Plant growth and production are faced with various biological and abiotic stresses,among which salt stress seriously affects the normal growth and development,quality and yield formation of plants.Plants have evolved morphological structure,physiological and biochemical reactions and genetic basis to adapt to salt stress during the long process of evolution.In terms of morphological structure,the leaves of salt-tolerant plants have waxy layer and lower stomatal density than those of salt-sensitive plants,and salt glands,microhairs,salt vesicles,and casparian strip have salt secretion or blocking functions.In terms of physiological activity regulation,on the one hand,salt-tolerant plants have high enzymatic and non-enzymatic antioxidant substances,such as SOD,CAT,phenolic substances,on the other hand,salt-tolerant plants have a high content of osmoregulatory substances,or can synthesize osmoregulatory substances under salt stress,including soluble proteins and sugars of organic substances and inorganic ions.In terms of molecular mechanism,SOS pathway is the most clearly studied ion regulation pathway,which maintains intracellular Na⁺/K⁺ balance through the synergistic action of SOS1,SOS2 and SOS3.In addition,plant hormones and carbon metabolism pathways also play an important role in the process of plant salt tolerance.This paper summarizes the research progress of salt-tolerant plants,and discusses the potential research focus and direction of salt-tolerant plants in terms of morphological structure,physiological basis,genetic molecular basis and transgenic methods in response to salt stress,which will help researchers quickly find the breakthrough point,gradually improve the mechanism system of salt-tolerant plants,and accelerate the efficient utilization of salt-tolerant plants.

The SiPRR73 gene was cloned from Yangu 11 using RT-PCR technology,and through analyzing tissue-specific expression,responsive features of SiPRR73 to different photoperiods,photo-thermal combinational treatments and five abiotic stress treatments,the regulation mode of photoperiod and temperature on SiPRR73,and the responsive pattern of SiPRR73 to abiotic stresses in foxtail millet were explored. The results showed that totally 2 928 bp cDNA sequence of SiPRR73 was obtained from Yangu 11,which included 2 283 bp CDS region,encoding 760 amino acids. The SiPRR73 proteins of C4 crops including Panicum miliaceum,Panicum hallii,Sorghum bicolor and Zea mays showed relatively close relationship with SiPRR73. The second parietal leaf was the highest expression tissue of SiPRR73,but the expression level at root,stem and panicle tissues was relatively lower. The expression level of SiPRR73 was higher at light period than that at dark period under both short-day and long-day conditions,and during the whole vegetative growth phase,SiPRR73 showed higher expression level under long-day compared to short-day,which indicated that the expression of SiPRR73 was induced by light and controlled by photoperiod. The temperature determined expression peak number of SiPRR73 and the photoperiod determined occurrence time of expression peaks,so temperature and photoperiod participated in regulating of SiPRR73 expression mutually. PEG and low temperature stresses induced SiPRR73 expression totally,NaCl induced SiPRR73 expression at early stress stage,but inhibited it at later stress stage. Fe stress inhibited SiPRR73 expression at early stage,but induced it at later stage. ABA stress caused the close responsive feature of SiPRR73 to NaCl. This study indicated that SiPRR73 showed light-dependent expression feature,and photoperiod and temperature regulated SiPRR73 by interaction pattern,suggesting that SiPRR73 participated in adaptability regulation process to different photo-thermal conditions and might play a certain role in coping with drought,low temperature,ABA,NaCl and Fe stresses in foxtail millet.

OFP is a class of plant-specific transcription factors that play important roles in the regulation of plant organ morphogenesis and response to abiotic stresses.In order to study the characterization of soybean OFP transcription factor family members and their roles in drought stress and salt stress,bioinformatics methods were applied to identify and analyze soybean OFP family members.The results showed that:a total of 41 GmOFPs,named GmOFP-1—GmOFP-41,were identified in soybean;these genes were unevenly distributed on 19 chromosomes of soybean,encoding 152—414 amino acids;subcellular localization predicted that soybean OFP proteins were mainly localized in nucleus,chloroplasts,and mitochondria;a total of 10 conserved motifs were identified in soybean OFP proteins,conservative Motifs 1 and 2 were present in all OFP members.Phylogenetic analysis classified soybean and Arabidopsis OFP proteins into five subfamilies ClassⅠ—Class V,of which soybean OFP family genes were mainly distributed in ClassⅠ and Class Ⅲ.The collinearity analysis revealed that 75 pairs of genes in the soybean genome had collinearity,four pairs of genes had tandem duplications,and only two genes,GmOFP-2 and GmOFP-39,did not have collinearity,which indicated that gene fragment duplication was the main reason for the increase in the number of soybean OFP family members.The expression patterns of GmOFP gene family members under drought stress and salt stress treatments were analyzed by qRT-PCR,and the results showed that,compared with the control,16 members out of 41 GmOFP genes exhibited significant differences in gene expression levels after drought treatments,with significant up-regulation of the expression of GmOFP-15,GmOFP-17,and GmOFP-32,while the GmOFP-4,GmOFP-5,GmOFP-6,GmOFP-9,GmOFP-12,GmOFP-21,GmOFP-23,GmOFP-25,GmOFP-26,GmOFP-27,GmOFP-38,GmOFP-39,and GmOFP-40 were significantly down-regulated after drought treatment.Eight members of GmOFPs showed significant differences in gene expression levels after salt treatment,among which GmOFP-7,GmOFP-14,GmOFP-31,GmOFP-32,GmOFP-36,and GmOFP-40 were significantly up-regulated,and GmOFP-1 and GmOFP-15 were significantly down-regulated.The above results suggest that the soybean OFP gene family may have important functions in response to drought stress and salt stress.

To improve the applicability of biochar in saline-alkali agroecosystem,the effect and microbial mechanism of modified biochar were studied.In a 2-year field experiment,common biochar(4.5 t/ha),nitrogen-rich modified biochar(7.5 t/ha)and phosphorus-rich modified biochar(15.0 t/ha)were added to investigate their impact on crop grain yield,soil physicochemical properties and soil microbial diversity.It had been observed that the addition of biochar enhanced the quality of saline-alkali soil,with nitrogen-rich modified biochar and phosphorus-rich modified biochar demonstrating more notable effects.Biochar could boost crop yield,improve soil structure and reduce soil bulk density in saline-alkali land.The effects of the three biochar types were not consistent.Among them,the application of 15.0 t/ha phosphorus-rich modified biochar showed favorable responses,with grain yield of(8.92±0.12)t/ha,representing a 110% increase compared to the control group.Biochar affected soil microbial diversity.Common biochar increased soil microbial diversity,whereas phosphorus-rich modified biochar decreased it.With the continuous addition of biochar,soil physical and chemical properties could affect the relationship between soil microorganisms and plant structure,weakening their relationships.In this study,the application of 15.0 t/ha phosphorus-rich modified biochar was recommended to improve saline-alkali agroecosystem.

To explore the relationship between soil bacterial community diversity and soil enzyme activity of Qinqiong(Q) and Magnum(M) under salinity stress treatment,the bacterial community structure and soil enzyme activity of Qinqiong and Magnum for 0,6,12,24,48 h were compared and analyzed by using high-throughput sequencing of bacterial 16S rRNA and colorimetry.The results indicated that at the phylum level,the relative abundances of Actinobacteria and Proteobacteria in the rhizosphere soil of Qinqiong were higher than those in Magnum.At the genus level,the relative abundances of Bacillus and Arthrobacter in the rhizosphere soil of Qinqiong were greater than those in Magnum,while the relative abundance of Pseudomonas was lower compared to Magnum.After 48 hours of saline-alkali stress,the activities of soil polyphenol oxidase(S-PPO),soil catalase(S-CAT),soil dehydrogenase(S-DHA),and soil invertase(S-AI) in the rhizosphere of Qinqiong were 1.32,1.53,1.38,and 1.28 times higher than those of Magnum,respectively.Furthermore,the S-CAT activity exhibited a significant positive correlation with the bacterial ACE and Chao diversity indices.Qinqiong may influence changes in bacterial community structure by altering the relative abundances of dominant bacterial groups,thereby enhancing the bacterial community diversity index and soil enzyme activity.In contrast,the changes in the bacterial community within the rhizosphere of Magnum were not significant.The diversity of soil microbial communities is a critical factor determining the saline-alkali tolerance of oat varieties.

