Light-harvesting chlorophyll a/b binding proteins are important in plant photosynthesis and abiotic stress response.To study the characteristics of GhLhcb2A1 and its expression patterns and functions in low temperature and drought response in upland cotton,full-length CDS of GhLhcb2A1 gene was cloned from the leaf cDNA of Jimian 262 by PCR.Bioinformatic analysis was conducted to learn the basic characteristics of the gene.The expression patterns and functions in low temperature and drought response were evaluated by qRT-PCR and virus-induced gene silencing.It was shown that the length of GhLhcb2A1 CDS was 798 bp,encoding 265 amino acids.GhLhcb2A1 was highly expressed in leaves and was significantly up-regulated in leaves and roots under low temperature and drought treatment.Compared with the control,its expression maximized at 3 h under low temperature and drought in leaves with 17.42 and 30.03 folds increase respectively,whereas maximized at 6 h under low temperature and 12 h under drought in roots with 11.65 and 65.04 folds respectively.Subcellular localization assay verified that GhLhcb2A1 was expressed in the chloroplasts of cells.Compared with the control plants,GhLhcb2A1 silenced plants showed a more severe phenotype of water loss and dryness under both low temperatures and drought.The accumulated malondialdehyde content in the leaves of the silenced plants was significantly higher than that of the control,while the proline content and superoxide dismutase activity were significantly lower than those of the controls,suggesting that GhLhcb2A1 silenced plant reduced the resistance to low temperature and drought.The above results implied that this gene played a positive role in regulating low temperature and drought response.

4-coumaric acid:coenzyme A ligase(4CL),as the main biosynthetic enzyme of flavonoids and lignin,is closely related to the formation of plant flavonoids.In order to explore the relationship between the 4CL gene family of Glycyrrhiza uralensis and the synthesis and accumulation of isoglycyrrhizin,this study determined the content of isoglycyrrhizin in G. uralensis after drought stress,and the expression characteristics and bioinformatics analysis of the 4CL gene family of G. uralensis Fisch.to understand the relationship between the accumulation characteristics of isoglycyrrhizin and the 4CL gene of G.uralensis.The results showed that isoliquiritigenin was mainly accumulated in the roots of G.uralensis,and drought stress could significantly increase the content of isoliquiritigenin in the roots of G.uralensis.The content of isoliquiritigenin after 2 h of polyethylene glycol(PEG)stress was 3.91 times that of the control group(0 h).Drought stress could induce the up regulation of Gu4CL gene in the underground part.The expression levels of Gu4CL2, Gu4CL4 and Gu4CL5 were higher after PEG stress induction,while Gu4CL2 was most significantly up-regulated after PEG stress.The expression of Gu4CL2 was similar to that of isoliquiritigenin.Bioinformatics analysis of Gu4CL gene showed that 11 genes had two conserved polypeptide motifs Box Ⅰ(SSGTTGLPKGV)and Box Ⅱ(GEICIRG),and 11 genes were distributed on 11 Scaffold fragments.Promoter cis-acting element analysis showed that Gu4CL2, Gu4CL4 and Gu4CL5 genes contained more abscisic acid and jasmonic acid response elements than other Gu4CL genes.Therefore,drought stress may induce the synthesis of jasmonic acid and abscisic acid,regulate the expression of Gu4CL2, Gu4CL4 and Gu4CL5 genes in licorice roots,and increase the accumulation of isoliquiritigenin.This study provides a research basis for optimizing the cultivation techniques of G.uralensis,improving the adaptability and quality of cultivated land in saline-alkali land,exploring the role of Gu4CL gene family in G.uralensis,and exploring the synthesis mechanism of isoliquiritigenin.

Tiller-related traits are important characteristics of wheat plant type,which determine plant structure and affect grain yield.In order to understand the inheritance and drought resistance of tiller-related traits in wheat under different water conditions,and to excavate the loci related to tiller-related traits,240 wheat varieties (lines) were selected as the subjects of this study,based on the phenotypic identification of tiller angle,effective tiller number and yield per unit area under normal irrigation (NI) and drought stress (DS) conditions,and the comprehensive evaluation of drought resistance,combined with 90K gene chip,genome-wide association study (GWAS) was to identify genetic loci for tiller-related traits and to screen for superior germplasm.The tiller angle,effective tiller number and yield per unit area showed significant difference,and the coefficient of variation ranged from 0.07 to 0.33.According to D-value,the drought resistance of Zhongyou 206 was the best.A total of 54 stable genetic loci significantly associated with tiller angle and other traits were detected, distributed on all chromosomes except 3D, 4D and 5D. Three identical stable loci were commonly detected under both treatments, located on chromosomes 2B, 4B, and 6B. Additionally, four pleiotropic loci were commonly detected in different traits, located on chromosomes 2B, 2D, and 5B.At the same time,the haplotype analysis of Ra_c491_902 (R²=5.45%—17.91%),which was significantly correlated with tiller angle on chromosome 2B,showed that there were three haplotypes:TA-Hap1,TA-Hap2 and TA-Hap3,the haplotypes (lines) containing TA-Hap1 were mainly derived from Huanghuai winter wheat regain.Five candidate genes related to tiller angle were screened by screening the stable genetic loci detected under different treatments.Gene annotation of the genes selected on Ra_c491_902 showed that the genes encoding cytochrome P450 family protein can be used as important genes such as regulating tillering angle,plant drought resistance and defense,to explore the association between genes and phenotype,and lay the foundation for the genetic improvement of tiller-related traits in wheat.

Drought stress has a serious effect on the growth and development of maize,which leads to a decrease of maize yield.Purple acid phosphatase is a phospholipase protein involved in many physiological and biochemical functions of plants.In order to further study the role of purple acid phosphatase family genes in the process of stress resistance of maize,this paper explored the response mode of ZmPAP26b gene under drought stress,and Real-time fluorescence Quantitavive analysis was used to analyze the relative gene expression in different maize inbreeding lines under simulated drought conditions;ZmPAP26b(GenBank:NC_050104.1)was cloned from maize,and PAP genes in Zea mays,Arabidopsis thaliana,Oryza sativa L.,Triticum aestivum L.,Sorghum bicolor and Brachypodium distachyon were identified and bioinformatic analysis was performed.Meanwhile,prokaryotic overexpression strains were constructed for functional verification.The results showed that the expression of this gene decreased in drought tolerant materials and increased in drought sensitive materials under drought stress.The CDS length of this gene was 1 431 bp,encoding 476 amino acids.A total of 228 PAP genes were found in six species,divided into 4 subfamilies by phylogenetic analysis.The 19 PAP genes in maize were distributed on 9 chromosomes and had similar conserved domains.Analysis of promoter cis-acting elements showed that they contained elements responding to drought and hormones.Prokaryotic expression experiments showed that the growth of strains containing the recombinant plasmid pET28a-ZmPAP26b was inhibited compared with non-loaded strains under 10% PEG-6000 and 15%PEG-6000 simulated drought stress.In summary,it is speculated that ZmPAP26b is negatively regulated under drought stress.

The WRKY transcription factor family plays an important role in regulating abiotic stress.To systematically analyze the sequence characteristics and expression patterns of NtWRKY11 gene in tobacco,and explore the response mechanism of NtWRKY11 under abiotic stress such as low temperature and drought,the full-length cDNA sequence of NtWRKY11 gene was amplified by PCR using common tobacco cDNA as a template.The basic properties of NtWRKY11 protein were analyzed by bioinformatics software and the subcellular localization of NtWRKY11 protein was studied by constructing a plant expression vector.The expression of NtWRKY11 gene was detected by qRT-PCR technology in different tissues at the full flowering stage and under different abiotic stresses.The results showed that the full-length cDNA of NtWRKY11 gene in tobacco was 999 bp,encoding 332 amino acids,and it shared 54.23% similarity with ramie BnWRKY11.Its promoter region contained three kinds of cis-acting elements(one MBS,one MYB and three ARBE),which probably worked together to enhance the drought resistance of plants.It also contained three salicylic acid-responsive cis-acting elements(TCA-element),which could improve the low temperature tolerance of plants.Subcellular localization results indicated that the NtWRKY11 protein was located in the nucleus.The expression analysis of NtWRKY11 in different tissues at the full flowering stage showed that NtWRKY11 was highly expressed in old leaves,significantly higher than in roots.However,the expression in flowers was significantly lower than that in roots,and there was no significant difference between stems,new leaves and roots. The expression analysis under abiotic stress showed that the relative expression of the gene was significantly higher than that of normal (CK).The relative expression level under high salt stress was not significantly different from CK,while the relative expression level under high temperature stress was significantly lower than CK.All in all,NtWRKY11 is highly expressed in old leaves,and its expression level is enhanced under abiotic stresses such as drought stress and low temperature stress,indicating that this gene acts as a forward transcription factor to regulate drought and low temperature stress.

Auxin response factor(ARF)is a class of transcription factors with B3 domain,which is a direct molecule regulating auxin response and controlling gene expression.A gene,ZmARF10,which encoded ARF protein and actively participated in drought-rehydration stress response,was previously screened in maize by analyzed transcriptome data.To further research the molecular mechanism of ZmARF10 regulating drought resistance of maize,and also provide a new idea for molecular breeding of drought resistance,the gene was firstly analyzed by bioinformatics software.Secondly,Quantitative Real-time polymerase chain reaction(qRT-PCR)was used to detect the expression pattern of ZmARF10 in different tissues,under high temperature,drought,high salt,ABA and restoring treatments,and in different inbred lines.Finally,the function of ZmARF10 was analyzed using CRISPR/Cas9 technology.The results showed that ZmARF10 was located on chromosome 3 of maize,with a total length of 2 127 bp,and encoded 708 amino acids with a typical B3 domain.The upstream 2 kb region of ATG of this gene contained response elements related to methyl jasmonate,auxin,abscisic acid and low temperature.The phylogenetic tree showed that the protein encoded by the ZmARF10 gene was closely related to sorghum.qRT-PCR results showed that ZmARF10 was a constitutive expression gene,and the expression level of ZmARF10 was the highest in mature corn roots of maize.Under high temperature,drought,high salt and ABA treatments,the expression of this gene was significantly up-regulated,and the up-regulation ratio was up to 8.2 times after drought stress.After drought stress,the expression level of ZmARF10 gene was significantly higher in the drought-resistant inbred line Zheng 36 than that in the drought-sensitive inbred line B73.Investigation of Arabidopsis wild type and ARF10-deficient mutants showed that,compared with wild type,the mutant plants showed leaf wilting and even dry death,roots curled,root branch number decreased,and lateral root growth and development were hindered under drought conditions.Determination of physiological and biochemical indexes showed that the relative water content,chlorophyll content and net photosynthetic rate of the deficient mutants were significantly lower than those of the wild-type plants after drought stress,indicating that the drought resistance of Arabidopsis decreased after ARF10 gene was knocked out.

