Search Results (877)

Coastal reclaimed polders with shallow saline groundwater support intensive greenhouse horticulture but require timely diagnosis of root-zone water and salinity conditions. This study developed a compact Internet-of-Things (IoT) monitoring system based on the M5Stamp Pico microcontroller to acquire SDI-12 soil-sensor data, buffer records locally, and transfer them to a low-cost cloud dashboard. Outside-greenhouse validation showed high operational reliability, with a missing observation rate of only 0.9%, and acceptable agreement with a reference TDR100 for both volumetric water content (θ) and bulk electrical conductivity (EC_b). The system was then applied to ridge-position monitoring in a commercial pepper greenhouse on a coastal reclaimed polder. The ridge records captured depth-dependent infiltration and salinity redistribution under drip irrigation, together with contrasting responses between the cultivated layer and shallow groundwater. Potential-based interpretation indicated that the monitored ridge root zone was often not strongly limited by matric potential, whereas osmotic potential derived from pore-water salinity showed reduced water availability even when the soil remained relatively wet. These results demonstrate that continuous real-time monitoring at the ridge position can support diagnosis of root-zone stress and provide useful information for irrigation and fertigation management in salt-affected greenhouse soils. Full article

Soil salinization is increasingly threatening global agricultural productivity and food security, currently affecting over 6% of the world’s land and one-third of irrigated areas. Tomato (Solanum lycopersicum L.), a major vegetable crop worldwide, exhibits moderate sensitivity to salinity, which limits both its yield and fruit quality. In recent years, epigenetic regulation has gained attention as a key mechanism enabling flexible and reversible control of gene expression without altering DNA sequences. This review synthesizes current knowledge on the epigenetic control of salt stress responses in tomato, focusing on three interconnected levels: DNA methylation dynamics, RNA-directed DNA methylation (RdDM), and histone modifications. We explore how DNA methyltransferases reshape the methylome under salinity, using examples such as PKE1 and SlGI to illustrate functional gene-body methylation. The RdDM pathway is discussed with emphasis on the unexpected role of SlAGO4A as a negative modulator of stress tolerance and the growing evidence for RdDM-mediated regulation of transcription factors. We also examine the balanced regulation of histone acetylation and deacetylation, highlighting the conserved role of GCN5 in maintaining cell wall integrity and the diverse functions of histone deacetylases, such as SlHDA1, SlHDA3, and SlHDA5, in stress adaptation. Additionally, insights from wild tomato species and grafting-induced epigenetic changes are presented, revealing new dimensions of stress memory. Collectively, these epigenetic mechanisms constitute a complex regulatory framework that integrates stress responses with growth and development, providing potential targets for epigenetic breeding of salt-tolerant tomatoes. Full article

Global warming and associated environmental changes are reducing arable land and intensifying salinization risks, posing growing threats to food security. Soil salinity is an increasing threat to agricultural productivity worldwide, particularly in arid and semi-arid areas. Wheat (Triticum aestivum L.) is one of the most important and widely cultivated cereal crops for human consumption and livestock feed. However, with increasing water scarcity and the incidence of salt-affected lands, wheat productivity is increasingly affected by salinity. Previous studies have investigated salinity tolerance mechanisms mainly at the seedling and reproductive stages of wheat; however, comparatively fewer studies integrate rapid biochemical and physiological responses during the first hours of germination stress exposure together with transcriptional analyses during early seedling establishment, even though this stage is critical for stand establishment. Here, we evaluated early physiological and transcriptional responses of salt-tolerant, moderate, and sensitive wheat cultivars exposed to 0 or 150 mM NaCl during germination and the early seedling stage. Tolerant and sensitive cultivars showed contrasting germination performance under salinity. Physiological analysis showed that salt-tolerant cultivars exhibited higher proline accumulation and higher antioxidant enzyme activities (CAT, SOD, and GR), while maintaining lower MDA levels under salinity compared with sensitive cultivars. Notably, tolerant cultivars showed marked upregulation of TaHKT1;4, TaP5CS, TaMYB, and TaDHN genes associated with ion homeostasis, osmoprotectant metabolism, and stress-responsive regulation. These responses represent integrated early-stage biochemical, physiological, and transcriptional indicators of salinity responsiveness rather than direct predictors of final yield performance. Full article

