Saline Alkali Research Articles

Effect of Sodium Carboxymethyl Cellulose on Water and Salt Transport Characteristics of Saline-Alkali Soil in Xinjiang, China.

The scientific use of sodium carboxymethyl cellulose (CMC) to improve the production capacity of saline–alkali soil is critical to achieve green agriculture and sustainable land use. It serves as a foundation for the scientific use of CMC to clarify the water and salt transport characteristics of CMC-treated soil. In this study, a one-dimensional soil column infiltration experiment was carried out to investigate the effects of different CMC dosages (0, 0.2, 0.4, 0.6, and 0.8 g/kg) on the infiltration characteristics, infiltration model parameters, water and salt distribution, and salt leaching of saline–alkali soil in Xinjiang, China. The results showed that the final cumulative infiltration of CMC-treated soil increased by 8.63–20.72%, and the infiltration time to reach the preset wetting front depth increased by 1.02–3.96 times. The sorptivity (S) in the Philip infiltration model and comprehensive shape coefficient (α) in the algebraic infiltration model showed a trend of increasing first and then decreasing with CMC dosage, revealing a quadratic polynomial relationship. The algebraic model could accurately simulate the water content profile of CMC-treated soil. CMC enhanced the soil water holding capacity and salt leaching efficiency. The average soil water content, desalination rate, and leaching efficiency were increased by 5.18–15.54%, 21.17–57.15%, and 11.61–30.18%, respectively. The effect of water retention and salt inhibition on loamy sand was the best when the CMC dosage was 0.6 g/ kg. In conclusion, the results provide a theoretical basis for the rational application of CMC to improve saline–alkali soil in arid areas.

Exogenous melatonin enhances soybean (Glycine max (L.) Merr.) seedling tolerance to saline-alkali stress by regulating antioxidant response and DNA damage repair.

Saline-alkali (SA) stress induces excessive reactive oxygen species (ROS) accumulation in plant cells, resulting in oxidative damages of membranes, lipids, proteins, and nucleic acids. Melatonin has antioxidant protection effects in living organisms and thus has received a lot of attention. This study aimed to investigate the effect and regulating mechanism of melatonin treatment on soybean tolerance to SA stress. In this study, cultivars Heihe 49 (HH49, SA-tolerant) and Henong 95 (HN95, SA-sensitive) were pot-cultured in SA soil, then treated with MT (0-300 μM) at V1 stage. SA stress induced ROS accumulation and DNA damage in the seedling roots of both cultivars, causing G1/S arrest in HN95 and G2/M arrest in HH49. Melatonin treatment enhanced the activity of antioxidant enzymes in soybean seedling roots and reduced ROS accumulation. Additionally, melatonin treatment upregulated DNA damage repair genes, thus enhancing the reduction of DNA oxidative damage under SA stress. The effects of melatonin treatment were manifested as decreased RAPD polymorphism, 8-hydroxy-2'-deoxyguanine (8-OH-dG) level, and relative density of apurinic sites (AP-sites). Meanwhile, melatonin treatment partially alleviated the SA-induced G1/S arrest in HN95 and G2/M arrest in HH49, thus enhancing soybean seedling tolerance to SA stress.

Performance of AquaCrop Model for Maize Growth Simulation under Different Soil Conditioners in Shandong Coastal Area, China

