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Introduction: Salinity negatively affects maize productivity. However, calcium lignosulfonate (CLS) could improve soil properties and maize productivity. Methods: In this study, we evaluated the effects of CLS application on soil chemical properties, plant physiology and grain quality of maize under salinity stress. Thus, this experiment was conducted using three CLS application rates, CLS0, CLS5, and CLS10, corresponding to 0%, 5%, and 10% of soil mass, for three irrigation water salinity (WS) levels WS0.5, WS2.5, and WS5.5 corresponding to 0.5 and 2.5 and 5.5 dS/m, respectively. Results and discussion: Results show that the WS0.5 × CLS10 combination increased potassium (K 0.167 g/kg), and calcium (Ca, 0.39 g/kg) values while reducing the sodium (Na, 0.23 g/kg) content in soil. However, the treatment WS5.5 × CLS0 decreased K (0.120 g/kg), and Ca (0.15 g/kg) values while increasing Na (0.75 g/kg) content in soil. The root activity was larger in WS0.5 × CLS10 than in WS5.5 × CLS0, as the former combination enlarged K and Ca contents in the root while the latter decreased their values. The leaf glutamine synthetase (953.9 µmol/(g.h)) and nitrate reductase (40.39 µg/(g.h)) were higher in WS0.5 × CLS10 than in WS5.5 × CLS0 at 573.4 µmol/(g.h) and 20.76 µg/(g.h), leading to the improvement in cell progression cycle, as revealed by lower malonaldehyde level (6.57 µmol/g). The K and Ca contents in the leaf (881, 278 mg/plant), stem (1314, 731 mg/plant), and grains (1330, 1117 mg/plant) were greater in WS0.5 × CLS10 than in WS5.5 × CLS0 at (146, 21 mg/plant), (201, 159 mg/plant) and (206, 157 mg/plant), respectively. Therefore, the maize was more resistance to salt stress under the CLS10 level, as a 7.34% decline in yield was noticed when salinity surpassed the threshold value (5.96 dS/m). The protein (13.6 %) and starch (89.2 %) contents were greater in WS0.5 × CLS10 than in WS5.5 × CLS0 (6.1 %) and (67.0 %), respectively. This study reveals that CLS addition can alleviate the adverse impacts of salinity on soil quality and maize productivity. Thus, CLS application could be used as an effective soil amendment when irrigating with saline water for sustainable maize production. [ABSTRACT FROM AUTHOR]

Soil salinization is one of the major factors limiting agricultural production. Utilizing beneficial microorganisms like Piriformospora indica (P. indica) to enhance plant tolerance to abiotic stresses is a highly effective method, but the influence of P. indica on the growth of soybean in natural saline-alkaline soil remains unclear. Therefore, we investigated the effects of non-inoculation, P. indica inoculation, and fertilization on the growth, antioxidant defense, osmotic adjustment, and photosynthetic gas exchange parameters of soybean under two different levels of saline-alkaline stress in non-sterilized natural salinealkaline soil. The study found that: 1) P. indica inoculation significantly promoted soybean growth, increasing plant height, root length, and biomass. Under mildly saline-alkaline stress, the increases were 11.5%, 16.0%, and 14.8%, respectively, compared to non-inoculated treatment. Under higher stress, P. indica inoculation achieved the same level of biomass increase as fertilization, while fertilization only significantly improved stem diameter. 2) Under saline-alkaline stress, P. indica inoculation significantly increased antioxidant enzyme activities and reduced malondialdehyde (MDA) content. Under mildly stress, MDA content was reduced by 47.1% and 43.3% compared to non-inoculated and fertilized treatments, respectively. Under moderate stress, the MDA content in the inoculated group was reduced by 29.9% and 36.6% compared to noninoculated and fertilized treatments, respectively. Fertilization only had a positive effect on peroxidase (POD) activity. 3) P. indica inoculation induced plants to produce more osmotic adjustment substances. Under mildly stress, proline, soluble sugars, and soluble proteins were increased by 345.7%, 104.4%, and 6.9%, respectively, compared to non-inoculated treatment. Under higher stress, the increases were 75.4%, 179.7%, and 12.6%, respectively. Fertilization had no significant positive effect on proline content. 4) With increasing stress, soybean photosynthetic capacity in the P. indica-inoculated treatment was significantly higher than in the non-inoculated treatment, with net photosynthetic rate increased by 14.8% and 37.0% under different stress levels. These results indicate that P. indica can enhance soybean's adaptive ability to saline-alkaline stress by regulating ROS scavenging capacity, osmotic adjustment substance content, and photosynthetic capacity, thereby promoting plant growth. This suggests that P. indica has great potential in improving soybean productivity in natural saline-alkaline soils. [ABSTRACT FROM AUTHOR]

In cold and arid saline areas, the mechanical properties of soils are usually significantly affected by some complicated conditions, especially the coupled effects of the freeze–thaw–dry–wet (F–T–D–W) cycles and soil salinization. This study experimentally investigated the effect of F–T–D–W cycles on the shear performances and microstructures of silty clay that was salinized during wetting processes. Three types of soil samples with different dry densities were designed: (1) silty clay samples without salt (Category Ⅰ); (2) silty clay samples with salt (Category Ⅱ); and (3) silty clay samples that were salinized during wetting processes (Category Ⅲ). Direct shear and scanning electron microscopy (SEM) tests were carried out, the variations in the shear strength, surface deterioration, and shear parameters (e.g., cohesion and internal friction angle) were analyzed, and the degradation mechanism was revealed. The results show that the F–T–D–W cycles and soil salinization significantly affect the shear strength of soils, especially for the samples with low dry densities. The shear strengths of soil samples with and without salt (Categories Ⅰ and Ⅱ) decrease as the F–T–D–W cycles increase. Besides, the cohesion of soil samples increases with dry density and declines with the F–T–D–W cycles due to the appearance of cracks and bond failure among soil particles. In addition, there is a threshold number of F–T–D–W cycles to significantly reduce the cohesion of soil samples, and the threshold numbers for soil samples Categories Ⅰ and Ⅱ are six and three, respectively. The repeated expansion and shrinking of soils accelerate the damage to the soil structure, which results in a decrease in cohesion and interparticle force. However, when the concentration of salt solution in soils exceeds the saturation concentration, a new denser soil skeleton is formed by the soil particles and surrounding salt crystals, which improves the shear strength of the soil samples. This study could provide deep insights into the shear performance and microstructures of silty clay exposed to F–T–D–W cycles. [ABSTRACT FROM AUTHOR]

Tomato (Solanum lycopersicum L.) belongs to the Solanaceae family and is considered an important vegetable worldwide. Its production has been challenged due to soil salinization and water shortages. Local tomato cultivars could be better adapted to salt stress. Based on this hypothesis, the present study was carried out to determine the variation in fourteen different tomato cultivars for salt tolerance. Seed germination, mean germination time, shoot length, and root length were examined under salinity stress (1.5 g L-1 NaCl). Plant growth and seed germination were severely affected by saline conditions. The results of this in vitro experiment showed that the seed germination of Yellow Milk was significantly increased (73.33%) however, Pink Jade and Red Jade cultivars were significantly decreased under the NaCl treatment. Similarly, among the fourteen tomato cultivars, the mean germination time of only Yellow Pearl and Black Current significantly increased. Moreover, the shoot length of eight tomato cultivars decreased compared with the control, while the highest shoot length (12.5 cm) was recorded in the case of Saint cultivar. The root length of Taiwan Red Saint, Purple Beauty, Yellow Milk, Red Pearl, Yellow Pearl, Pink Cooperative 906, Qinzu Shanghai 903, and Scarlet cultivars significantly increased, while the other five cultivars significantly decreased under NaCl treatment compared to control. It is concluded that NaCl stress significantly affects the vegetative growth of tomato cultivars under in vitro culture. [ABSTRACT FROM AUTHOR]

Soil salinization leads to a reduction in arable land area, which seriously endangers food security. Developing saline-alkali land has become a key measure to address the contradiction between population growth and limited arable land. Rice is the most important global food crop, feeding half of the world's population and making it a suitable choice for planting on saline-alkali lands. The traditional salt–alkali improvement method has several drawbacks. Currently, non-thermal plasma (NTP) technology is being increasingly applied in agriculture. However, there are few reports on the cultivation of salt/alkali-tolerant rice. Under alkaline stress, argon NTP treatment significantly increased the germination rate of Longdao 5 (LD5) rice seeds. In addition, at 15 kV and 120 s, NTP treatment significantly increased the activity of antioxidant enzymes such as catalase and SOD. NTP treatment induced changes in genes related to salt-alkali stress in rice seedlings, such as chitinase and xylanase inhibitor proteins, which increased the tolerance of the seeds to salt-alkali stress. This experiment has expanded the application scope of NTP in agriculture, providing a more cost-effective, less harmful, and faster method for developing salt-alkali-tolerant rice and laying a theoretical foundation for cultivating NTP-enhanced salt-alkali-tolerant rice. [ABSTRACT FROM AUTHOR]

