Saline-alkaline Soil Research Articles

TaWRKY55-TaPLATZ2 module negatively regulate saline-alkali stress tolerance in wheat.

Saline-alkaline soils are a major environmental problem that limit plant growth and crop productivity. Plasma membrane H+-ATPases and the salt overly sensitive (SOS) signaling pathway play important roles in plant responses to saline-alkali stress. However, little is known about the functional genes and mechanisms regulating the transcription of H+-ATPases and SOS pathway genes under saline-alkali stress. In the present study, we identified that the plant AT-rich sequence and zinc-binding (TaPLATZ2) transcription factor are involved in wheat response to saline-alkali stress by directly suppressing the expression of TaHA2/TaSOS3. The knockdown of TaPLATZ2 enhances salt and alkali stress tolerance, while overexpression of TaPLATZ2 leads to salt and alkali stress sensitivity in wheat. In addition, TaWRKY55 directly upregulated the expression of TaPLATZ2 during saline-alkali stress. Through knockdown and overexpression of TaWRKY55 in wheat, TaWRKY55 was shown to negatively modulate salt and alkali stress tolerance. Genetic analyses confirmed that TaPLATZ2 functions downstream of TaWRKY55 in response to salt and alkaline stresses. These findings provide a TaWRKY55-TaPLATZ2-TaHA2/TaSOS3 regulatory module that regulates wheat responses to saline-alkali stress.

Microbiomes-Plant Interactions and K-Humate Application for Salinity Stress Mitigation and Yield Enhancement in Wheat and Faba Bean in Egypt’s Northeastern Delta

Salinity, resulting from climate change and excessive mineral fertilization, burdens farmers and negatively impacts soil and water ecosystems in the Northeastern Nile Delta. Organic and biological approaches are crucial for addressing these issues. This study examined the effects of individual and combined inoculations with cyanobacteria, yeast, and Arbuscular Mycorrhizal Fungi (AMF), with or without K-Humate and reducing Nitrogen, phosphorus and potassium (NPK) mineral fertilizers application rates to crop quality of wheat and faba bean. In preliminary laboratory experiments, the interactive effects of these microbiomes on plant antioxidant and soil enzyme production were examined under salinity stress. Results showed that co-inoculation, especially with K-Humate, yielded superior outcomes compared to individual inoculations. These findings were validated by a field trial conducted in saline-alkaline soil in the Northeastern Nile Delta region. All biological treatments 25% of recommended doses, and enhancing salinity tolerance, increasing yield, and improving enhanced rhizosphere microbial activity, including soil enzyme activity, AMF colonization, spore density, and the total numbers of bacteria, cyanobacteria, and yeast. These effects were further amplified by K-Humate and were more pronounced with combined inoculations than with individual ones, leading to improved soil fertility and significant increases in both crop quantity and quality compared to control treatments. The triple treatment, combining cyanobacteria, yeast, and mycorrhizae in the presence of K-Humate while reducing the mineral NPK rate by 75%, achieved superior increases in the productivity of wheat grains and faba bean seeds, reaching 54.72% and 128.92%, respectively, compared to the 100% NPK mineral control. This treatment also significantly improved crop quality, with notable increases in nitrogen, potassium, phosphorus, and protein percentages in wheat grains and faba bean seeds. Microbiomes-interaction increased potassium uptake over sodium, enhancing the plant’s potassium/sodium ratio and improving salt stress tolerance. This approach reduces reliance on costly mineral fertilizers, enabling bio-organic farming in marginal lands, optimizing resource utilization, and preserving natural resources.

