Search Results (22)

Salinity and heavy metal stress significantly reduce agricultural productivity in arable lands, particularly affecting crops like rice (Oryza sativa L.). This study aimed to evaluate the efficacy of heavy metal-tolerant plant growth-promoting rhizobacteria (HMT-PGPR) in mitigating the harmful effects of salt (NaCl), chromium (Cr), and combined NaCl + Cr stress on rice plants. Two pre-isolated and well-characterized heavy metal-tolerant epiphytic (Ochrobactrum pseudogrignonense strain P14) and endophytic (Arthrobacter woluwensis strain M1R2) PGPR were tested. The LSD test (p ≤ 0.05) was used to assess the statistical significance between treatment means. Stresses caused by NaCl, Cr, and their combination were found to impair plant growth and biomass accumulation through mechanisms, including osmotic stress, oxidative damage, ionic imbalance, reduced photosynthetic pigment, lowered relative water content, and compromised antioxidant defense systems. Conversely, inoculation with HMT-PGPR alleviated these adverse effects by reducing oxidative stress indicators, including malondialdehyde (MDA), hydrogen peroxide (H₂O₂) content and electrolyte leakage (EL) and enhancing plant growth, osmolyte synthesis, and enzymatic antioxidant activity under single- and dual-stress conditions. The application of HMT-PGPR notably restricted Na⁺ and Cr⁶⁺ uptake, with an endophytic A. woluwensis M1R2 demonstrating superior performance in reducing Cr⁶⁺ translocation (38%) and bioaccumulation (42%) in rice under dual stress. The findings suggest that A. woluwensis effectively mitigates combined salinity and chromium stress by maintaining ion homeostasis and improving the plant’s antioxidant defenses. Full article

Soil salinization is an important stress factor that limits plant growth and yield. Increased salinization is projected to affect more than 50% of all arable land by 2050. In addition, the growing demand for food, together with the increase in the world population, forces the need to seek salt-tolerant crops. Quinoa (Chenopodium quinoa Willd.) is an Andean crop of high importance, due to its nutritional characteristics and high tolerance to different abiotic stresses. The aim of this work is to determine the physiological, anatomical, and biochemical salt-tolerance mechanisms of a salt-tolerant (Vikinga) and a salt-sensitive (Regalona) quinoa variety. Plants were subjected to salinity stress for 15 days, starting at 100 mM NaCl until progressively reaching 400 mM NaCl. Physiological, anatomical, and biochemical parameters including growth, chlorophyll content, quantum yield of PSII (ϕ_PSII), gas exchange, stomatal density, size, and lipid peroxidation (via malondialdehyde, MDA) were measured. Results show that chlorophyll content, ϕ_PSII, and MDA were not significantly reduced under saline stress in both varieties. The most stress-affected process was the CO₂ net assimilation, with an up to 60% reduction in both varieties, yet Vikinga produced higher dry weight than Regalona due to the number of leaves. The stomatal densities increased under salinity for both varieties, with Regalona the one showing higher values. The averaged stomatal size was also reduced under salinity in both varieties. The capacity of Vikinga to generate higher dry weight is a function of the capacity to generate greater amounts of leaves and roots in any condition. The stomatal control is a key mechanism in quinoa’s salinity tolerance, acquiring higher densities with smaller sizes for efficient management of water loss and carbon assimilation. These findings highlight the potential of Vikinga for cultivation in temperate salinized environments during winter, such as Deltas and lowlands where rice is grown during summer. Full article