To clarify the effects of drought stress and cultivars on the net photosynthetic rate(Pn),the activities of photosynthetic enzymes in flag leaf in the afternoon(FLA)during grain filling stage and grain yield of winter wheat,a pond culture experiment with four water levels and two winter wheat cultivars was conducted under the condition of rainproof pond cultivation in 2019—2021.The four water treatments included severe drought(W1),moderate drought(W2),mild drought(W3),and suitable water supply(W4).The Pn,and the activities of Rubisco,RCA,PEPC,ATPase and PPDK in flag leaf from 14:00 to 16:00 during the early(EGFS)and medium(MGFS)grain filling stage,and the grain yield at maturity of strong drought resistance cultivar Jinmai 47(JM47)and weak drought resistance cultivar Yanzhan 4110(YZ4110)were investigated.Drought stress decreased the FLA Pn and activities of most photosynthetic enzymes,and the grain yield of wheat.The decrease of these indexes increased with drought stress degree,but the effects were different among varieties and years.Compared with W4,the FLA Pn of JM47 under W1,W2 and W3 decreased by 33.6%—40.6%,12.0%—30.5% and 5.0%—13.5%,as well as YZ4110 decreased by 44.0%—52.0%,22.5%—38.1% and 11.5%—20.5%,respectively.Compared with W4,the FLA Rubisco activity decreased during EGFS but increased during MGFS for JM47,while it decreased by 13.3%—25.6%,7.1%—14.0% and 11.2%—11.6% for YZ4110,respectively,under W1,W2 and W3.Compared with W4,the FLA RCA activity significantly decreased under most drought treatments during EGFS,while increased under W2 and W3 for JM47 and decreased under W1 and W2 for YZ4110 during MGFS.Compared with W4,the FLA ATPase activity of JM47decreased under W1 but increased under W3,while that of YZ4110 decreased under W1,W2 and W3 by 19.3%—48.7%,7.2%—24.2% and 0.1%—8.9%,respectively.The FLA PEPC activity under different treatments varied with growing seasons and varieties.Compared with W4,the FLA PPDK activities of JM47 and YZ4110 under W1 were decreased by 12.4%—18.8% and 16.7%—18.2%.Compared with YZ4110,in most conditions,the FLA Pn and photosynthetic enzyme activities of JM47 had no significant difference under suitable water supply(W4),but increased under drought treatments(W1,W2 and W3).The results of correlation analysis showed that yield,FLA Pn were significantly positively correlated to FLA ATPase activity during EGFS and MGFS,as well as FLA PEPC activity during EGFS.Thus,increasing the FLA ATPase and PEPC activities during the grain filling period is conducive to the increase of FLA Pn and grain yield of wheat.

To investigate the effects of Piriformospora indica combined with Arbuscular mycorrhizal fungi (AMF) on drought resistance of tobacco,Yunyan 87 was inoculated with sterile water (CC),P.indica (CP),AMF (PC),P.indica and AMF (PP),and the contents of proline (Pro),superoxide dismutase (SOD),peroxidase (POD),malondialdehyde (MDA) and the expression of drought-related genes NTNAC1 and NAC4 in tobacco leaves were determined under stress in the form of natural drought.The results showed that P.indica and AMF could promote the growth of above-ground and underground parts of tobacco,and chlorosis of leaves and symptoms of their drought were slight.After 7 days of drought stress,the contents of Pro in tobacco leaves of CP,PC and PP groups were 1.39,1.59 and 1.78 times higher than those of CC in group,respectively.The activities of SOD and POD in tobacco leaves increased first and then decreased.The activities of SOD in CP,PC and PP groups were 1.15,1.22 and 1.33 times higher than those in CC group,POD activity was 1.33,1.46 and 1.85 times higher than those of CC group,respectively.The content of MDA in tobacco leaves was decreased by 21.98%,23.98% and 24.84% in CP,PC and PP groups respectively.The expression levels of NTNAC1 and NAC4 in tobacco leaves were up-regulated.The expression levels of NTNAC1 in CP,PC and PP groups were 3.37,3.88 and 5.07 times higher than those in CC group,the expression levels of NAC4 gene were 3.04,3.59 and 5.56 times higher than those of CC group,respectively.This study indicates that P.indica and AMF showed significant synergistic effects,which could significantly improve the drought resistance of tobacco.

To investigate the molecular response to drought stress of silks,two treatments with soil moisture content of 80% field holding capacity (CK) and 60% field holding capacity (DS) were set up using Annong 591 and Xianyu 335,and the maize silks were sampled during the rapid increase in silk elongation,and transcriptome sequencing was performed.By comparing the gene expression differences between the drought and control groups of the two varieties,the key pathways and related candidate genes of maize silks in response to drought were clarified.The results showed that the phenylpropane biosynthesis pathway (ko00940) and starch and sucrose metabolism pathway (ko00500) were the key pathways in maize silk response to drought.In the phenylpropane biosynthetic pathway 4CL,CCR,CAD and POD genes were lowly expressed in drought-prone maize silks.Correlation analysis showed that down-regulation of 4CL,CCR,CAD and POD genes was associated with reduced lignin content.Converting enzyme and sucrose synthase genes in the starch and sucrose metabolic pathways were lowly expressed in drought maize silks.Correlation analysis indicated that down-regulation of convertase and sucrose synthase genes was associated with sucrose metabolism.In summary,this study identified key genes and metabolites involved in sucrose and lignin metabolism.The lignin synthesis are associated with drought tolerance in maize silks,and 4CL, CCR,CAD,and POD are the candidate genes for drought tolerance in maize silks.In addition,the starch and sucrose metabolic pathways are associated with silk elongation and drought tolerance of silks,and invertase and sucrose synthase are the main candidate key enzymes.

HD-Zip transcription factors play an important regulatory role in stress resistance in plants,in order to reveal the characteristics and potential functions of the HD-Zip gene family in the hemp genome,and to provide important clues for further study on the regulation of CsHDZ gene under drought stress.Here this study based on the reference sequence in the hemp whole genome database,perform a genome-wide analysis of HD-Zip gene family by bioinformatics methods in hemp,and their physical and chemical characteristics,evolutionary relationship,gene structure,the cis-acting elements and transcript patterns in drought stress were analyzed.The results showed that a total of 20 hemp HD-Zips (CsHDZs),they were non-evenly distributed on seven chromosomes,and classified into four distinctive subfamilies.Their amino acid sequence size and isoelectric point were 204—837 aa and 4.54—9.04,they were all unstable proteins,and subcellular localization analysis indicated that HD-Zip protein was targeted to the nucleus.Analysis of protein conserved motifs showed that there was a total of 10 conserved motifs in CsHDZs,of which motif 1 and motif 9 were shared by all numbers.In addition,the regulatory element analysis showed that a variety of elements related to abiotic stresses were identified in the promoter region of CdHDZs.The results of Real-time Fluorescence Quantitative analysis showed that the transcription level of CsHDZ1/8/10 gene had no significant difference in the early stage of drought,but was significantly upregulated in the late stage.The results indicated that CsHDZs gene was involved in the stress response process and could actively respond to drought.

WRKY transcription factors play an important role in the regulation of plant growth and defence responses.In order to explore the function of WRKY gene family in chestnut under drought resistance,the chestnut WRKY gene family members were identified and the physical and chemical properties,phylogeny and structure of the encoded proteins were analyzed.Transcriptome sequencing and qRT-PCR were used to analyze the expression characteristics of WRKY gene family members under drought stress.The results showed that 65 WRKY gene family members were identified and divided into three groups:Ⅰ,Ⅱ and Ⅲ,among which group Ⅱ was divided into five subgroups according to its structure and phylogenetic relationship.Analysis of WRKY gene structure and conserved motif showed that the number of exons ranged from 1 to 7,and the number of exons and motif distribution in the same subgroup were similar.The conserved domain of WRKY gene had certain variation,including the deletion of WRKY heptapeptide domain,the deletion of zinc finger structure,and the heptapeptide domain was mutated into WRKYGKK,WRKYGRK and WRKYGRK.Transcriptome sequencing data showed that 4 WRKY family members were not expressed in the samples,and 49 WRKY family members were up-regulated under drought stress,while 11 WRKY family members were down-regulated under drought stress.The above results showed that,chestnut WRKY genes played an important role in response to drought stress.

By analyzing different materials of Medicago sativa L. and Medicago falcata L.,this study aims to observe the leaf morphology and tissue anatomical structure of alfalfa under drought stress,and explore the adaptive changes in leaf morphology and anatomical structure of alfalfa seedlings under natural drought stress.This study used three alfalfa and two Medicago falcata L. as research materials,and set four different soil relative moisture contents(70%,55%,40%,and 25% of the maximum soil moisture capacity)for experiments. After 30 days of treatment,the morphological and anatomical structures of the leaves were determined. To investigate the response of alfalfa seedling leaves to natural drought stress by observing the leaf morphology and anatomical structure of purple and sickle alfalfa seedlings through electron microscopy. Drought stress would inhibit the growth of alfalfa leaves. With the increase of drought stress,the soil moisture decreased,the leaf length,leaf width,and leaf area of alfalfa and sickle alfalfa decreased,the thickness of upper epidermis increased,the thickness of leaf,mesophyll,and lower epidermis decreased,the thickness of palisade cell and sponge tissue decreased,the thickness of midrib center decreased,the palisade sea ratio gradually decreased,and the compactness of leaf tissue structure increased,the degree of looseness decreased and the degree of leaf vein protrusion increased. The intensity of drought stress was negatively correlated with leaf length,leaf width,leaf area,leaf thickness,mesophyll thickness,lower epidermis thickness,palisade cell thickness,sponge tissue thickness,midvein center thickness,palisade sea ratio,and leaf tissue structure porosity.It was positively correlated with the thickness of the upper epidermis,the tightness of leaf tissue structure,and the degree of leaf vein protrusion.