The primary objective of this study is to evaluate soil evaporation in arid regions using a minimal set of readily accessible parameters, which are represented through a nomogram. This work explores the relationships between soil evaporation, soil water deficit, and air temperature. Evaporation is a critical factor influencing the soil water regime. Irrigation artificially adjusts soil moisture to maintain it within optimal limits for vegetation. This regulation can only be effectively managed if the principles of soil-water balance are thoroughly understood. In arid and semi-arid regions, where water quality is often poor (high salinity), prolonged excessive irrigation can lead to soil salinization, thereby reducing agricultural productivity. In this study, ten lysimeters were used to measure soil evaporation at different levels of soil water saturation. The highest evaporation rate was recorded in fully saturated soil, peaking at 548 mm. This rate decreased as the soil water saturation decreased. Therefore, a good knowledge of the evaporation value is necessary to establish appropriate irrigation and soil leaching rates and consequently, an adequate water balance. [ABSTRACT FROM AUTHOR]

Soil cover as a systemic formation is characterized by the formation of properties of different taxonomic levels and signs of structural organization with hierarchical subordination. As an integral natural formation, soils have resource potential, subject to the active influence of factors of the physical and geographical environment. Individual soil properties and their overall functional purpose may differ in time and space. Such properties are formed in different regions, reflecting the influence of local conditions. Typical representatives of soils with signs of salinity, excluding the implementation of production processes, are formed in arid conditions (Caspian lowland, Volga delta). The difference in the target functioning of soils in the region is expressed in the presence of a special natural combination of properties that the components of a typical soil profile do not possess (Neustruev, 1915). This is due to the fact that, when determining the classification characteristics of saline soils, processes that occur between individual horizons and are reversible in nature remain unaccounted for to date. The possibility of reversibility and restoration of physicochemical properties to the level of indicators characteristic of the climatic regime with the duration of geological periods of time remains in the shadows for many types of soils to this day (the water-soluble part of carbonates, silicates, and organic matter). We consider it appropriate to use a systematic approach when analyzing the temporal and seasonal functions of various types of soils (especially saline ones) under conditions of desertification and arid degradation. [ABSTRACT FROM AUTHOR]

Background: Astragalus cicer L. is a perennial rhizomatous legume forage known for its quality, high biomass yield, and strong tolerance to saline-alkaline soils. Soil salinization is a widespread environmental pressure. To use A. cicer L. more scientifically and environmentally in agriculture and ecosystems, it is highly important to study the molecular response mechanism of A. cicer L. to salt stress. Results: In this study, we used RNA-seq technology and weighted gene coexpression network analysis (WGCNA) were performed. The results showed 4 key modules were closely related to the physiological response of A. cicer. L. to salt stress. The differentially expressed genes (DEGs) of key modules were mapped into the KEGG database, and found that the most abundant pathways were the plant hormone signal transduction pathway and carbon metabolism pathway. The potential regulatory networks of the cytokinin signal transduction pathway, the ethylene signal transduction pathway, and carbon metabolism related pathways were constructed according to the expression pathways of the DEGs. Seven hub genes in the key modules were selected and distributed among these pathways. They may involved in the positive regulation of cytokinin signaling and carbon metabolism in plant leaves, but limited the positive expression of ethylene signaling. Thus endowing the plant with salt tolerance in the early stage of salt stress. Conclusions: Based on the phenotypic and physiological responses of A. cicer L. to salt stress, this study constructed the gene coexpression network of potential regulation to salt stress in key modules, which provided a new reference for exploring the response mechanism of legumes to abiotic stress. [ABSTRACT FROM AUTHOR]

The Yellow River Delta (YRD) has the world's highest land formation rate. However, soil salinization has caused severe land degradation in the region. Understanding the distribution of soil salinity and its variation is essential for saline soil management. This study combined soil salinity sampling data, remote sensing imagery, and layers of geographic environmental factors. Three different models, including Ordinary Kriging (OK), Geographically Weighted Regression (GWR), and Bayesian Maximum Entropy (BME), were used and compared to predict the soil salinity of two soil layers in 2006 and 2022. Then the spatial distribution characteristics and development trends of soil salinity in the YRD were analyzed. The results indicated that (1) The BME model is an optimal salinity prediction model that integrates soft data from multiple sources to perform nonlinear estimates. Compared to the OK and GWR models, the RMSE was reduced by up to 25% and 13%, respectively, and the greatest improvement in R2 was increased from 0.0534 and 0.2718 to 0.5569, respectively. (2) Soil salinity in the YRD shows a spatially increasing trend from the southwestern inland to the northeastern coast. Over the past 16 years, the salinization pattern has become more complex: soil salinization has been mitigated in the central and southern regions, with the average salinity decreasing from 1.03% to 0.86% and the salinization rate decreasing from 99% to 88%; and it has significantly intensified in the northern part of the study area near the old Yellow River channel and the Gubei Reservoir, and in some scattered inland areas. Continuous water and sediment regulation in the Yellow River basin and ecological management of natural reserves can generally alleviate soil salinization, but the risk of soil salinization can be increased by seawater erosion, inappropriate land use, and resource exploitation. [ABSTRACT FROM AUTHOR]

Summary The salinization of soil constitutes a substantial hindrance to the advancement of sustainable agriculture. Our research seeks to elucidate the role of a Rab GTPase‐activating protein (RabGAP) family member, SlRabGAP22, in salt tolerance and its translational regulation under salt stress in tomatoes, employing gene‐editing techniques and ribosome profiling methodologies. Findings demonstrate that SlRabGAP22 acts as a positive regulator of tomato salt tolerance, with four predicted upstream open reading frames (uORFs) classified into three categories. Functional uORFs were found to be negative regulation. Editing these uORFs along with altering their classifications and characteristics mitigated the inhibitory effects on primary ORFs and fine‐tuned gene expression. Enhanced tomato salt tolerance was attributed to improved scavenging of reactive oxygen species, reduced toxicity Na+, and diminished osmotic stress effects. Furthermore, we conducted genome‐wide analysis of ORFs to lay the foundation for further research on uORFs in tomatoes. In summary, our findings offer novel perspectives and important data for the enhancement of genetic traits via uORF‐based strategies and translational regulation against the backdrop of salt stress. [ABSTRACT FROM AUTHOR]

Background: Rice is a staple crop for over half of the global population, but soil salinization poses a significant threat to its production. As a type of polyamine, spermidine (Spd) has been shown to reduce stress-induced damage in plants, but its specific role and mechanism in protecting rice roots under salt stress require further investigation. Results: This study suggested spermidine (Spd) mitigates salt stress on rice root growth by enhancing antioxidant enzyme activity and reducing peroxide levels. Transcriptomic analysis showed that salt stress caused 333 genes to be upregulated and 1,765 to be downregulated. However, adding Spd during salt treatment significantly altered this pattern: 2,298 genes were upregulated and 844 were downregulated, which indicated Spd reverses some transcriptional changes caused by salt stress. KEGG pathway analysis suggested that Spd influenced key signaling pathways, including MAPK signaling, plant hormone signal transduction, and phenylalanine metabolism. Additionally, the bZIP transcription factor OsbZIP73 was upregulated after Spd treatment, which is confirmed by Western blot. Further insights into the interaction between OsbZIP73 and Spd were gained through fluorescence polarization experiments, showing that Spd enhances protein OsbZIP73's affinity for RNA. Functional enrichment analyses revealed that OsPYL1, OsSPARK1, and various SAUR family genes involved in Spd-affected pathways. The presence of G/A/C-box elements in these genes suggests they are potential targets for OsbZIP73. Conclusions: Our findings suggest a strategy of using spermidine as a chemical alleviator for salt stress and provide insights into the regulatory function of OsbZIP73 in mitigating salt stress in rice roots. [ABSTRACT FROM AUTHOR]