Layered saline soils containing weakly permeable interlayers exhibit restricted infiltration, surface salt accumulation, and limited deep salt discharge. This study investigated how weakly permeable interlayer thickness, hydraulic-parameter scenario, hole diameter, hole spacing, and irrigation salinity affect soil water redistribution, salt leaching, and profile desalination under vertical-hole treatment. Pilot-scale soil-box experiments were used for model calibration and validation, and HYDRUS-3D simulations were then used for controlled-condition scenario analysis and preliminary layout screening. The weakly permeable interlayer reduced hydraulic connectivity, increased water retention above the interface, and intensified surface salt enrichment, with stronger effects at greater thickness. Vertical holes improved hydraulic continuity and promoted downward percolation and salt leaching, but their effectiveness depended on layout. At a spacing of 30 cm, increasing hole diameter from 5 to 10 cm increased the mean desalination rate from 7.07% to 13.44% in the surface layer and from 4.06% to 18.61% in the deep layer. Irrigation salinity had little effect on water content but increased soil salt accumulation. Under the assumed conceptual cost–performance framework, the 10 cm diameter and 30 cm spacing combination showed the highest composite performance within the tested parameter range. These findings provide a mechanistic basis and preliminary layout-screening reference for vertical-hole treatment in layered saline soils with weakly permeable interlayers. Full article

Moisture, salinity and aeration in saline–alkali soil are three critical factors affecting the biotic and abiotic environment. A three-factorial experiment including two tillage measures (ridge and flat tillage, denoted as R and F, respectively), three drip irrigation levels (soil wetting proportion of 40, 55 and 70%, denoted as P₁, P₂ and P₃) and the presence or absence of air injection (AI) were investigated to determine their effects on soil moisture, salinity, aeration and sunflower growth and yield. Field trials were conducted in the Hetao irrigation district of Inner Mongolia in 2021 and 2022. Results showed that R increased daily average topsoil (0–20 cm depth) temperature by 0~4.7 °C, water-filled pore space (WFPS) by 4.3~9.1% and redox potential (Eh) by 16.7~31.6% compared to F. P₂ reduced the Eh of topsoil by 50.4% and 55.1% respectively under R and F. Under the same P, the effect of different tillage methods (R and F) on salt accumulation was not notable. AI increased topsoil temperature under R (0.1~2.7 °C) and F (0~2.2 °C) and increased salt accumulation in the topsoil. Compared with other treatments, the yield of sunflower increased by 10~36% and 12~37% respectively under the conditions of P₃R and P₂FAI. The net profit of P₃R treatment was 3421–3551 USD ha⁻¹, which was 12.0–71.5% higher than the other treatments. Furthermore, random forest analysis revealed that air injection, salinity, tillage method, and Eh were the primary determinants of sunflower yield and quality, while WFPS and temperature were of secondary importance. These findings also suggest that, in heavily saline–alkali soils, sunflower yield can be effectively enhanced either by adopting flat tillage with air injection or by using ridge tillage without air injection. Full article

The deposition of volcanic ash in areas affected by erupting volcanoes can contaminate the soil with heavy metals, thereby jeopardizing food security and public health. This study focused on the use of compost for the bioremediation of this type of contaminated soil and on evaluating the effectiveness of this remediation technique in a horticultural crop. To this end, composts made from organic waste generated in the areas with volcanic-ash-affected soil, such as crop residues, cow manure, and cheese whey, were used. The design and optimization of the composting process for these wastes were described using three piles with the same proportion of crop residues and cow manure but different doses of whey (pile 1: without whey, pile 2: whey diluted with water (1:2 (v:v)); and pile 3: with undiluted whey) and by monitoring the evolution of physicochemical and biological parameters throughout the compositing process. The effectiveness of the composts obtained for soil remediation was evaluated by assessing the physiological response of a lettuce crop in pots. Five treatments were used: control soil without fertilization, inorganic fertilization, and the three composts obtained. The main agronomic properties of the soil and heavy metal availability were measured, along with the physiological and chemical parameters of the lettuce, including growth and macronutrient and heavy metal content. The results obtained in the composting experiment showed that the addition of cheese whey only affected the rate of organic matter degradation and the salt content of the final composts, without negatively affecting the stability and humification of their organic matter or their plant nutrient content. In the pot experiment, all composts improved soil fertility and reduced the availability of Ni, As, Cd, and Pb, but this did not consistently reduce uptake into lettuce, except in the case of Pb. Therefore, it is advisable to adjust the compost application rate and optimize crop selection to minimize the impact of heavy metals on the food chain, thereby ensuring safe production. Full article