Evaluating the performance of AquaCrop models under the drip irrigation of maize with soil conditioners is of great significance for improving coastal saline–alkali land crop management strategies. This study aimed to evaluate the performance of an AquaCrop model for maize growth simulation under different soil conditions (humic acid (HA) and sodium carboxymethyl cellulose (CMC)) and dosages and different levels of irrigation in the Shandong coastal saline–alkali area, China, and to optimize the amount of irrigation. Three years of experiments were carried out in the growing season of maize (Ludan 510) in 2019, 2020, and 2021. The dosages of HA were 5, 15, 25, and 35 g/m2, the dosages of CMC were 1, 2, 3, and 5 g/m2, and the levels of irrigation from 2019 to 2021 were all 120 mm. The model was calibrated with data from 2019, and the model was verified with data from 2020 to 2021, according to the recommended corn parameters in the AquaCrop model manual. The results showed that the model had a good simulation effect on canopy coverage, with a root-mean-square error (RMSE) of less than 15.2%, and the simulated aboveground biomass and yield were generally low. The simulated value of soil water content was generally high, with some treatments having errors of more than 15.0%. The simulation effect of irrigated maize from 2019 to 2020 was better than maize in 2021. The simulation effect of HA was better than that of CMC, while the simulation effect of a low-gradient modifier was better than that of high-gradient conditioner when compared with CMC. In conclusion, the AquaCrop model could be a viable method for predicting maize development under different soil conditioners in this area. The suitable levels of irrigation under HA and CMC treatments were 47.0–65.9 mm and 61.0–92.4 mm, respectively, according to the principle of high yield and water use efficiency. The results provided a reference for optimizing the drip irrigation of maize under the application of soil conditioners in coastal saline–alkali areas.

Amelioration of Coastal Salt-Affected Soils with Biochar, Acid Modified Biochar and Wood Vinegar: Enhanced Nutrient Availability and Bacterial Community Modulation.

As an important part of the ecological environment, degraded coastal soils urgently require efficient and eco-friendly soil amendment. Biochar and wood vinegar have been proved to be effective soil amendments, and acid-modified biochar has great potential in ameliorating the degraded coastal saline–alkali soil. However, the effects of individual or combined application of biochar (BC), acid-modified biochar (ABC), and wood vinegar (WV) on coastal saline–alkali soil are unknown. Hence, biochar, wood vinegar, and acid-modified biochar were prepared by pyrolysis of poplar wood. The properties of biochar were characterized, and soil incubation experiments were conducted. The results showed that ABC decreased the soil alkalinity by acid-base neutralization and improved the soil fertility by increasing the nutrients (C, N, P). ABC provided a more suitable environment and changed the abundance and diversity of soil microorganisms. ABC increased the relative contents of specific families (e.g., Pseudomonadaceae and Sphingomonadaceae), which had strong ecological linkages in the C, N, and P cycles and organic matter degradation. The results indicated that WV had little effect on coastal saline–alkali soil, whereas individual and combined application of biochar (especially ABC) showed an efficient remediation effect. Our preliminary study demonstrated that the ABC could be a suitable solution for ameliorating degraded coastal saline–alkali soils.

Quantitative Analysis of Temporal and Spatial Variations of Soil Salinization and Groundwater Depth along the Yellow River Saline–Alkali Land

To study the spatial distribution of soil salinization, the temporal and spatial variations of groundwater depth, along the Yellow River saline–alkali land, were analyzed. GIS technology was used to conduct spatial interpolation and quantitative analysis in Shahao, including salinization data obtained before summer irrigation, and groundwater depth data for one hydrological year from long-term observation wells. The results indicate that the groundwater depth gradually shallows from south to north, consistent with the topography of the area, and soil salinization is greater in the central and northern parts of the study area. Alkaline soils are widespread in the surface-to-middle soil, accounting for 55.2–62.5% of the total land area. A total of 28.6% of the surface layer is heavily salinized. The crop emergence rate of heavily salinized cropland is only 30–50%. The high salt content of the Yellow River itself, freeze–thaw change and poor drainage are three important factors causing the high soil salinity along the Yellow River saline–alkali land. The changes of groundwater depth are divided into autumn irrigation, the freezing period and the crop-growth period. The return of soil salt in spring caused by autumn irrigation mainly affects the uppermost soil layer (0–100 mm depth).

Robinia pseudoacacia decline and fine root dynamics in a plantation chronosequence in the Yellow River Delta, China

Abstract Fine roots (<2 mm in diameter) play a significant role in tree growth and stand productivity. However, knowledge of fine root dynamics in saline alkali soil remains limited. Using sequential soil core and ingrowth core methods, we assessed the dynamics of aboveground biomass (AGB) and production (AGP), fine root biomass (FRB), production (FRP) and turnover (FRT), and soil properties (water content [SWC], salt content [SSC], pH and nutrients) in 2-, 18-, 32- and 42-year-old black locust (Robinia pseudoacacia L.) stands in the Yellow River Delta, China. Corresponding to the unimodal growth pattern in AGP, the AGB of black locust rapidly increased until age 32 and then slowed down. In contrast, across all depths, FRB and FRP took a unimodal pattern with a decrease in growth around age 32, and FRT continually decreased with stand age. SWC and soil nutrients increased with stand age, whereas SSC and pH decreased with stand age until age 32 and then increased. Based on the correlation analysis, we may presume that in addition to the age effect, the decline of black locust in AGP is most likely caused by SWC, SSC, and pH stresses through the dysfunction in nutrient absorption by fine roots.