Coastal saline soils are an important soil resource that, when restored, can enhance arable land and preserve the natural ecology. With the aim of improving the use of coastal saline soils, we conducted a spot survey at Bohai coastal saline land to investigate the differences in soil properties between different vegetation types. The soil physical and chemical properties of various vegetation types, including Aeluropus sinensis, Imperata cylindrica, Tamarix chinensis, Lycium chinense, Hibiscus moscheutos, Helianthus annuus, Gossypium hirsutum, and Zea mays, were examined at two depth layers: 0–20 cm and 20–40 cm, and in two seasons, spring and autumn. The soil properties were compared with bare land as a control. The results indicated that the electrical conductivity, total soil salt content, sodium adsorption ratio, and bulk density of soils with vegetation cover were lower than those with bare land. On the other hand, soil pH, organic matter content, mean weight diameter, and saturated hydraulic conductivity were higher. The redundancy analysis results revealed a substantial positive correlation between soil pH, saturated hydraulic conductivity, water content, mean weight diameter, and organic matter content, as well as a significant positive correlation between soil electrical conductivity, total soil salt content, sodium adsorption ratio, and bulk density. Soil pH, saturated hydraulic conductivity, water content, mean weight diameter, organic matter content, and soil electrical conductivity, total soil salt content, sodium adsorption ratio, and bulk density were negatively correlated. The results of the structural equation model and variance decomposition showed that soil organic matter and bulk density were the key factors affecting the degree of soil salinization, and compared with their independent effects, their combined effect on soil salinization was greater. This study’s conclusions can provide a point of reference for further research on the mechanisms of soil improvement and desalinization in coastal saline land. Full article

The accumulation of salt in arable lands is a source of significant abiotic stress, contributing to a 10% decline in the world’s total arable lands and threatening food productivity and the sustainability of agriculture. About 76 million hectares of productive land are estimated to have been affected by human-induced salinization such as extreme salt deposits in soil, which are mainly caused by the actions of humans. For instance, continued irrigation and the frequent use of chemical fertilizers need to be understood. To ensure food availability, it is essential to improve upon traditional farming methods using current technologies to facilitate the reclamation of saline-affected arable lands to achieve high and sustainable food production. This review details current innovative strategies such as the modification of metabolic pathways, manipulation of antioxidant pathways, genetic engineering, RNA interference technology, engineered nanoparticles, arbuscular mycorrhizal fungi (AMF), organic amendments, and trace elements for improving saline marginal lands. These strategies were identified to have contributed to the improvement of plants salinity tolerance in diverse ways. For instance, the accumulation of plant metabolites such as amino acids, sugars, polyols, organic acids, saponins, anthocyanins, polyphenols, and tannins detoxify plants and play crucial roles in mitigating the detrimental effects of oxidative damage posed by salinity stress. Multiple plant miRNAs encoding the up- and down-regulation of single- and multi-ion transporters have been engineered in plant species to enhance salt tolerance. Nanomaterials and plant root system colonized by arbuscular mycorrhizal increase water uptake, photosynthetic efficiency, and biomass allocation in plants exposed to saline stress by excluding 65 percent of the Na⁺ uptake and enhancing K⁺ uptake by 84.21 percent. Organic amendments and trace elements reduced salinity concentrations by 22 percent and improved growth by up to 84 percent in maize subjected to salinity stress. This study also discusses how researchers can use these strategies to improve plants growth, development, and survival in saline soil conditions to enhance the productivity and sustainability of agriculture. The strategies discussed in this study have also proven to be promising approaches for developing salinity stress tolerance strategies for plants to increase agricultural productivity and sustainability. Full article