Effects of Long-Term Reed Plantation on Saline Habitat

In recent years, the improvement and utilization of saline-alkaline soil has gradually shifted from engineering measures to biological measures. As a salt-tolerant plant, the reed has been preliminarily proven to have a role in improving saline-alkaline land. In order to explore the long-term effect of planting unharvested reeds on the improvement of saline-alkaline land, a pilot plot was set up in Fuping Pilot Test Base (34° 42'180"E; 109°11'49" N) near Lubo Beach, Fuping, Shaanxi, in 2012 to ascertain the improvement effect of long-term reed cultivation on saline–alkaline land. The objective was to study the long-term changes in soil pH, electrical conductivity, Ca2+, Mg2+, Cl-, SO42-, HCO3-, and CO32- contents, soil particle size and soil fertility. Results showed that (i) reed cultivation could effectively reduce soil salinization in the long term. From 2012 to 2022, the average pH of saline soil decreased from 9.42 to 8.86, and the electrical conductivity decreased from 1.20 μS/cm to 0.70 μS/cm. (ii) Reed cultivation considerably reduced the contents of Ca2+, Mg2+, Cl-, SO42-, HCO3-, and CO32- in the soil in the long term, and the reduction in each index was 5.9, 41.7, 63.5, 90.6, 81.7, 90.6, 77.9and 90.3%, respectively. (iii) Reed cultivation changed the soil structure. The soil texture of the 0–60 cm soil layer changed from silty sandy loam to silty loam from 2018 to 2022. (iv) Long-term reed planting without harvesting effectively improved soil fertility. In 2012, the content of soil organic matter was only 2.74 g/kg, but in 2022, the value reached 12.8 g/kg. Reed planting improved the physical and chemical properties of saline soil. Therefore, biological restoration of reed can be considered in low-lying saline–alkaline areas with high water volumes. Bangladesh J. Bot. 53(3): 665-672, 2024 (September) Special

At the core of salinity: Divergent transcriptomic responses to neutral and alkaline salinity in Arabidopsis thaliana

In the context of current climate change, alkaline salinity is increasingly challenging crop yields, especially in arid and semiarid regions. Alkaline salinity is more detrimental to plant performance than neutral salinity and tolerance to neutral salinity may not confer tolerance to alkaline salinity. The mechanisms behind are still poorly understood. This study aims to identify physiological and genetic traits underlying this differential tolerance to neutral and alkaline salinity by exploiting the variation present in natural populations (demes) of Arabidopsis thaliana. Growth, photosynthesis, phytohormone and mineral nutrient profiles, plant water status and transcriptomic changes were analyzed in four demes with contrasting tolerance to neutral and alkaline salinity. Results of this novel holistic approach suggest low internal Fe use efficiency caused by bicarbonate as a driver of enhanced sensitivity to alkaline salinity in plants adapted to neutral salinity prompting photosynthesis inhibition and alteration of the plant’s carbon budget for primary and secondary metabolism. Moreover, alkaline salinity specifically altered the auxin and jasmonic acid signaling pathways, while sustained ABA biosynthesis was an adaptive trait under neutral salinity. Exploring the genes with non-shared expression trends between salinity types, we identified sequence variation at the BGAL4 locus associated with advantageous responses to each type of salinity. Weighted correlation network analysis (WGCNA) validated the significant involvement of gene co-expression modules targeted by the enrichment analyses, highlighting the hubs correlated with favorable responses to both salinity types. Overall, the present study points out the complex physiological and genetic mechanisms responsible for plant tolerance to alkaline salinity and proposes target genes for breeding strategies under alkaline saline soils.

Appropriate Amount Application of Manure is Conducive to Improve Soil Aggregate Stability in Saline-Alkaline Soil: Analyzed from Soil Organic Carbon Mediated by Microbial Necromass Carbon

Appropriate Amount Application of Manure is Conducive to Improve Soil Aggregate Stability in Saline-Alkaline Soil: Analyzed from Soil Organic Carbon Mediated by Microbial Necromass Carbon