Bacterial Community Structure and Potential Microbial Coexistence Mechanism Associated with Three Halophytes Adapting to the Extremely Hypersaline Environment.

Halophytes play a crucial ecological role in drought and saline–alkali environments. However, there is limited knowledge about the structure of bacterial communities and the potential microbial coexistence mechanism associated with halophytes. This study investigated the diversity and community structure of endophytic and rhizospheric bacteria associated with three halophytes by applying high-throughput sequencing and geochemistry analyses on the studied soils. We collected 18 plant and 21 soil samples, and sequenced the V3 and V4 hypervariable regions of the 16S rRNA gene using next-generation sequencing (NGS). We also assessed geochemistry of the studied soils. The research suggested that rhizospheric bacterial richness and diversity associated with three halophytes were all significantly higher than for endophytic bacteria. The microbial community analysis indicated that Actinobacteria, Firmicutes, Bacteroidetes and Proteobacteria were the dominating bacterial phyla. Most unassigned operational taxonomic units (OTUs) implied that the microbes associated with halophytes contained abundant potential novel taxa, which are significant microbial resources. The high-abundance OTU phylogenetic tree supported the above views as well. Additionally, network analysis indicated that some conditional rare taxa (CRT) also might be keystone taxa during halophyte microbial community construction. The results of non-metric multidimensional scaling (NMDS) ordination analysis indicated significant dissimilarities in the microbial community among different sample groups. Sixty-two biomarkers were detected from seven different sample groups by linear discriminant analysis effect size (LEFSe) analysis. Microbial functions predicted based on phylogenetic investigation of communities by reconstruction of unobserved states (PICRUSt2) demonstrated that the abundances of nitrogen metabolism genes of endophytic bacteria were significantly higher than in rhizobacteria. Environmental factor analysis confirmed that different soil properties have different degrees of influence on the abundance and composition of the microbiota. To better adapt to the extreme hypersaline environment, halophytes could specifically recruit some plant beneficial bacterial taxa, such as nitrogen-fixing bacteria and extremely halophilic or halotolerant bacteria, to help them robustly grow and proliferate. All our preliminary results highlight microbial diversity and community related to halophytes grown on saline–alkali land of arid areas. Simultaneously, this work also advanced our further understanding of the halophyte microbiome associated with plants, and their role in plant adaptation to the extremely hypersaline environment.

Assessing the Effect of Physicochemical Properties of Saline and Sodic Soil on Soil Microbial Communities

Soil physicochemical properties are the main driving factors affecting the stability and diversity of the soil microbial community. The impacts of the saline–alkali situation and associated soil degradation need to be understood and reversed as soil diversity and communities are increasingly affected by saline–alkaline soil. However, the differences between salinization and alkalization soil and their impact on microbiota have been overlooked. The object of this study is to demonstrate the differences in salinization and alkalization soil and the driving factors affecting microbiota. In this study, 12 soil samples collected from saline–alkaline spots were used to detect the differences in soil physicochemical properties. The soil microbial community was sequenced by high-throughput sequencing. The results of ESP and EC in the soil samples indicated that the soil samples were categorized as saline soil and sodic soil. Venn diagrams indicated that unique OTUs in saline soil showed higher adaptation and environmental tolerance. Partial Mantel tests showed that the differences in pH, exchangeable sodium percentage (ESP), C/N, Na, and K between saline and sodic soil were the primary determinants affecting the relative abundance of bacterial and fungal communities, besides electrical conductivity (EC). In the KEGG analysis, ESP mainly affected the cellular processes in the archaea. Metabolism in the bacterial function was positively correlated with K only in sodic soil. These results indicated that the proportions in sodic soil were more strongly affecting soil microbiota.