Soil salinization severely limits the quality and productivity of economic crops, threatening global food security. Recent advancements have improved our understanding of how plants perceive, signal, and respond to salt stress. The discovery of the Salt Overly Sensitive (SOS) pathway has been crucial in revealing the molecular mechanisms behind plant salinity tolerance. Additionally, extensive research into various plant hormones, transcription factors, and signaling molecules has greatly enhanced our knowledge of plants' salinity tolerance mechanisms. Cucurbitaceae plants, cherished for their economic value as fruits and vegetables, display sensitivity to salt stress. Despite garnering some attention, research on the salinity tolerance of these plants remains somewhat scattered and disorganized. Consequently, this article offers a review centered on three aspects: the salt response of Cucurbitaceae under stress; physiological and biochemical responses to salt stress; and the current research status of their molecular mechanisms in economically significant crops, like cucumbers, watermelons, melon, and loofahs. Additionally, some measures to improve the salt tolerance of Cucurbitaceae crops are summarized. It aims to provide insights for the in-depth exploration of Cucurbitaceae's salt response mechanisms, uncovering the roles of salt-resistant genes and fostering the cultivation of novel varieties through molecular biology in the future. [ABSTRACT FROM AUTHOR]

Soil salinization is an important factor that jeopardizes agricultural production and ecological environment. Rapid and accurate acquisition of soil salinity information in farmland is instructive for sustainable agricultural development and land resource management. In order to improve the accuracy of soil salinity prediction under vegetation cover conditions by satellite remote sensing, the eighth Agricultural Division of Xinjiang Production and Construction Corps was taken as the study area in this study. The soil surface (0-20 cm) samples were collected under high fractional vegetation cover conditions in July and August 2023, respectively, and synchronized satellite images were acquired. Sentinel-1, Sentinel-2 and environment variables provide 3 different types of explanatory variables. The dataset A (polarization indices, spectral indices), dataset B (polarization indices, environment variables), dataset C (spectral indices, environment variables), and dataset D (polarization indices, spectral indices, environment variables) were constructed separately from different combinations of Sentinel-1 radar information, Sentinel-2 multispectral information and environment variables. Then, three integrated machine learning algorithms, namely adaptive boosting (AdaBoost), gradient boost regression Tree (GBRT) and eXtreme gradient boosting tree (XGBoost), were applied to construct soil salinity inversion models based on different datasets. The results showed that Models constructed from dataset B (polarization indices and environmental variables) and C (spectral indices and environmental variables) achieved higher prediction accuracies compared to dataset A (polarization indices and spectral indices). It is shown that when environmental variables are involved in the prediction of soil salinity, the model effect is more effective than the model constructed by polarization and spectral indices suggesting that the model effects are more effective than those constructed from polarization and spectral indices. When environmental variables were applied to dataset D together with polarization indices and spectral indices, the prediction accuracy of all models constructed based on dataset D are generally higher than those constructed on dataset A, B, and C, and that the synergy of environmental variables with radar data and multispectral data can effectively improve the model accuracy. Radar information, spectral information and environmental variables are complementary in soil salinity prediction. Based on the correlation analysis, it can be seen that radar information, spectral information and environmental variables can be used as effective characteristic variables for soil salinity prediction in the study area. It was worth noting that the correlation between topographic factors and land surface temperature with soil salinity is relatively high, with the highest correlation between elevation and surface soil salinity (r = 0.52). Considering the spatial characteristics of soil salinity distribution in the study area can provide effective characteristic variables for soil salinity prediction under vegetation cover condition. In all datasets, the XGBoost had the best performance, followed by GBRT, and the AdaBoost had a large validation error. The D-XGBoost model having the highest accuracy with a validation set R² of 0.72, an RMSE of 2.40 g/kg, and an MAE of 1.29 g/kg. The integrated learning algorithms based on the combination of multiple source variables has a strong nonlinear fitting ability. XGBoost can better model the complex nonlinear relationship between soil salinity content and remote sensing information, environmental factors, and obtain ideal fitting results. The joint application of multi-source remote sensing data and integrated learning algorithms can obtain the ideal soil salinity inversion accuracy under vegetation cover conditions. This study provides an effective technical means for real-time dynamic monitoring of soil salinity by satellite remote sensing in farmland to optimize irrigation strategies and manage saline soils comprehensively in Xinjiang. [ABSTRACT FROM AUTHOR]

In semi-arid irrigated environments, agricultural drainage is at the heart of three agro-environmental issues: it is an indicator of water productivity, it is the main control to prevent soil salinization and waterlogging problems, and it is related to the health of downstream ecosystems. Crop water balance models combined with subsurface models can estimate drainage quantities and dynamics at various spatial scales. However, such models' precision (capacity of a model to fit the observed drainage using site-specific calibration) and accuracy (capacity of a model to approximate observed drainage using default input parameters) have not yet been assessed in irrigated areas. To fill the gap, this study evaluates four parsimonious drainage models based on the combination of two surface models (RU and SAMIR) and two subsurface models (Reservoir and SIDRA) with varying complexity levels: RU-Reservoir, RU-SIDRA, SAMIR-Reservoir, and SAMIR-SIDRA. All models were applied over two sub-basins of the Algerri–Balaguer irrigation district, northeastern Spain, equipped with surface and subsurface drains driving the drained water to general outlets where the discharge is continuously monitored. Results show that RU-Reservoir is the most precise (average KGE (Q0.5) of 0.87), followed by SAMIR-Reservoir (average KGE (Q0.5) of 0.79). However, SAMIR-Reservoir is the most accurate model for providing rough drainage estimates using the default input parameters provided in the literature. [ABSTRACT FROM AUTHOR]

The precise quantification of soil salinity and the spatial distribution are paramount for proficiently managing and remediating salinized soils. This study aims to explore a pioneering methodology for forecasting soil salinity by combining the spectroscopy of soda saline–alkali soil with crack characteristics, thereby facilitating the ground-based remote-sensing inversion of soil salinity. To attain this objective, a surface cracking experiment was meticulously conducted under controlled indoor conditions for 57 soda saline–alkali soil samples from the Songnen Plain of China. The quantitative parameters for crack characterization, encompassing the length and area of desiccation cracks, together with the contrast texture feature were methodically derived. Furthermore, spectral reflectance of the cracked soil surface was measured. A structural equation model (SEM) was then employed for the estimation of soil salt parameters, including electrical conductivity (EC1:5), Na+, pH, HCO3−, CO32−, and the total salinity. The investigation unveiled notable associations between different salt parameters and crack attributes, alongside spectral reflectance measurements (r = 0.52–0.95), yet both clay content and mineralogy had little effect on the cracking process due to its low activity index. In addition, the presence of desiccation cracks accentuated the overall spectral contrast of salt-affected soil samples. The application of SEMs facilitated the concurrent prediction of multiple soil salt parameters alongside the regression analysis for individual salt parameters. Nonetheless, this study confers the advantage of the swift synchronous observation of multiple salt parameters whilst furnishing lucid interpretation and pragmatic utility. This study helps us to explore the mechanism of soil salinity on the surface cracking of soda saline–alkali soil in the Songnen Plain of China, and it also provides an effective solution for quickly and accurately predicting soil salt content using crack characteristics, which also provides a new perspective for the hyperspectral measurement of saline–alkali soils. [ABSTRACT FROM AUTHOR]

The confined groundwater of arid sedimentary plains has been disturbed by long‐term anthropogenic extraction, and its hydrochemical quality is required for sustainable development. The present research investigates the hydrochemical characteristics, formation, potential health threats, and quality suitability of the confined groundwater in the central North China Plain. Results show that the confined groundwater has a slightly alkaline nature in the study area, predominantly dominated by fresh‐soft Cl‐Na and HCO3‐Na types. Water chemistry is governed by water–rock interactions, including dissolution of evaporites and cation exchange. Approximately 97% of the sampled confined groundwaters exceed the prescribed standard for F−. It is mainly due to geological factors such as mineral dissolution, cation exchange, and competitive adsorption of HCO3− and may also be released from compacted soils because of groundwater extraction. Enriched F− in the confined groundwater can pose an intermediate and higher non‐carcinogenic risk to more than 90% of the population. It poses the greatest health threat to the population in the north‐eastern part of the study area, especially to infants and children. For sustainable development, the long‐term use of confined groundwater for irrigation in the area should be avoided, and attention should also be paid to the potential soil salinization and infiltration risks. In the study area, 97% of the confined groundwaters are found to be excellent or good quality for domestic purposes based on Entropy‐weighted Water Quality Index. However, the non‐carcinogenic health risk caused by high contents of F− cannot be ignored. Therefore, it is recommended that differential water supplies should be implemented according to the spatial heterogeneity of confined groundwater quality to ensure the scientific and rational use of groundwater resources. Practitioner Points: The hydrochemistry quality of confined groundwater in an arid sedimentary plain disturbed by long‐term anthropogenic extraction was investigated.The suitability of confined groundwater for multiple purposes such as irrigation and drinking were evaluated.The hydrochemical characteristics and formation mechanism of confined groundwater under the influence of multiple factors were revealed. [ABSTRACT FROM AUTHOR]