Exogenous Substances Improved Salt Tolerance in Cotton

Soil salinization is a major limiting factor for cotton growth in Southern Xinjiang. Studying technologies and mechanisms to improve cotton salt tolerance is of significant importance for the development and utilization of saline–alkaline land. In this study, ‘Xinluzhong 40’ cotton was used as the material, and 150 mmol·L−1 sodium chloride (NaCl) and 1.2% natural saline–alkaline soil extract were employed to simulate single-salt (SS) and mixed-salt (MS) stresses, respectively. The effects of different exogenous substances (sodium nitrophenolate, 24-epibrassinolide, and γ-aminobutyric acid) on the growth characteristics of cotton under salt stress were investigated. The results show that: (1) Under salt stress, the height and biomass of cotton (50 d old) were reduced. Both SS and MS stresses led to increased superoxide dismutase (SOD) activity, elevated proline (PRO) content (with an increase of 50.01% and no significant difference), and increased malondialdehyde (MDA) content (with increases of 63.14% and 32.42%, respectively). At the same time, catalase (CAT) activity decreased, Na+ and Cl− contents increased, K+ content decreased, and the K+/Na+ ratio was reduced. (2) Application of sodium nitrophenolate (S), 24-epibrassinolide (E), and γ-aminobutyric acid (G) significantly improved SOD activity and PRO content while reducing MDA content (decreased by 29.33%, 25.48%, and 30.47% compared to SS treatment; and 1.68%, 5.21%, and 5.49% compared to MS treatment, respectively). They also increased CAT activity (increased by 75.97%, 103.24%, and 80.79% compared to SS treatment; and 91.06%, 82.43%, and 119.68% compared to MS treatment, respectively) and K+/Na+ ratio (increased by 57.59%, 66.35%, and 70.50% compared to SS treatment; and 38.31%, 42.97%, and 66.66% compared to MS treatment, respectively), reduced Cl− content, and promoted increases in plant height and biomass. The effects of exogenous substances on antioxidant capacity and ion balance under salt stress were significant, particularly under SS stress. (3) Principal component analysis revealed that under SS and MS stresses, principal component 1 mainly reflects cotton’s antioxidant capacity, with SOD, CAT, and PRO having high weights; principal component 2 mainly reflects cotton’s ion balance and nutrient absorption, with root Na+, stem Na+, leaf Na+, root K+, and root Cl− having high weights. These findings highlight the potential of exogenous substances to improve cotton salt tolerance and provide scientific evidence for cotton cultivation on saline–alkaline land, offering new insights into cultivation techniques from an applied research perspective.

Detection of Quantitative Trait Loci Associated with Alkaline Tolerance Using Recombinant Inbred Line Population Derived from Longdao5 × Zhongyouzao8 at Seedling Stage.

Salt-alkaline stress is one of the most stressful occurrences, causing negative effects on plant development and agricultural yield. Identifying and utilizing genes that affect alkaline tolerance is an excellent approach to accelerate breeding processes and meet the needs for remediating saline-alkaline soil. Here, we employed a mapping population of 176 recombinant inbred lines (RILs) produced from a cross between alkali-tolerant Longdao5 and alkali-sensitive Zhongyouzao8 to identify the quantitative trait loci (QTLs) determining alkali tolerance at the seedling stage. For the evaluation of alkali tolerance, the recovered seedling's average alkali tolerance index (ATI), root number (RN), root length (RL), seedling dry weight (SW), root dry weight (RW), and seedling height (SH) were assessed, together with their relative alkaline damage rate. Under alkaline stress, the ATI was substantially negative connected with the root number, seedling height, seedling dry weight, and root dry weight; however, it was considerably positive correlated with the relative alkaline damage rate of the root number and root dry weight. A total of 13 QTLs for the root number, root length, seedling height, seedling dry weight, root dry weight, and alkali tolerance index under alkaline stress were identified, which were distributed across chromosomes 1, 2, 3, 4, 5, 7, and 8. All of these QTLs formed two QTL clusters for alkali tolerance on chromosome 5 and chromosome 7, designated AT5 and AT7, respectively. Nine QTLs were identified for the relative alkaline damage rate of the root number, root length, seedling height, seedling dry weight, and root dry weight under alkali stress. These QTLs were located on chromosome 2, 4, 6, 7, 8, 9, and 12. In conclusion, these findings further strengthen our knowledge about rice's genetic mechanisms for alkaline tolerance. This research offers clues to accelerate breeding programs for new alkaline-tolerance rice varieties.