Quantitative Response of Gray-Level Co-Occurrence Matrix Texture Features to the Salinity of Cracked Soda Saline-Alkali Soil.

Desiccation cracking during water evaporation is a common phenomenon in soda saline–alkali soils and is mainly determined by soil salinity. Therefore, quantitative measurement of the surface cracking status of soda saline–alkali soils is highly significant in different applications. Texture features can help to determine the mechanical properties of soda saline–alkali soils, thus improving the understanding of the mechanism of desiccation cracking in saline–alkali soils. This study aims to provide a new standard describing the surface cracking conditions of soda saline–alkali soil on the basis of gray-level co-occurrence matrix (GLCM) texture analysis and to quantitatively study the responses of GLCM texture features to soil salinity. To achieve this, images of 200 field soil samples with different surface cracks were processed and calculated for GLCMs under different parameters, including directions, gray levels, and step sizes. Subsequently, correlation analysis was then conducted between texture features and electrical conductivity (EC) values. The results indicated that direction had little effect on the GLCM texture features, and that four selected texture features, contrast (CON), angular second moment (ASM), entropy (ENT), and homogeneity (HOM), were the most correlated with EC under a gray level of 2 and step size of 1 pixel. The results also showed that logarithmic models can be used to accurately describe the relationships between EC values and GLCM texture features of soda saline–alkali soils in the Songnen Plain of China, with calibration R2 ranging from 0.88 to 0.92, and RMSE from 2.12 × 10−4 to 9.68 × 10−3, respectively. This study can therefore enhance the understanding of desiccation cracking of salt-affected soil to a certain extent and can also help to improve the detection accuracy of soil salinity.

Effect of Saline–Alkali Stress on Sugar Metabolism of Jujube Fruit

Sugar, an osmoregulatory substance used by plants to adapt to abiotic stresses such as drought and salinity, is one of the most important indexes of fruit quality. In this study, 0–150 mM saline–alkali solutions (NaCl:NaHCO3 = 3:1) were used to irrigate the roots of 10-year-old “Junzao” fruit trees during the growth period to explore the regulation mechanism of different concentrations of saline–alkali stress on sugar and reactive oxygen metabolism in jujube fruit at maturity. The results showed that under low stress (0~90 mM), the contents of sucrose, glucose, and fructose in the jujube fruit and the activities of sucrose phosphate synthase (SPS), sucrose synthase decomposition direction (SS-I), and sucrose synthase synthesis direction (SS-II) increased with increases in stress concentration, results that were consistent with the relative expression trends of the SPS and SS genes; however, the results were reversed under high concentrations (120 and 150 mM). The soluble acid invertase (S-AI) activity decreased with increases in stress concentration under low stress, and the results were reversed with high stress, which was consistent with the relative expression trends of the ZjcINV3, ZjnINV1, and ZjnINV3. Research regarding the response of antioxidant enzymes in fruits under saline–alkali stress showed that only the differences in peroxidase (POD) activity under saline–alkali stress were consistent with sugar accumulation; the proline (PRO), catalase (CAT) decreased and the malondialdehyde (MDA) superoxide dismutase (SOD) increased with increases in saline–alkali stress. These results indicate that the sugar metabolism and antioxidase jointly promote and regulate sugar accumulation in jujube fruits in a low saline–alkali environment.

Sprinkler Drip Infiltration Quality Prediction for Moisture Space Distribution Using RSAE-NPSO

