This study aimed to clarify the regulatory mechanism of exogenous glycine betaine(GB)on the antioxidant and photosynthetic systems of maize seedling leaves under combined heat and drought stress(TD),providing a theoretical basis for alleviating crop stress under extreme environments.Using the maize variety Xianyu 335 as experimental material,different concentrations of GB(0,50,100,200,and 400 mmol/L)were applied to the leaves at the three-leaf-one-heart stage.After 24 hours,combined stress was simulated in a climate chamber with high temperature(day/night temperature of 40 ℃/28 ℃)and 20% PEG-6000 to induce moderate drought,exploring the regulatory effects of GB on the antioxidant system and photosynthesis of maize seedlings.The results showed that 100 mmol/L GB significantly promoted plant growth.Compared with the TD treatment,plant height,leaf area,shoot dry weight,and root dry weight increased by 27.48%,27.45%,28.33%,and 78.26%,respectively,while the root-to-shoot ratio increased by 14.91 percentage points.On the 5th day after stress,100 mmol/L GB significantly enhanced antioxidant enzyme activities,with superoxide dismutase(SOD),peroxidase(POD),and catalase(CAT)activities increasing by 69.09%,69.02%,and 41.81%,respectively.Simultaneously,the contents of malondialdehyde(MDA),superoxide anion($\mathrm{O}^{\bar{.}}_{2}$),and hydrogen peroxide(H₂O₂)decreased by 21.92%,6.50%,and 25.33%,respectively.Furthermore,soluble sugar(SS)and soluble protein(SP)contents increased by 31.69% and 18.98%.Photosynthetic characterization analysis indicated that GB effectively improved the lamellar system structure of chloroplast grana and stroma thylakoids,thereby significantly increasing the SPAD value under combined stress and alleviating damage to the photosystem Ⅱ(PSⅡ)reaction center.This was manifested by a decrease in minimal fluorescence(F0)and increases in variable fluorescence(Fv)and maximum fluorescence(Fm).Additionally,by mitigating the stomatal and non-stomatal limitations caused by combined stress,GB treatment significantly enhanced photosynthetic performance,increasing the net photosynthetic rate(Pn)by 24.14% on the 5th day after stress.In conclusion,under combined heat and drought stress,exogenous GB can protect the photosynthetic system by enhancing antioxidant enzyme activities and osmotic adjustment capacity,thereby alleviating stress damage and promoting the growth of maize seedlings.

The aim was to elucidate the effects of different foliar fertilizer nitrogen application amounts on nitrogen accumulation,translocation,and utilization in maize.This experiment was conducted in 2021—2022 using a randomized block design,with maize variety Lihe 1 as the research object.No fertilization treatment (CK),conventional root fertilization treatment (CF),foliar nitrogen reduction treatment of 20% (LF1),foliar conventional nitrogen application treatment (LF2),and foliar nitrogen increase treatment of 20% (LF3) were set up to analyze the differences in nitrogen accumulation,translocation,and utilization of maize under different nitrogen fertilizer application amounts,no fertilization and conventional root fertilization.The results showed that the nitrogen accumulation in maize stems and leaves showed a trend of first increasing and then decreasing with the advancement of the growth stage,reaching the maximum value at the tasseling and silking stage.The nitrogen accumulation per plant gradually increased with the advancement of the growth stage and reached its maximum value at mature stage,the nitrogen accumulation per plant was highest in the LF2 treatment.The proportion of nitrogen distribution in leaves was highest before the silking stage;after the silking stage,the proportion of nitrogen distribution in grains gradually increased,reaching its peak at mature stage.The CK had the lowest proportion of nitrogen accumulation in grains,while the LF1 treatment had the highest proportion of nitrogen distribution in grains in 2021,and the LF3 treatment had the highest proportion of nitrogen distribution in grains in 2022.The nitrogen transport rate and the contribution rate of nitrogen transport to grains first increased and then decreased with the increase of nitrogen application amounts,the nitrogen harvest index and nitrogen utilization efficiency decreased with the increase of nitrogen application amounts;in 2021 and 2022,the nitrogen utilization efficiency of LF1 treatment,LF2 treatment,and LF3 treatment was higher than that of CF treatment,and the nitrogen utilization efficiency of LF1 treatment was the highest.The nitrogen absorption efficiency of foliar nitrogen application treatment for two years was higher than that of CF treatment.There were no significant differences in ear length,ear thickness,and ear row number among the treatments.CK had the longest bald tip length,and the row number and hundred grain weight of each nitrogen application treatment were higher than those of CK.CF treatment had the highest biological yield,while LF1 treatment had the highest grain yield and harvest index.The grain yield of each treatment was significantly higher than CK,and the harvest index decreased with increasing nitrogen application amounts.Therefore,maize can achieve better growth effects under LF1 foliar nitrogen application in the central and western regions of Inner Mongolia.