Mining rhizobacteria from indigenous halophytes to enhance alfalfa (Medicago sativa L.) growth and soil reclamation in saline soils of Northwest China

Enhancing the growth of alfalfa (Medicago sativa L.) through inoculation with rhizobacteria represents a sustainable strategy for reclaiming saline soils. However, the lack of suitable strains and practical application guidelines poses significant challenges to the utilization of Plant Growth-Promoting Rhizobacteria (PGPR) in salt-affected soils of Northwest China. In this study, we selected four PGPR strains derived from indigenous halophytes based on their growth-promoting characteristics. These strains underwent further selection via a petri dish assay. Subsequently, the effects of the selected PGPR strains on alfalfa growth and soil fertility were rigorously examined through pot trials. The results demonstrated that Bacillus filamentosus HL3, B. filamentosus HL6, Bacillus subtilis subsp. stercoris HG12, and Paenibacillus peoriae HG24 significantly produced indole-3-acetic acid (IAA), solubilized phosphorus, and fixed nitrogen (except for B. filamentosus HL6, which did not significantly fix nitrogen). Compared to non-inoculated plants, B. filamentosus HL6 and B. subtilis subsp. stercoris HG12 significantly enhanced seed germination, root elongation, and seedling biomass in a 150 mM NaCl saline solution. In saline-alkaline soils, PGPR inoculation under brackish water irrigation did not restore alfalfa growth to the levels observed under freshwater irrigation. Principal Component Analysis (PCA) condensed ten indicators into two indices, explaining 86.85% of the variance. Using these two indices as weights, an evaluation model for the PGPR-alfalfa symbiosis indicated that B. subtilis subsp. stercoris HG12 had the most substantial effect under freshwater irrigation, while co-inoculation with B. subtilis subsp. stercoris HG12 and B. filamentosus HL6 had the most significant impact on alfalfa growth and soil improvement under brackish water irrigation. Available phosphorus was identified as the primary factor influencing alfalfa growth, contributing 82.3% to the growth variation. These findings provide suitable microbial strains for the utilization of saline-alkali land and underscore the potential of applying indigenous PGPR-alfalfa symbiotic techniques to improve soil fertility and crop yield in the arid regions of Northwest China.

Effects of Organic Fertilizer and Biochar on Carbon Release and Microbial Communities in Saline–Alkaline Soil

Climate change and aridification have increased the risk of salinization and organic carbon loss in dryland soils. Enrichment using biochar and organic fertilizers has the potential to reduce salt toxicity and soil carbon loss. However, the effects of biochar and organic fertilizers on CO2 and CH4 emissions from saline soils in dryland areas, as well as their microbial mechanisms, remain unelucidated. To clarify these issues, we performed a 5-month incubation experiment on typical soda-type saline soil from the western part of the Songnen Plain using five treatments: control treatment (CK), 5% urea (U), straw + 5% urea (SU), straw + 5% urea + microbial agent (SUH), and straw + 5% urea + biochar (SUB). Compared with the SU treatment, the SUH and SUB treatments reduced cumulative CO2 emissions by 14.85% and 35.19%, respectively. The addition of a microbiological agent to the SU treatment reduced the cumulative CH4 emissions by 19.55%, whereas the addition of biochar to the SU treatment increased the cumulative CH4 emissions by 4.12%. These additions also increased the relative abundances of Proteobacteria, Planctomycetes, and Ascomycota. Overall, the addition of biochar and organic fertilizer promoted CO2 emissions and CH4 uptake. This was mainly attributed to an improved soil gas diffusion rate due to the addition of organic materials and enhanced microbial stress due to soil salinity and alkalinity from the release of alkaline substances under closed-culture conditions. Our findings have positive implications for enhancing carbon storage in saline soils in arid regions.

Comparative transcriptome and coexpression network analysis revealed the regulatory mechanism of Astragalus cicer L. in response to salt stress

BackgroundAstragalus 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.ResultsIn 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.ConclusionsBased 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.