Soil salinization, intensified by climate change, reduces soil quality and crop yields, posing a severe threat to food security. The present study focuses on the effects of two doses of a biostimulant, based on plant protein hydrolysates, on improving the root system and the quality of NaCl-affected soil. For this purpose, several experiments were conducted on Solanum lycopersicum plants that were grown for 60 days under four salinity conditions, obtained by combining two salinity levels and two irrigation water types (a total of 36 treatments). Several physical and chemical soil properties and root characteristics were evaluated, and it was shown that the application of the biostimulant (BALOX^®) significantly increased root length and total root area, even under high salinity conditions. An increase of up to 70% over the control was achieved, mostly in roots smaller than 2 mm in diameter, which are primarily responsible for nutrient absorption. It was also revealed that BALOX^®’s interaction with the root system favorably influenced soil properties, particularly Cation Exchange Capacity (CEC). Likewise, the Aggregate stability (AS) increased up to 36%, and the percentage of organic matter (OM) up to 6.4%. The CEC increased by 66–72% with the biostimulant application, and there were reductions in soil salinity and Na⁺ and Cl⁻ concentrations (20%, 19%, and 24%, respectively). In addition, BALOX increased the area and length of fine roots, thereby expanding the rhizosphere and enhancing its interaction with the soil. The use of the biostimulant may help prevent soil degradation and contribute to tomato plants’ tolerance mechanisms under salt stress. Full article

Salinity is a major abiotic stress that limits wheat productivity in arid and semi-arid regions. The present study evaluated 20 wheat (Triticum aestivum L.) genotypes, including local and improved varieties, under saline soil conditions (ECe ≈ 6.3 and 12.5 dS m⁻¹) to assess their performance and tolerance mechanisms. The experiment was conducted using a randomized complete block design with three replicates. Data were recorded for grain yield, number of spikes per square meter, number of kernels per spike, 1000-grain weight, sodium (Na⁺), potassium (K⁺), and K⁺/Na⁺ ratio. Analysis of variance revealed significant differences among the genotypes for all traits. Grain yield ranged from 0.51 t ha⁻¹ to 1.14 t ha⁻¹, with Bhan 2000, Local, P7, and Sakha 93 showing superior performance, whereas IC15, P6, and IC96 were most affected. A strong positive correlation was observed between grain yield and both kernels per spike (r = 0.75) and K/Na ratio (r = 0.55), whereas Na content was negatively correlated with yield (r = −0.35). Genotypes with higher K⁺/Na⁺ ratios exhibited better ionic balance and salt tolerance. Based on the combined evaluation of productivity and ionic homeostasis, Bhan 2000, Local, P7, and Sakha 93 were clearly identified as the most salt-tolerant genotypes. These genotypes maintained higher grain yields together with optimal K⁺/Na⁺ ratios, reflecting efficient ionic regulation mechanisms. The integrated approach adopted in this study strengthens selection accuracy and highlights these genotypes as promising candidates for cultivation in saline environments and as donor parents in wheat breeding programs targeting salinity tolerance. Full article

Soil salinity as a major abiotic stressor has significantly affected crop production worldwide. However, plants have developed complex signaling networks that enable them to adapt and cope with such environmental shifts. Recent research has demonstrated the involvement of hydrogen sulfide (H₂S) in signaling cascades that link plant development with stress tolerance management. Similarly, glutathione (GSH), a non-enzyme antioxidant, and a vital tripeptide, has been found to protect plants from oxidative damage and regulate metabolic functions under abiotic stress. As a potential scavenger of ROS, GSH maintains cellular redox homeostasis through the ascorbate-GSH cycle and acts as a signaling molecule for the sulfur-status of plants. This review focusses on: (i) revisiting the concept and current status of soil salinity; (ii) highlighting its impact at cellular and whole-plant levels; (iii) elucidating the role of a H₂S and GSH in plant salt stress tolerance; and (iv) exploring the potential interactive roles of H₂S and GSH in mitigating salinity impacts. This review will provide valuable insights into the complex network involving H₂S and GSH, suggesting pathways for developing climate-resilient crops. Full article