In order to investigate the physiological regulation mechanism of exogenous H₂O₂ on the cotton seedlings under NaCl stress,the cotton variety Xinluzao 48 was used as the test material in an outdoor potting method.Two-factor random combinations of salt stress (NaCl,concentration gradients of 0,100,200 mmol/L) and H₂O₂ (concentration gradients of 0,0.005,0.010,0.020,0.050 mmol/L) were set,to study the change rule of fresh weight,dry weight,chlorophyll content,chlorophyll fluorescence parameters,photosynthetic gas parameters,antioxidant enzyme activities and osmotic regulation system of cotton seedlings.The results showed that exogenous H₂O₂ effectively alleviated the inhibitory effect of salt stress on the growth of cotton seedlings,increased chlorophyll content,photosynthetic gas parameters and chlorophyll fluorescence parameters of cotton seedlings,maintained the normal operation of photosynthesis of cotton seedlings and ensured the accumulation of dry matter.Meanwhile,exogenous H₂O₂ could increase the activity of antioxidant enzymes (POD,APX,CAT),accelerated the removal of ROS from cotton seedlings.Exogenous H₂O₂ reduced the electrolyte leakage rate,MDA content,the content of osmoregulation substances such as pro,free amino acid and SS,and improved the salt resistance of cotton seedlings.Among all treatment,0.020 mmol/L exogenous H₂O₂ had the best effect in alleviating the salt stress suffered by cotton seedlings.In summary,exogenous H₂O₂ improves the adaptation of cotton seedlings to salt stress by improving photosynthetic performance,keeping stable photosynthesis in cotton seedlings,and maintaining the dynamic balance between ROS production and elimination in cotton seedlings.

Salt stress causes a significant threat to crop yield and quality.As one of the pioneer crop species in salt tolerance research,barley holds critical significance;the exploration of its salt tolerance mechanisms is capable of providing a theoretical foundation for crop salt-tolerance breeding programs.Two naked barley landraces,namely B87 with salt-sensitivity and B94 with salt-tolerance,were employed as experimental materials.At the three-leaf stage,their seedlings were exposed to a 200 mmol/L NaCl treatment for 7 days.Subsequent to the treatment,the above-ground tissues were collected for transcriptomic and metabolomic sequencing.By means of integrated multi-omics analysis,this study was designed to elucidate the molecular mechanisms governing salt tolerance in naked barley.The results demonstrated that 2 240 differentially expressed genes (DEGs) and 198 differentially abundant metabolites (DAMs) were identified in B87 via transcriptomic and metabolomic profiling,whereas 923 DEGs and 232 DAMs were detected in B94.Venn diagram analysis further revealed that the salt-tolerant naked barley B94 contained 480 specific DEGs and 129 specific DAMs.Furthermore, GO and KEGG analyses were separately performed on the DEGs and DAMs. And the DEGs of B94 were significantly enriched in 11 unique pathways, while its DAMs were only significantly enriched in 1 unique pathway. In addition, correlation analysis between the transcriptome and metabolome was conducted, and it was found that the changes in genes and metabolites exhibited both consistency and inconsistency. These research efforts not only enhance the current understanding of the molecular mechanisms underlying salt tolerance in naked barley,but also provide valuable insights and candidate targets for the development of salt-tolerant naked barley cultivars in future breeding.

In order to study the tolerance of heterologously overexpressed Atvip1 gene in sorghum to defense saline-alkali stress and the corresponding growth, NaHCO₃:Na₂CO₃ of 5:1 solution with 75 mmol/L and pH 9.63 was used in sorghum at the stage of three leaves and one heart. The root growth index, chlorophyll content, antioxidant enzyme activity and MDA content were measured at 0, 4, 12, 24, 72, and 120 h of stress. The results indicated that the heterologous overexpression of Atvip1 gene could alleviate the damage of saline-alkali stress on the growth of sorghum seedlings, increase the root surface area and root volume, the number of root tips and branches, and also cause the browning of sorghum main roots to appear later and mild symphonys, and the earlier and more lateral roots occurrence. The new leaves could still be normally extended at 72 h and present little effect on the growth of aboveground. Overexpression of Atvip1 gene could increase the activity of O₂^-· resistance, decrease the content of MDA and enhance the activities of antioxidant enzymes in transgenic sorghum roots. SOD, CAT and GR had obvious effects at 4-12 h during the early stage of stress, respectively. All enzymes played roles during the middle of stress at 24-72 h. CAT and GSH-PX played important roles at the later stage of stress at 120 h. On the base of differential transcriptome analysis of saline-alkali stress, COG analysis of differentially expressed genes(DEGs) showed that defense mechanisms accounted for a relatively large proportion during various periods, and 42 DEGs related to antioxidant enzymes were obtained. Heterologous overexpression of Atvip1 gene can improve the resistance of transgenic sorghum to saline-alkali stress by alleviating the effects on photosynthesis, growth and development, reducing the damages of reactive oxygen species and membrane damage.

To investigate the effect of exogenous melatonin (MT) on salt tolerance of soybean seedlings,and to screen the appropriate application concentration under different salt stress.The soybean variety Tianyou-2986 was used as the test material,and 3 salt concentrations (low salt S₃:3 g/L,medium salt S₅:5 g/L,high salt S₇:7 g/L ) and 6 MT concentrations were set(M₀:0 μmol/L,M₁:25 μmol/L,M₂:50 μmol/L,M₃:75 μmol/L,M₄:100 μmol/L,M₅:150 μmol/L),the morphological parameters,biomass,antioxidant enzyme activity and osmoregulatory substance content of soybean seedlings were analyzed.With the increase of salt stress,the root morphological parameters,biomass,root-shoot ratio,antioxidant enzyme activity and osmoregulatory substance content of soybean seedlings decreased,while the malondialdehyde content increased.Under low salt (S₃) and medium salt (S₅) stress,The number of total length,lateral roots,SOD and POD of 50 μmol/L MT were increased by 52.30%,19.98%,74.10%,40.03% (low salt) and 68.52%,19.24%,81.72% and 37.42% (medium salt),respectively.Under high stress (S₇),75 μmol/L MT increased by 71.17%,19.11%,80.79% and 27.01%,respectively.Under salt stress,exogenous 25—100 μmol/L MT promoted soybean seedling growth and improved salt tolerance to different degrees.The overall evaluation of the affiliation function showed that 50 μmol/L MT was the most effective in alleviating salt damage under low and medium salt stress,and the suitable concentration of MT was 75 μmol/L under high salt stress,and the main reason for the alleviation of salt damage in soybean seedlings was that MT increased the activities of antioxidant enzymes and osmoregulatory substance content,and reduced the content of malondialdehyde,which could alleviate oxidative and osmotic stresses of soybeans under salt stress.

The transcription factor BnHY5-2 is associated with plant stress resistance.In order to reveal the response of Brassica napus L.transcription factor BnHY5-2 to salt alkali stress in B.napus,the response of BnHY5-2 to light and salt and alkali was analyzed by transient overexpression,qRT-PCR analysis and subcellular localization.The results revealed that under light conditions,the expression level of the BnHY5-2 gene in B.napus leaves and stems was 29.22 and 3.15 fold higher,respectively,compared to dark conditions.The higher sensitivity to light in leaves suggested that they were the primary site for light signal response.Under light conditions,the expression of BnHY5-2 in leaves and stems was significantly downregulated by 53.1% and 31.0%,respectively,when B.napus was planted in Dalian coastal saline-alkali soil;after applying saline-alkali treatment under dark conditions,the expression of BnHY5-2 was downregulated by 48.2% in the stem,while the difference in expression in the leaves was not significant,indicating organ differences,indicating that the leaves had stricter requirements for light conditions.In B.napus leaves with transient overexpression of BnHY5-2,two out of six genes related to saline-alkali stress(BnNAC32 and BnGS)showed upregulation by 1.25,3.28 fold,respectively,while the other four genes(Bnamy,BnAsp,BnNHX7,BnTPS)were downregulated by 24.8%,25.4%,71.0%,and 82.0%,respectively.Meanwhile,the content of the resistance substance betaine in B.napus increased from 0.256 to 0.573 mg/g,indicating an enhancement by 1.24 fold,suggesting that the overexpression of BnHY5-2 gene could improve the saline-alkali tolerance of B.napus.Subcellular localization results showed that the transcription factor BnHY5-2 was localized in the nucleus and regulates the expression of functional genes.Therefore,BnHY5-2 is not only related to light signaling but also participates in the saline-alkali resistance of Brassica napus L.