Genome-Wide Identification and Expression Analyses of the Thaumatin-Like Protein Gene Family in Tetragonia tetragonoides (Pall.) Kuntze Reveal Their Functions in Abiotic Stress Responses.

Thaumatin-like proteins (TLPs), including osmotins, are multifunctional proteins related to plant biotic and abiotic stress responses. TLPs are often present as large multigene families. Tetragonia tetragonoides (Pall.) Kuntze (Aizoaceae, 2n = 2x = 32), a vegetable used in both food and medicine, is a halophyte that is widely distributed in the coastal areas of the tropics and subtropics. Saline-alkaline soils and drought are two major abiotic stress factors significantly affecting the distribution of tropical coastal plants. The expression of stress resistance genes would help to alleviate the cellular damage caused by abiotic stress factors such as high temperature, salinity-alkalinity, and drought. This study aimed to better understand the functions of TLPs in the natural ecological adaptability of T. tetragonoides to harsh habitats. In the present study, we used bioinformatics approaches to identify 37 TtTLP genes as gene family members in the T. tetragonoides genome, with the purpose of understanding their roles in different developmental processes and the adaptation to harsh growth conditions in tropical coral regions. All of the TtTLPs were irregularly distributed across 32 chromosomes, and these gene family members were examined for conserved motifs of their coding proteins and gene structure. Expression analysis based on RNA sequencing and subsequent qRT-PCR showed that the transcripts of some TtTLPs were decreased or accumulated with tissue specificity, and under environmental stress challenges, multiple TtTLPs exhibited changeable expression patterns at short (2 h), long (48 h), or both stages. The expression pattern changes in TtTLPs provided a more comprehensive overview of this gene family being involved in multiple abiotic stress responses. Furthermore, several TtTLP genes were cloned and functionally identified using the yeast expression system. These findings not only increase our understanding of the role that TLPs play in mediating halophyte adaptation to extreme environments but also improve our knowledge of plant TLP evolution. This study also provides a basis and reference for future research on the roles of plant TLPs in stress tolerance and ecological environment suitability.

Piriformospora indica alleviates soda saline-alkaline stress in Glycine max by modulating plant metabolism.

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 saline-alkaline 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 non-inoculated 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.

Effect of Organic Manure on Crop Yield, Soil Properties, and Economic Benefit in Wheat-Maize-Sunflower Rotation System, Hetao Irrigation District.

The combined application of manure and mineral fertilizer represents an effective strategy for enhancing crop yield. However, the relationship between soil fertility and crop yield remains unclear in saline-alkaline soil. Here, a 9-year field experiment (2015-2023) was conducted to investigate the effects of manure application and crop rotations on crop yield and economic efficiency as well as potential associated mechanisms in the Hetao Irrigation District. The results showed that in the third cropping rotation cycle, combined application of manure and mineral fertilizers (NPKO) caused a 6.2%, 38.9%, 65.3%, and 132.2% increase in wheat, sunflower, wheat equivalent yield, and the economic income of sunflower, respectively. The average grain yield had a positive correlation with soil organic matter and nutrient supply. This suggested that the soil organic matter had a positive effect on the crop yield due to its impact on nutrient supply. Simultaneously, the sunflower seed setting rate increased by 65.2% under NPKO. The linear regression model revealed that each additional input of 20 Mg ha-1 of manure resulted in an increase of 3.56 kg ha-1 in crop phosphorus harvest and a 0.05 Kg ha-1 increase in wheat equivalent yield compared to NPK. In conclusion, our results highlighted that manure application promotes soil properties and improves crop yield.

Biochar Improves Yield by Reducing Saline-Alkaline Stress, Enhancing Filling Rate of Rice in Soda Saline-Alkaline Paddy Fields.