Soil salinity affects approximately 20% of the world’s arable land, presenting a significant challenge for studying the mechanisms by which plants adapt to saline environments. Cyclocarya paliurus, an invaluable research model due to its ecological and medicinal significance, is primarily concentrated in central and southern China. Nevertheless, Cyclocarya paliurus faces challenges from environmental factors such as soil salinization, which adversely impacts its growth, subsequently affecting the yield and quality of its bioactive compounds. The NAC gene family, a critical group of plant-specific transcription factors, plays pivotal roles in responding to abiotic stresses. However, there has not yet been any studies on NAC genes under salt stress in Cyclocarya paliurus. In this study, we identified 132 NAC genes within the Cyclocarya paliurus genome. Our analysis of the conserved structures and gene organization revealed a high degree of conservation in the proteins of the CpNAC gene family. Cis-element analysis unveiled the participation of these genes in a variety of biological processes, including light responses, phytohormone responses, cell cycle responses, and abiotic stress responses. Under salt stress conditions, the expression of 35 CpNAC genes changed significantly, indicating a response to salt treatment. Furthermore, we provided additional evidence for the identification of the NAC gene family and revealed their potential positive regulatory role in signal transduction by conducting a transcriptional activation activity analysis of CpNAC132(D) and CpNAC040, which are homologous to Arabidopsis thaliana NAC062/91 and NAC103, respectively. This research not only advances our comprehension of the salt stress adaptation in Cyclocarya paliurus but also provides robust support for future investigations into plant responses to environmental stress and the cultivation of salt-tolerant crops. Full article

Climate change and human activities lead to freshwater shortage, soil salinization, and food security crises in arable land. To explore the natural and irrigation factors on soil water and salt movement, this study quantitatively analyzed the dynamic characteristics of soil water and salt movement under precipitation, groundwater irrigation, and brackish water irrigation conditions for the next 30 years using Hydrus-1D model-based parameters obtained from the winter wheat–summer maize rotation experiments in the Yellow River Irrigation District. The results showed that precipitation was the key factor of climate change affecting soil water and salt migration, especially in the 0–20 cm soil layer. Under both SSP585 and SSP245 climate scenarios, rainfall in normal and wet years promoted salt leaching up to 1 m below the surface soil. But in dry years, salt washing treatment was required for the tillage layer to prevent salt accumulation. The higher the groundwater level was, the higher the soil water and salt content was in the 0–100 cm soil layer. In this soil layer, a 2 m groundwater level contributed 30% to wheat water needs, while a 3 m groundwater level contributed 18%, and no significant contribution was observed for a 4 m groundwater level. The salinity of the soil profile showed an overall increasing trend with irrigation using 1–3 g/L brackish water for 30 years. However, the salinity in the 0–100 cm soil layer was below the salt tolerance threshold of winter wheat and summer maize with salts accumulated in the 1–2 m soil layer. Considering the salinization of the root zone and crop water needs, it is recommended that the safe groundwater level for brackish water irrigation should be 3 m in the study region. This study provides scientific reference for groundwater–farmland ecosystems to utilize brackish water and treat saline–alkali lands. Full article

To provide the population with food, it is very important to re-cultivate “abandoned lands” that have been retired from agricultural use. The conversion of arable land into agricultural abandoned lands in the south of Kazakhstan is, first of all, primarily associated with salinity. For the purposes of sustainable development, there is a need to develop proposals for re-mastering by studying their current state and reviewing world studies on the reclamation of salt-affected soils. Therefore, this study is devoted to the study of the current environmental and reclamation conditions of the abandoned areas of the Otyrar region in southern Kazakhstan. The proposed directions of changes in their development were also presented. In the course of the research, the historical method is used in the study of the emergence and formation of abandoned lands; the method of geographical analysis during the territorial analysis of the research object; the statistical and comparison methods in showing the complexity and intensity of the problems; the cartographic, geo-informational and field research (reconnaissance) methods in the study of the condition of the abandoned lands in the research object and methods of grouping and analysis were used in the work with scientific data on the topic of research. Using Sentinel-2 images, the GIS program created phenological dynamics of crops based on NDVI vegetation indices during the vegetation period of the irrigated range. By classifying them, abandoned lands due to salinization were separated from fields. By deciphering space images with the help of geoinformation technologies, it was revealed that the area of abandoned lands in the research object is 13,688.9 ha, including the area of non-saline soils—83.9 ha, weakly saline soils—984.4 ha, medium saline soils—2398.3 ha, and highly saline soils—10,222.1 ha. A review of the methods and technologies proposed by scientists for the development and amelioration of salt-affected lands was made. Taking into account the ecological and reclamation state of the object of research along with the material and technical capabilities of farms, two methods of developing abandoned lands (organic and agro-innovative) in the research object are proposed and the need for their use in case of soil salinization has been scientifically justified. Full article