In order to explore the effects of saline-alkali stress on the physiological and molecular mechanism of Brassica napus L.,using Huayouza 62 as experimental material.The seedlings of Brassica napus L.were treated with different concentrations of compound salt,compound alkali and compound saline-alkali solution.Physiological indexes such as seed germination rate,chlorophyll content,proline content,soluble sugar content and antioxidant enzyme activity in Brassica napus L.leaves were determined.The accumulation of betaine in rape leaves was determined by high performance liquid chromatography(HPLC).The key enzyme gene choline monooxygenase gene(CMO)in betaine synthesis pathway was analyzed by qRT-PCR technique.The results showed that the degree of damage to seed germination in artificially simulated saline-alkali solution of different concentrations was compound saline-alkali>alkali>salt.Low concentration saline-alkali solution promoted chlorophyll formation in rape leaves,while high concentration saline-alkali solution inhibited chlorophyll formation,saline-alkali stress significantly increased the contents of proline and soluble sugar,and the contents of proline and soluble sugar in high saline-alkali solution(YJ75,saline-alkali 75 mmol/L)for 21 d were 65.99 and 5.21 times higher than those in the control group,respectively,and the content of malondialdehyde was increased by saline-alkali stress.Saline-alkali stress significantly increased the activity of peroxidase(POD).Compared with the control group,the content of POD in high saline-alkali solution(YJ75)increased by 2.26 times after 21 d,and the content of POD reached the highest value on the 14th day after treatment with compound salt and compound alkali,however, the activity changes of superoxide dismutase (SOD) and catalase (CAT) were not obvious, and the role of species in the process of saline-alkali stress was low.Saline-alkali stress significantly increased the expression of key enzyme gene CMO,thus regulating the accumulation of betaine.In summary,the damage degree of saline-alkali stress to Brassica napus L. was compound saline-alkali > alkali > salt.Under high saline-alkali stress,Brassica napus would accumulate a large amount of betaine to reduce the damage.

To provide a solid foundation for studying the biological function of WRKY family members in kenaf in response to salt stress,all members of WRKY family were identified and their expression patterns were analyzed.Physical and chemical properties,phylogeny and conserved functional domains of WRKY gene family members were analyzed by bioinformatics method.The expression characteristics of WRKY gene family members under salt stress were analyzed by RT-PCR.The results showed that a total of 33 WRKY family members were identified,which were unevenly distributed on 12 chromosomes.There were certain differences in the physical and chemical properties of each member,such as amino acid number,molecular weight and theoretical isoelectric point.The conserved sequence WRKYGQK of each member did not change.Phylogenetic tree analysis showed that 33 WRKY family members were divided into 3 groups,GroupⅠ,GroupⅡ,Group Ⅲ,of which Group Ⅲ contained 5 subgroups.The real-time fluorescence quantitative RT-PCR results showed that there were 26 WRKY family members induced by salt stress,of which 23 had positive regulation and 3 had negative regulation.A total of 33 WRKY family members of kenaf were identified,of which 26 WRKY family members were involved in the salt stress response of kenaf.

NRL(NPH3/RPT2-Like)is a type of light-responsive protein unique to plants and plays a vital role in the phototropic signal pathway. To reveal the NRL gene maize genome's characteristics and expression,we analyzed them using bioinformatics methods combined with qRT-PCR technology. The property,structure,evolution of their encoded proteins,and growth period tissue expression and stress expression were analyzed. 31 ZmNRL genes identified were located in nine maize chromosomes,encoding protein amino acids 464-749 aa,which predicted to have chloroplast,nuclear and cytoplasmic locations. According to protein conservation,ZmNRL family was divided into four categories. Their gene structure also presented certain conservation,the most contained four exons. Analysis of the cis-elements of gene promoters revealed a large number of abscisic acids,jasmonic acid,light response,and anti-oxidation elements,among which G-box and Sp1 were two types of light-related elements. The expression of ZmNRL family genes in tissues during the growth period showed a temporal and spatial specificity,and the majority expression level was not high. Only ZmNRL2,ZmNRL4,ZmNRL24,and ZmNRL29 highly expressed. Furthermore,the characteristic modules were produced based on the data of the tissue co-expression genes. And the GO enrichment analysis of a particular leaf growth module containing six ZmNRL genes,mainly associated with the plastid organization biological processes and rRNA binding molecular functions. The expression of ZmNRL5,ZmNRL7,ZmNRL12,and ZmNRL19 genes were analyzed by qRT-PCR under salt,drought,high temperature,and Rhizoctonia solani inoculation treatments. The results showed that ZmNRL12 was significantly up-regulated in maize seedlings treated with high temperature,while ZmNRL5,ZmNRL7 and ZmNRL19 genes were down-regulated in drought,salt and pathogen treatments. In summary,31 ZmNRL genes were identified in the maize genome. They not only had apparent specific tissue expression but also participated in biotic and abiotic stress responses.

To investigate the function of soybean GmPP2C89 gene in plant abiotic stress response and adaptation. The expression patterns of GmPP2C89 under NaCl,PEG and mannitol treatments were detected by transcriptome data and Real-time quantitative PCR. Then,the cis-acting elements on the promoter of GmPP2C89 in response to abiotic stress were analyzed,and promoters of different lengths were cloned according to the distribution of cis-elements to construct fusion GUS vectors to obtain the corresponding transgenic Arabidopsis. The response of the promoters to NaCl,PEG and mannitol was analyzed by GUS staining. Transgenic Arabidopsis overexpressing the GmPP2C89 was constructed,and the root length,leaf MDA content and electrolytic leakage,and the expression of salt stress-related genes(SOD,POD,CAT,RD26,RD29A,and RD29B)were measured under normal and NaCl treatment conditions. The results showed that NaCl,PEG and mannitol treatments all led to a significant increase in the expression level of soybean GmPP2C89;the promoter region contained many cis-acting elements such as ABRE,DRE,G-box,MBS,MYB,MYC and TC-rich repeats which were involved in abiotic stress response,and this promoter was more responsive to NaCl treatment. In addition,under the salt treatment,the root length of transgenic Arabidopsis GmPP2C89-OX was significantly greater than that of WT,while the MDA content and electrolytic leakage were significantly lower than those of WT,and the salt tolerance was significantly enhanced;the expression of antioxidant enzyme genes(SOD and POD)and ABA pathway key gene RD29B in GmPP2C89-OX was significantly higher than that in WT. These results indicated that soybean GmPP2C89 was induced by NaCl,PEG and mannitol,and GmPP2C89 overexpression could enhance the salt tolerance of transgenic Arabidopsis by activating antioxidant and ABA pathways.