Considering the high quality requirements related to agricultural production, the intelligent prediction of sprinkler drip infiltration quality (SDIQ) of the moisture space distribution in soil fields is an important issue in precision irrigation. The objective of this research is to adaptively predict an optimal data set of SDIQ indices using a robust prediction algorithm called the regulated sparse autoencoder–niche particle swarm optimization (RSAE-NPSO) system, so that the SDIQ indices of various irrigated layers of loam, sandy, chernozem, saline–alkali, and clay soils can be predicted and analyzed. This prediction procedure involves the following steps. First, the drip infiltration effectiveness of the moisture on specific irrigated soil layers is measured. Second, a complete set of SDIQ indices used for assessing the moisture space distribution is introduced. Third, an analytical framework based on the RSAE-NPSO algorithm is established. Fourth, the intelligent prediction of SDIQ indices using RSAE-NPSO computation is achieved. This research indicates that when the irrigation parameters include the sprinkling pressure (Pw) at 224.8 KPa, irrigation duration time (Id) at 2.68 h, flow discharge amount (Fq) at 1682.5 L/h, solar radiation (Sr) at 17.2 MJ/m2, average wind speed (Aw) at 1.18 m/s, average air temperature (At) at 22.8 °C, and average air relative humidity (Ah) at 72.8%, as well as the key variables of the irrigation environment, including the soil bulk density (Sb) at 1.68 g/cm3, soil porosity (Sp) at 68.7%, organic carbon ratio (Oc) at 63.5%, solute transportation coefficient (St) at 4.86 × 10−6, evapotranspiration rate (Ev) at 33.8 mm/h, soil saturated hydraulic conductivity rate (Ss) at 4.82 cm/s, soil salinity concentration (Sc) at 0.46%, saturated water content (Sw) at 0.36%, and wind direction Wd in the north–northwest direction (error tolerance = ±5%, the same as follows), an optimal data set of SDIQ indices can be ensured, as shown by the exponential entropy of the soil infiltration pressure (ESIP) at 566.58, probability of moisture diffusivity (PMD) at 96.258, probabilistic density of infiltration effectiveness (PDIE) at 98.224, modulus of surface radial runoff (MSRR) at 411.25, infiltration gradient vector (IGV) at [422.5,654.12], and normalized infiltration probabilistic coefficient (NIPC) at 95.442. The quality inspection of the SDIQ prediction process shows that a high agreement between the predicted and actual measured SDIQ indices is achieved. RSAE-NPSO has extraordinary predictive capability and enables much better performance than the other prediction methods in terms of accuracy, stability, and efficiency. This novel prediction method can be used to ensure the infiltration uniformity of the moisture space distribution in sprinkler drip irrigation. It facilitates productive SDIQ management for precision soil irrigation and agricultural crop production.

Description and characterization of three endophytic Bacillaceae from the halophyte Suaeda salsa: Paenalkalicoccus suaedae gen. nov., sp. nov., Cytobacillus suaedae sp. nov., and Bacillus suaedae sp. nov.

Three strains of members of the family Bacillaceae, which can inhibit the growth of some Gram-stain-positive strains, designated M4U3P1T, HD4P25T and RD4P76T, were isolated from Suaeda salsa halophytes in Baotou, Inner Mongolia, PR China. A phylogenetic analysis based on the 16S rRNA gene and the whole genome sequences revealed that HD4P25T clustered with Cytobacillus luteolus YIM 93174T with a similarity of 98.4 %, and RD4P76T shared the highest similarity of 16S rRNA gene with Bacillus mesophilus SA4T (97.5 %). M4U3P1T clustered with strains of genera Salipaludibacillus and Alkalicoccus based on whole-genome sequence analyses, but its 16S rRNA gene had the highest similarity to 'Evansella tamaricis' EGI 80668 (96.1 %). The average nucleotide's identity by blast (ANIb) and digital DNA-DNA hybridization (dDDH) values of the three isolated strains to their close relatives were well below the threshold value for identifying a novel species.On the basis of the phylogenetic, physiological and phenotypic results, Paenalkalicoccus suaedae gen. nov., sp. nov. [type strain M4U3P1T (=CGMCC 1.17076T=JCM 33851T)], Cytobacillus suaedae sp. nov. [type strain HD4P25T (=CGMCC 1.18651T =JCM 34524T)], and Bacillus suaedae sp. nov. [type strain RD4P76T (=CGMCC 1.18659T=JCM 34525T)] were proposed, respectively. All three species are ubiquitous in the bulk saline-alkaline soils, but only the species represented by strain RD4P76T was widely distributed in the rhizosphere soil, the above-ground part and the roots of S. salsa. The species represented by M4U3P1T can be detected in the roots of S. salsa, and rarely detected in the above-ground parts of S. salsa. The species represented by HD4P25T was rarely detected in the interior of S. salsa. The three strains could inhibit some of the Gram-stain-positive bacteria (i.e. members of the genera Planococcus, Zhihengliuella and Sanguibacter) in the saline-alkali soil. A genomic analysis of these three strains revealed that they can synthesize different antagonistic compounds, such as aminobenzoate and bacitracin or subtilisin.