Soil salinity is a major environmental constraint affecting avocado (Persea americana Mill.) productivity. In this study, we evaluate the physio-morphological and molecular responses of two avocado varieties, drymifolia (sensitive) and americana (tolerant), subjected to increasing NaCl concentrations for 60 days. Our results reveal distinct adaptive strategies. While salinity reduced total biomass in both genotypes, var. americana exhibited superior resilience, characterized by preferential biomass allocation to the root system. Ion analysis demonstrated that tolerance was not mediated by K⁺ homeostasis, but rather by the differential management of toxic ions. var. americana effectively sequestered chloride Cl⁻ in the roots, whereas var. drymifolia exhibited a breakdown of the exclusion mechanism at 60 mM NaCl, with shoot Cl⁻ concentrations exceeding those of the root, leading to severe toxicity. At the molecular level, qPCR analysis of the Na⁺ transporters PaHKT1 and PaSOS1 showed no expression pattern correlated with salt stress. Bioinformatic assessment revealed significant structural divergences and a lack of conserved functional domains in these proteins. These findings challenge the applicability of the classical sodium-exclusion model (typical of Liliopsida and Magnoliopsida) to avocado. We conclude that salt tolerance in this Lauraceae species is primarily driven by root-mediated Cl⁻ exclusion rather than canonical Na⁺ transport pathways. Full article

Soil salinization is a major abiotic stressor limiting global agricultural and forestry productivity. This study aimed to assess the tolerance of four wild cherry (Prunus avium L.) genotypes (8-A, F-12, F-19, F-15) to salinity stress using the in vitro culture technique. Shoots were exposed to three NaCl concentrations (0—control treatment, 33, and 100 mM) in micropropagation medium under controlled laboratory conditions for 35 days. Morphological parameters, including shoot length, shoot number, survival and multiplication rate, shoot fresh and dry biomass, and shoot water content, were evaluated alongside biochemical markers such as total phenolic content (TPC), total flavonoid content (TFC), and antioxidant activities assessed through ferric reducing–antioxidant power (FRAP), ABTS radical scavenging, DPPH radical scavenging and nitric oxide (NO•) scavenging. Consistent with the experimental design, exposure to 100 mM NaCl significantly inhibited shoot growth and biomass accumulation, while survival was comparatively less affected. Genotypic variation was evident, with genotypes F-19 and F-12 demonstrating higher tolerance, maintaining greater growth and antioxidant capacity (FRAP and ABTS) under salt stress compared to more sensitive genotypes like 8-A and F-15. Phenolic and flavonoid contents were also reduced at 100 mM NaCl, suggesting that intense salinity stress limited the biosynthesis and accumulation of these antioxidant compounds. Nitric oxide scavenging activity remained largely unaffected by salinity in all genotypes, which may indicate that the applied stress levels were insufficient to markedly alter this component of the antioxidant response. The genotype F-19 emerged as the strongest salinity-tolerant genotype, retaining superior shoot number, multiplication rate, fresh/dry biomass and stable/increased total phenolic content (TPC) under 100 mM NaCl compared to other genotypes. This integrative in vitro approach effectively distinguished salt-tolerant wild cherry genotypes and offers a valuable screening tool for breeding and selection programmes targeting improved resilience to salinity stress. The findings have practical relevance for forestry, horticulture, landscape architecture and the restoration of salt-affected sites, particularly in the context of climate change. They also align with current European and global priorities focused on identifying genetically suitable reproductive material for resilient afforestation and ecosystem restoration under increased environmental stress. Full article

Alhagi camelorum is a dominant leguminous shrub distributed in the Taklamakan Desert, an area characterized by extreme drought and high soil salinization, which can complete its life cycle normally in salt-affected soils. However, the underlying molecular regulatory mechanism of its salt tolerance remains largely unclear. The AcABI5 gene was successfully cloned and characterized, and it encodes a typical nuclear-localized bZIP transcription factor. Functional characterization demonstrated that overexpression of AcABI5 markedly improved the salt stress tolerance of A. camelorum calli, whereas silencing of AcABI5 via virus-induced gene silencing (VIGS) rendered the plant more sensitive to salt stress. Further mechanistic investigations revealed that AcABI5 enhanced salt tolerance by regulating the expression of superoxide dismutase (SOD)- and peroxidase (POD)-related antioxidant genes. Compared with the wild type, AcABI5-overexpressing calli exhibited significantly increased SOD and POD activities and remarkably reduced malondialdehyde (MDA) content under salt treatment, whereas AcABI5-silenced lines exhibited the opposite physiological phenotypes. Furthermore, heterologous silencing of AcABI5 in Nicotiana benthamiana via virus-induced gene silencing (VIGS) produced comparable salt-sensitive phenotypes, similar to those observed in A. camelorum AcABI5-silenced lines. Collectively, these results provide insights into the molecular mechanism by which AcABI5 enhances salt tolerance in A. camelorum, and lay a solid theoretical foundation for the optimization of the A. camelorum genetic transformation system and the expansion of related salt-tolerant crop research. Full article