In order to explore the effects of growth and aging characteristics of peanut under drought and salt stress,using Huayu 25 as material,potted experiment was carried out to study the change of peanut growth and aging characteristics due to the stress of drought and salt at flowering stage.The results showed that drought treatment (D),salt stress treatment (S),drought and salt stress (DS) increased the content of soluble protein,soluble sugar,free amino acid,proline,O₂^· and MDA. S treatment and DS treatment reduced the activity of SOD,POD and CAT in the leaves,which continued to decrease as time prolonged. But D treatment enhanced SOD and CAT activity in the leaves. After 10 days of rehydration,the content of soluble sugar,soluble protein,free amino acid,proline,O₂^· and MDA of D treatment reduced compared with the numerical values which detected before rehydration.D treatment had no significant difference with CK,including activity of SOD and POD and content of O₂^·,MDA,soluble sugar,free amino acid,proline. However,the difference of the activity of SOD,POD,CAT of DS treatment was significant compared with S treatment,so did the content of O₂^· and MDA.In the harvest time,single plant yield and the kernel rate of D treatment had no significant difference with CK,but DS treatment had significant difference with S treatment. Data from DAT9 showed that drought and salt stress had no significant interaction with soluble sugar,soluble protein,free amino acid and proline content in leaves. However,there was significant interaction of SOD,POD,CAT activity and O₂^·,MDA content between drought stress and salt stress. The interaction between drought stress and salt stress inhibited the activity of SOD,POD and CAT and exacerbated the peroxidation of plant cell membranes. Eventually it decreased the single plant yield and the kernel rate. Therefore,peanuts planting under salt stress should avoid the drought at flowering stage to reduce the harm of salt stress,drought stress and the interaction between salt stress and drought stress.

The effect of different concentrations salt stress on seedling growth and expression of related genes were explored in this study. Firstly, salt tolerant variety Yura Hama Daikon and susceptible variety Wujinhong were selected according to germination under salt stress conditions among 11 cultivars.And then the seedling height(SH) and the leaf scorch index(LSI) of Yura Hama Daikon and Wujinhong were investigated under salt stress treatment.The results showed that SH decreased and LSI increased under salt stress in both varieties.Compared with the salt-sensitive variety Wujinhong,the salt-tolerant variety Yura Hama Daikon had a smaller decrease in SH and lower LSI.Under 200 mmol/L salt stress,SH and LSI of salt-tolerant Yura Hama Daikon were 46.18% and 20.56,respectively,while those of salt-sensitive Wujinhong were 75.25% and 56.11.The transcription of RsCAT and RsSOD genes was studied in salt-tolerant and susceptible varieties under different salt concentrations by qPCR.The expression of RsCAT gene was first increased and then decreased under low salt concentration treatment,and reached the maximum at 7 day.When treated with high salt concentration,the transcription of RsCAT in Wujinhong was the highest at 48 h,while the expression level in salt-tolerant varieties increased gradually and maintained for a longer time,reaching the highest at 7 day.After high salt concentration treatment,the transcription of RsSOD gene reached the highest expression level at 24 hours,and then maintained a higher level in salt-tolerant variety.In salt-sensitive varieties,the maximum expression level of RsSOD appeared at 14 day.The above results will lay foundation for revealing the mechanism of salt stress in radish and provide technical support for radish salt-tolerant breeding.

To investigate the influence of green manure cultivation on the carbon and nitrogen content of saline-alkali soil under freshwater leaching,a field experiment was conducted from October 2021 to May 2022.Three treatments were set up:winter fallow(T1),Dongmu 70 rye(T2),and rape(T3).The spatial distribution of soil organic carbon(SOC),nitrate nitrogen($\mathrm{NO}_{3}{ }^{-}-\mathrm{N}$),and ammonium nitrogen($\mathrm{NH}_{4}^{+}-\mathrm{N}$)in the soil and leachate were measured.The results revealed that in the 0—30 cm soil layer,the soil organic carbon content of T1,T2,and T3 increased from 6.20,6.58,7.24 g/kg before leaching to 6.48,7.39,8.06 g/kg after leaching,representing an increase of 4.41%,12.20%,and 11.23%,respectively.After freshwater leaching,the nitrate nitrogen content in the 0—60 cm soil layer of T1 was significantly higher than that of T2 and T3.In the 0—30 cm soil layer,the respective reductions for each treatment were 42.42%,3.85%,and 10.84%.In the 60—90 cm soil layer,the reductions were 1.38%,7.96% and 18.11%.There were no significant differences in ammonium nitrogen content among the different treatments before leaching,but after leaching,the highest ammonium nitrogen content was observed in T2.In conclusion,after leaching irrigation,the soil organic carbon content in different soil layers increased compared to before leaching,while soil nitrogen showed a significant decrease.Analysis of nitrogen content in the soil and leachate indicated that the main nitrogen loss caused by leaching irrigation was in the form of nitrate nitrogen.Compared to winter fallow farmland,the cultivation of rapeseed green manure had a significant effect on increasing soil nitrogen content,while Dongmu 70 green manure was the the most effective in reducing soil nitrogen loss.

Plant sodium-hydrogen antiporter(NHX,Na⁺/H⁺ antiporter)plays a crucial role in plant sodium and potassium ion balance and cellular pH regulation.In order to investigate the relationship between salt tolerance and ScNHXs,it was conducted to identify and analyze the ScNHXs by bioinformatics process,and to examine the expression pattern of ScNHXs under salt stress by RT-qPCR,which can provide the reference information for the investigation of the potential functions of ScNHXs as well as the mining of salt tolerance genes in rye.A total of 10 rye NHX gene family members(ScNHX1—ScNHX10)were identified,and the phylogenetic tree analysis showed that they could be divided into two subfamilies,Vac and Endo,containing four and six genes,respectively.Physicochemical property analysis of the encoded proteins showed that most of the molecular weight ranged from 27.92 to 59.72 ku,the number of amino acids from 253 to 546 aa,and the isoelectric point between 5.17 and 8.81,with most of proteins being classified as acidic proteins.Signal peptide prediction indicated the absence of signal peptides in the members,and transmembrane structure analysis revealed that all members possessed transmembrane structures.The subcellular localization prediction indicated that ScNHXs were located in the plasma membrane and vesicles.Spatial structure prediction showed that their secondary structures mainly consisted of α-helices and irregular convolutions.Gene structure and motif analyses revealed that the number of exons of the ScNHXs varied from 13 to 24,and all of them possessed a conserved Na⁺/H⁺ exchange structural domain.In addition,cis-acting element analysis revealed that numerous elements related to hormone response and abiotic stresses were found in the promoter region of ScNHXs.Analysis of rye transcriptome data revealed significant differences in the expression patterns of ScNHXs in different tissues of rye.RT-qPCR analysis showed that ScNHXs responded differently to different concentrations of NaCl stress,and were able to persistently respond to salt stress over a long period of time.In summary,ScNHXs may be involved in the biological regulation during salt stress in rye.

Application of some hormonal signaling compounds,as brassinolides and their derivatives,could significantly improve the salt stress resistance in plants.The purpose of present work was to test whether the over-expressing of Methylsterol monooxygenase gene(SMO),a key gene coding a bio-synthesizing enzyme of sterol in plants,could promote the salt-stress tolerance of target plants.PnSMO1.1,gene encoding of methylsterol monooxygenase in the plant species of Pharbitis nil was firstly cloned and then used as target gene for following genetic transformation process,while wild-type Pharbitis nil seedlings were used as the receptor plants for constructing of the transgenic lines which over-expressed PnSMO1.1 genes.In this work,the PnSMO1.1 gene transformed Pharbitis nil lines were constructed via an ovary injection transformation method.Plantlets from individual PCR identified transgenic plant lines were used as materials to detect vegetative growth figures and some pivotal physiological indicators,for instance,contents of malondialdehyde (MDA),relative conductivity,as well as castasterone and 6-deoxo-castasterone contents in cells under stresses with gradient NaCl conditions varied from 0—200 mmol/L.The results showed that the over-expression PnSMO1.1 significantly improved the relative growth of roots and hypocotyls in transformants than in wild-type (WT) or vacant plasmid transformed control (BL) plants under 100—250 mmol/L NaCl stresses.Compared to WT and BL seedlings,significantly higher accumulation of 6-deoxo-castasterone,but lower relative conductivity (rEC) values,castasterone accumulation or MDA contents were found in transgenic lines under various NaCl stresses.Stresses such as salinity,drought and freezing temperatures,had severely suppressed the vegetative growth of plants,as well as their yields.These results highlighted that over-expression of the PnSMO1.1 gene could significantly improve the salinity-stress resistance of transgenic plants by delicately adjusting the dynamic homeostasis of brassinolides in cells,and protecting the structural integrity of plasma membrane.