Soda saline-alkaline stress significantly impedes the rice grain filling process and ultimately impacts rice yield. Biochar has been shown to mitigate the negative impacts of saline-alkaline stress on plants. However, the exact mechanism by which biochar influences the rice grain-filling rate in soda saline-alkaline soil is still not fully understood. A two-year field experiment was conducted with two nitrogen fertilizer levels (0 and 225 kg ha-1) and five biochar application rates [0% (B0), 0.5% (B1), 1.5% (B2), 3.0% (B3), and 4.5% (B4) biochar, w/w]. The results demonstrated that biochar had a significant impact on reducing the Na+ concentration and Na+/K+ ratio in rice grown in soda saline-alkaline lands, while also improving its stress physiological conditions. B1, B2, B3, and B4 showed a notable increase in the average grain-filling rate by 5.76%, 6.59%, 9.80%, and 10.79%, respectively, compared to B0; the time to reach the maximum grain-filling rate and the maximum grain weight saw increases ranging from 6.02% to 12.47% and from 7.85% to 14.68%, respectively. Meanwhile, biochar, particularly when used in conjunction with nitrogen fertilizer, notably enhanced the activities of sucrose synthase (SuSase), ADPG pyrophosphorylase (AGPase), starch synthase (StSase), and starch branching enzyme (SBE) of rice grains in soda saline-alkaline lands. Furthermore, rice yield increased by 11.95-42.74% in the B1, B2, B3, and B4 treatments compared to the B0 treatment. These findings showed that biochar improves yield by regulating ionic balance, physiological indicators, starch synthesis key enzyme activities, and the grain-filling rate in soda saline-alkaline paddy fields.

Long-Term Planting of Taxodium Hybrid ‘Zhongshanshan’ Can Effectively Enhance the Soil Aggregate Stability in Saline–Alkali Coastal Areas

Not enough research has been conducted on the mechanisms influencing the stability of soil aggregates in coastal saline–alkaline soil and the dynamic changes in aggregates in the succession process of coastal saline–alkaline soil brought on by longer planting times. In this study, soil aggregate composition, stability, and influencing factors of 0–20 cm, 20–40 cm, and 40–60 cm soil layers in different planting time stages were analyzed in the reclaimed land at the initial stage of afforestation and the Taxodium hybrid ‘Zhongshanshan’ plantation with planting times of 6, 10, 17, and 21 years. The results show that, with the increase in planting time, the aggregate stability of the plantation increased significantly. In the 0–20 cm soil layer, the geometric mean diameter (GMD) and aggregate size >0.25 mm (R0.25) increased by 81.15% and 89.80%, respectively, when the planting time was 21 years, compared with the reclaimed land. The structural equation (SEM) showed that planting time had a direct positive effect (path coefficient 0.315) on aggregate stability. However, soil sucrase (0.407) and β-glucosidase (0.229) indirectly improved the stability of aggregates by affecting soil organic carbon. In summary, the establishment of Taxodium hybrid ‘Zhongshanshan’ plants on coastal saline–alkali land is beneficial for stabilizing soil aggregates, improving soil structure, and boosting soil quality. Long-term planting of Taxodium hybrid ‘Zhongshanshan’ can be an effective measure for ecological restoration in this region.

Differential Strategies of Two Arbuscular Mycorrhizal Fungi Varieties in the Protection of Lycium ruthenicum under Saline-Alkaline Stress.