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.

To clarify the regulatory effect of nitrogen(N)fertilizer reduction and postponing on the productivity of wheat-maize double cropping system in Huang-Huai-Hai Plain.The annual N fertilizer experiment of summer maize and winter wheat was established of four N application systems:annual N fertilizer application 400 kg/ha of traditional farmer treatment(F₄₀₀),10% reduction of annual N fertilizer(FN),20% reduction of annual N fertilizer(FH),and 30% reduction of annual N fertilizer(FL)from 2020 to 2023 at Jiyang Experimental Base of the Shandong Academy of Agricultural Sciences in Jinan.The grain yield,aboveground N accumulation characteristics,N use efficiency,and the nitrate residue after harvest in the 0—200 cm soil layer of wheat-maize double cropping system were tested,in order to provide the theoretical basis for further optimization of N fertilizer management in Huang-Huai-Hai Plain.The results indicated that N fertilizer postponing was optimized the grain yield of summer maize and winter wheat under the condition of N reduction,and the averaged across the three years,FL significantly increased by 9.2%—18.1%,13.5%—20.5%,and 11.1%—19.1%,respectively,compared with F₄₀₀ and FN.N fertilizer postponing improved the N accumulation rate,and promoted aboveground N accumulation at wheat-maize different growth stages,and the averaged across the three years,FL significantly increased plant N accumulation by 5.7%—12.3% and 5.0%—12.8% under silking and maturity,respectively,compared with F₄₀₀,FN,and FH,as well as 8.2%—17.2% in grain N accumulation.For winter wheat,FL and FH treatments were significantly higher than F₄₀₀ and FN at jointing,anthesis,and maturity,and the averaged across the three years,FL and FH significantly increased by 23.4%—28.1%,20.7%—26.3%,and 12.6%—20.8%,respectively,compared with F₄₀₀,FN and FH,at the same time the grain N accumulation under FL significantly increased by 16.4%,15.0% and 5.8%,respectively,compared with F₄₀₀ and FN.N fertilizer postponing optimized the N use efficiency of wheat-maize double crop system,the averaged across the three years,FL significantly increased N uptake efficiency by 4.8%—57.7% and 32.0%—72.4% of summer maize and winter wheat,respectively,compared with F₄₀₀,FN,and FH;and FL significantly increased N partial factor productivity by 68.8% and 40.4% in summer maize,respectively,compared with F₄₀₀ and FN,as well as by 38.4%—71.8% in winter wheat compared with F₄₀₀,FN,and FH.At harvest of summer maize and winter wheat,the soil nitrate residue was mainly enrichment in the 0—40 cm soil layer under four N application systems,the averaged across the three years,accounted for 40.0%,38.9%,44.9%,42.5% and 37.3%,36.9%,46.7%,38.3% of the 0—200 cm soil layer,respectively.In addition,the obvious accumulated effects in 0—200 cm soil layer nitrate residue under F₄₀₀ and FN treatments at harvest of summer maize and winter wheat,but there was the relative balance was achieved under FL and FH treatments.In conclusion,a 30% reduction of annual N fertilizer by N fertilizer postponing could optimize plant N accumulation characteristics and realized synergistic improve grain yield and N use efficiency.Therefore,FL treatment was an optimal N application system for realizing the collaborative target of high-yield,high-efficiency,and environment-friendly of wheat-maize double cropping system in Huang-Huai-Hai Plain.

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.

IQM(IQ-motif containing protein),a plant-specific calmodulin-binding protein,plays crucial roles in plant growth,development,and responses to various stresses.In order to study the characteristics and potential functions of the maize IQM gene family,bioinformatics approaches were used to identify IQM genes in the maize whole genome,and protein properties,phylogenetic relationship,gene structure,chromosome location,gene replication,cis-acting element,tissue-specific expression and expression patterns under various stresses were investigated.A total of 11 ZmIQMs genes were identified in the whole genome of maize,named ZmIQM1 to ZmIQM11 based on their chromosomal locations.ZmIQMs genes could be classified into three subfamilies,with genes within different subfamilies exhibiting similar structures.Segment duplication was found to play a major role in the amplification and evolution of the ZmIQMs gene family.Cis-acting element analysis showed that the promoter region of ZmIQMs gene contained multiple hormone and stress response elements.The expression pattern of ZmIQMs genes was investigated,and it was found that ZmIQMs genes had different expression patterns in different tissues,and the expression levels of several ZmIQMs genes were changed under different abiotic and biotic stresses.qRT-PCR results showed that under drought stress,the expression of ZmIQM3,ZmIQM4 and ZmIQM10 was up-regulated, and ZmIQM3,ZmIQM4,ZmIQM5,ZmIQM10 and ZmIQM11 responded to Cochliobolus heterostrophus infection.The results showed that ZmIQMs genes played an important role in stress response.