To study the effects of salt stress on growth and physiological characteristics of sorghum at different growth stages(elongation, flowering, and maturity), two sorghum varieties with different salt tolerances, Gaoliangzhe(salt tolerance) and Henong No.16(salt sensitive), were planted at four salt treatment levels(CK:0 g/kg, S3:3 g/kg, S5:5 g/kg, S7:7 g/kg). Moreover, the two varieties were compared under different salt treatment levels, plant morphology, root morphology, leaf photosynthetic characteristics and antioxidant enzyme activities at different growth stages. The results showed that with increasing salt treatment concentration, the antioxidant enzyme activity and relative chlorophyll content(SPAD) of the two varieties increased first and then decreased. The antioxidant enzyme activity reached the maximum value under S3 or S5 treatment, and there were significant differences between the maximum and CK. With the increase of salt treatment concentration, the malondialdehyde(MDA) of the two sorghum varieties increased significantly, which S7 treatment was significantly higher than CK. Under the same treatment, the antioxidant enzyme activity of salt-tolerant varieties(Gaoliangzhe) was higher than that of salt-sensitive varieties(Henong No.16), but the content of MDA was lower than that of salt-sensitive varieties. The photosynthetic capacity of the two varieties was significantly affected by salt stress. In elengation, S7 treatment significantly reduced the Pn of Gaoliangzhe, and Ci of the two varieties under S7 treatment was higher than that of CK. Under salt stress, the growth of the sorghum aerial portion and underground portion of sorghum were affected. The basal stem diameter, total length of root, root surface area, number of root tips, and number of root branches for two varieties reached the maximum under S3 treatment. And basal internode length, plant height, total length of root and root volume reached the lowest value under S7 treatment. In addition, grain fat content and grain starch content in two sorghum varieties decreased under salt stress.The grain tannin content was significantly higher than CK in low-salt (S3, 3 g/kg). In general, low-salt can promote the growth of sorghum, while medium-salt (S5, 5 g/kg) and high-salt (S7, 7 g/kg) conditions have a significant inhibitory effect on sorghum growth. And Gaoliangzhe is more salt-tolerant than Henong No.16.

To investigate the effects of different dosages of biochemical fulvic acid (BFA) on the improvement of soda saline-alkali soil and the response mechanism of maize growth,a pot experiment was conducted using soda saline-alkali soil from Inner Mongolia as the test soil and maize Dongdan 181 as the test variety.Four BFA application rates were set as 0(CK),2(FA2),4(FA4),8 g/kg(FA8).Soil nutrients,microbial diversity,maize salt tolerance,biomass,and other indicators were measured.The results showed that compared to the CK,soil pH decreased with increasing BFA dosage.The soil available phosphorus content increased significantly after the application of BFA,but there was no significant difference among the three treatments of FA2,FA4 and FA8 at 30,62 and 80 days after sowing.Soil salinity increased with the increase of BFA dosage,with an increase of 23.30%—89.32%.Soil exchangeable potassium content increased with increasing BFA dosage,while exchangeable calcium content gradually decreased.The proportion of <0.053 mm silt and clay fractions in the soil decreased by 6.49,9.92 and 13.97 percentage points under FA2,FA4,and FA8 treatments,respectively,compared to the CK treatment.Meanwhile,the proportion of 0.053—0.250 mm aggregates increased by 5.90,8.99 and 13.75 percentage points,the proportion of 0.250—2.000 mm aggregates increased by 0.55,0.87 and 0.21 percentage points,while the proportion of >2.000 mm aggregates increased by 0.04,0.06 and 0.01 percentage points,respectively,under the FA2,FA4,and FA8 treatments relative to the CK.Soil microbial diversity was significantly higher than that of CK after the application of BFA,but the FA8 treatment was lower than the FA4 treatment.The Na⁺/K⁺ ratio in both shoots and roots of maize was lower under FA2 and FA4 treatments than under the CK treatment,while the FA8 treatment increased the Na⁺/K⁺ ratio in the shoots.Maize biomass significantly increased in the mid-to-late growth stages under FA2 and FA4 treatments,while biomass significantly decreased under the FA8 treatment.In summary,the application of 2 g/kg or 4 g/kg of biochemical fulvic acid can positively reduce the alkalinity of soda saline-alkali soil,increase the content of available phosphorus in the soil,improve soil structure,improve soil microbial diversity,and enhance maize salt tolerance and biomass.However,exceeding this dosage range will significantly increase soil salinity and inhibit maize growth.

In order to explore the effects of cattle manure on soil salinity and sodicity on the sodic soil in long-term experiments,the experiments were performed in a randomized complete block design with four treatments;soils that received manure applications for 8,12,18 years were used as the experimental treatments,and soil that did not receive cattle manure application was used as the control treatment(CK).The results showed that the application of cattle manure to saline-sodic soil resulted in a reduction in the bicarbonate ion(HCO₃^-)contents,the elimination of carbonate ions(CO₃^2-),the decrease in soil bulk density(ρ_b),the increases in soil porosity(f_t)and soil organic matter(SOM),the decreases in the exchangeable and soluble sodium ion (Na⁺)contents associated with increases in the exchangeable calcium ion(Ca²⁺),soluble potassium ion(K⁺),and magnesium ion(Mg²⁺)contents compared to those in untreated soil.The soil exchangeable sodium percentage(ESP)and pH were both significantly and positively correlated with the exchangeable Na⁺ and HCO₃^-,and CO₃^2- contents,and soil pH was significantly and negatively correlated with SOM.Regression analysis showed that the dominant factors affecting the sodium absorption ratio(SAR)were the soluble Mg²⁺ and Na⁺ contents in the soil.Pearson correlation analysis showed that there were significantly negative correlation between the accumulated amount of cattle manure among the indicators of soil salinization degree,such as pH,EC,ESP and SAR.It was concluded that long-term manure application significantly decreased the soil pH,ESP,electrical conductivity(EC)and SAR due to the replacement of soil colloidal Na⁺ with Ca²⁺,the leaching of soil soluble salts from the topsoil and changes in the soil soluble salt ion composition.These outcomes were likely due to the decrease of ρ_b associated with increase of f_t and Ca²⁺ and Mg²⁺ contents caused by annual manure application.