Soil salinization restricts crop growth and yield, thereby adversely affecting agricultural development. The stage of seed germination is the most crucial and sensitive stage in the plants' life cycle and is particularly sensitive to saline-alkali stress. We investigated the effects of different hormonal priming agents, namely melatonin (MT), abscisic acid (ABA) and brassinosteroid (BR), as well as the osmopriming agent, calcium chloride (CaCl2), on the germination of wheat (Triticum aestivum L.) seeds under saline-alkali stress. Saline-alkali stress was simulated with the solution of 100 mM NaCl and 50 mM NaHCO3/Na2CO3 (9:1). The results indicated that hormonal priming agents (ABA, MT, or BR) significantly alleviated saline-alkali stress-induced inhibition of wheat seed germination. The germination rate of seeds primed with ABA, MT, or BR increased by 21.0%, 11.0%, and 10.5%, respectively. The seeds primed with ABA, MT or BR showed improved activities of α- and β-amylase under saline-alkali stress, with corresponding increases in starch hydrolysis and soluble sugar content, which contributed to seed germination and embryo growth. Hormonal priming (ABA, MT, or BR) also significantly improved antioxidase activities to alleviate oxidative damage in germinating seeds under saline-alkali stress. Seeds primed with ABA (38.7%), MT (37.0%), and BR (31.3%) displayed lower malondialdehyde (MDA) content than the H2O-primed seeds. The ABA exerted the most significant promoting effect on wheat seed germination under saline-alkali stress. The promotional effect of CaCl2 on seed germination was nonsignificant compared with that of hydropriming. The results offer a theoretical and practical basis for applying seed priming to enhance the saline-alkali tolerance of wheat in production. [ABSTRACT FROM AUTHOR]

Grains, pulses and oil seeds are vital food crops, around the world and serve as essential sources of healthy nutrients for human well-being. However, their quality and production face significant challenges due to salinity stress posing a formidable threat to conventional agriculture by impeding its growth and development. The economic impact of saline soil on irrigated land is estimated to be $27.3 billion annually, underscoring the severity of the issue. Salinity stress induces profound changes in physiological, molecular, and biochemical processes. While adaptive mechanisms at various levels have been identified, a comprehensive understanding of salinity tolerance in food crops remains elusive. Human activities such as deforestation and poor irrigation management, are major contributors to soil salinity. The socio-economic repercussions include diminished crop yield reduced profit margins, unemployment and declining land value due to soil infertility. Remarkably, a review focusing on salinity tolerance responses and mechanisms in key food crops (barley, oats, rye, pulses and oilseeds) is not present. This review aims to fill this gap by offering a comprehensive overview of plants responses to salinity stress across different levels, unravelling the intricacies of tolerance mechanism. Furthermore, the review delves into biotechnological approaches and strategies employed thus far to enhance salinity tolerance in major food crops. [ABSTRACT FROM AUTHOR]

Biochar is a soil amendment that has the potential to effectively improve soil salinization. However, there is a paucity of studies on sodium adsorption using biochar, and the adsorption mechanism remains unclear. To better understand the adsorption mechanism of Na+ on the surface of biochar, both pyrochar and hydrochar were produced at different temperatures. The capacity and influencing factors of Na+ adsorption in biochar were analyzed via batch adsorption experiments. Pore filling dominated the Na+ adsorption in the concentration of the NaCl solution when it was ≤100 mg/L, where wheat straw pyrochar (WB, 3.95–4.94 mg/g Na) and poplar wood chip pyrochar (PB, 0.62–0.70 mg/g Na) presented the release and adsorption of Na+, respectively. When the concentration of the NaCl solution was >100 mg/L, the adsorption capacity of WB (25.44–36.45 mg/g) was significantly higher than PB (4.46–6.23 mg/g). Both the adsorption and release of Na+ in hydrochar was insufficient. In a high concentration of NaCl solution, ion exchange became the key mechanism determining the adsorption of Na+ in pyrochar, in which K+ contributed to more than 94% of the Na+ adsorption. The findings proposed strategies for the structural design of biochar used for Na adsorption. These will promote the utilization of solid biowaste for sodium adsorption and the potential of soil salinization amendment for agriculture in arid lands. [ABSTRACT FROM AUTHOR]

Soil salinization is a significant threat to soil health, especially to the agricultural ecosystem; it reduces vegetation biomass, destroys ecosystem diversity, and limits land use efficiency. This area of investigation has garnered extensive attention in China, especially in the arid and semi-arid areas, totaling 7.66 × 106 ha. A variety of theoretical research and technology developments have contributed to soil water and salt regulation and the screening of salt-tolerant varieties to improve nutrient utilization efficiency and microbial control and reduce ecological problems due to saline-based obstacles. These techniques can be classified into physical treatments, chemical treatments, biological treatments, and combined treatments; these different measures are all aimed at primarily solving saline–alkali stress. In general, the improvement and utilization of saline–alkali soil contribute to soil health improvement, concentrating on high-quality development, food security, ecological security, cultivated land protection, and agricultural upgrading. However, the risks of various technologies in the practical production process should be highlighted; green and healthy measures are still expected to be applied to saline–alkali land. [ABSTRACT FROM AUTHOR]

[Objective] To reveal the present situation and problems of soil in Beijing-Tianjin-Hebei fruit and vegetable base. [Method] Taking soil of Raoyang fruit and vegetable base as the evaluation object in Hebei Province, 12 soil samples were collected, the main physical and chemical property indicators were determined, the soil salinity was evaluated, and correlation analysis was carried out; the fuzzy evaluation method was used to evaluate the soil fertility; the status of soil heavy metals was evaluated by the comprehensive quality impact index evaluation method. [Result] The soil in Raoyang fruit and vegetable base was alkaline, and the soil appeared weak secondary salinization. The electrical conductivity increased with the increase of salt content, and the phenomenon of alkalization occurred at the same time as the salinization. The soil fertility level was at a moderate level. The evaluation results of soil heavy metal pollution showed that different degrees of heavy metal accumulation occurred in the study area, which may be related to the unreasonable fertilization methods, which had potential risks and needs to be paid attention to. The conversion of orchards to greenhouse vegetable cultivation significantly reduced the content of soil organic matter and increased the risk of soil salinization. [Conclusion] The research results provide scientific basis for the rational use of land, rational fertilization, soil nutrient management and high-quality fruit and vegetable production in the fruit and vegetable base of Raoyang County. [ABSTRACT FROM AUTHOR]

The intensification of the global hydrological cycle is anticipated to increase the variability of precipitation patterns. Brackish wetlands respond to changes in precipitation patterns by regulating the absorption and release of CO2 and H2O to maintain the stability of ecosystem functions. However, there is limited understanding of how the inter‐seasonal precipitation distribution (SPD) affects ecosystem CO2 and H2O exchange compared with annual precipitation totals. Here, we conducted four consecutive years of field experiments in a brackish wetland, manipulating the proportion of precipitation across different seasons while maintaining a constant annual precipitation total. We utilized five inter‐SPD proportions (+73%, +56%, control (CK), −56%, −73%) to examine the effects of SPD on ecosystem CO2 and H2O exchange. Our findings revealed that the annual ecosystem CO2 and H2O fluxes showed a trend of decreasing with the decrease in spring precipitation distribution. Among them, the annual net ecosystem CO2 exchange, evapotranspiration, carbon use efficiency and water use efficiency were shown to be more sensitive to decrease in spring precipitation distribution and increase in summer and autumn precipitation distribution. This negative asymmetric response pattern suggests that annual ecosystem CO2 and H2O exchange is primarily governed by seasonal precipitation variability, with spring soil water–salt dynamics identified as the key driver. Therefore, this association can be explained by the fact that drought of the early growth stage exacerbates soil salinization and inhibits vegetation colonization and growth, thereby greatly impairing the annual CO2–H2O exchange capacity of brackish wetlands. Our results emphasized that the spring extreme precipitation‐induced soil water–salt conditions will greatly influence CO2 and H2O exchange in brackish wetlands in the future. These findings are crucial for improving predictions of the carbon sequestration and water‐holding capacity of brackish wetlands. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