This research studied the effects of different phosphorus and potassium fertilization methods on maize growth,nutrient uptake and utilization.It was determined suitable fertigation timings and frequencies of phosphorus and potassium fertilizer,and to provide a theoretical basis for drip fertilization technology of maize with phosphorus and potassium in semi-arid areas of northeast China.A field experiment was conducted in 2018—2019,with Xiangyu 998 as a test material,six treatments were set up,P0 (No phosphorus fertilizer),K0 (No potassium fertilizer),P1(100% basal application of P fertilizer,50% basal application of K fertilizer,the other 50% fertigation three times),K1(100% basal application of K fertilizer,50% basal application of P fertilizer,the other 50% fertigation four times),P1K1(100% basal application of P and K fertilizer),and P4K3(50% basal application of P and K fertilizer,the other 50% P fertigation four times and the other 50% K fertigation three times).The results showed that compared with the P1 treatment,the P4K3 treatment increased maize yield by 4.2%,dry matter accumulation at maturity by 6.8% (P<0.05),post silking P accumulation by 33.3% (P<0.05),and significantly improved the P fertilizer recovery efficiency and agronomic efficiency by 21.6 percentage points and 28.5%,respectively.Compared with the K1 treatment,the P4K3 treatment increased maize yield by 3.5%,dry matter accumulation at maturity by 5.1%,and significantly improved the K fertilizer recovery efficiency and agronomic efficiency by 14.9 percentage points and 53.5%,respectively;compared with the single application of phosphorus and potassium treatment,maize yield was increased by 5.0%,the uptake of phosphorus after silking was increased by 26.3%,and P fertilizer recovery efficiency and P agronomic efficiency were increased by 19.5 percentage points and 32.6%,respectively;K fertilizer recovery efficiency and agronomic efficiency increased by 15.2 percentage points and 95.5%,respectively.Fractional fertigation of phosphorus and potassium fertilizer could not only be beneficial to improve yield of maize,but also promote post-silking nutrient uptake and improve nutrient utilization under drip irrigation conditions.Comprehensive consideration,P4K3 treatment is a more suitable drip fertigation technique for field production.

bZIP transcription factors are widely found in plants and play an important role in regulating plant growth and development and abiotic stress response.In order to explore the functional role of bZIP transcription factor in maize drought stress response,transcriptome sequencing technology was used to analyze the expression changes of transcription factors in maize seedlings treated with drought stress for 5 days and rehydration for 3 days,and a bZIP transcription factor(ZmbZIP26)was screened from transcriptome data in response to drought and rewatering treatment.Co-expression network analysis revealed that ZmbZIP26 was at the core node of network regulation.The gene contained a 558 bp open reading frame encoding 185 amino acids,which was a hydrophilic protein.Phylogenetic tree and conserved sequence analysis showed that ZmbZIP26 protein had high homology with homologous proteins of sorghum and Miscanthus,and also had the same conserved motifs at the same amino acid positions.Cis-element analysis showed that the upstream 2 000 bp region of the ATG site contained drought response elements,hormone response elements and light response elements.qRT-PCR analysis showed that ZmbZIP26 was a constitutively expressed gene,which was highly expressed in young stems,female panicles and roots.ZmbZIP26 positively responded to drought,high temperature,high salt and nitrogen stress and the process of restoring,which might play an important role in the process of plant resistance.Subcellular localization analysis revealed that ZmbZIP26 was a nuclear protein localized in the nucleus.Protein interaction prediction showed that ZmbZIP26 might interact with zinc finger protein,serine protein,Ca-dependent protein and glutathione transfer protein to construct a regulatory network,which cooperatively regulated maize growth and development and stress response process.

To reveal the mechanism of drought resistance of different resistant rice during germination period,Rice drought-sensitive materials(Calrose,Jingning 10,Shanxing 86)and drought resistance materials(Farry,Songjing 3,Ningjing 36)were studied on the effects of simulated drought stress(15% PEG-6000)on the growth index,physiological indexes and corresponding gene expression of different rice seeds.The results showed that under normal conditions,there were no significant differences in the expression levels of growth indicators and stress-related genes between drought-sensitive and drought-resistant cultivars.However,changes in physiological indicators were shown that there were no significant differences in the activities of superoxide dismutase(SOD) and peroxidase(POD),the contents of soluble sugar(SS) and hydrogen peroxide(H₂O₂) among different genotypes.The contents of malondialdehyde(MDA) and superoxide anion($\mathrm{O}_{2}^{\bar{.}}$) in the drought-sensitive cultivar Shanxing 86 were significantly higher than those in other materials,and the contents of catalase(CAT),proline(Pro) and soluble protein(SP) of drought resistant Ningjing 36 were significantly higher than those of other materials as well.Under drought stress,the relative germination potential(RGP),relative bud length(RSL),germination drought resistance index(GDRI)and vitality index(VI)of germinating seeds increased by 0.03—0.07 percentage,0.32—0.39 percentage,0.12—0.18 percentage and 92.41%—108.39%,respectively;MDA and reactive oxygen species($\mathrm{O}_{2}^{\bar{.}}$,H₂O₂) contents in germinating seeds of drought-resistant cultivars decreased by 2.54%—61.64%,19.60%—46.30% and 35.61%—62.02% respectively compared with drought-sensitive cultivars.The contents of osmotic regulating substances(Pro,SS,SP) increased by 5.93%—18.29%,1.08%—7.97% and 3.47%—6.03% respectively.The activities of antioxidant enzymes(SOD,POD, CAT) were increased by 17.29%—33.12%,15.24%—76.06% and 14.68%—18.61% respectively.The relative expression levels of OsP5CS,antioxidant enzyme synthesis genes (OsALM1, OsPOX1, OsCATC) were up-regulated by 2.66%—182.31% and 57.14%—513.27%,0.38%—109.06% and 63.39%—184.25% respectively.Comprehensive analysis showed that drought stress inhibited the germination of rice seeds and affected the physiological characteristics of seeds and the expression of corresponding genes during germination.Under drought stress,vigor index(VI),peroxidase(POD)and peroxidase synthesis gene(OsPOX1)are the key indicators affecting rice seed germination,whether it is drought-resistant or drought-sensitive materials.In addition to the above indicators,soluble protein(SP),proline synthesis gene(OsP5CS)and catalase gene(OsCATC)are other key indicators affecting drought-resistant materials.Relative shoot length(RSL),hydrogen peroxide(H₂O₂)and superoxide dismutase gene(OsALM1)are other key indicators affecting drought-sensitive materials.

To investigate the function and possible molecular mechanisms of soybean GmGRAS69 gene,which belongs to the GRAS transcription factor family,in plant drought stress.Sequence conservation and evolutionary relationship between soybean GmGRAS69 and GRAS members of other species were analyzed by amino acid sequence alignment and phylogenetic tree construction.Quantitative Real-time PCR was used to detect the expression pattern of GmPP2C69 in soybean roots and leaves treated with PEG.Then,GmPP2C69 overexpression vector was constructed,and then wild-type Arabidopsis was transformed by Agrobacterium-mediated floral dip method.The growth phenotypes of wild-type and transgenic Arabidopsis were observed under normal culture and drought treatment.The fresh weight per plant,relative water content of leaf,soluble sugar content of shoot,antioxidant enzymes(SOD,POD and CAT)activities and corresponding antioxidant enzyme gene expression levels were measured.The results showed that GmGRAS69 was significantly up-regulated in both roots and leaves of PEG-treated soybean plants,and the response was more significant in roots.In addition,GmGRAS69-overexpressed Arabidopsis was successfully obtained,and the drought tolerance of the GmGRAS69-overexpressed plants was significantly enhanced compared with WT.Under drought treatment,the fresh weight,leaf relative water content and soluble sugar content of GmGRAS69-overexpressed plants were significantly higher than those of WT.The activities of antioxidant enzymes SOD,POD and CAT and the expression levels of corresponding genes SOD,POD and CAT were also significantly higher than those of WT.The results showed that the expression of GmGRAS69 was up-regulated under drought stress,and the transgenic plants were enhanced drought tolerance by activating SOD,POD and CAT antioxidant enzyme encoding genes,enhancing antioxidant enzyme activities and increasing soluble sugar accumulation.

To clarify the effect of different drought resistance genes on wheat grain weight, 352 main varieties (or lines) in Huang and Huai Valley wheat region were used as experimental materials. Two experimental treatments were designed, normal irrigation and drought condition. Grain weight data were investigated for three consecutive years from 2019 to 2021. KASP markers of three drought resistance genes (1-fehw3, TaDreb-B1 and Cwi-4A) were used to genotype the experimental materials, and the effects of different drought resistance genes on wheat grain weight were studied. The results showed that the KASP markers of the three genes could be used for genotyping of the experimental materials, and the effects of KASP marker of 1-fehw3 and Cwi-4A genes were better than that of TaDreb-B1 gene. The distribution frequency of the dominant alleles of 1-fehw3,TaDreb-B1 and Cwi-4A genes was 36.9%, 41.1% and 35.1%, respectively. When genotyping by single gene marker, the thousand grain weight between drought resistant and susceptible genotypes did not reach a significant level in different years and conditions. When tested using two gene markers, 1-fehw3+TaDreb-B1 showed significant differences in thousand grains weight between drought resistant and susceptible genotypes under normal irrigation in 2019 and drought in 2020; 1-fehw3+Cwi-4A reached a significant level in the 2019 and 2020 drought environments; TaDreb-B1+Cwi-4A achieved a significant level in 2020 drought environment. When tested using three genes (1-fehw3, TaDreb-B1 and Cwi-4A) markers, the thousand grains weight of drought resistant genotypes was significantly higher than that of drought susceptible genotypes in all five environments except for irrigation conditions in 2020. The results indicated that because drought resistance was a complex trait controlled by multiple genes, the contribution of a single drought resistance gene to wheat drought resistance was relatively small. However, using molecular marker assisted selection for multi gene pyramiding breeding could significantly improve wheat drought resistance.

Luyu 13 is an excellent maize hybrid bred by the Millet Research Institute of Shanxi Agricultural University.It has strong drought and stress tolerance,and has achieved remarkable social benefits.In order to compare the drought and stress tolerance characteristics of the parents 1572 and Hai 921 of maize hybrid Luyu 13,we analyzed the related parameters of seed germination and seedling growth under simulated drought stress with 20% PEG solution.Results showed that there was no significant difference in the germination parameters between Luyu 13,1572 and Hai 921 under normal conditions,but the germination rate,germination energy,germination index and sprout index were inhibited under drought conditions,while the inhibition degree of Hai 921 was significantly higher than that of 1572 and Luyu 13.These results showed that the seed vigor of 1572 was higher than that of Hai 921,indicating inbred line 1572 had higher germination rate and germination advantage under drought stress,and possess stronger adaptability to drought.Subsequently,the important stresses response genes,ZmCIPK16 and ZmSAM1,were selected and analyzed their expression in 1572 and Hai 921 inbred lines under different abiotic stresses at seedling stage and under drought stress at different growth stages by Real-time PCR.Results showed that ZmCIPK16 and ZmSAM1 were widely responses to drought,salt,low temperature,high temperature,and ABA at seedling stage of 1572 and Hai 921 and responses to drought at different growth stages.ZmCIPK16 and ZmSAM1 showed more actively participated in the response to drought and other stresses in 1572.These results indicated that the inbred line 1572 was an excellent germplasm with drought and stress tolerance,and its contribution to drought resistance of hybrid Luyu 13 was greater than that of inbred line Hai 921.