To clarify the alterations of rice straw decomposition,nutrients release and chemical components in coastal saline paddy soils under different nitrogen (N) application rate,for optimizing the technology of straw returning and realizing the efficient utilization of straw resources in coastal areas.The experimental site was located in Caofeidian District,Tangshan City,Hebei Province.The decomposition characteristics of rice straw and its lignocellulose,as well as the nutrient release characteristics of N,phosphorus (P) and potassium (K) were studied,using a 360-day straw-bag burying method with four different N fertilizer levels,including N0 (0 kg/ha),N1 (225 kg/ha),N2 (300 kg/ha) and N3 (375 kg/ha).Pyrolysis gas chromatography-mass spectrometry (Py-GC-MS) method was used to study the dynamic alterations of principal chemical components of the rice straw residues.The results showed that:the decomposition period of rice straw was divided into three stages,namely,rapid decomposition (0—30 d),slow decomposition (30—210 d) and slow decomposition (210—360 d),and the average decomposition rate of rice straw was 72.5% after 360 days with different N application rates.Increasing N application significantly increased the decomposition rate of rice straw.Compared with the N0 treatment,the N1,N2 and N3 treatments,increased the straw decomposition rate by 6.1, 7.4 and 9.2 percentage points,respectively.The trend of straw carbon (C) release rate was similar to that of straw decomposition rate,while the C release rate was only 43.2% at the end of the experiment.The nutrient release rates of rice straw were as follows:K>P>N.The N,P and K rapid release periods of rice straw was in the 0—30th (38.4%),0—60th (63.7%) and 0—15th (76.7%) days after straw decomposition,respectively.Both N and P of rice straw were enriched during the decomposition period.N application significantly increased the release of N from straw during the decomposition period,P in the early (0—15 d) and late (150—360 d) period,and K in the early period (0—15 d).Compared with the N0 treatment,the N1,N2,and N3 treatments,increased the straw N release by 6.6, 11.1, and 14.7 percentage points,P release by 2.2, 4.0, and 5.6 percentage points,and K release by 1.4, 2.1, and 2.8 percentage points,respectively.The lignocellulose decomposition rates of rice straw were as follows:hemicellulose>cellulose>lignin.Increasing N application significantly promoted the cellulose and hemicellulose decomposition rate of rice straw from day 0—90 and the lignin decomposition rate after day 90.Compared with the N0 treatment,the N1,N2,and N3 treatments,increased the cellulose decomposition rate of rice straw by 5.4, 7.3, and 8.4 percentage points, hemicellulose decomposition rate by 4.9, 6.4, and 7.4 percentage points,and lignin decomposition rate by 2.1, 5.1, and 5.7 percentage points, respectively.2-methoxy-4-vinylphenol,hydroxyacetone,2,3-dihydrobenzofuran,acetosyringone,eugenol,n-hexadecanoic acid,p-methylphenol,2,6-dimethoxyphenol,guaiacol,p-ethylphenol,and stigmasta-3,5-diene were the major (>1% relative) chemical components of straw residues during the decomposition period.Correlation analyses showed that straw decomposition rate,C release rate and cellulose,hemicellulose and lignin decomposition rates,were significantly positively correlated with eugenol,acetosyringone and 2,3-dihydrobenzofuran,while significantly negatively correlated with hydroxyacetone;straw P release rate was significantly positively correlated with hydroxyacetone and significantly negatively correlated with p-ethylphenol,eugenol and acetosyringone;straw K release rate was significantly correlated with p-ethylphenol,eugenol,acetosyringone and 2,3-dihydrobenzofuran,while significantly positively correlated with hydroxyacetone.In conclusion,increasing N application could promote the decomposition rates of rice straw and its lignocellulosic cellulose,and the nutrients release of straw N,P and K in coastal saline paddy field.The recommended optimal N application rate was 300 kg/ha under straw returning 10 500 kg/ha in coastal saline soils.p-ethylphenol,eugenol,acetosyringone,2,3-dihydrobenzofuran,hydroxyacetone,and stigmasta-3,5-diene could indicate the process of straw decomposition in straw residues.Py-GC-MS technique shows a good capability to monitor the chemical components alterations of straw residues,further deepening the understanding of straw decomposition mechanism.

In order to clarify whether existed autophagy phenomenon in sugar beet under salt stress and its relationship with plant salt-resistant physiological characteristics, the self-phage occurrence, reactive oxygen species content, osmosis regulating substance content and their relationship under different salt gradients were studied with salt-resistant sugar beet variety LS2004 and salt-sensitive sugar beet variety KWS7125 as experimental materials. The results showed that salt stress could induce autophagy in sugar beet seedlings. Autophagy was involved in the defense process of sugar beet seedlings against salt stress. The specific manifestation was that autophagy increased with the increase of salt concentration. Under the salt stress condition of 300 mmol/L, LS2004 had the strongest autophagy and the largest number of autophagosomes, which was 1.22 times that of KWS7125. The hydrogen peroxide content of KWS7125 and LS2004 reached the peak under the treatment of 200 mmol/L, which were increased by 40.06% and 41.54% respectively compared with that of the control. Under each treatment, the superoxide anion content and relative electrical conductivity of KWS7125 were higher than those of LS2004. The soluble protein content, proline content and total soluble sugar content of LS2004 firstly increased and then decreased with the increase of salt concentration, but there were differences in change rules with KWS7125. In summary, autophagy existed in sugar beet seedlings under salt stress, and the comprehensive effect of autophagy, alleviating oxidative damage, and osmotic adjustment substance content could be used by sugar beet seedlings to improve the salt tolerance of sugar beet.

The number and the length of roots as well as its QTL would provide theoretical basis for genetic mechanisms and molecular marker assisted breeding of salt and alkaline tolerance. Recombinant inbred lines(RIL)of sensitive varieties Dongnong 425 tolerant varieties Changbai 10 cross were treated with 140 mmol/L NaCl and 0.15% Na₂CO₃ as salt and alkali stress,and normal condition as control. The number and the length of roots during seedling stage were measured,and using complete interval mapping(ICIM)of QTL IciMapping v3.3 software to analysis the QTL under salt,alkali and normal conditions. We detected eighteen additive QTL located on 1,2,3,4,5,7,8,9 and 10 chromosomes with LOD 2.01-3.35,and the contribution rate to phenotypic variation was 6.02%-20.06%.Under natural conditions,four QTL related to the root number were detected,among which,12.46% was the largest contribution rate of qNRN7-2,while no QTL were detected related to the root length. Under salt stress,five QTL were detected related to the number and length of roots,among which,20.06% was the largest contribution rate of qSRN3. Under alkali stress,three QTL related to the root number and root length were detected. The contribution rate of qARN2 was 12.99%,and the contributions of qARL3 and qARL5 were 7.04% and 8.88% respectively. We found four different number and length related QTL between normal and salt condition. Among them,the contribution rates of qN-SRN8-2 and qN-SRL1 were relatively large,14.01% and 14.12%,respectively.In normal and alkali conditions,two number and length related QTL were detected on 3 and 10 chromosomes. One QTL associated with root number, qN-ARN3,located on chromosome 3,with contribution rate 6.02%.One QTL were detected related to the number and length of roots,among which,7.45% was the largest contribution rate of qN-ARL10 on chromosome 10. Under alkali and salt stress conditions,the number and length of rice seedling roots were significantly affected,and compared with salt stress,rice was more sensitive to alkali stress.

In order to investigate the effect of salt stress on starch synthesis and accumulation of Japonica rice in cold-region and enrich the physiological basis of salt tolerance research.The paper used pot experiment to study the influence of different concentrations of salt stress on the key enzymes activities related to starch of Japonica rice in cold-region and the relationships between the changes rule in key enzymes activities and starch content, revealed the response mechanism of Japonica rice in cold-region kernel starch anabolism under salt stress,studied the effect of yield and yield components of Japonica rice in cold-region under salt stress, as well as the effect of yield formation mechanism of Japonica rice in cold-region under salt stress. The results showed that compared with the control, the activities of soluble starch synthase (SSS),ADPG pyrophosphorylase and starch branching enzyme(Q enzyme) in grain of Japonica rice in cold-region decreased under salt stress, and the contents of total starch and amylopectin in grain decreased, while the amylose content in grain increased. Meanwhile,with the increased of salt concentration, the indicators of yield components gradually declined, salt stress mainly affected the grain number per panicle and seed setting rate of MDJ30 and thus affected the yield, while LD5 was the effective panicle number and seed setting rate. When soil salt content was more than 0.075%, the theoretical yield was greatly affected. In terms of variety, compared with MDJ30, the salt-tolerance variety LD5 had relatively high starch synthase activity, which results in a higher content of starch and its components.This was beneficial to grain dry matter accumulation and ensure that its yield could still be maintained at relatively high levels under salt stress. Thus, the key enzyme activite of starch synthesis in kernel is different product of different salt-tolerant varieties responding to salt stress, the change rule and the level of its activity can be used as an indicator for salt tolerance identification.

To identify the miRNAs and their response regular patterns to salt stress and drought stress,rice seedlings at three leaves stage were used to quantify the expression of miRNAs and their targets when treated with salt and drought stresses at 0,3,6,12,24,48 h by qRT-PCR. The results demonstrated that expression patterns of miRNAs were affected by space-time and tissues under salt and drought treatments. Further analysis indicated that the expressions of miR156,miR164,miR167,miR169, and miR171 upregulated in roots with time and expressions of miR159,miR160,miR319,miR398, and miR1848 downregulated at 3 h and then upregulated when treated with salt(NaCl). And the 10 miRNAs were performed their lowest expressions in shoots at 3 or 6 h under NaCl treatment. On the other hand,the expressions of the most of the 10 miRNAs downregulated in roots generally and expressions of miR156,miR159 and miR160 downregulated in shoots and the expression patterns of miR167,miR169,miR319,miR398, and miR1848 down regulated first and then upregulated when treated with drought(PEG). Furthermore,expression patterns of targets were also affected by space-time and tissues. And only few expression patterns of the 10 miRNAs negatively correlated with its target,which implied the complexity of the regulation network of miRNA and its target in response to stresses.