To delve into the growth and physiological adaptations exhibited by the economically vital black wolfberry (Lycium ruthenicum) upon inoculation with arbuscular mycorrhizal fungi (AMF) under varying levels of saline-alkaline stress A series of pot experiments were conducted in a gradient saline-alkaline environment (0, 200, 400 mM NaCl: NaHCO3 = 1:1). One-year-old cuttings of black wolfberry, inoculated with two AMF species-Funneliformis mosseae (Fm) and Rhizophagus intraradices (Ri)-served as the experimental material, enabling a comprehensive analysis of seedling biomass, chlorophyll content, antioxidant enzyme activities, and other crucial physiological parameters. This study demonstrated that both Fm and Ri could form a symbiotic relationship with the root of Lycium ruthenicum. Notably, Fm inoculation significantly bolstered the growth of the underground parts, while exhibiting a remarkable capacity to scavenge reactive oxygen species (ROS), thereby effectively mitigating membrane oxidative damage induced by stress. Additionally, Fm promoted the accumulation of abscisic acid (ABA) in both leaves and roots, facilitating the exclusion of excess sodium ions from cells. Ri Inoculation primarily contributed to an enhancement in the chlorophyll b (Chlb) content, vital for sustaining photosynthesis processes. Furthermore, Ri's ability to enhance phosphorus (P) absorption under stressful conditions ensured a steady influx of essential nutrients. These findings point to different strategies employed for Fm and Ri inoculation. To holistically assess the saline-alkaline tolerance of each treatment group, a membership function analysis was employed, ultimately ranking the salt tolerance as Fm > Ri > non-mycorrhizal (NM) control. This finding holds paramount importance for the screening of highly resilient Lycium ruthenicum strains and offers invaluable theoretical underpinnings and technical guidance for the remediation of saline-alkaline soils, fostering sustainable agricultural practices in challenging environments.

Combined alkali-photocatalytic stimulation enables click microbial domestication for boosted ammonia nitrogen removal

Microbe-driven ammonia nitrogen removal plays a crucial role in the nitrogen cycle and wastewater treatment. However, the rational methods and mechanisms for boosting nitrogen conversion through microbial domestication are still limited. Herein, a combined alkali-photocatalytic stimulation strategy was developed to activate the Halomonas shizuishanensis DWK9 for efficient ammonia nitrogen removal. The strain DWK9 selected from saline-alkaline soil in Northwestern China possessed strong resistance to stress of saline-alkaline environment and free radicals, and was abundant in nitrogen conversion genes, thus is an ideal model for advanced microbial domestication. Bacterial in the combined alkali-photocatalytic stimulation group achieved a high ammonia nitrogen conversion rate of 67.5 %, 10 times outperforming the non-stimulated and single alkali/photocatalytic stimulation control groups. Morphology analysis revealed that the bacteria in the alkali-photocatalytic stimulated group formed a favorable structure for bioelectric transfer. Remarkably, the domesticated bacteria demonstrated improved electrochemical properties, including increased current capacity and lower overpotentials and impedance. Prokaryotic transcription genetic analysis together with qPCR analysis showed upregulation of denitrification-related metabolic pathway genes. A novel FAD dependent and NAD(P)H independent energy mode has been proposed. The universality and effectiveness of the as-developed combined alkali-photocatalytic microbial domestication strategy were further validated through indicator fish survival experiments. This work provides unprecedented degrees of freedom for the exploration of rational microbial engineering for optimized and controllable biogeochemical conversion.

Maize, Peanut, and Millet Rotations Improve Crop Yields by Altering the Microbial Community and Chemistry of Sandy Saline-Alkaline Soils.

Crop rotation increases crop yield, improves soil health, and reduces plant disease. However, few studies were conducted on the use of intensive cropping patterns to improve the microenvironment of saline soils. The present study thoroughly evaluated the impact of a three-year maize-peanut-millet crop rotation pattern on the crop yield. The rhizosphere soil of the crop was collected at maturity to assess the effects of crop rotation on the composition and function of microbial communities in different tillage layers (0-20 cm and 20-40 cm) of sandy saline-alkaline soils. After three years of crop rotation, the maize yield and economic benefits rose by an average of 32.07% and 22.25%, respectively, while output/input grew by 10.26%. The pH of the 0-40 cm tillage layer of saline-alkaline soils decreased by 2.36%, organic matter rose by 13.44%-15.84%, and soil-available nutrients of the 0-20 cm tillage layer increased by 11.94%-69.14%. As compared to continuous cropping, crop rotation boosted soil nitrogen and phosphorus metabolism capacity by 8.61%-88.65%. Enrichment of Actinobacteria and Basidiomycota increased crop yield. Crop rotation increases microbial community richness while decreasing diversity. The increase in abundance can diminish competitive relationships between species, boost synergistic capabilities, alter bacterial and fungal community structure, and enhance microbial community function, all of which elevate crop yields. The obtained insights can contribute to achieving optimal management of intensive cultivation patterns and green sustainable development.