In order to explore the molecular mechanism of diploid potato material response to drought stress under different drought stress time treatment,and explore drought resistance related genes.The high drought-resistant diploid resource A90 was used as experimental material,and transcriptome sequencing technology was used to analyze the differentially expressed genes under PEG-6000 stress at different times.Differentially expressed genes involved in drought stress response of potato were predicted by GO enrichment,KEGG pathway analysis and transcription factors,and key genes of drought resistance regulation were preliminarily explored.The expression of three candidate genes was analyzed by RT-qPCR.The results showed that there were 2 519 differentially expressed genes in the A90 treated with 20% PEG-6000 for 3,6,24 h compared with the control,and these genes were mainly enriched in plant hormone signal transduction,glutathione metabolism,phenylpropanoid biosynthesis,pentose and glucuronate interconversions and other drought-related processes.In addition,among 340 codifferentially expressed genes significantly enriched in the pathway,53 genes were annotated to 15 transcription factor families including RLKs,AP2/ERF and Tify.Among which StST/K1,StERF1 and StTify1 had higher expression levels,which might be key genes in drought resistance regulation.StST/K1 and StERF1 were mainly up-regulated in roots and leaves under drought and low temperature stress,StERF1 was up-regulated in roots,stems and leaves under salt stress.StTify1 was up-regulated in stems and leaves of the material under drought,and it was up-regulated in roots,stems and leaves under salt stress.But it was down-regulated only in stems of the material under low temperature stress.These results indicate that the three selected genes can respond to drought,salt and low temperature stress,it can provide a theoretical basis for study on drought resistance candidate genes in potato molecular breeding in the future.

Grapes are often subjected to various abiotic stress during their growth and development,such as drought,salt,heat or chilling,among them,drought stress is one of the most important abiotic stresses inhibiting vegetative and reproductive growth of grape.Although grapes are more resistant to drought stress,about half of our country's main grape cultivation area belongs to arid and semi-arid climates,drought is one of the main factors restricting the development of our country's grape industry.To ensure the healthy development of our country's grape industry,the research on the effects of drought stress on grape,the formulation of rational irrigation system and the breeding of drought-resistant varieties have become the research hotspots in recent years.Due to the extensive effects of drought stress on grape,in older to cope with drought stress,grapes have evolved many regulatory mechanisms to balance the effects of drought stress in grape growth.Firstly,the water demand degree of grape in different growth period was analyzed according to the law of grape water consumption,and the effects of drought stress on main physical and chemical indexes were exhibited,including photosynthesis,osmotic regulation and reactive oxygen regulation.And then,the quality and yield of grape fruit were analyzed under drought stress,the effects of drought stress on grape fruit quality were reviewed.We give the prospect for how to use drought stress strategy to improve grape quality and how to further study the molecular mechanism of grape response to drought stress at last.

In order to clarify the drought resistance and drought resistance mechanism of Allium polyrhizum in Inner Mongolia grassland,potted water control method was adopted.Two gradients were set,75% of the maximum field water capacity as the control(CK),and 25% of the soil relative water content under 30 days of drought stress.The root morphology,physiological characteristics and leaf photosynthetic characteristics of Allium polyrhizum from different sources were analyzed under drought stress. The result showed that Allium polyrhizum in Siziwang Banner compared with the Chifeng and Ordos was remaining relatively high root surface area,root volume and root length 0-0.5 mm in diameter. Allium polyrhizum root growth was relatively less affected by drought stress,chloroplasts were relatively stable and strong drought resistance in Siziwang Banner. Drought stress significantly decreased the above ground biomass,below ground biomass and total biomass of Allium polyrhizum in Chifeng and Ordos,but had no significant effects on Siziwang Banner(P>0.05). The Pn,Tr,Gs,Ci and leaves relative water content of Allium polyrhizum seedlings were significantly decreased and the relative permeability of cytoplasmic membrane was markedly increased under the whole drought stress treatment. Drought stress induced stomatal closure of Allium polyrhizum leaves and reduced transpiration to decrease water loss.The root characteristics,relative water content,chlorophyll and photosynthetic characteristics of Allium polyrhizum in different sources were certain differences under the same treatment. In general,the effect of drought stress on Allium polyrhizum in Siziwang Banner was relatively weak,it was indicating stronger drought tolerance.

In order to explore the molecular mechanism of Zoysia grass in resistance to abiotic stresses,in the present study we reported the function of a cold responding gene from Zoysia matrella designated as ZmCOR410. The sequence information of the gene was obtained on the base of transcriptome and genomic data. The expression profile of ZmCOR410 in response to low temperature was detected by qRT-PCR,and the functions of the gene under abiotic stresses were estimated in Arabidopsis and yeast by genetic transformation.The results showed that the CDS of the gene was 927 bp in length,encoding an acid dehydrin that contains 308 amino acids. In the polygenetic tree of COR410 homologues from gramineous grasses,ZmCOR410 had a close relationship with the homologues of Cleistogenes songorica and Eragrostis curvula,two species that were high tolerant to drought stress. In the genomic DNA,there were four copies of core sequence of DRE-cis element in the 1 700 bp region upstream of the CDS of ZmCOR410,and its mRNA was accumulated in leaves exposed to cold. Compared to WT plants,Arabidopsis plants over expressing ZmCOR410 showed reduced injury in leaves after a freezing-temperature exposure,and showed higher survival rates under drought and high temperature stresses. Yeast cells harboring ZmCOR410 were also more tolerant to high temperature stress than the control cells. The results indicated that the product of ZmCOR410 could enhance cells resistance to freezing cold,high temperature and drought stresses,which would help Zoysia matrella going through adverse environments.

Increasing the planting density is still the main way to improve the yield of maize,but the group light will be affected by increasing planting density,which leads to premature leaf senescence. Therefore,it is of great significance to study the effect of the mixture of diethyl aminoethyl hexanoate(DA-6)and chloroquine(CCC)on the photosynthesis intensity and time of maize leaves in the process of improving maize yield by increasing planting density. In 2018 and 2019,a maize variety of Zhengdan 958 was used as experiment material in field. Two planting densities were set(6.75×10⁴,9.00×10⁴ plants/ha)and the mixtures with two concentrations(0 mg/L DA-6+0 g/L CCC and 15 mg/LDA-6+2 g/L CCC)were sprayed on the whole plant at 7-leaf stage. The leaf area index,specific leaf weight,leaf photosynthetic performance,antioxidant capacity and yield differences of maize population of different planting densities were studied under the control of compounding agents,in order to provide a theoretical basis for the application of chemical regulators in maize dense planting. Results showed that when the planting density increased from 6.75×10⁴ plants/ha to 9.00×10⁴ plants/ha,the leaf area index of maize was increased,and the specific leaf weight was also increased at the late silking stage. The leaf area index of the low-density group sprayed with the compounding agent was decreased,while the high-density group had no significant change. The specific leaf weight in the plants sprayed with the compounding agent enhanced,but the difference was not significant compared to the control. After dense planting,the SPAD value and photosynthesis intensity of ear leaves significantly decreased,and the chlorophyll fluorescence parameters negatively affected. In the dense planting group treated with the compounding agent,the SPAD value,the net photosynthetic rate,transpiration rate,stomatal conductance,intercellular carbon dioxide concentration of ear leaves were significantly increased overall as well as the maximum fluorescence,variable fluorescence and Fv/Fm,and initial fluorescence decreased. After dense planting,the relative senescence rate of leaves increased,the activity of antioxidant enzymes decreased,while reactive oxygen species and malondialdehyde accumulated excessively,and the content of soluble protein decreased. In the dense planting group treated with the compounding agent,the relative senescence rate of leaves decreased,the activity of superoxide dismutase,peroxidase,catalase and soluble protein content significantly increased,and the content of ROS and MDA significantly decreased on the whole. A negative effect on the agronomic traits of ears could be observed in dense planting,but the yield was not significantly affected due to the increase in density. After spraying the compounding agent,the photosynthetic capacity and time of maize ears promoted,resulting in improvement of ear traits and significant increase of yield. Compared to the high-density group non-treated by compounding agent,the yields of the group treated by compounding agent increased by 14.61% and 6.64% in 2018 and 2019,respectively. To sum up,the compounding agent increased the material accumulation by improving the photosynthetic capacity and time of maize group,thereby increasing the maize yield.

In order to clarify the regulating effects of different irrigation stages and irrigation times under border irrigation on wheat yield formation and water use efficiency of winter wheat,field experiments were established in 2018-2019 and 2019-2020,and four supplemental irrigation treatments were set up:no-irrigation after emergence(W0),irrigation at jointing stage(W1),irrigation at jointing and anthesis stages(W2),irrigation at rejuvenation,jointing and anthesis stages(W3).The results showed that the spike number and grains per spike of winter wheat increased with the increase of irrigation times under the condition of consistent water management during the sowing period in the two years,and there was a significant difference between treatments. The 1 000-grain weight varied significantly in different years,and it was significantly positively correlated with the amount of pre-anthesis dry matter remobilization.In 2018-2019,the grain yield of W3 treatment reached 10 100.05 kg/ha,with no significant difference compared with W2 treatment,but they were all significantly higher than the other treatments.The grain yield of W3 treatment in 2019-2020 was 9 604.00 kg/ha,significantly higher than other treatments,while the water use efficiency and irrigation benefit were significantly lower than other treatments.There was no significant difference in water use efficiency between W1 and W2,but both were higher than other treatments.Correlation analysis showed that grain yield was significantly positively correlated with post-anthesis dry matter accumulation and contribution of post-anthesis dry matter accumulation to grain.Therefore,irrigation stage and frequency during wheat growing period should be considered in conjunction with the soil moisture during the sowing period and the precipitation in the key growing stages,and supplemental irrigation at jointing and anthesis stages could achieve a synergistic increase of both yield and water use efficiency under the condition of sufficient moisture during the sowing period.