In order to study the influence of silicon on the expression of pepper CaMADS-box gene under abiotic stress,such as the high temperature and salt stress,we used pepper 101 as experimental materials,the physical and chemical properties of encoding protein was analyzed,phylogenetic tree was constructed,subcellular localization was predicted through bioinformatics software on the base of the cloning of pepper CaMADS-box gene.The results showed that the cloned gene encoding protein CaMADS-box was hydrophilic protein,containing MADS domain structure,belonged to MADS gene families.And its subcellular localization was in the nucleus,the molecular evolutionary tree showed that close to Nicotiana,the similarity was 67%.Fluorescence quantitative analysis showed that CaMADS-box gene expression after high temperature stress and salt stress were presented first rise after the fall of the model, the difference was to peak at 48 h, under high temperature stress, salt stress peak at 24 h, silicon handle could induce gene expression CaMADS-box, under high temperature stress and salt stress were expressed at 12 h to reach peak, which suggested that CaMADS-box was a silicon quick response genes, speculated that the silicon handle in alleviating pepper abiotic stress such as high temperature and salt stress plays an important role.

In order to investigate the effect of exogenous 24-epibrassinolide(EBR)on the physiological characteristics of Lycium barbarum seedlings under salt stress,Ningxia L. barbarum Ningqi 7 was used as the experimental material.Five treatments were set up,namely 0 mmol/L NaCl+distilled water spray(CK),150 mmol/L NaCl+distilled water spray(N0 treatment),150 mmol/L NaCl+0.005 mg/L EBR(T1 treatment),150 mmol/L NaCl+0.050 mg/L EBR(T2 treatment),and 150 mmol/L NaCl+0.500 mg/L EBR(T3 treatment).The seedling plant height,basal diameter,aboveground and underground biomass,chlorophyll content,photosynthetic parameters,antioxidant enzyme activity and the content of osmoregulatory were measured on the 7th day,14th day,and 21st day respectively.The results showed that compared with N0 treatment,T1,T2,T3 treatments significantly increased the plant height,basal diameter,aboveground and underground biomass,photosynthetic pigments in leaves,net photosynthetic rate (Pn), stomatal conductance (Gs), transpiration rate (Tr), superoxide dismutase (SOD), peroxidase (POD), catalase(CAT)activities,as well as the content of osmoregulatory in L.barbarum seedlings,intercellular CO₂ concentration (Ci) and malondialdehyde (MDA) content significantly decreased,T2 treatment had the best effect.On the 21st day of salt stress,compared to the N0 treatment,the plant height,basal diameter,aboveground and underground biomass of L.barbarum seedlings increased by 23.63%,15.45%,17.70%,and 47.06%,the content of Chlorophyll a,Chlorophyll b,and Chlorophyll a+b increased by 10.68%,12.31%,and 6.57%,respectively;Pn,Tr,and Gs increased by 55.53%,27.83%,and 9.76%,respectively;the Ci value decreased by 14.42%;the activities of SOD,POD,and CAT increased by 13.23%,20.10%,and 9.31%,respectively;the MDA content decreased by 35.28%;the proline content,soluble sugar content,and soluble protein content increased by 45.17%,86.54%,and 57.00%,respectively.In summary,an appropriate concentration of exogenous 24-epibrassinolide can promote the growth of L.barbarum seedlings under salt stress,improve the photosynthetic capacity and antioxidant enzyme activity of L.barbarum seedlings,increase the content of osmoregulatory substances,alleviate the damage of salt stress to L.barbarum seedlings,and enhance the salt tolerance of L.barbarum seedlings.Among them,exogenous 0.050 mg/L EBR has the best effect.

In order to study the effects of NaCl stress with different concentrations on physiological characteristics and gene expression of TaNHX1,two new wheat varieties (Luyuan 502 and Qingmai No.6)were used as the experimental materials.Physiological indexes of seeds germination rate,seedlings fresh weight,roots vigor,plasmalemma permeability,MDA content and Na⁺ content of the two wheat varieties were determined under above 100 mmol/L NaCl stress of 50,100,150 and 200 mmol/L,and compared the relative expression of tolerant gene TaNHX1 in roots and stem base of wheat through RT-qPCR method.The results showed that the seeds germination rate of Qingmai No.6 was more than that of Luyuan 502 under above 100 mmol/L NaCl stress.Low concentration NaCl stress had significant promoting effect on seedlings growth of Qingmai No.6,and the seedlings fresh weight of Qingmai No.6 significantly decreased under NaCl stress of 150 mmol/L,while that of Luyuan 502 began to decreased significantly under NaCl stress of 100 mmol/L.The roots vigor of Luyuan 502 decreased significantly more than that of Qingmai No.6 under high concentration NaCl stress.Under the same concentration NaCl stress,the leaf plasmalemma permeability and MDA content of Luyuan 502 were significantly more than that of Qingmai No.6,it indicated that NaCl stress had less damage on leaf cell membrane of Qingmai No.6.Na⁺ content of roots and stem base of Qingmai No.6 were all significantly more than that of Luyuan 502 under high concentration NaCl stress,it indicated that Na⁺ exclusion capability of roots and stem base of Qingmai No.6 was significantly more than that of Luyuan 502,which could effectively restrict Na⁺ transporting to shoot.The TaNHX1 gene of Luyuan 502 and Qingmai No.6 respectively reached the highest expression level under NaCl stress of 100,150 mmol/L.It indicated that Qingmai No.6 is more salt tolerant than Luyuan 502,and the maximum concentration of salt tolerance of Luyuan 502 is 100 mmol/L,while that of Qingmai No.6 is 150 mmol/L.

To address issues such as shallow soil layers,upward movement of the plowpan,and soil salinization in the saline-alkali soils of the West Liaohe Plain,field trials were conducted in Huatugula Town,Horqin Zouyi Middle Banner,Tongliao City,Inner Mongolia Autonomous Region,from 2020 to 2021.Two tillage methods(traditional rotary tillage and powder ridge plowing),two irrigation quotas(2 100,2 700 m³/ha),and mulching and shallow burial measures were set up,resulting in six experimental treatments:2 100 m³/ha irrigation quota+traditional rotary tillage+shallow burial(CK×NM),2 100 m³/ha irrigation quota+traditional rotary tillage+mulching(CK×DM),2 100 m³/ha irrigation quota+powder ridge plowing+shallow burial(FA×NM),2 100 m³/ha irrigation quota+powder ridge plowing+mulching(FA×DM),2 700 m³/ha irrigation quota+powder ridge plowing+shallow burial(FB×NM),2 700 m³/ha irrigation quota+powder ridge plowing+mulching(FB×DM).The effects of powder ridge plowing and mulching treatments on soil properties,structure,saline and alkaline content,and maize yield in the 0—40 cm soil layer under different irrigation quotas were analyzed. The result showed that compared to the CK×NM treatment, in the 0—40 cm soil layer, the soil bulk density decreased by 8.4%—22.9%, the total soil porosity increased by 4.9—14.8 percentage points, and the soil three-phase ratio R value decreased by 34.6%—88.2% under powder ridge plowing + mulching treatment,among them, the bulk density, total porosity, and three-phase ratio R value of the soil treated with FB×DM treatment were significantly reduced by 20.0%,-13.1 percentage points, and 88.2%, respectively;soil moisture content after sowing increased by 5.5—12.1 percentage points in the 20—40 cm soil layer, soil hardness increased by 33.4%—397.5% in the 7.5—17.5 cm soil layer,among them, the soil moisture content, hardness of the FB×DM treatment increased significantly by 12.1 percentage points, 214.3%,respectively;CO₂ flux of the FB×DM treatment increased significantly by 496.4%.Compared to the CK×NM treatment, the powder ridge plowing+mulching treatment reduced the soil pH value, total alkalinity, electrical conductivity, and total salt content in the 0—40 cm soil layer, with reduction rates of 0.7%—10.9%, 2.5%—67.5%, 24.3%—68.7%, and 10.3%—81.0%, respectively. Among them, the soil pH value, total alkalinity, electrical conductivity, and total salt content of the FB×DM-treated soil were significantly reduced by 10.9%, 48.2%, 59.2%, and 80.0%, respectively.Maize germination rate, ear fresh weight, and yield were increased by 13.2—20.1 percentage points,52.5%—68.2%, and 22.4%—45.5%, respectively,among them, the germination rate, ear fresh weight, and yield of the FB×DM treatment were significantly increased by 20.1 percentage points,68.2%, and 45.5%, respectively, compared to the CK×NM treatment. Considering the comprehensive improvement effects and maize yield, it is concluded that the 2 700 m³/ha irrigation quota+powder ridge plowing+mulching(FB×DM) is a more suitable cultivation mode for saline and alkaline land in the West Liaohe Plain.