Study on the Effects of Salt Tolerance Type, Soil Salinity and Soil Characteristics on the Element Composition of Chenopodiaceae Halophytes.

With the continuous increase in saline–alkali land, sustainable development of the global environment and ecology have been seriously affected. This study compared the absorption and accumulation patterns of 11 elements in different parts (roots, stems and leaves) of different leaf Na regulation strategies of the pioneer plant Chenopodiaceae in saline–alkali land and evaluated the effects of soil nutrient status and soil salinity on the distribution of plant elements. The results showed that the changes in the content of Ca, Mg and Na in plants are affected by the salt-tolerant type and on different parts. Soil salinity had no significant effect on element concentrations in different parts of plants. The Pearson correlation coefficient showed that the correlation between plants and soil elements was different, and different parts of plants had the characteristics of selective absorption of soil elements. The salt tolerance type and soil mineral element concentrations explained most of the variation observed in element concentrations in Chenopodiaceae plants; the soil salinity property played only a minor role. It was concluded that the genetic factors are the prerequisite in the composition pattern of leaf elements in Chenopodiaceae, and soil factors are the key to determining element accumulation. These conclusions provide an effective reference for evaluating plant breeding and its response to environmental change in saline–alkali arid areas in Hulunbuir grassland and other parts of the world.

Integrated Analyses of Transcriptome and Chlorophyll Fluorescence Characteristics Reveal the Mechanism Underlying Saline-Alkali Stress Tolerance in Kosteletzkya pentacarpos.

In recent years, soil salinization has become increasingly severe, and the ecological functions of saline–alkali soils have deteriorated because of the lack of plants. Therefore, understanding the tolerance mechanisms of saline–alkali-tolerant plants has become crucial to restore the ecological functions of saline–alkali soils. In this study, we evaluated the molecular mechanism underlying the tolerance of Kosteletzkya pentacarpos L. (seashore mallow) seedlings treated with 0.05 or 0.5% saline–alkali solution (NaCl: NaHCO3 = 4:1 mass ratio) for 1 and 7 days. We identified the key genes involved in tolerance to saline–alkali stress using orthogonal partial least squares regression analysis (OPLS-RA) based on both chlorophyll fluorescence indexes and stress-responsive genes using transcriptome analysis, and, finally, validated their expression using qRT-PCR. We observed minor changes in the maximum photochemical efficiency of the stressed seedlings, whose photosynthetic performance remained stable. Moreover, compared to the control, other indicators varied more evidently on day 7 of 0.5% saline–alkali treatment, but no variations were observed in other treatments. Transcriptome analysis revealed a total of 54,601 full-length sequences, with predominantly downregulated differentially expressed gene (DEG) expression. In the high concentration treatment, the expression of 89.11 and 88.38% of DEGs was downregulated on days 1 and 7, respectively. Furthermore, nine key genes, including KpAGO4, KpLARP1C, and KpPUB33, were involved in negative regulatory pathways, such as siRNA-mediated DNA methylation, inhibition of 5′-terminal oligopyrimidine mRNA translation, ubiquitin/proteasome degradation, and other pathways, including programmed cell death. Finally, quantitative analysis suggested that the expression of key genes was essentially downregulated. Thus, these genes can be used in plant molecular breeding in the future to generate efficient saline–alkali–tolerant plant germplasm resources to improve the ecological functions of saline–alkali landscapes.

Hardwood modified and unmodified biochar amendments used for saline alkali soil remediation: phosphorus availability and its plant uptake

Hardwood modified and unmodified biochar amendments used for saline alkali soil remediation: phosphorus availability and its plant uptake

Intelligent Identification and Features Attribution of Saline-Alkali-Tolerant Rice Varieties Based on Raman Spectroscopy.