In order to determine the appropriate nitrogen application level and irrigation mode for rice production in Hunan double cropping rice area,a randomized block design was adopted.Lingliangyou 942 and Lingyouhuazhan were used as early and late rice materials respectively.Three nitrogen application levels of N1-N3(150,120,0 kg/ha for early and late rice respectively)and three irrigation modes of W1-W3(water layer irrigation,wet irrigation and dry wet alternating irrigation for early and late rice respectively)were set.The effects of different water and fertilizer synergistic treatments on agronomic characters and yield of Double-cropping Hybrid rice were studied.The results were as follows:The increase of nitrogen fertilizer could significantly improve the SPAD value of rice, but the SPAD values of N1 and N2 were similar in early and late rice as a whole, while the irrigation method was W3, which could not only maintain a high SPAD in early and late rice, but also avoided late green and late ripening. Rice leaf area index (LAI) was directly proportional to the amount of nitrogen applied to a certain extent. The LAI values between N1 and N2 were similar in the whole growth period of early rice and the early growth stage of late rice, but N1 was higher than N2 in the late growth stage of late rice, while irrigation methods had little effect on the LAI value of early and late rice, mainly W3 was slightly higher. The increase of nitrogen fertilizer could significantly promote the accumulation of dry matter mass of rice. Except that the dry matter mass per plant of early rice at milk stage was N2 higher than N1 and the dry matter mass per plant of late rice at full heading stage was N1 higher than N2, the dry matter mass per plant of early and late rice at other stages was N1 and N2 similar, which showed that nitrogen reduction would not significantly have reduced the dry matter mass per plant of paddy rice on the whole. The irrigation method had little impacted on early rice and great impacted on late rice. The overall dry matter mass per plant of early and late rice increases better with W3, W2 followed. Increasing nitrogen fertilizer application could significantly improve the theoretical, actual yield and effective panicle number of rice, but they were similar in N1 and N2. Compared with the control group N3, the actual yield of early and late rice N1 and N2 increased by 53.21%-59.64% and 21.65%-32.68% respectively, indicated that the effect of nitrogen reduction and yield increase in early rice was obvious, and the poor effect of nitrogen reduction and yield increase in late rice was mainly because high nitrogen was not the nitrogen application level of conventional late rice.There was no significant difference between irrigation methods and yield and yield components. Under the cooperation of water and fertilizer,N2W2,N2W3 treatment could make early and late rice obtain higher leaf SPAD and LAI. Under the factors of dry matter accumulation, yield and yield components, the effect of N2W3 treatment was better for early rice, and N1W3 treatment was better for late rice. In conclusion, N2W3 treatment of early rice could not only met high yield, but also saved fertilizer and water;although N2W3 treatment of late rice performed better in SPAD and LAI, its dry matter accumulation and yield performance were lower than N1W3 treatment, so N1W3 treatment of late rice had obvious yield increasing effect. Therefore, from the perspective of economic and ecological benefits, under the alternative mode of dry and wet, the nitrogen application rate of early rice was 120 kg/ha and that of late rice was 150 kg/ha, which could give full play to the interaction effect of water and fertilizer. They had good yield increasing potential, which was more conducive to the growth and development of rice and increased yield.

In order to clarify the expression characteristics and biological functions of the sucrose phosphate phosphatase gene(SPP),and further understand the regulatory mechanism of SPP involved in sucrose biosynthesis.Herein,three TaSPP homologs,TaSPP-5A,TaSPP-5B and TaSPP-5D,located on the fifth homologous group,were cloned using the cDNA of wheat variety Jinmai 47 as the template.The physical and chemical properties,gene structure,cis-acting elements,phylogenetic tree and protein conserved domains of TaSPP were analyzed by the method of bioinformatics.The expression pattern of TaSPP was analyzed by qRT-PCR.The results showed that TaSPP-5A,TaSPP-5B and TaSPP-5D contained eight exons and seven introns.TaSPP-5A and TaSPP-5D encoded 422 amino acids,while TaSPP-5B encoded 413 amino acids.Phylogenetic analysis showed that TaSPP in wheat and its related species belonged to the same evolutionary branch with highly genetic similarity.The specific expression analysis showed that TaSPP genes were expressed in roots,stems,flag leaves,leaf sheaths,flower and seeds,whereas the higher expression levels were identified in flag leaves and stems.The expressions of TaSPP gene could be induced by ABA,PEG-6000,NaCl and IAA,indicating that TaSPP genes could play an essential role in abiotic stress tolerance in wheat.

In order to clarify the effects of drought stress on the photosynthetic characteristics in flag leaf in the afternoon during grain filling stage and grain yield of winter wheat with different drought resistance,an experiment with two winter wheat cultivars and four water levels was conducted under the condition of rainproof pond cultivation in 2018—2019 and 2019—2020.The two winter wheat cultivars were Jinmai 47(JM47,strong drought resistance)and Yanzhan 4110(YZ4110,weak drought resistance).The four water treatments included severe drought(W1:65% MFC(maximum field water capacity)before sowing + 45%—55% MFC after jointing),moderate drought(W2:75% MFC before sowing + 55%—65% MFC after jointing),mild drought(W3:75% MFC before sowing+65%—75% MFC after jointing),suitable water supply(W4:75%MFC before sowing+75%—85% MFC after jointing).The net photosynthetic rate(Pn),stomatal conductance(Gs),intercellular CO₂ concentration(Ci),transpiration rate(Tr),instantaneous water use efficiency(IWUE),maximum photochemical efficiency of PS Ⅱ (Fv/Fm)and actual photochemical efficiency of PS Ⅱ(ΦPS Ⅱ)in flag leaf from 14:00 to 16:00 during the early,medium and medium-late grain filling stage and the grain yield and its components at maturity were investigated.The results showed that both water and cultivars had significant effects on the photosynthetic and fluorescence characteristics in flag leaf in the afternoon during the grain filling stage and the grain yield at maturity of winter wheat.From the two-year average,compared with W4,the Pn,Gs and ΦPSⅡ in flag leaf in the afternoon during the grain filling stage under drought stress(W1,W2 and W3)respectively decreased by 2.07%—68.92%,-3.23%—50.00% and -1.89%—30.19% in JM47,and decreased by 7.71%—80.19%,11.11%—59.26% and 0—73.47% in YZ4110;the flag leaf Tr values in the afternoon during the medium grain filling stage in JM47 and YZ4110 respectively decreased by 6.30%—32.87% and 6.49%—41.74%,and the flag leaf Fv/Fm values in the afternoon during the medium-late grain filling stage decreased by 1.20%—18.52% and 2.50%—30.00%.In general,for all the above indexes,the decreasing amplitude for the same index was JM47<YZ4110.Compared with YZ4110,the Pn,Gs,ΦPSⅡ and Fv/Fm in flag leaf in the afternoon during the grain filling stage under drought stress(W1,W2 and W3)of JM47 respectively increased by 0.86%—64.89%,8.33%—36.36%,1.96%—184.62% and 1.25%—17.86%,and the grain yields of JM47 were respectively increased by 28.91%,8.06% and 5.40%.Except for IWUE,the flag leaf photosynthetic parameters in the afternoon during the grain filling stage were significantly and extremely significant correlated with grain yield,but the correlation indexes varied with variety and grain filling stage.For JM47,the correlation indexes between the grain yield and flag leaf photosynthetic parameters were highest for Pn,Gs and Fv/Fm during the medium-late grain filling stage,for ΦPSⅡ during the medium grain filling stage,and for Tr during the early grain filling stage.For YZ4110,the correlation indexes were highest for Pn,Gs and Tr during the early grain filling stage,for ΦPSⅡ during the medium grain filling stage and for Fv/Fm during the medium-late grain filling stage.In summary,drought stress decreased the photosynthetic function of flag leaf in the afternoon during grain filling stage and thus decreased the grain yield of winter wheat,the strong drought resistance variety could maintain better flag leaf photosynthetic characteristics in the afternoon during the grain the filling stage under drought stress condition,and significantly improved the ΦPSⅡ of flag leaf in the afternoon during the medium grain filling stage and the Pn,Gs and Fv/Fm of flag leaf in the afternoon during the medium-late grain filling stage,thereby increasing the grain yield.

The purpose of this study was to explore the effects of different drought stress levels on maize growth traits and yield in the semi-arid region of Northeast China, and to lay a theoretical foundation for further research on the physiological mechanism of maize drought resistance.Three kinds of maize varieties with different drought tolerance were selected and five water gradients of normal water supply(CK), light drought(LS), moderate drought(MS), severe drought(SS)and lethal(S)were set at maize jointing, tasselling and filling stages, respectively. The effects of different drought stress on the growth traits and yield related indexes of three maize varieties were comprehensively analyzed. The plant height, ear position and dry matter weight of maize decreased with the increasing of drought degree, but the stem diameter had no significant difference with the increasing of drought degree. The plant height, ear position and dry matter accumulation of maize variety Jinqing 707 was the highest, followed by Nendan 19 and Fudan 16. During tasselling stage, the spike characters of maize changed most obviously under drought stress, and the maize yield was the lowest under severe drought, and no yield under continuous drought.Under the same drought degree, the worse the drought tolerance of maize varieties, the greater the yield reduction. The specific performance of maize yield is Jinqing 707 > Nendan 19 > Fudan 16.A comprehensive analysis of multiple indicators shows that tasselling stage is the key period of water requirement of maize, which is easily affected by drought stress. At the same time, it is pointed out that drought stress or serious degree of drought stress in tasselling stage is the main factor leading to the decrease of maize yield.

In order to explore the effects of irrigation times in spring on starch contents and physicochemical properties of strong gluten wheat in Eastern Hebei Plain, the experiment was conducted with Zhongmai 998 and Jinnong 7.This study researched the effect of three irrigation treatments (W₀:no irrigation in spring;W₁:irrigation in jointing stage;W₂:irrigation in jointing stage and flowering stage) on starch contents and composition, thermodynamic properties, gelatinization properties and crystal properties of strong gluten wheat grains, and analyzed the correlation between starch composition and physicochemical properties of starch.The results showed that amylopectin and total starch contents of 2 varieties significantly improved when irrigation in jointing stage(W₁), Zhongmai 998 increased by 9.88%, 8.45%, Jinnong 7 increased by 9.35%, 6.34%, and the yield was higher, second only to W₂ treatment.With the increase of irrigation times, the peak temperature and gelatinization enthalpy of 2 varieties rose and then decreased, but the peak viscosity and breakdown were highest at W₀ treatment, gelatinization time rose and then decreased, final viscosity and gelatinization temperature was difference between varieties, Zhongmai 998 rose and then decreased while Jinnong 7 showed upward trend;Crystal strength and relative crystallization rose and then decreased.The correlation analysis showed that the content of amylose had significantly positively correlated on trough viscosity, the content of amylopectin had significantly or very significantly positively correlated on peak temperature, final temperature, gelatinization enthalpy, gelatinization temperature, gelatinization time, relative crystallization, and had very significantly negative correlated to peak viscosity and breakdown.In conclusion, under the experimental conditions, it can effectively improve amylopectin content, total starch content and grain yield of strong gluten wheat when irrigation in jointing stage(W₁), and then affect the physicochemical properties of starch;compared with amylose, the amylopectin content was closer to the physicochemical properties of starch.