Soil salinization is a serious global issue; by 2050, without intervention, 50% of the cultivated land area will be affected by salinization. Therefore, estimating and predicting future soil salinity is crucial for preventing soil salinization and investigating potential arable land resources. In this study, several machine learning methods (random forest (RF), Light Gradient Boosting Machine (LightGBM), Gradient Boosting Decision Tree (GBDT), and eXtreme Gradient Boosting (XGBoost)) were used to estimate the soil salinity in the Werigan–Kuqa River Delta Oasis region of China from 2001 to 2021. The cellular automata (CA)–Markov model was used to predict soil salinity types from 2020 to 2050. The LightGBM method exhibited the highest accuracy, and the overall prediction accuracy of the methods had the following order: LightGBM > RF > GBRT > XGBoost. Moderately saline, severely saline, and saline soils were dominant in the east and south of the research area, while non-saline and mildly saline soils were widely distributed in the inner oasis area. A marked decreasing trend in the soil salt content was observed from 2001 to 2021, with a decreasing rate of 4.28 g/kg·10 a⁻¹. The primary change included the conversion of mildly and severely saline soil types to non-saline soil. The generalized difference vegetation index (51%), Bio (30%), and temperature vegetation drought index (27%) had the greatest influence, followed by variables associated with soil attributes (soil organic carbon and soil organic carbon stock) and terrain (topographic wetness index, slope, aspect, curvature, and topographic relief index). Overall, the CA–Markov simulation resulted exhibited suitable accuracy (kappa = 0.6736). Furthermore, areas with non-saline and mildly saline soils will increase while areas with other salinity levels will continue to decrease from 2020 to 2050. From 2046 to 2050, numerous areas with saline soil will be converted to non-saline soil. These results can provide support for salinization control, agricultural production, and soil investigations in the future. The gradual decline in soil salinization in the research area in the past 20 years may have resulted from large-scale land reclamation, which has turned saline alkali land into arable land and is also related to effective measures taken by the local government to control salinization. Full article

Soil salinity is a major abiotic stress in global agricultural productivity with an estimated 50% of arable land predicted to become salinized by 2050. Since most domesticated crops are glycophytes, they cannot be cultivated on salt soils. The use of beneficial microorganisms inhabiting the rhizosphere (PGPR) is a promising tool to alleviate salt stress in various crops and represents a strategy to increase agricultural productivity in salt soils. Increasing evidence underlines that PGPR affect plant physiological, biochemical, and molecular responses to salt stress. The mechanisms behind these phenomena include osmotic adjustment, modulation of the plant antioxidant system, ion homeostasis, modulation of the phytohormonal balance, increase in nutrient uptake, and the formation of biofilms. This review focuses on the recent literature regarding the molecular mechanisms that PGPR use to improve plant growth under salinity. In addition, very recent -OMICs approaches were reported, dissecting the role of PGPR in modulating plant genomes and epigenomes, opening up the possibility of combining the high genetic variations of plants with the action of PGPR for the selection of useful plant traits to cope with salt stress conditions. Full article

Salt-affected arable land is distributed widely in China, especially in the North China Plain. Crop residue management under appropriate tillage is critical to improving salt-affected soil organic carbon and reducing the carbon footprint. This study conducted four-year field experiments including two treatments (residue incorporated into soil with plough tillage (CT+); residue mulching with no-till (NT+)) in two sites (non-saline soil and salt-affected soil); the carbon footprint of wheat production was analyzed by life cycle assessment. The results showed that the carbon footprint of wheat production in the salt-affected soil was significantly larger than that in the non-saline soil, because the salt-affected soil exhibited higher N₂O emission than the non-saline soil. CT+ has lower carbon footprint than the NT+, mainly due to the lower N₂O emission and higher carbon sequestration in the CT+ compared to NT+. As for the salt-affected soil, the largest contributor of the carbon footprint per unit area was soil N₂O emission, with a relative contribution of 40%; the largest contributor of the carbon footprint per unit yield was carbon sequestration, with a relative importance of 47–50%. Our results indicated that wheat production in salt-affected land has a high carbon footprint, while it can be decreased by incorporating crop residue into the soil under the plough tillage. Full article