Planting rice in saline–alkali land can effectively improve saline–alkali soil and increase grain yield, but traditional identification methods for saline–alkali-tolerant rice varieties require tedious and time-consuming field investigations based on growth indicators by rice breeders. In this study, the Python machine deep learning method was used to analyze the Raman molecular spectroscopy of rice and assist in feature attribution, in order to study a fast and efficient identification method of saline–alkali-tolerant rice varieties. A total of 156 Raman spectra of four rice varieties (two saline–alkali-tolerant rice varieties and two saline–alkali-sensitive rice varieties) were analyzed, and the wave crests were extracted by an improved signal filtering difference method and the feature information of the wave crest was automatically extracted by scipy.signal.find_peaks. Select K Best (SKB), Recursive Feature Elimination (RFE) and Select F Model (SFM) were used to select useful molecular features. Based on these feature selection methods, a Logistic Regression Model (LRM) and Random Forests Model (RFM) were established for discriminant analysis. The experimental results showed that the RFM identification model based on the RFE method reached a higher recognition rate of 89.36%. According to the identification results of RFM and the identification of feature attribution materials, amylum was the most significant substance in the identification of saline–alkali-tolerant rice varieties. Therefore, an intelligent method for the identification of saline–alkali-tolerant rice varieties based on Raman molecular spectroscopy is proposed.

Arbuscular Mycorrhizal Fungi Promote Gleditsia sinensis Lam. Root Growth under Salt Stress by Regulating Nutrient Uptake and Physiology

Towards the improvement of plant productivity in saline–alkali soils, the application of arbuscular mycorrhizal fungi (AMF) is an intensive topic of research. For this study, three inoculation treatments, namely, autoclaved AMF inocula (CK), Funneliformis mosseae (FM), and Corymbiglomus tortuosum (CT), and four NaCl levels, namely, 0, 50, 100, and 150 mM were established to investigate the growth and physiological responses of mycorrhizal Gleditsia sinensis Lam. root systems to increase salinity through root dry weight, morphology, nutrient content, and physiology, and soil nutrient content. As NaCl levels increased, root dry weight, morphology, and nutrient content under the CK treatment exhibited a downward trend, while FM and CT treatments weakened this trend and significantly improved root dry weight and morphology, which increased by more than 200%. Under high NaCl levels, root activity under the FM treatment was significantly higher than that under the CK, with an average increase of 120.86%. In contrast to the activity of nitrate reductase, niacinamide adenine dinucleotide oxidase activity under CK was significantly less than that in FM and CT treatments. Moreover, inoculation with AMF significantly affected soil alkali-hydrolyzable nitrogen (AN), total nitrogen (TN), and phosphorus (TP), while NaCl had no significant impact on soil nutrients. Further, both soil salinity and mycorrhizal colonization rate had significant direct effects on root growth. However, soil salinity primarily influenced root growth through indirect effects on root nitrogen content, while mycorrhizal colonization rate indirectly impacted root nitrate reductase activity, and root nitrogen and phosphorus content. Our results suggested that the use of suitable AMF (e.g., Funneliformis mosseae) might effectively improve the currently unfavorable situation of economic tree species production on land with saline soils, which may greatly optimize the utility of these areas.

Modification and Validation of Ritchie Model for Evaporation of Maize Field in Saline Alkali Soil

In order to study the evaporation law of the soil between the corn trees of Daqing salt-alkali soil, the evaporation simulation value of different growth stages in the experimental period was compared with the measured value according to the Ritchie model theory, and the model fit was not well matched by using a homemade microsteaming seepage instrument to study the evaporation of the whole fertility period of corn in the green wind garden test area of Daqing High-tech Zone, as well as rainfall and soil moisture content. The accuracy of the two parameters in Ritchie’s model directly determines the accuracy of the model’s prediction of evaporation. The first U value and the second-stage α values were revised, respectively, and the model verification was based on the different growth-and-long-term values of corn, and the analysis showed that the average monthly rainfall was a function relationship with the average monthly evaporation. The modified Ritchie model has a maximum evaporation fit of 0.96 for maturity and a minimum fit of 0.91 for seedling. It provides an accurate evaporation prediction model for the accurate prediction of evaporation between saline soil corn classes in Daqing area and provides a theoretical basis for water quantity management and soil salinization prevention and control in the corn planting process.