In order to explore the effects of drought priming on antioxidant properties of wheat seedlings, control treatment and drought training treatment were set up in this experiment. PEG6000 nutrient solution was used for drought training when one heart and one leaf, and then Hoagland's total nutrient solution was restored. When three leaves are one heart, the drought stress is treated separately, and the dynamic changes of the substances related to the antioxidant properties in the young leaves were observed. The results showed that with the increase of drought degree and stress time, SOD, POD activity and soluble protein decreased, but MDA and soluble sugar content increased significantly. Compared with the control, the leaf SOD, POD activity and soluble protein decreased less after drought exercise, the soluble sugar content increased more, and the MDA increased less. Under the different drought stress, the antioxidative capacity of drought-stressed wheat under 25% PEG6000 stress was higher than that of 35% PEG6000. This showed that a certain concentration of drought training in wheat can significantly enhance its ability to adapt to drought conditions, which was beneficial to the growth of the seedling stage and provides theoretical support for the research on wheat resistance.

The purpose of this study was to study the effects of TSINGKE water retaining agent on physiological and biochemical characteristics and plant morphology of indoor greening plant Epipremnum aureum, so as to provide reference for the application of water retaining agent in drought resistance of indoor greening plants. The method was to use Epipremnum aureum as the experimental object, under natural drought stress, using water control pot culture method, make the dosage of water retaining agent and the weight ratio of basin to soil 0(control), 0.05%, 0.10%, 0.15%, 0.20% concentration gradient respectively, to detect the changes of external morphological indexes and internal physiological indexes of Epipremnum aureum. The results showed that after the application of different concentrations of water retaining agent, the performance of lüluo was different in different periods, the difference of each index in the early stage was small, and the difference in the later stage was large. The index change time of the control group was earlier than that of the experimental group, and the overall performance was as follows 0.10% treatment>0.15% treatment>0.20% treatment>0.05% treatment>0 treatment, it cluld be seen that a certain concentration of water retaining agent could delay the decline of green pineapple and improve the ability of water retaining and drought resistance, and the water retaining agent with the concentration of 0.10% had the best performance. The results showed that under drought stress, the growth and biomass of Epipremnum aureum were inhibited under different conditions. In the experimental group with water retaining agent, the inhibition effect was significantly less than that of the control group. The results showed that the addition of TSINGKE water retaining agent had a certain effect on the external morphology and physiological indexes of Epipremnum aureum. After the application of different concentrations of water retaining agent, the growth and physiological indexes of Epipremnum aureum would show varying degrees of change. The application of water retaining agent could improve the ability of water absorption and water retention, slow down the senescence process and improve the resistance to drought stress. Therefore, in the later stage of the water retaining agent into the practical application process, we need to combine different plants to develop different water retaining agent application scheme, in order to give full play to the water retaining and drought resistance ability of water retaining agent.

In order to understand the differential gene mining and molecular regulation mechanism of abscisic acid metabolism of oil sunflower in response to drought stress, high-throughput transcriptome sequencing and physiological characteristics were measured on oil sunflower under normal water supply (CK) and drought stress (T) treatments. The results showed that the content of abscisic acid (ABA) was the highest at 8 d of drought stress, at 23.55 ng/mL, and higher than 0 d at 4,8 d of drought stress. The differentially expressed genes were screened and compared with CK on 8 and 16 days of drought stress, the number of differentially expressed genes in the treatment group was 940, 1 743, and the number of genes that were significantly down-regulated was 1 752, 3 037, respectively. According to the functional annotations of KEGG and GO, there were more gene types under drought stress at 16 d than at 8 d. Among them, the most involved biological processes, the second was involved in cell components, and the least involved in molecular functions. The main metabolic pathways annotated by KEGG were plant MAPK signal transduction pathway, plant hormone signal transduction, glycerophospholipid metabolism and so on. Analyzed the hormone-related genes under drought stress for 8 days. A total of 39 differentially expressed genes were found, and 7 genes were related to abscisic acid metabolism. The transcription factors involved in abscisic acid metabolism were ABF2, SAPK2, PP2C, AHG1, PYL2 and SAPK3 were up-regulated, and the expression level of drought stress was higher than that of CK. The conclusion of this study was that 7 different genes related to the up-regulation of ABA metabolism in oil sunflower under drought stress were discovered. The transcription factors involved in the metabolism of abscisic acid (PYR/PYL→PP2C→SnRK2→ABF) were all up-regulated, indicating that the plant when suffering from drought stress, it would resist drought stress by accumulating hormones such as abscisic acid.

The OsSP1 gene encodes a chloroplast localized protein in rice, and its expression clearly responds to drought stress.In order to elucidate the effect of OsSP1 gene on rice growth and drought stress tolerance, OsSP1 gene-edited and overexpressed rice plants were created by using CRISPR/Cas9 gene editing technology and gene overexpression technology, respectively. The mutation pattern of OsSP1 gene in the gene-edited plants was determined by sequencing analysis, and homozygous overexpression plants were selected by hpt sequence detection and hygromycin B screening assay. The results of phenotypic comparison, chlorophyll content and reactive oxygen species(ROS) determination and drought tolerance analysis showed that overexpression of OsSP1 gene in rice had almost no effect on rice growth and drought stress tolerance. However, after the OsSP1 gene was mutated through gene editing, the growth and fruiting of rice T₀ and T₁ gene-edited plants were severely affected with biallelic heterozygous or homozygous mutations, and all showed severe growth inhibition such as dwarf, etiolation, premature aging, and non-tillering, T₀ plants produced very few seeds, while the T₁ plants did not head at all, and the chlorophyll content in leaf of the gene-edited plants was significantly or extremely significantly lower than that of the wild-type and overexpressed plants. These results indicated the essential role of OsSP1 gene in rice growth and yield, and provided a theoretical and material basis for elucidating the underlying mechanism of OsSP1 gene in rice.

In order to reveal the effect of DNA methylation under drought stress toward rice with high expression of C₄-PEPC (PC), germination test, hydroponics experiments and pot experiments respectively were used in this study. By introducing different concentrations of DNA methylation inhibitor (5-Azacytidine, 5-azaC), the drought simulation treatments combining with the inhibitors were used for the stages of seed germination, seedling and late growth, respectively. The changes including germination rate of seed, the relative water content, malondialdehyde content, proline content, soluble sugar, soluble protein content, PEPC activity and the gene expression levels of related genes, C₄-PEPC genes, SnRK1s gene, and methyltransferase 1 genes of rice leaves at seedling stage, the photosynthesis characteristics of flag leaves at flowering stage were measured, and their yield component were investigated after harvest as well. The results showed that:In bud and seedling stages, the effect of 5-azaC on drought stress present dose effect in rice as following:promoting under low concentrations and inhibiting under high concentrations, the concentrations of the bud stageOsMET1b on this concentration of 5-azaC, and the expression of C₄-PEPC in PC also presented the dose effect. In brief, DNA methylation was involved in rice drought response, but the effects were different in different growth stages, and sugar signal might enhance drought tolerance of PC by participating in DNA methylation.

In order to explore the effects of water and planting density on nitrogen use efficiency of cotton, a field experiments was carried out in Qingyuan Experimental Station of Agricultural University of Hebei between 2019 and 2020. Nongdamian 601 was taken as the experimental material, and two-factor split zone experiment was adopted, with water treatment as the main area:W1(60%-70% soil relative water content) and W2(40%-50% soil relative water content), the secondary areas were planting densities D6(60 000 plants/ha), D9(90 000 plants/ha) and D12(120 000 plants/ha). The nitrogen accumulation, distribution and yield of cotton organs under different water and planting densities were measured.The results showed as follows:Under different water treatments, the total nitrogen accumulation and reproductive organs in cotton was the highest under high density condition, and the trend was consistent during the two years. Compared with the drought treatment, the nitrogen accumulation and total nitrogen accumulation in the reproductive organs of the control group were significantly increased, but there was no significant difference in the proportion of nitrogen distribution in the reproductive organs among different water treatments. The yield of seed cotton increased with the increase of planting density.Under the same density treatment, the seed cotton yield under the drought condition in 2019 was 13.74% lower than that of the control group, and the seed cotton yield under the drought condition in 2020 was only 2.54% lower.Correlation analysis showed that the accumulation and distribution of nitrogen in various organs of cotton were significantly positively correlated with the yield of seed cotton and boll number per unit area.In conclusion, reducing irrigation amount and increasing planting density(90 000-120 000 plants/ha) are effective ways to save water and increase nitrogen uptake in local cotton.

To understand the bioinformatics function of the NHX gene family in pepper, explore its gene expression characteristics under abiotic stress, and provide a basis for the function development of pepper CaNHX gene and the pepper salt and drought resistance breeding genes. The pepper NHX gene family was identified by bioinformatics methods, and the gene structure, domains, phylogenetic relationships, gene expression patterns and abiotic stress expression were analyzed. The results showed that there were 7 GME family members in pepper, which could be divided into 3 subgroups, and all contained Na⁺/H⁺ exchange conserved domains;they were mainly distributed on 6 chromosomes, and their gene sizes had obvious differences. The number was mainly maintained between 198-952, and the exon content was between 7-21. All proteins except CaNHX5 had no signal peptides and were hydrophobic proteins, which were most likely to be located in the vacuole. They were all transmembrane proteins;Motif analysis found that the N-terminal contained the zinc finger structure of CXC24XC, and the C-terminal contained Trp(W)-24 and TrKA-N, the highly conserved secondary structure in the sequence was mainly irregular coils and α-helices. Multi-sequence evolutionary tree construction analyses indicated that aminoacid sequence encoded by this gene was closely related to tomato. The results of qRT-PCR analysis showed that under osmotic and salt stress, the gene expression of CaNHX6 increased significantly, which was 13.5 and 13.6 times that at 0 h, respectively;after treatment with methyl jasmonate and gibberellin.The expression of CaNHX5 and CaNHX6 in pepper leaves showed a significant up-regulation trend, while the others were on the contrary. The different expressions indicated that they played a role in abiotic stress.

