore structure of the mortar specimens was analyzed using X-ray diffraction (XRD), scanning electron microscopy (SEM), and computerized tomography (CT), revealing the mechanisms by which various factors influenced the microstructure. XRD indicated that SW-GGBS-FA geopolymer mortar newly produced Friedel salt and calcium silicate sulfate hydrate (C-S-S-H). The microstructures observed by CT and SEM showed that the pore radius of the seawater specimens was mainly less than 10 mu m, and the maximum crack length was 92.55 mu m. The pore radius of freshwater specimens was larger than that of seawater specimens, and the largest crack was 148.44 mu m, which confirmed that Friedel salt and C-S-S-H fill the pores and increase the UCS of the specimens.