Full-Length Transcriptome Analysis of the Halophyte Nitraria sibirica Pall.

Background: Nitraria sibirica Pall. is one of the pioneer tree species in saline–alkali areas due to its extreme salt tolerance. However, the lack of information on its genome limits the further exploration of the molecular mechanisms in N. sibirica under salt stress. Methods: In this study, we used single-molecule real-time (SMRT) technology based on the PacBio Iso-Seq platform to obtain transcriptome data from N. sibirica under salt treatment for the first time, which is helpful for our in-depth analysis of the salt tolerance and molecular characteristics of N. sibirica. Results: Our results suggested that a total of 234,508 circular consensus sequences (CCSs) with a mean read length of 2121 bp were obtained from the 19.26 Gb raw data. Furthermore, based on transcript cluster analysis, 93,713 consensus isoforms were obtained, including 92,116 high-quality isoforms. After removing redundant sequences, 49,240 non-redundant transcripts were obtained from high-quality isoforms. A total of 37,261 SSRs, 1816 LncRNAs and 47,314 CDSs, of which 40,160 carried complete ORFs, were obtained. Based on our transcriptome data, we also analyzed the coding genes of H+-PPase, and the results of both bioinformatics and functional analyses indicated that the gene prediction via full-length transcripts obtained by SMRT technology is reliable and effective. In summary, our research data obtained by SMRT technology provides more reliable and accurate information for the further analysis of the regulatory network and molecular mechanism of N. sibirica under salt stress.

Changes in understory vegetation during the reclamation of saline-alkali soil by drip irrigation for shelterbelt establishment in the Hetao Irrigation Area of China

A two-year experimental field study was conducted to monitor the changes in understory vegetation during reclamation of saline-alkali land by ridge cultivation with drip irrigation for the establishment of ecological shelterbelts in the Hetao Irrigation Area in northern China. The experiment carried out in 2019 and 2020, included four drip irrigation treatments, designated 0 (control, no irrigation, no trees), 1 (1 year of drip irrigation plus trees), 2 (2 years of drip irrigation plus trees), and 3 (3 years of drip irrigation plus trees). Treatments 1, 2, and 3 resulted in decreases in soil salinity (relative to the control) of 75.76%, 85.98%, and 85.58%, respectively, over a depth of 0–40 cm, and 51.65%, 81.85%, and 70.80%, respectively, over a depth of 0–120 cm. The pH of the saturated soil paste extract (pHe) of the 0–40 cm and 0–120 cm soil layer decreased from 9.68 and 9.54 in the first year to 9.07 and 8.44 in the third year, in response to drip irrigation. The coverage, plant species and plant density of understory vegetation (following natural germination of seeds from the seed bank under the shelterbelt trees) was increased significantly from treatment 0 to 3, with values of 5.7%, 2 and 15 plants/m2 (treatment 0), respectively, to 94.4%, 20 and 416 plants/m2, (treatment 3), respectively. The biomass of the understory vegetation increased dramatically (after treatment 1), then decreased slightly more (after treatment 2), until the maximum value occurred after treatment 3. The dominant species of the vegetation gradually changed from the halophytic annual herb Suaeda glauca to the halophytic perennial grass Leymus chinensis. The research showed that, when the electrical conductivity of the saturated soil paste extract (ECe) exceeded 4.5 dS/m, there was sparse vegetation; At lower salinity (2.6 < ECe < 4.5 dS/m) and higher pH (8.9 < pHe < 9.2), the species diversity gradually increased but without a clearly dominant species; At ECe < 2.8 dS/m, and pHe < 8.6, the dominance of plants of the Poaceae and Asteraceae families became apparent with L. chinensis developing into the dominant plant species in this area. This study contributes to our understanding of revegetation of saline alkali soils vegetation construction by salt regulation using drip irrigation and can inform ecological reconstruction in saline alkali regions in the future.