In order to effectively utilize the introduced wheat germplasm resources and evaluate the effectiveness of molecular markers associated with wheat drought resistance, 48 wheat germplasms were used to identify the relative germination rate of seeds under drought conditions, and 4 drought resistance related molecular markers were used to detect the distribution of drought resistance genes(1-feh-w3, Dreb-B1, NRX-B1 and FerA1). The results showed that the average relative germination rate of the introduced germplasms was 70.0%, the variation range was 34.9%-94.5%, and 85.4% of germplasm materials displayed moderate or above drought resistance level. There were 8 haplotypes in 4 drought resistance-related genes in the introduced wheat germplasms. The difference in the average relative germination rate between the 2 haplotypes of the Dreb-B1 gene and FerA1 gene reached significant levels, while there was no significant difference in the average relative germination rate between the Westonia type haplotype and Kauz type haplotype of the 1-feh-w3 gene, and the TaNRX-B1a haplotype and the TaNRX-B1b haplotype of the NRX-B1 gene;The haplotypes TaDreb-B1a, TaFer-A1 (H) were significantly positively correlated with the average relative germination rate, while 1-feh-w3 and NRX-B1 genes were not significantly correlated with the average relative germination rate. The average relative germination rate was the highest in the haplotype combination Westonia type/TaDreb-B1a/TaFer-A1 (H)/TaNRX-B1a, reaching 77.35%. The effectiveness of the molecular marker of the drought resistance gene Dreb-B1 was verified, and the two haplotypes of the 1-feh-w3 gene were invalid for drought resistance selection.

In order to explore the effect of nitrogen management on double cropping super rice late rice under drought conditions.Wufengyou T025, a super hybrid late rice variety, was selected. Under the normal or drought conditions at the young panicle differentiation stage, the yield and related physiological and ecological indexes were investigated by applying more nitrogen tiller fertilizer (before drought) and nitrogen panicle fertilizer (after drought).The results showed that:Drought lead to a significant decrease in rice yield, and the young panicle differentiation stage was the sensitive stage of water deficit in late rice. Under the condition of normal water or drought conditions, the yield of higher tiller fertilizer application was significantly higher than that of higher panicle fertilizer application, and the tillering stage was the key period for nitrogen requirement of late rice. The effective panicles per plant and seed setting rate of higher tiller fertilizer application were significantly higher than those of higher panicle fertilizer application. Compared with the application of higher nitrogen tiller fertilizer, the photosynthetic rate (Pn), transpiration rate (Tr) and other photosynthetic indexes of higher panicle fertilizer application were increased in different degrees at heading and flowering stages, but the nitrogen and dry matter transport rate of stem and leaf to panicle was low. The retention was serious, and the nitrogen transported to the panicle was relatively low. The contents of osmotic adjustment substances and the malondialdehyde (MDA) content in leaves decreased in the late growth stage, and the activities of nitratase (NR) and glutamic-pyruvic transaminase(GPT) increased in the short term after drought for higher tiller fertilizer application.Therefore, there is a certain effect of "regulating water with nitrogen" in rice. Properly increasing the ratio of nitrogen fertilizer at tillering stage can reduce the yield loss of late rice caused by drought stress at young panicle differentiation stage.

In order to study the role and function of DNA-binding with one finger (DOF) proteins in maize growth and development, the expression profiles of 10 ZmDOFs genes in different tissues or in response to various abiotic stresses have been carefully studied using qRT-PCR. The result of the phylogenetic tree and gene structure analysis showed that 10 ZmDOFs divided into three subclasses. The result of qRT-PCR revealed that 10 ZmDOFs exhibited obvious expression preference or specificity in different organs, 7 ZmDOFs high expression in tassels, 2 ZmDOFs in young embryo after pollination 15 days and 1 ZmDOF in root, indicating the important roles in the processes of maize growth and development. Results by qRT-PCR revealed the altered expression pattern of most of ZmDOFs in response to salt or osmotic stresses, indicating these gene involved in the regulation of salt or osmotic stress response pathway. ZmDOF3 was up-regulated by at least 5-fold under NH₄⁺ depletion treatment, while ZmDOF23 and ZmDOF46 reduced by 90% under NO₃^- depletion treatment, indicated these genes were involved in nitrogen homeostasis or signaling pathway.

Abiotic stress environment severely restricted tomato production, so it is particularly important to find genes related to abiotic stress tolerance in tomato.In the early stage of this study, UDP-glycyltransferase gene screened by high-throughput sequencing was able to participate in the response to cadmium stress in tomatoes. Therefore, this study took tomatoes as the test material to further study the anti-resistance function of this gene.First, the full length UDP cDNA sequence was obtained by homologous cloning method, and the sequence was analyzed by bioinformatics.Phylogenetic tree was used to analyze the phylogenetic relationship between the protein and plants.Secondly, Real-time fluorescence quantitative PCR was used to analyze the tissue expression characteristics of the gene and its expression patterns under three different abiotic stress conditions (Cd, PEG-6000, NaCl).The stress phenotype of transgenic yeast was further analyzed.The sequencing results showed that the cDNA of this gene was 1 486 bp in length, containing a 1 452 bp open reading frame (ORF), encoding 483 amino acids, and was named SlUDP.Phylogenetic tree analysis showed that the protein was most closely related to potato.The results of Real-time fluorescence quantitative PCR showed that the expression of this gene was different in different tissues of tomato, and the expression level was the highest in leaves, and the expression level in each part was root > fruit > lateral stem > main stem > flower.The stress phenotype analysis results of transgenic yeast showed that SlUDP gene improved the yeast's tolerance to Cd and drought.According to the above results, SlUDP may play a certain role in tomato response to abiotic stresses such as heavy metals cadmium, high salt and drought.

In order to understand the dynamic rules of sugars, starch, protein and trace elements of different types of wheat during grain filling stage under drought stress, and to identify the difference of nutriment between drought and irrigation in the process of grain-filling by high-yield wheat, high-quality wheat and water-saving wheat, the wheat varieties of Jimai 325, Jimai 418 and Jimai 323 in the North of Huang-Huai Region were used as experimental materials. The plants heading and flowering on the same day were selected for marking, and the grains of each variety were taken every 6 days after 7-31 days after anthesis. The effects of drought during grain filling on the contents of total soluble sugar, sucrose, glucose, fructose, protein, Fe, Zn, Mn, Cu, amylose and amylopectin accumulation, starch accumulation rate and the activities of key enzymes in starch synthesis were studied. The results showed that the content of sucrose and glucose in wheat grains was significantly decreased under drought stress, and the effect on fructose content was relatively small, and the sucrose and fructose of high-yielding variety Jimai 325 were less affected by drought in the filling process. Drought stress decreased the content of amylopectin and total starch in wheat grains, but had relatively little effect on the content of amylose. The effect of drought stress on starch content of high-yield and high-quality varieties was significantly greater than that of drought-tolerant variety Jimai 418. The activity of starch synthase was increased in the early and middle stages of filling stage under drought stress, and decreased rapidly in the middle and late stages compared with irrigation control. The content and accumulation of four mineral elements in wheat grains were Mg>Fe>Zn>Mn. With the progress of grain filling, the content of trace elements showed a downward trend. The accumulation of Fe, Zn and Mg in grains of Jimai 325 was higher. The difference of nutrient accumulation in grain filling process of different types of wheat under drought conditions were studied to provide theoretical data and reference basis for optimizing cultivation measures and realizing high quality, high yield and water saving of special wheat.

The aim of this research was to clone the aquaporin 2 (AQP2) gene, identify its expression pattern in various tissues, and to analyze the expression in different growth periods of the male reproductive system in yak.This research may provide important foundation for exploration the role of AQP2 for reproductive development in yak.The samples of yak kidney, testis, epididymis, spleen, brain, lung, heart and liver were collected after slaughtering. The total RNA of different samples were extracted and the coding sequence of AQP2 gene was cloned by RT-PCR. Meanwhile the function and structure of AQP2 gene were analyzed by bioinformatics softwares.Then, the mRNA expression of AQP2 in different tissues and in different growth periods of the male reproductive system was detected by quantitative real-time PCR (qRT-PCR). The results showed that the CDS region of AQP2 gene was 816 bp, encoding 271 amino acids. It had high homology with cattle, buffalo and goat. The tissues expression analysis showed that AQP2 highly expressed in testis and kidney, which was significantly higher than other tissues (P<0.05). The results of immunohistochemistry indicated that AQP2 was expressed in round spermatids of seminiferous tubules, but no expression was found in spermatogonia, spermatocytes, elongated spermatids, leydig cells and sertoli cells. The results of qRT-PCR was found that the expression of AQP2 in vas deferens was the highest(P<0.05). The expression trend of AQP2 mRNA in testis and vas deferens was increased with age (P<0.05). While the expression level in prostate was slightly decreased with age, but the difference was not significant(P>0.05). The above results indicated that AQP2 was highly conserved during evolution, and it was highly expressed in testis and kidney. It was involved in sperm maturation and transportation, which might be completed by water reabsorption and liquid formation.

Drought stress is one of the most serious threats to cucumber quality and yield. In order to better understand the molecular mechanism of cucumber's response to water stress,this experiment obtained a differentially expressed gene CsaV3_3G039670 (log₂FC=1.10) related to drought and significantly up-regulated expression from the previous work. Its homologous gene AtMYB94 was passed in Arabidopsis regulating the epidermal wax content of the plant to improve drought resistance,it was named CsMYB94. The CDS sequence of CsMYB94 gene was 885 bp in length and encoded 294 amino acids. By analyzing the protein domain,the CDS sequence contained two DNA-binding domains,which were R2R3 type MYB transcription factors. Protein analysis found that the molecular formula of CsMYB94 protein was C₁₄₂₆H₂₂₄₂N₄₀₄O₄₅₄S₁₁; the expected molecular weight was 3.27 ku; the theoretical isoelectric point was 6.53; it was a hydrophobic protein and an unstable protein. Analysis by subcellular localization software revealed that CsMYB94 protein was localized in the nucleus. The phylogenetic tree analysis showed that CsMYB94 in cucumber had the closest relationship with MYB94 in white algae and closer to MYB94 in pumpkin,bitter gourd and melon. The results of qRT-PCR analysis showed that CsMYB94 had the highest expression in cucumber leaves,but relatively low expression in male flowers,tendrils and stems. Therefore,it is speculated that CsMYB94 also responds to drought stress by regulating the wax content of cucumber,and the specific regulation path needs further study.

To obtain specific genetic materials for the study of gene function and genetic improvement of wheat,ethyl methyl sulfonate (EMS) chemical mutagenesis was used to treat the drought-resistant,high-yield,and multi-resistant wheat variety Jimai 418. The field agronomic traits and biological characters were observed and investigated in the M₂. 416 mutant spike lines were selected from 6 961 spike lines,with a mutation frequency of 5.98%.Among them,11 lines were seedlings habit mutants,with a mutation frequency of 0.16%; 12 lines were tiller mutants,with a mutation frequency of 0.17%; 34 lines were leaf mutants,with a mutation frequency of 0.48%; there were 68 plant height mutants with a mutation frequency of 0.97%,62 spike mutants with a mutation frequency of 0.89%,and 132 sterility mutants with a mutation frequency of 1.90%,15 root mutants (0.26%) and 82 other types of mutants. Through the verification of biological and agronomic characters,84 lines with stable inheritance were obtained in M₃,including 43 stem mutants,23 spike mutants,7 leaf mutants,4 early-maturing mutants,2 late-maturing mutants,2 awn mutants,2 root mutants and 1 sterile mutant. The analysis of agronomic characters showed that the mutant library was rich in variation types,and the mutation frequencies of plant height,growth period and 1000-grain weight were relatively high. These new mutants provided new materials for the study of wheat functional genome and wheat genetic improvement.