Soil salinization is a major abiotic factor threatening rapeseed yields and quality worldwide, yet the adaptive mechanisms underlying salt resistance in rapeseed are not clear. Therefore, this study aimed to explore the differences in growth potential, sodium (Na+) retention in different plant tissues, and transport patterns between salt‐tolerant (HY9) and salt‐sensitive (XY15) rapeseed genotypes, which cultivated in Hoagland's nutrient solution in either the with or without of 150 mM NaCl stress. The results showed that the inhibition of growth‐related parameters of the XY15 genotype was higher than those of the HY9 in response to salt stress. The XY15 had lower photosynthesis, chloroplast disintegration, and pigment content but higher oxidative damage than the HY9. Under NaCl treatment, the proline content in the root of HY9 variety increased by 8.47‐fold, surpassing XY15 (5.41‐fold). Under salt stress, the HY9 maintained lower Na+ content, while higher K+ content and exhibited a relatively abundant K+/Na+ ratio in root and leaf. HY9 also had lower Na+ absorption, Na+ concentration in xylem sap, and Na+ transfer factor than XY15. Moreover, more Na+ contents were accumulated in the root cell wall of HY9 with higher pectin content and pectin methylesterase (PME) activity than XY15. Collectively, our results showed that salt‐tolerant varieties absorbed lower Na+ and retained more Na+ in the root cell wall (carboxyl group in pectin) to avoid leaf salt toxicity and induced higher proline accumulation as a defense and antioxidant system, resulting in higher resistance to salt stress, which provides the theoretical basis for screening salt resistant cultivars. [ABSTRACT FROM AUTHOR]

The hysteresis effect of water retention curve (WRC) has significant implications for comprehending soil water and salt transport, especially in areas with soil salinization. This study evaluates the hysteresis of WRC in saline soils by measuring the drying and wetting WRC of silty clay loam exposed to different salinities using a tension meter. We find that WRC is influenced by the superposition coupling effect of salinity and dry density, which results in an upward shift of WRC and increases the soil water holding capacity. In addition, soil matrix suction also rises with the increasing salt concentration, leading to a gradual upward shift in WRC. The presence of salt in pore spaces weakens the "ink-bottle" effect, disjoining pressure and air entrapment effect, results in a 30.9% reduction in hysteresis of WRC with increasing salinity. Additionally, the volumetric shrinkage of low dry density silty clay loam also weakens the WRC hysteresis. Furthermore, we utilized a WRC hysteresis model that considers the "ink-bottle" effect and entrapped air, which reasonably predicts the main wetting WRC of saline silty clay loam. The root-mean-square error and mean absolute error between predicted and measured values are 0.027–0.039 and 0.036–0.060, respectively. These findings are significant to the research and guidance of salinization in expansive soil and heavy textured soil area where salinization occurs. [ABSTRACT FROM AUTHOR]

Saline‐sodic paddy soils in the Songnen Plain suffer from nitrogen loss due to nitrification. The purpose of the study is to explore soil saline improvement and nitrification mitigation effects of polyaspartic calcium (PASP‐Ca) by evaluating changes of soil quality, nitrification, and microbial communities. Four PASP‐Ca application treatments (additions of 0, 500, 1000, and 1500 kg hm−2) were studied in an experiment in saline‐sodic paddy soils of the Songnen Plain, China. Results showed that PASP‐Ca application significantly decreased soil pH, electrical conductivity (EC), and water‐soluble salt ions, and significantly increased soil total carbon (TC), total nitrogen (TN), urease activity (UA), and sucrase activity (SA). PASP‐Ca application significantly slowed down soil nitrification, which was manifested in a significant increase in ammonium nitrogen (NH4+−N$$ {\mathrm{NH}}_4^{+}-\mathrm{N} $$) and a significant decrease in nitrate nitrogen (NO3−−N$$ {\mathrm{NO}}_3^{-}-\mathrm{N} $$) and ammonia monooxygenase activity (AMO). The composition and distribution of soil nitrifying microbial communities were affected by soil salinity, nutrient, and enzyme activities. Ammonia‐oxidizing bacteria (AOB) plays an important role in the nitrification process of saline‐sodic paddy soils, while PASP‐Ca application significantly inhibited nitrification by suppressing AOB amoA gene abundance. This study shows that PASP‐Ca, as an effective amendment, can improve soil salinization and slow down nitrification, which has an important role and significance in improving nitrogen utilization and reducing nitrogen loss of saline‐sodic soils. [ABSTRACT FROM AUTHOR]

Soil salinization is a global agro-ecological problem and a major factor impeding agricultural development. Planting salt-tolerant plants to improve saline soils offers both ecological and economic benefits. Currently, there are few studies addressing the combined effects of salt and alkali stress. Quinoa is known for its salinity tolerance. However, research has predominantly focused on the effects of salinity stress on quinoa's morphology and physiology, with its molecular mechanisms remaining unclear. To better understand quinoa's response mechanisms to salinity and alkali stress, we employed RNA-seq technology to analyze transcriptomes under these conditions. We identified 1833 differentially expressed genes (DEGs) under salt stress and 2233 DEGs under alkali stress. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) annotations revealed that quinoa responds to salt and alkali stress through similar mechanisms. Both stresses promoted sucrose synthesis, starch synthesis and catabolism, which increased the osmotic potential of quinoa leaves. Additionally, there was a regulation of the down-regulated expression of the abscisic acid receptor PYR/PYL and the up-regulated expression of the serine/threonine protein kinase (PP2C) gene in the ABA signaling pathway. Contrasting with salt tolerance, the mechanism specific to quinoa's alkalinity tolerance involves the up-regulation of the citric acid cycle via an active γ-aminobutyric acid (GABA) branch, enhancing quinoa's energy metabolism. In summary, our transcriptome analysis revealed key regulatory mechanisms in quinoa's response to saline and alkaline stress. This study deepens the understanding of quinoa's stress response mechanisms and provides theoretical references for the biological improvement of salinized soils. [ABSTRACT FROM AUTHOR]

Water resources are scarce, and secondary soil salinization is severe in the Hetao Irrigation District. Farmland shelterbelt systems (FSS) play a critical role in regulating soil water and salt dynamics within the irrigation district. However, the understanding of soil water and salt migration within FSS during the freeze–thaw period remains unclear due to the complex and multifaceted interactions between water and salt. This study focused on a typical FSS and conducted comprehensive monitoring of soil moisture, salinity, temperature, and meteorological parameters during the freeze–thaw period. The results revealed consistent trends in air temperature and soil temperature overall. Soil freezing durations exceeded thawing durations, and both decreased with an increasing soil depth. At the three critical freeze–thaw nodes, the soil moisture content at a 0–20 cm depth was significantly lower than at a 40–100 cm depth (p < 0.05). The soil water content increased with time and depth at varying distances from the shelterbelt, with an average increase of 7.63% after freezing and thawing. The surface water content at the forest edge (0.3H, 4H) was lower than inside the farmland (1H, 2H, 3H). Soil salt accumulation occurred during both freezing stable periods and melting–thawing periods in the 0–100 cm soil layer near the forest edge (0.3H, 4H), with the highest soil salinity reaching 0.62 g·kg−1. After the freeze–thaw period, the soil salt content in each layer increased by 11.41–47.26% compared to before the freeze–thaw period. Salt accumulation in farmland soil near the shelterbelt was stronger than in the far shelterbelt. The multivariate statistical model demonstrated goodness of fit for soil water and salt as 0.94 and 0.72, respectively, while the BP neural network model showed goodness of fit for soil water and salt as 0.82 and 0.85, respectively. Our results provide an efficient theoretical basis for FSS construction and agricultural water management practices. [ABSTRACT FROM AUTHOR]

A novel method, ECWS, is proposed for measuring soil initial salinity content (b), based on the soil electrical conductivity EC and soil moisture content WS. This pioneering model rigorously establishes and incorporates the inherent potential correlation among soil bulk conductivity ( E C a ), soil solution conductivity ( E C w ), volume water content ( θ c ), and soil salinity content (SSC). First of all, in order to delve the deeper relationship between E C a , E C w , θ c and SSC, the soil salinity conductivity conversion coefficient ρ a and soil leaching solution salinity conductivity conversion coefficient ρ w were employed based on the formula of parallel conducting channels of the soil–water system, and a new measurement model of salinity content was constructed. After that, a mathematical analysis method was used to transform the coefficients of multiple sets of regression equations into matrices to solve ρ a , ρ w and b. Finally, to validate the accuracy of the proposed ECWS method, verification tests were conducted by utilizing TDR and PWMER sensors. The results with different salinity contents showed that the b size obtained by ECWS model were K 2 SO 4 (1.84 g/kg), NaCl (1.91 g/kg), and KCl (1.92 g/kg). The maximum deviation was less than 0.08 g/kg (relative error less than 5%). The results showed that the influence of different anions and cations on the measurement of salinity content Cl− is greater than that of SO 4 2 − , and K+ is greater than that of Na+. This study revealed the relationship between soil electrical conductivity and soil salinity content to a certain extent, and realized the transformation between them, which provided a new method for the measurement of soil salinity content, and also provided a reference for related research on the measurement of soil salinization. [ABSTRACT FROM AUTHOR]