To assess the peanut rhizosphere bacteria community structure in response to salt stress at different development stages, the peanut variety Huayu 25 was used as experimental material, and a pot experiment was set with three salt concentrations to study the effect of salt stress on peanut yield and analyze the changes of microbial community structure of peanut rhizosphere at flowering and harvest stage under salt stress by high-throughput sequencing technology. The results showed that the rhizosphere microbial composition of peanut were basically similar under different salt stress treatments, but the diversity and richness significantly varied between flowering and harvest stage. Under higher salt stress, the diversity and richness of rhizosphere bacterial community were increased at the flowering and needling stage but decreased at the harvest stage. The dominant bacteria phyla of all soil groups were Proteobacteria, Actinobacteria, Chloroflexi, Acidobacteria, Verrucomicrobia, Bacteroidetes, and Patescibacteria. The relative abundance of Cyanobacteria, Gammaproteobacteria, Verrucomicrobiae and Bacteroides significantly increased under salt stress, especially at the flowering and needling stage. Hierarchical clustering revealed that the microbial community diversity was markedly altered by the salt concentrations and growth stages, samples of the same growth period were clustered into one group under salt stress. KEGG functional prediction analysis indicated that sequences related to carbohydrate metabolism, amino acid metabolism, energy metabolism, and metabolism of cofactors and vitamins were enriched, whereas that of signal transduction mechanisms, lipid metabolism, replication and repair, xenobiotics biodegradation and metabolism, metabolism of other amino acids, and folding, sorting and degradation were decreased. Among them, salt stress increased the abundance of functional groups involved in substance and energy metabolism, membrane transport, translation, replication and repair, and signal transduction, but decreased the 100 fruit weight and 100 kernel weight of peanut resulted in the decrease of peanut yield. Therefore, salt stress had a great impact on the peanut rhizosphere bacterial community structure and peanut yield. The salt tolerance of peanut could be enhanced by improving soil microbial environment. The results provided a theoretical basis for the development of peanut production in saline-alkali areas.

In order to determine the molecular characterization and expression patterns of TIFY family genes involved in saline and alkali stress in Glycine soja, according to previous transcriptome data, GsTIFY6B was obtained by homologous cloning using cDNA of Glycine soja G07256, with extremely tolerant ability to saline and alkali stress, as its template. The full-length CDS was 1 047 bp. GsTIFY6B protein was an unstable protein with 348 amino acids. Its molecular weight was 36.8 ku and its isoelectric point was 9.12. Phylogenetic tree analysis showed the closest homology of GsTIFY6B to the TIFY family proteins of GmTIFY6B, VrTIFY6B, CcTIFY6B and AdTIFY6A. All those proteins had the conserved domains TIFY and Jas. The transcription level of GsTIFY6B in different parts of Glycine soja as well as response to saline and alkali stress and hormone treatment was detected by Real-time fluorescence quantitative PCR. The results showed that the highest relative expression level of GsTIFY6B in roots. Under salt stress, the expression of GsTIFY6B in roots and leaves showed an up-regulation.Under alkali stress, the expression of GsTIFY6B in roots and leaves showed the first down-regulation and then up-regulation expression. It is speculated that the gene might be involved in the defense reaction of saline-alkali stress.Under the ABA treatment, GsTIFY6B showed down-regulated expression in the roots and up-regulated expression at 6, 12 h in leaves. Under MeJA stress, GsTIFY6B expression was decreased first and then increased in roots, but showed up-regulation in leaves. This study suggested that GsTIFY6B could positively respond to saline and alkali stress by participating in the ABA and MeJA signaling pathways. These results will provide a theoretical basis for the later study on the molecular mechanism of saline-alkali-tolerant response of Glycine soja.

To study the function of lipid transfer proteins(LTP)in abiotic stress,the ZmLTP3 gene was transferred into maize Jing 2416 inbred lines by pollen tube pathway method. Positive transgenic lines were obtained by continuous selfing based on the screening of PCR and EPSPS. Three transgenic lines OE6,OE10 and OE18 were selected as the experimental group,and Jing 2416 inbred lines(WT)were used as CK. Both of them were subjected to salt stress. Morphological and physiological indexes were compared between OE and WT lines. The results showed that OE and WT plants showed no significant differences in both morphological and physiological indexes under normal condition. Under the salt stress condition,compared with WT plants,the OE plants had significantly higher height,stem diameter,root length,fresh weight,dry weight and chlorophyll content,significantly higher activities of superoxide dismutase(SOD),peroxidase(POD)and catalase(CAT),significantly lower malondialdehyde(MDA)content and relative conductivity ratio level,showing their better growth status,higher active oxygen radicals scavenging capacity and less cell injury. These results indicated that overexpression of ZmLTP3 gene could improve the salt tolerance in transgenic maize.

In order to explore the effect of straw interlayer on soil respiration and the chemical structural stability of organic carbon components during the remediation of saline-alkali soil,two experimental treatments were set up in the alfalfa-planting farmland at the Saline-Alkali Soil Improvement Experimental Demonstration Base in the Agricultural High-Tech Zone of Dongying City,Shandong Province:a straw interlayer treatment (S,with a 5 cm thick straw layer buried at a 35 cm depth) and a control (CK,without an interlayer). Soil respiration characteristics of the different treatments were analyzed,and comprehensive discussions were conducted in conjunction with soil pH,electrical conductivity(EC),organic carbon component content,and chemical structure characteristics of the soil profile.The results showed that:compared with CK,the S treatment significantly increased the soil respiration rate during the alfalfa growth period, with a maximum increase of 79.84%. Furthermore, the S treatment reduced soil EC in the straw interlayer (35—40 cm) and the overlying soil layer (0—35 cm), effectively inhibiting the upward migration of salt. The 40—50 cm soil layer was identified as a critical zone for organic carbon transformation. In this layer, the S treatment significantly increased SOC content (by 16.67%) and highly significantly elevated particulate organic carbon (POC) and dissolved organic carbon (DOC) contents (by 208.07% and 83.41%, respectively) compared with CK. Characterization of the molecular structure of organic carbon in the 40—50 cm layer revealed distinct responses. For DOC, the S treatment reduced the magnitude-weighted averages of unsaturation (by 30.60%) and aromaticity index (by 4.84%) compared with CK, decreasing the proportion of unstable carbon. For POC, the S treatment increased the relative abundances of alkyl C(10.32 percentage points)and O-alkyl C (8.39 percentage points) while reducing carboxyl C (14.24 percentage points), thereby enhancing POC structural stability. However, for bulk SOC, the S treatment decreased the proportions of alkyl C(3.14 percentage points) and aromatic C(3.38 percentage points) while increasing O-alkyl C(5.17 percentage points)and carboxyl C(1.56 percentage points). This shift indicated a decrease in recalcitrant carbon and an increase in labile carbon, resulting in reduced SOC structural stability. Correlation analysis showed that the significant increased in soil respiration was highly significantly and significantly positively correlated with POC and SOC contents in the critical soil layer, respectively. Specifically, the accumulation of O-alkyl C(a labile component) in the chemical structure of SOC reduced the stability of organic carbon,which was the main reason for the increase in soil respiration.In conclusion,incorporating a straw interlayer significantly increased soil respiration in the short term,which was closely related to the reduction in the stability of the organic carbon chemical structure in the key soil layer.Under future "carbon neutrality" strategies,research on the selection of interlayer materials should be considered.