An experimental system created by grafting technology was used in this study to evaluate the contributions of different genotypic roots to grain yield, and clarify its relation to root traits, so as to provide a theoretical basis for root improvement in soybean. A total of 22 cultivars were used as rootstocks to graft with the same scion of Liaodou 21, respectively. The root traits and grain yield were measured under different soil water treatments, and then the self-grafted Liaodou 21 was used as check to calculate the ratio of yield change of each graft, which was defined as root contribution values. Results showed that significant difference in grain yield was found among grafts. The root contribution value of 22 soybean cultivars varied from -33.61% to 26.77% under well-watered condition, while varied from -29.26% to 62.80% under water stress condition. Under well-watered condition, the root contribution value had no significant relationships with root length, root surface area, root volume and root tissue density, but negatively correlated with root dry mass and root-shoot ratio. Under water stress, the root contribution value was negatively correlated with root length, root surface area, root volume, root dry weight, root-shoot ratio and root tissue density. The results suggested that the soybean germplasms which had developed rooting with a low investment on dry matter should have important utilization value for soybean breeding with high yield and drought resistance.

In order to explore the different fertilization treatments to improve the soil moisture status and the mechanism of maize yield preservation in the semi-arid area of Northeast China,it provides a theoretical basis for the technical measures of drought resistance and yield increase of maize in the semi-arid area of Northeast China. This study used field tests to set four treatments:farmer habits(CK),single application of straw(S),combined application of chemical fertilizer and organic fertilizer(NPK+M),and combined application of chemical fertilizer and straw(NPK+S). Effects of different fertilization treatments on soil physical and chemical properties,corn physiological indexes and yield indexes. The results showed that fertilization could increase the content of N,P,K and organic matter in the soil,reduce the soil pH,and organic and inorganic fertilizers combined with the best application effect. The moisture content of different soil layers in the soil was little affected by the fertilization treatment,but from the data obtained from the experiment,in the 0-20 cm soil layer,the organic and inorganic fertilizers combined with the application of the treatment of the soil moisture content,field water holding capacity, the saturated water content reached the maximum value. Reasonable application of organic and inorganic fertilizers could promote plants to absorb nutrients more balancedly,increase the net photosynthetic rate,stomatal conductance,and chlorophyll content of corn leaves,reduce the moisture lost by evaporation,and then promote the increase of fresh and dry weight of plants. The combined application of organic and inorganic fertilizers had the effect of increasing the length of corn ears,the number of rows of grains,and the weight of thousand kernels,and increasing the yield of corn. Compared with the habits of farmers,the application of organic fertilizer and inorganic fertilizer on the soil in the semi-arid area of Northeast China could effectively improve the soil nutrient status,increase the soil moisture content of different soil layers,increase the water storage capacity of the soil,and increase the index of corn photosynthetic traits,promote the growth and development of corn,improve the yield index,and then increase corn yield. Combined application of organic and inorganic fertilizers is a technical measure suitable for drought resistance and yield maintenance of maize in arid areas.

Acta Agriculturae Boreali-Sinica is a comprehensive agricultural core journal,which is jointly sponsored by 6 units across different provinces,cities or regions in North China.In order to make the features,research hotspots and development trends of Acta Agriculturae Boreali-Sinica clear from 2010 to 2019,visualized quantitative analysis was carried out on the relevant data of Acta Agriculturae Boreali-Sinica from 2010 to 2019,such as paper carrying capacity,fund projects,authors,institutions,research hotspots and research frontier based on the publication data of this journal on CNKI and using CNKI bibliometrics tool and CiteSpace visual analysis software.The results showed that 3 178 papers were published in the Journal from 2010 to 2019,but from the perspective of annual change trend,the number of papers published showed a downward trend,from 418 in 2010 to 239 in 2019;on the contrary,there was an increase of 60.29% in the average page number,from 4.81 pages in 2010 to 7.72 pages in 2019.After 2010,the ratio of fund papers in this journal was higher than 0.98,and reached 1 in 2019,which was dominated by national funds.From 2010 to 2019,according to the Price law,there were 148 key authors in Acta Agriculturae Boreali-Sinica.The overall structure of the authors' cooperative network was loose,which was mainly manifested in internal cooperative research within the same institution but less external cooperation.A total of 42 authors were highlighted by using Citespace Burst detection function.In addition,the publishing institutions are mainly agricultural universities,and the contributions of agricultural research institutions are relatively weak,and the cooperative network of institutions is generally loose and relatively centralized.The paper focuses on yield,gene cloning,expression analysis,genetic diversity,quality traits,physiological characteristics,drought stress,soil nutrients and so on.To sum up,as a comprehensive agricultural journal,it should further stabilize the core authors and core institutions,create feature columns,highlight the characteristics of regional agriculture,and enhance the influence of the journal.

In order to explore the genetic basis of drought resistance and guide drought resistance breeding, mapping of QTL associated with drought resistance at germination stage of foxtail millet was done. An F₂ segregating population was constructed using 100 individuals derived from a cross between Shanxi 2010 and K359×M4-1. A genetic linkage map was constructed based on 2b-RAD sequencing, which was then combined with the phenotypic trait of drought resistance for QTL mapping. The results showed that drought resistance at germination stage of foxtail millet was a complex quantitative trait and controlled by multiple genes. A genetic map containing 583 SNP makers was constructed by 2b-RAD of parents and F₂ population. The map covered 9 chromosomes of foxtail millet, with an average number of 64.8 and an average genetic distance of 0.97 cM between markers. A total of 3 QTLs were identified:qSIDR-5a, qSIDR-6a and qSIDR-6b, located in foxtail millet chromosome 5 and 6, respectively, which explained 12.4%-14.3% of phenotypic variation. Among them, phenotypic contribution rate of qSIDR-5a was the highest, which explained 14.3% of phenotypic variation. These QTLs were not included in the same chromosome interval as the identified drought resistance related QTLs of foxtail millet, and thus were described as new candidate gene loci associated with germination stage drought resistance.These QTLs can be used for fine mapping and gene cloning, as well as molecular regulation mechanism of drought resistance of foxtail millet.

In order to explore a fast and efficient way to screen drought-resistant varieties of winter wheat, and to select drought-resistant winter wheat varieties. Six winter wheat varieties, Yannong 999, Taimai 1918, Jimai 22, Jimai 23, Taishan 27 and Shiluan 02-1 were used in this study. Normal water treatment(75% relative soil water content), mild drought treatment(55% relative soil water content) and moderate drought treatment(40% relative soil water content) were arranged to explore the chlorophyll fluorescence parameters, biomass, root-shoot ratio, SPAD, superoxide dismutase(SOD) activity, malondialdehyde(MDA) content and their correlations. Results showed that, compared with other varieties, under drought stress, Taimai 1918 obtained the highest drought resistance coefficient(DTC). The smallest reduction of root to shoot ratio, SPAD value, photosystem Ⅱ maximum photosynthetic efficiency(Fv/Fm), photosystem Ⅱ actual photosynthesis efficiency(φPSⅡ), relative electron transfer rate(ETR), SOD, and the largest increasing in non-photochemical quenching(NPQ) and minimal increasing in MDA content were observed in Taimai 1918. The order of drought resistance of 6 winter wheat varieties was Taimai 1918 > Yannong 999 > Jimai 22 > Jimai 23 > Taishan 27 > Shiluan 02-1. The chlorophyll fluorescence parameters were significantly correlated with drought resistance coefficient, SOD activity and MDA content. Sum up, the drought resistance in Taimai 1918 was strongest, and chlorophyll fluorescence parameters can be used for screening drought-resistant winter wheat varieties at seedling stage.

In order to explore the optimal water saving and efficiency model of wheat under different irrigation technologies and water-nitrogen coupling, an experiment was carried out with three irrigation technologies, such as conventional irrigation, sprinkler irrigation(PG)and drip irrigation(DG), four irrigation amounts of B1,B2,B3 and B4, and two nitrogen application amounts C1 and C2, and the same non-irrigation treatments (B1C1 and B1C2) were carried out with three irrigation technologies, therefore there were 20 treatments. The winter wheat cultivar Zhengmai 103 was used as the testing material. The results showed that irrigation significantly increased the SPAD value, net photosynthetic rate, transpiration rate and yield of winter wheat. The highest values of SPAD were 51.1 and 52.1 with B2C2 treatments in conventional irrigation and sprinkler irrigation technologies, respectively, while the highest value of SPAD was 51.8 of B2C1 treatment under drip irrigation technology. The highest net photosynthetic rates and grain yields of winter wheat were all the B2C1 treatments under three different irrigation technologies, the net photosynthetic rates reached to 13.84, 14.44,14.22 μmol/(m²·s), respectively; and the yield reached to 10 802, 10 559,10 641 kg/ha, separately, in conventional irrigation, sprinkler irrigation and drip irrigation technologies. The irrigation water use efficiency and irrigation benefit increased with the decreasing in irrigation amount (except the irrigation efficiency under common irrigation). The highest irrigation water use efficiency of conventional irrigation, sprinkler irrigation and drip irrigation technologies were all the B4C1 treatments, reaching to 227.8, 247.4,249.7 kg/m³, respectively. The highest irrigation benefit of sprinkler irrigation and drip irrigation technologies were all the B4C2 treatments, reaching to 66.3,69.0 kg/m³, respectively. However, the highest irrigation benefit was 47.5 kg/m³ of B3C2 treatment under conventional irrigation technology. The results also showed that there were no significant differences in photosynthetic characteristics, irrigation water use characteristics and yield of the winter wheat between water-saving irrigation technology and conventional irrigation technology under relatively sufficient irrigation water (B2 and B3) conditions. However, under low irrigation water (B4) conditions, the net photosynthetic rate, transpiration rate, irrigation water use efficiency, irrigation benefit and yield of winter wheat in the water-saving irrigation technology were significantly higher than those of conventional irrigation technology. Comprehensively considered irrigation water use characteristics and yield of the winter wheat, the B4C1 with sprinkler irrigation and drip irrigation technologies were the optimal water saving and efficiency model.