Over the last decade, electromagnetic induction (EMI) measurements have been increasingly used for investigating soil salinization caused by the use of brackish or saline water as an irrigation source. EMI measurements proved to be a powerful tool for providing spatial information on the investigated soil because of the correlation between the output geophysical parameter, i.e., the electrical conductivity, to soil moisture and salinity. In addition, their non-invasive nature and their capability to collect a high amount of data over broad areas and in a relatively short time makes these measurements attractive for monitoring flow and transport dynamics, which are otherwise undetectable with conventional measurements. In an experimental field, EMI measurements were collected during the growth season of tomatoes and irrigated with three different irrigation strategies. Time-lapse data were collected over three months in order to visualize changes in electrical conductivity associated with soil salinity. A rigorous time-lapse inversion procedure was set for modeling the soil salinization induced by brackish irrigation water. A clear soil response in terms of an increase in electrical conductivity (EC) in the upper soil layer confirmed the reliability of the geophysical tool to predict soil salinization trends. [ABSTRACT FROM AUTHOR]

Soil salinization poses a significant threat to agricultural production in Portugal. Collaborative research spanning three decades with the U.S. Salinity Laboratory in Riverside, California, has been instrumental in advancing our understanding of this issue. This study provides a concise overview of the causes of soil salinization in Portugal, focusing on ongoing efforts to comprehensively address this challenge. Key advancements highlighted in this study encompass the meticulous characterization of soil hydraulic and solute transport parameters, the application of cutting‐edge modeling tools for water flow and solute transport in diverse agricultural systems, and the utilization of innovative proximal and remote sensing methods for mapping soil salinity. Noteworthy results and practical implications of these advancements underscore their relevance in real‐world scenarios. While celebrating these achievements, the study emphasizes the current nature of the ongoing research, highlighting the dynamic landscape of soil salinization. The study underscores the imperative need for further advancements to effectively cope with soil salinization, especially in anticipation of the intensification of agricultural practices and the looming impacts of climate change. This comprehensive overview not only encapsulates past achievements but also sets the stage for future research endeavors in mitigating the pervasive effects of soil salinization on agricultural sustainability in Portugal. Core Ideas: Three decades of studies on soil salinization in Portugal are reviewed, with an overview of the extent and causes.Studies were started by characterizing soil hydraulic and solute transport parameters of Portuguese soils. They then extended to water flow and multicomponent solute transport modeling using the HYDRUS software package.Mapping of soil salinity using proximal and remote sensing methods is the most recent advance.Several research developments are discussed as well as priorities for the coming years. [ABSTRACT FROM AUTHOR]

The osmotic potential in soil solutions decreases as salinity increases, and plants cannot take up enough soil water. Therefore, the osmotic potential of soil solutions can serve as an important metric of plant growth conditions in regions affected by soil salinization. Measurements of osmotic potential are labor and time consuming. This work aimed to determine more readily available soil salinity metrics to estimate the osmotic potential in soil solutions. A model to compute the osmotic potential from soil solution composition was developed and validated with data from the U.S. states of Washington, Oregon, Colorado, and Idaho. The mean relative error was 7%. Then, this model was applied to 230 datasets on soil solutions from various salinity‐affected regions of Eurasia. The correlation coefficient between logarithms of concentration of highly soluble (not including carbonates and sulfates of calcium and magnesium) in soil solutions at saturation and logarithms of osmotic potential values was above 0.99. The concentration of highly soluble salts in soil solution at saturation was chosen as the predictor of the osmotic potential. It was used to develop nomograms for evaluating the salinity‐related yield loss for major field crops, vegetables, and fruits. This work is a part of the Vadose Zone Journal tribute to the scientific legacy of Martinus van Genuchten, who championed the use of the osmotic potential for better quantification of crop salt tolerance at the macroscale and provided invaluable contributions to modeling soil salinity development and mitigation as a part of the global struggle for food security. Core Ideas: Root zone salinity characterization can benefit from osmotic potential estimates from soil solution composition.The proposed model relates osmotic potential to concentrations of major ions in soil solution.Osmotic potential estimates correlate well with major salinity metrics.Regressions of osmotic pressure on salinity metrics are affected by the salinity type. [ABSTRACT FROM AUTHOR]

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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 × 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 μg/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. [ABSTRACT FROM AUTHOR]

Soil salinization has damaged the soil biological environment and chemical structure, resulting in a decline in soil quality and crop yields, which has caused harm to the ecological environment and human health, and severely hindered the development of the economy. In this experiment, using the 'Ningdan 33' maize seeds as materials, the maize was treated with histidine and salt stress (100 mM NaCl), and photosynthesis, photosynthetic enzyme activity, relative expression of photosynthetic genes of maize were measured. The anatomical structure of the leaves was also observed. The study explored the impact of exogenous histidine treatment on the photosynthesis of maize under salt stress. When the concentration of histidine sprayed on the leaves was 0.5 mM, it had the best effect on promoting photosynthesis in maize under salt stress. 0.5 mM histidine significantly improved the photosynthetic performance (PN, gs, E, Chl a/Chl b) of maize under salt stress, significantly improved photosynthesis efficiency (Fv/Fm, ΔF/F'm, qP were significantly increased. NPQ was significantly decreased), significantly increased the activity of photosynthetic enzymes (PEPC, NADP-ME, PPDK, Rubisco) and the relative expression of photosynthetic genes (ZmPEPC, ZmNADP-ME, ZmPPDK, ZmRCA), increased the length of the vascular bundle in the cross-section of the leaf, played a certain protective role on the vascular bundle, and improved the efficiency of material transportation under salt stress. Based on the above analysis, 0.5 mM histidine can significantly improve the tolerance of maize under salt stress, which has great application value for planting maize in saline environments. [ABSTRACT FROM AUTHOR]

Hyperspectral technology is widely recognized as an effective method for monitoring soil salinity. However, the traditional sieved samples often cannot reflect the true condition of the soil surface. In particular, there is a lack of research on the spectral response of cracked salt-affected soils despite the common occurrence of cohesive saline soil shrinkage and cracking during water evaporation. To address this research, a laboratory was designed to simulate the desiccation cracking progress of 57 soda saline–alkali soil samples with different salinity levels in the Songnen Plain of China. After completion of the drying process, spectroscopic analysis was conducted on the surface of all the cracked soil samples. Moreover, this study aimed to evaluate the predictive ability of multiple linear regression models (MLR) for four main salt parameters. The hyperspectral reflectance data was analyzed using three different band screening methods, namely random forest (RF), principal component analysis (PCA), and Pearson correlation analysis (R). The findings revealed a significant correlation between desiccation cracking and soil salinity, suggesting that salinity is the primary factor influencing surface cracking of saline–alkali soil in the Songnen Plain. The results of the modeling analysis also indicated that, regardless of the spectral dimensionality reduction method employed, salinity exhibited the highest prediction accuracy for soil salinity, followed by electrical conductivity (EC) and sodium (Na+), while the pH model exhibited the weakest predictive performance. In addition, the usage of RF for band selection has the best effect compared with PCA and Pearson methods, which allows salt information of soda saline–alkali soils in Songnen Plain to be predicted precisely. [ABSTRACT FROM AUTHOR]

Salicornia europaea L. is a well-known model plant for studying the mechanism of salt tolerance. A substantial decline in the S. europaea population has been observed in the semi-arid steppe of the Mongolian Plateau. The relationship between environmental factors and its population dynamics in the grassland ecosystem remains inadequately investigated. Rhizosphere microbial communities, representing the most direct and influential biological factors affecting plant populations, have received limited research attention in the context of halophytes. Four density treatments of S. europaea (bare land—SEB, low density—SEL, medium density—SEM, and high density—SEH) in a single-factor randomized-block design with five replications were established to evaluate the relationship between rhizosphere soil bacterial communities and environmental factors. The results showed that as the density of S. europaea increased, the soil pH decreased, while available phosphorus increased. Rhizosphere soil bacterial communities associated with S. europaea populations in the saline-alkali wetland were dominated by Proteobacteria, Bacteroidota, Actinobacteria, Gemmatimonadota, and Halobacterota. Notably, the genera Antarcticibacterium, Wenzhouxiangella, BD2-11_terrestrial_groupBD2-11, Halomonas, and Natronorubrum were found to be particularly abundant. The Simpson index of the rhizosphere soil bacterial community in the S. europaea treatments was significantly higher than that in bare land. Soil pH and nitrate nitrogen were the primary environmental drivers of the rhizosphere bacterial community. Overall, the rhizosphere soil's bacterial diversity in saline wetlands under a high-salt environment was not affected by the decrease in the S. europaea population. S. europaea plays an important role in shaping soil bacterial community structure through its influence on the surrounding soil environment. The cultivation of S. europaea is a phytoremediation strategy to improve soil salinization. [ABSTRACT FROM AUTHOR]