Biochar amendment holds promise for improving saline soils, yet its efficacy is often constrained by the uncertainty of application rates. In this study, a large field trial and associated statistical modeling were conducted to explore the mechanisms by which biochar affects wheat yield in coastal saline soils of northern China. Results showed that biochar application significantly increased soil organic carbon (SOC) content (R² = 0.615, p < 0.001) but induced marked spatial heterogeneity across the field, with the coefficient of variation (CV) reaching 30.2%. Given the difficulty of uniformly applying biochar in the field, subplot-level SOC was used as a proxy for effective biochar distribution. Stepwise regression identified soil electrical conductivity (EC) as the dominant yield constraint (standardized coefficient = −0.69), rather than water and nutrients, and a quadratic relationship was observed between SOC and EC. Structural equation modeling (SEM) further suggested a trade-off: SOC was associated with higher yield through reduced bulk density (BD) (path coefficient = −0.603), whereas high SOC levels were also associated with increased EC under this coastal saline field setting (path coefficient = 0.243), thereby indirectly constraining growth. Consequently, the agronomic response showed a threshold-like transition: the peak wheat yield occurred at an SOC threshold of 13.87 g kg⁻¹ (equivalent to 44.41 t ha⁻¹), which exceeded the point of minimum salinity (11.71 g kg⁻¹, equivalent to ~29.90 t ha⁻¹ biochar). These results suggest that the agronomic benefit of biochar in saline soils depends on maintaining application within an estimated beneficial buffering zone. Full article

Treated wastewater (TWW) reuse mitigates water scarcity but may induce soil salinization and trace metal accumulation if improperly managed. This field study evaluated the combined effects of irrigation water quality (TWW vs. well water) and irrigation method (surface vs. subsurface drip irrigation, SDI) on soil chemical properties, okra growth, yield, and nutrient/trace element dynamics under semi-arid Mediterranean conditions. Soil pH remained stable across treatments. Electrical conductivity was not significantly affected by water quality but increased in deeper layers under surface drip irrigation, indicating salt migration. SDI promoted more uniform nutrient distribution and favored Na⁺ displacement toward deeper layers, reducing root-zone exposure. Cations stratified vertically, with Ca²⁺, Mg²⁺, and K⁺ concentrated in surface layers and Na⁺ at depth. Water quality exerted a stronger influence than irrigation method. The fertilizing effect of TWW significantly enhanced plant height (53%), leaf dry matter (43%), aboveground biomass (81%), and fruit yield (16.3%). When combined with SDI, TWW improved irrigation water use efficiency by 20%. Although fruit Cd concentrations increased under TWW irrigation, all trace metals remained below international food safety standards. These findings indicate that integrating TWW with SDI enhances productivity and water use efficiency while maintaining short-term food safety, though long-term monitoring remains essential. Full article

Microplastics (MPs) pose a significant threat to soil ecosystems based on their small size and resistance to biodegradation. Soil organic carbon (SOC) in saline–alkaline ecosystems has significantly affected maintain the ecological balance. This paper aims to review the mechanisms underlying the influence of MPs on SOC in saline–alkaline soils combining bibliometric mapping (VOSviewer). The results revealed that: (1) MPs mainly enter the saline–alkaline soil through water irrigation, sewage sludge, and agricultural films. (2) The interaction between the salt ions in saline–alkaline soils and the negatively charged surface of MPs will intensify the dispersion of soil aggregates, resulting in a significant decline in soil structure stability and nutrient imbalance. (3) MPs and the high-salt environment of saline–alkaline soils form a synergistic stress, significantly reducing the activities of key enzymes such as catalase and dehydrogenase in the soil, and it selectively promotes the enrichment of salt-tolerant bacterial communities (such as Halomonas and Bacillus species). (4) Using biodegradable plastic materials, setting up ecological buffer zones and planting halophytic plants (in coastal saline–alkaline areas), adding windbreak and sand-fixing buffer zones (in inland desert-type saline–alkaline areas), promoting precise irrigation and fertilization technologies (in areas with uneven irrigation conditions), and emergency soil amendment treatment (for severely polluted and ecologically fragile saline–alkaline soils) were all effective measures to dealing with the MPs pollution in saline–alkaline soils. This review provides a theoretical basis for the prevention and control of MPs pollution and the sustainable use of saline–alkaline soils. Full article