Soil salinity is one of the main barriers to increasing global food production as it reduces crop growth and productivity. While irrigated lands in arid climates (about 20% of total affected) are more prone to salinization, many other natural and anthropogenic factors contribute to an increase in salinity in arable lands that currently affects over 100 countries and more than one billion ha. Management of agro-ecosystems at every level, including soil, water, and the plant itself, is important in mitigating the effects of salinity. Plant hormones control cellular metabolism, and mediate plant defense response mechanisms against abiotic and biotic stresses. Foliar fertigation with plant growth regulators has been shown to improve growth and metabolism under stress conditions. Strigolactones (SLs) have emerged as a group of novel phytohormones with several functions in plant interactions with microorganisms, plant metabolism, development, and in responding to many environmental cues. The present research addressed SL (GR24) effects on growth, photosynthetic parameters, and oxidative stress in Solanum lycopersicum under salinity stress. Growth indices, photosynthesis and related attributes, antioxidant enzyme activity, and malondialdehyde (a product of lipid peroxidation) and hydrogen peroxide concentrations were compared in unstressed and salt-stressed (NaCl; 150 mM) S. lycopersicum seedlings untreated or treated with GR24 (2 µM). Improved antioxidant enzyme activity, proline (8%) and protein (14%) contents, and photosynthetic (33%) and transpiration (34%) parameters under GR24 treatment result in a significant increase in plant growth parameters, viz., shoot length (29%), root length (21%), shoot fresh weight (31%), root fresh weight (23%), shoot dry weight (26%), and root dry weight (19%). Increased chlorophyll index (14%) and stomatal conductance (16%) in GR24-applied plants under salinity stress results in improved growth and photosynthetic efficiency of S. lycopersicum. Our results add to the existing knowledge of the relatively new function of SLs in mitigating abiotic stress, particularly that of salinity stress in crop plants. Full article

Soil salinization is one of the main threats to soils worldwide, which has serious impacts on soil functions. Our objective was to map and assess salt-affectedness on arable land (0.85 km²) in Hungary, with high spatial resolution, using a combination of ensemble machine learning and multivariate geostatistics on three salt-affected soil indicators (i.e., alkalinity, electrical conductivity, and sodium adsorption ratio (n = 85 soil samples)). Ensemble modelling with five base learners (i.e., random forest, extreme gradient boosting, support vector machine, neural network, and generalized linear model) was carried out and the results showed that ensemble modelling outperformed the base learners for alkalinity and sodium adsorption ratio with R² values of 0.43 and 0.96, respectively, while only the random forest prediction was acceptable for electrical conductivity. Multivariate geostatistics was conducted on the stochastic residuals derived from machine learning modelling, as we could reasonably assume that there is spatial interdependence between the selected salt-affected soil indicators. We used 10-fold cross-validation to check the performance of the spatial predictions and uncertainty quantifications, which provided acceptable results for each selected salt-affected soil indicator (for pH value, electrical conductivity, and sodium adsorption ratio, the root mean square error values were 0.11, 0.86, and 0.22, respectively). Our results showed that the methodology applied in this study is efficient in mapping and assessing salt-affectedness on arable lands with high spatial resolution. A probability map for sodium adsorption ratio represents sodic soils exceeding a threshold value of 13, where they are more likely to have soil structure deterioration and water infiltration problems. This map can help the land user to select the appropriate agrotechnical operation for improving soil quality and yield. Full article