The response of microbiomes to salinity has been clarified in different geographic scales or ecosystems. However, how soil microbial community structure and interaction respond to salinity across wide salinity range and climatic region is still unclearly resolved. To address this issue, we examined the microbial community's composition in saline soils from two climatic regions (coastal wetland and arid desert). Our research confirms that soil salinity had a negative effect on soil nutrient content. Salinity decreased the relative abundance of bacteria, but increased archaea abundance, leading to the shifts from bacteria dominant community to archaea dominant community. Low-water medium-salinity soil (LWMS) had the most complex archaeal community network, whereas for bacteria, the most complex bacterial community network was observed in low-water high-salinity soils (LWHS). Key microbial taxa differed in three salinity gradients. Salinity, soil water content, pH, total nitrogen (TN), and soil organic carbon (SOC) were the main driving factors for the composition of archaeal and bacterial community. Salinity directly affected archaeal community, but indirectly influenced bacteria community through SOC; pH affected archaeal community indirectly through TN, but directly affected bacterial community. Our study suggests that soil salinity dramatically influences diversity, composition, and interactions within the microbial community. [ABSTRACT FROM AUTHOR]

The El Haouz and El Kelaa Des Sraghna region is renowned for its agriculture, but is facing problems of salinisation due to its arid climate and unfavourable weather conditions. To remedy this, localised irrigation systems have been introduced to provide water for crops and improve yields. This study examines the impact of these irrigation systems on soil salinity in the region by comparing upstream and downstream areas. Using remote sensing techniques, we identify areas at risk of high salinity and collect soil samples for physical and chemical analysis in the field. These analyses enable us to monitor changes in salinisation and assess the effectiveness of localised irrigation in the areas concerned. Our results reveal two distinct zones in the region: an upstream zone with low salinity, with electrical conductivity ranging from 66 µS/cm to 345 µS/cm, and a downstream zone with higher salinity, with electrical conductivity ranging from 228 µS/cm to 1.075 µS/cm, attributed to the use of localised irrigation for crops. The remote sensing maps anticipated this difference, which was confirmed by the field analyses. [ABSTRACT FROM AUTHOR]

Salinization in inland soil is a major impediment to food security and sustainable development goals. For several decades farmers were abandoning their lands, which were deteriorated due to salinization, and forced to take up alternate livelihoods. However, proper scientific and technological interventions came forward in the form of inland saline water (ISW) aquaculture of several euryhaline fish and shellfish species. Among them, ISW-based Penaeus vannamei farming was found to be the most viable and profitable venture for farmers. Although this practice was appropriated with the culture parameters guided for the natural seawater system; over time it become important to determine the optimal stocking density for this novel ISW system and its impact on various physio-metabolic and molecular changes in the cultured shrimp. Given this, the present study was undertaken wherein, post-larvae 8 (PL8) of P. vannamei were experimentally reared in ISW ponds with three different stocking densities viz., n = 30 PL8/m2 (T1); n = 45 PL8/m2 (T2); and n = 60 PL8/m2 (T3), for 75 days followed by evaluation of various parameters related to stress and immune system. The study revealed significant (p < 0.05) increase in the activities of antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) in the highest stocked (T3) group. Further, the T3 group demonstrated lower haemato-biochemical indices viz., haemocyte count, haemocyanin concentration, serum protein, and triglyceride levels. However, the serum glucose and malondialdehyde (MDA) as well as stress-related genes viz., heat shock protein 70 (HSP70) and SOD genes showed significant (p < 0.05) upregulation in the T3 group as compared to the T1 group. Thus, the present study delineates the negative impact of crowding density on the overall health status of the cultured shrimp and recommends the optimum stocking density for P. vannamei in ISW ponds to be 30 PL8/m2 to obtain a healthy and disease-free crop. [ABSTRACT FROM AUTHOR]

This study focuses on detecting and mitigating soil salinization in four coastal areas of the Mekong Delta (Vietnam). Salinity patterns in the soils of the Mekong River Delta are not random but linked to land use practices and distance to the sea. We examine two quick yet reliable remote sensing-based techniques to detect the coastal aquaculture area and separate it from the inland freshwater farmland. These techniques can eventually be used to identify locations with an elevated risk of salinization in other coastal regions. Finally, we investigate a salinization mitigation solution based on creating a managed aquifer recharge system along the buffer zone that separates the coastal aquaculture area from the inland freshwater agriculture area. The implementation of an infiltration pond system is technically feasible in the Mekong Delta provided that hydrogeological characteristics, the fresh-saline interface position, and freshwater demands are considered. The transitional zone between freshwater agriculture and brackish water aquaculture in Bac Lieu, Soc Trang, Tra Vinh and Ben Tre provinces is optimal for implementing an aquifer recharge/freshwater barrier scheme. [ABSTRACT FROM AUTHOR]

Water shortage and salinization are the main challenges confronted by irrigated agriculture in semiarid and arid regions. As one of the top-three largest irrigation districts in China, the Hetao Irrigation District faces pressing challenges to reduce irrigation water use and mitigate soil and groundwater salinization. Managing water and salinity requires understanding and analyzing not only the hydrologic and agronomic processes involved but the cropping and irrigation decision-making of farmers. With this aim, we build a hydroeconomic optimization model, which integrates the agrohydrological processes of water and salt balance in the crop root zone and underlying aquifer into economic optimization of water allocation and crop production. The positive mathematical programming method is used to calibrate the model such that it can replicate base-year observations. Model results highlight that a portfolio of interventions is necessary for alleviating soil and groundwater salinization and maintaining agricultural productivity and revenues; it is thus crucial to understand their long-term, cumulative effects for the sake of sustainable irrigated agricultural production. The model can assist decision-making for water and salinity management in the HID and offer useful insights for water and salinity management in irrigated agriculture of other arid regions in the world. [ABSTRACT FROM AUTHOR]

The water and salt movement and crystallization deformation of saline soil in cold and arid regions is a complex hydrothermal–salt–mechanical coupling problem. Based on the law of mass conservation, the law of energy conservation, and the theory of permafrost mechanics, the hydrothermal–salt–mechanical coupling mathematical model of unsaturated sodium sulfate saline soil is established. The model takes into account the latent heat of phase transition, crystallization impedance, consumption of crystallization, ice crystal self-cleaning behavior, and temperature as mechanical parameters. Numerical simulations using COMSOL Multiphysics (version 5.5) software were carried out, and the outcomes were analyzed and compared with unidirectional freezing test data. The findings show that the coupled model accurately simulates heat–mass transfer, crystallization, and salt freeze–thaw deformation in unsaturated saline soil. In the unidirectional freezing process, the temperature, salt freezing deformation, and freezing depth within the saline soil showed a three-stage rule of change, and the migration of water and salt to the freezing front made the water and salt content in the freezing zone increase significantly and form a laminar distribution, and the peak of the water and salt content appeared at the freezing front. The migration of water and salt aids in forming ice and salt crystals that rapidly grow within the soil pores of the freezing zone, leading to salt freeze–thaw deformation. Furthermore, the models and results of this study offer crucial insights into the mechanisms of soil salinization, desertification, and salt freeze–thaw deformation in cold and arid regions. [ABSTRACT FROM AUTHOR]

Abstract Soil salinization threatens agricultural productivity, leading to desertification and land degradation. Given the challenges of conducting labor-intensive and expensive field studies and laboratory analyses on a large scale, recent efforts have focused on leveraging remote sensing techniques to study soil salinity. This study assesses the importance of soil salinity indices’ derived from remotely sensed imagery. Indices derived from Landsat 8 (L8) and Sentinel 2 (S2) imagery are used in Random Forest (RF), eXtreme Gradient Boosting (XGBoost), Decision Tree (DT), and Support Vector Machine (SVR) are associated with the electrical (EC) conductivity of 280 soil samples across 24,000 hectares in Northeast Iran. The results indicated that the DT is the best-performing method (RMSE = 12.25, MAE = 2.15, R2 = 0.85 using L8 data and RMSE = 10.9, MAE = 2.12, and R2 = 0.86 using S2 data). Also, the results showed that Multi-resolution Valley Bottom Flatness (MrVBF), moisture index, Topographic Wetness Index (TWI), and Topographic Position Indicator (TPI) are the most important salinity indices. Subsequently, a time series analysis indicated a reduction in salinity and sodium levels in regions with installed drainage networks, underscoring the effectiveness of the drainage system. These findings can assist decision-making about land use and conservation efforts, particularly in regions with high soil salinity.