Effects of FeSO4 and Organic Additives on Soil Properties and Microbiota during Model Soybean Planting in Saline-Alkali Soil

Saline soils are characterized by organic matter and nutrient deficiencies, and their mineral fraction consists almost exclusively of fine sand particles, resulting in an unstable soil formation process. Due to the high amount of soluble salts in the soil, the osmotic pressure of the soil is elevated, restricting water absorption. This ultimately leads to the death of the plant and adversely impacts crop growth and yield. Incorporating Fe2+ can improve fertilizer utilization efficiency by reducing the oxidation of NH4+ to nitrogen (N2). However, reports on the usage of iron addition for the improvement of saline-alkali soils are scanty. This study conducted an outdoor simulation in pots to assess the soils of soybean crops during the podding stage. The effects of Fe2+ along with organic fertilizer or bio-C addition were elucidated on the composition and function of saline and alkaline microbial communities. The findings were correlated with soil environmental factors to analyze the dynamic changes in soil microbial communities. The soil pH decreased by 1.22–2.18% and SOM increased by 2.87–11.77% with organic fertilizer (OF) treatment. Compared to the ck treatment (control without iron supplementation), other treatments showed an average increase in abundance of dominant phylum by 8.25–11.23%, and an increase in the diversity and richness of the microbial community by 1.73–10.87%. The harmful bacteria in the Actinobacteriota, Chloroflexi, and Basidiomycota groups reduced by 57.83%, 74.29%, and 67.29%, and the beneficial bacteria in Ascomycota increased by 18.23–20.39%. Fe2+ combined with organic fertilizer or bio-C treatment could weaken the competitive relationship between the various bacterial lineages, enhance synergistic ability, favor the function and structure of the microbial community, and thus, improve the soil environment. Overall, the application of Fe2+ combined with organic fertilizers improved the saline-alkali soil, while the biochar (C) treatment mainly affected the soil nutrients. Through its detailed analysis, the study provides actionable insights for farmers to manage soil fertility in saline-alkaline soils, thereby overcoming the challenges of poor yields due to salinity stress. This will lead to resilient and sustainable farming systems, contributing to global food security.

Effect of Salt-Induced Stress on the Calorific Value of Two Miscanthus sacchariflorus (Amur Silvergrass) Varieties

This study was designed to investigate the relationship between the caloric value and salt tolerance of two varieties of Miscanthus sacchariflorus (Amur silvergrass: M127 and M022). The salt tolerance capacity, photosynthetic characteristics, Na+ and K+ uptake by the roots and aboveground parts, and caloric value of different parts of the aboveground parts were obtained under hydroponic conditions. The results showed that M022 was more tolerant to salt stress than M127 and the former had a higher photosynthetic efficiency as well as a lower aboveground Na+ accumulation, K+ efflux, and larger K+/Na+ ratio. The calorific values of stems, spear leaves, aging leaves, and functional leaves of the two varieties showed a decreasing trend with increasing NaCl concentration. At 270 mM NaCl, the calorific values of the stems, aging leaves, functional leaves, and spear leaves was reduced by 18.10%, 46.73%, 26.11%, and 18.35% for M022 and 41.99%, 39.41%, 34.82%, and 45.09% for M127 compared to the controls, respectively. We observed that the aging leaves of M022 had a faster decline rate in calorific value than those of M127, indicating that the aging leaves of M022 preferentially isolated the harmful Na+ ion, reduced its accumulation in other parts, and increased the K+/Na+ ratio in the corresponding parts, thus inhibiting the decrease in calorific value. Following this result, it can be inferred that M022 inhibited the decline in calorific values during stress by efficiently compartmentalizing the distribution of Na+ and K+. Our results provide a theoretical basis and technical support for the efficient cultivation of salt-tolerant energy plants in saline–alkaline soil.