Saudi Arabia’s topographic features have great significance and impact on the diversity of physical environments for plant growth and agricultural activities. Cultivated land is at a premium in Saudi Arabia, and soil evaluation is increasingly important. Thus, the intended purpose of this investigation was to determine both the genesis and soil properties to improve the management of arid soil, which is represented by Al-Aflaj Oasis, during tillage operations. The parameters of this research output were the soil’s chemical and physical properties. Data were collected from field experiments by drilling and evaluating soil profiles using soil sampling tools. This study classified the soil of Al Aflaj Oasis, which is a part of the Najd Plateau. It analyzed the soil profile, the failure to provide nutrients for agricultural production, and the impact of spring floods, modern equipment, fertilizer management, and irrigation methods on agricultural prospects. Topographic and geological maps provided the origin of the soils in the area. The morphological description included measurements and characterization of soil horizons and boundaries, moisture status, soil texture, construction, cohesion, estimation of calcium carbonate, and other morphological phenomena. Laboratory analysis measured the soil particle size, soluble salts, calcium carbonate, organic material, electrical conductivity, and percentages of silt, clay, and sand. The soil was deep, with a coarse texture characterized as sandy to sandy clay; the gravel content ranged from 19.70 to 62.50%, with a cohesive structure at the bottom of the soil profile and slight cohesion at the surface. The soil had low organic matter content, and a hard layer of calcium existed at a depth of 100 cm. The soil was classified as arable land within a subgroup of Typic Haplocalcids. Chemical analysis showed low salinity, slight alkalinity, and high calcium carbonate (22–64%). The soil underwent a historical transformation. To enhance agricultural potential, the chemical and physical properties need adjustment by introducing organic matter, intensive deep cultivation, diversification of agricultural fertilizers, and careful irrigation management. Since recent cultivation has been limited to a depth of 100 cm, the hard calcium carbonate layer should be considered carefully. Future crop cultivation should include deep plowing (e.g., chisel and furrow plows) to fragment the solid soil structure and facilitate suitable farming practices, and the growth of plants in the lands affected by the ancient overflows of the Al Aflaj springs, such as the Al Aflaj Oasis, can be made productive and consistent with other agricultural areas. Full article

In salt affected soils, neither physical nor chemical remediation methods are cost-effective for saline/sodic soil reclamation. Salt-affected lands are estimated at about 955 million ha worldwide, afflicting over 6% of the world’s total arable land, of which sodic soils constitute 581 million ha. Regaining the agricultural potential and enhancing the productivity and profitability of rice in sodic soils, it necessitates the development of advanced technologies for the sustainable reclamation of these soils, suitable salt tolerant varieties (STVs) through farmer’s participatory varietal selection (FPVS) approaches and their matching management practices (Mmp).The results from the study showed that combining Mmp with STV resulted in 35% higher yields over traditional variety (TV) with farmer’s management practices and proved cost effective nutrient management approach to maximize the productivity and profitability of rice in sodic soils. Full article

China is facing a shortage of arable land resources, and the mudflat salt-affected soil along the east coast of China is an important reserve arable land resource. In this study, we conducted a randomized field trial to investigate the effects of vermicompost application rate (0, 25, 50, 125, and 250 t ha⁻¹) on barley growth and heavy metal accumulation in mudflat salt-affected soil. We found that vermicompost application decreased bulk density, electrical conductivity (EC), and pH of mudflat salt-affected soil while increasing its organic carbon, nitrogen, and phosphorus contents. With the increase in vermicompost application rate, the yield of grain and total biomass of barley plants increased. The yield of grain in the vermicompost application treatments of 25, 50, 125, and 250 t ha⁻¹ increased by 66.0%, 226.0%, 340.0%, and 512.0%, respectively, relative to the control. In addition, the concentrations of heavy metals (Cd, Cr, Cu, and Zn) in mudflat salt-affected soil and barley plant increased as the vermicompost application rate increased. Full article