Background: Soil salinization threatens food security and ecosystem health, and is one of the important drivers to the degradation of many ecosystems around the world. Soil microorganisms have extremely high diversity and participate in a variety of key ecological processes. They are important guarantees for soil health and sustainable ecosystem development. However, our understanding of the diversity and function of soil microorganisms under the change of increased soil salinization is fragmented. Aim of Review: Here, we summarize the changes in soil microbial diversity and function under the influence of soil salinization in diverse natural ecosystems. We particularly focus on the diversity of soil bacteria and fungi under salt stress and the changes in their emerging functions (such as their mediated biogeochemical processes). This study also discusses how to use the soil microbiome in saline soils to deal with soil salinization for supporting sustainable ecosystems, and puts forward the knowledge gaps and the research directions that need to be strengthened in the future. Key Scientific Concepts of Review: Due to the rapid development of molecular-based biotechnology (especially high-throughput sequencing technology), the diversity and community composition and functional genes of soil microorganisms have been extensively characterized in different habitats. Clarifying the responding pattern of microbial-mediated nutrient cycling under salt stress and developing and utilizing microorganisms to weaken the adverse effects of salt stress on plants and soil, which are of guiding significance for agricultural production and ecosystem management in saline lands.

Sesuvium portulacastrum L. is a flowering succulent halophyte in the ice plant family Aizoaceae. There are various ecotypes distributed in sandy coastlines and salty marshlands in tropical and subtropical regions with the common name of sea purslane. These plants are tolerant to salt, drought, and flooding stresses and have been used for the stabilization of sand dunes and the restoration of coastal areas. With the increased salinization of agricultural soils and the widespread pollution of toxic metals in the environment, as well as excessive nutrients in waterbodies, S. portulacastrum has been explored for the desalination of saline soils and the phytoremediation of metals from contaminated soils and nitrogen and phosphorus from eutrophic water. In addition, sea purslane has nutraceutical and pharmaceutical value. Tissue analysis indicates that many ecotypes are rich in carbohydrates, proteins, vitamins, and mineral nutrients. Native Americans in Florida eat it raw, pickled, or cooked. In the Philippines, it is known as atchara after being pickled. S. portulacastrum contains high levels of ecdysteroids, which possess antidiabetic, anticancer, and anti-inflammatory activities in mammals. In this review article, we present the botanical information, the physiological and molecular mechanisms underlying the tolerance of sea purslane to different stresses, its nutritional and pharmaceutical value, and the methods for its propagation and production in saline soils and waterbodies. Its adaptability to a wide range of stressful environments and its role in the production of valuable bioactive compounds suggest that S. portulacastrum can be produced in saline soils as a leafy vegetable and is a valuable genetic resource that can be used for the bioremediation of soil salinity and eutrophic water. [ABSTRACT FROM AUTHOR]

Background: Seed aging, a natural and inevitable process occurring during storage. Oats, an annual herb belonging to the Gramineae family and pooideae. In addition to being a healthy food, oats serve as ecological pastures, combating soil salinization and desertification. They also play a role in promoting grassland agriculture and supplementing winter livestock feed. However, the high lipid and fat derivatives contents of oat seeds make them susceptible to deterioration, as fat derivatives are prone to rancidity, affecting oat seed production, storage, development, and germplasm resource utilization. Comparative studies on the effects of aging on physiology and cytological structure in covered and naked oat seeds are limited. Thus, our study aimed to determine the mechanism underlying seed deterioration in artificially aged 'LongYan No. 3' (A. sativa) and 'BaiYan No. 2' (A. nuda) seeds, providing a basis for the physiological evaluation of oat seed aging and serving as a reference for scientifically safe storage and efficient utilization of oats. Results: In both oat varieties, superoxide dismutase and catalase activities in seeds showed increasing and decreasing trends, respectively. Variance analysis revealed significant differences and interaction in all measured indicators of oat seeds between the two varieties at different aging times. 'LongYan No. 3' seeds, aged for 24–96 h, exhibited a germination rate of < 30%, Conductivity, malondialdehyde, soluble sugar, and soluble protein levels increased more significantly than the 'BaiYan No. 2'. With prolonged aging leading to cell membrane degradation, reactive oxygen species accumulation, disrupted antioxidant enzyme system, evident embryo cell swelling, and disordered cell arrangement, blocking the nutrient supply route. Simultaneously, severely concentrated chromatin in the nucleus, damaged mitochondrial structure, and impaired energy metabolism were noted, resulting in the loss of 'LongYan No. 3' seed vitality and value. Conversely, 'BaiYan No. 2' seeds showed a germination rate of 73.33% after 96 h of aging, consistently higher antioxidant enzyme activity during aging, normal embryonic cell shape, and existence of the endoplasmic reticulum. Conclusions: ROS accumulation and antioxidant enzyme system damage in aged oat seeds, nuclear chromatin condensation, mitochondrial structure damage, nucleic acid metabolism and respiration weakened, oat seed vigor decreased. 'LongYan No. 3' seeds were more severely damaged under artificial aging than 'BaiYan No. 2' seeds, highlighting their heightened susceptibility to aging effects. [ABSTRACT FROM AUTHOR]

The increasing global phenomenon of soil salinization has prompted heightened interest in the physiological ecology of plant salt and alkali tolerance. Halostachys caspica belonging to Amaranthaceae, an exceptionally salt-tolerant halophyte, is widely distributed in the arid and saline-alkali regions of Xinjiang, in Northwest China. Soil salinization and alkalinization frequently co-occur in nature, but very few studies focus on the interactive effects of various salt and alkali stress on plants. In this study, the impacts on the H. caspica seed germination, germination recovery and seedling growth were investigated under the salt and alkali stress. The results showed that the seed germination percentage was not significantly reduced at low salinity at pH 5.30–9.60, but decreased with elevated salt concentration and pH. Immediately after, salt was removed, ungerminated seeds under high salt concentration treatment exhibited a higher recovery germination percentage, indicating seed germination of H. caspica was inhibited under the condition of high salt-alkali stress. Stepwise regression analysis indicated that, at the same salt concentrations, alkaline salts exerted a more severe inhibition on seed germination, compared to neutral salts. The detrimental effects of salinity or high pH alone were less serious than their combination. Salt concentration, pH value, and their interactions had inhibitory effects on seed germination, with salinity being the decisive factor, while pH played a secondary role in salt-alkali mixed stress. [ABSTRACT FROM AUTHOR]

Introduction: Soil salinization poses a significant environmental challenge affecting plant growth and agricultural sustainability. This study explores the potential of salt-tolerant endophytes to mitigate the adverse effects of soil salinization, emphasizing their impact on the development and resistance of Arachis hypogaea L. (peanuts). Methods: The diversity of culturable plant endophytic bacteria associated with Miscanthus lutarioriparius was investigated. The study focused on the effects of Bacillus tequilensis, Staphylococcus epidermidis, and Bacillus siamensis on the development and germination of A. hypogaea seeds in pots subjected to high NaCl concentrations (200 mM L-1). Results: Under elevated NaCl concentrations, the inoculation of endophytes significantly (p < 0.05) enhanced seedling germination and increased the activities of enzymes such as Superoxide dismutase, catalase, and polyphenol oxidase, while reducing malondialdehyde and peroxidase levels. Additionally, endophyte inoculation resulted in increased root surface area, plant height, biomass contents, and leaf surface area of peanuts under NaCl stress. Transcriptome data revealed an augmented defense and resistance response induced by the applied endophyte (B. tequilensis, S. epidermidis, and B. siamensis) strain, including upregulation of abiotic stress related mechanisms such as fat metabolism, hormones, and glycosyl inositol phosphorylceramide (Na+ receptor). Na+ receptor under salt stress gate Ca2+ influx channels in plants. Notably, the synthesis of secondary metabolites, especially genes related to terpene and phenylpropanoid pathways, was highly regulated. Conclusion: The inoculated endophytes played a possible role in enhancing salt tolerance in peanuts. Future investigations should explore protein--protein interactions between plants and endophytes to unravel the mechanisms underlying endophyte-mediated salt resistance in plants. [ABSTRACT FROM AUTHOR]