This study aimed to elucidate the compositional differences and molecular regulatory mechanisms of anthocyanins in kernels of fresh-eating maize with different colors by integrating metabolomic and transcriptomic analyses,thereby providing candidate genes and a theoretical basis for molecular breeding of colored fresh-eating maize.White WN2000,yellow HN,colored CN1,and black HTN188 were used as materials.Metabolomics was employed to identify anthocyanin-related metabolites and screen differential metabolites;transcriptome sequencing was conducted to obtain differentially expressed genes(DEGs).Metabolite gene associations were analyzed through GO annotation and KEGG pathway enrichment,and key structural genes and transcriptional regulators were mined within the anthocyanin biosynthetic pathway.The results showed that 49 anthocyanin-related metabolites were identified in total.Major anthocyanins,including cyanidin,peonidin,and pelargonidin,accumulated significantly in HTN188,indicating stronger pigment deposition.Transcriptome analysis identified 12 557 DEGs,among which structural genes such as F3H,DFR,and UFGT,as well as transcription factors including MYB and bHLH,were significantly up-regulated in varieties with high anthocyanin content.Correlation analysis revealed that the expression level of Zm00001d011438 was significantly and positively correlated with total anthocyanin content,suggesting that it may play a key role in kernel anthocyanin accumulation.Overall,the integrated metabolomic and transcriptomic analyses characterized differences in anthocyanin composition and related gene expression among differently colored fresh-eating maize kernels,and identified structural genes,transcription factors,and the candidate Zm00001d011438 associated with the anthocyanin biosynthetic pathway,providing references for subsequent functional validation and genetic improvement.

To clear under the condition of slow release nitrogen fertilizer applying different content of maize development rule of the diurnal change of photosynthetic characteristics and growth,the light response curve was to fit,so as to farming-pastoral zone of spring maize cultivation and nitrogen utilization to provide theoretical basis.This study took Guangde 5 as the research object,and based on the long-term positioning experiment in 2018,the leaves ear position in spinning—tasseling stage of maize were mesured and analyzed under six nitrogen gradient of N 0(N0,CK), 120(N8), 180(N12), 240(N16), 300(N20),360(N24) kg/ha in 2019 and 2020. SPAD value, intercellular carbon dioxide concentration, stomatal conductivity, diurnal variation of net photosynthetic rate, transpiration rate, light response curve and dry matter accumulation rule.The results showed that with the increase of nitrogen fertilizer application, the changes of SPAD value, net photosynthetic rate, transpiration rate and stomatal conduction degree day of maize increased first and then decreased,and N16 treatment was the highest,and intercellular carbon dioxide concentration was the lowest.The changes of net photosynthetic rate,transpiration rate and stomatal conduction degree day showed unimodal curve.The light response curve fitting analysis showed that the maximum net photosynthetic rate of N16 treatment was the highest.In 2019 and 2020,N16 treatments were 37.48%,29.51%,31.85%,18.17%,37.32% and 80.04%,59.73%,50.30%,6.42%,62.51% higher than N0,N8,N12,N20 and N24 treatments,respectively.Dry matter mass accumulation in whole plant and ear were positively correlated with maximum net photosynthetic rate,apparent quantum efficiency and SPAD value.Comprehensive analysis showed that the most suitable nitrogen fertilizer application rate in western Inner Mongolia was 240 kg/ha.

In the early stage, the dwarf dwarf-12 was successfully selected by distant hybridization of dwarf sorghum and local maize.After previous studies, the dwarf gene may be controlled by br2.Since there were no adverse traits, in order to utilize and discover excellent dwarf inbred lines, and then crossed dwarf-12 with local white maize, and selected the excellent dwarf inbred line d8227. The dwarf maize material d8227 obtained by predecessors was combined with maize of different heights, and it was identified that it has good combining ability. In order to increase the germplasm resources of dwarf maize and improve the yield of maize, in-depth research was carried out.d8227 and dwarf-12 were used as research materials to compare the differences in main agronomic traits between dwarf parents and progeny to observe the differences in stem cytology;d8227 and four inbred lines with different backgrounds were used for genetic mating design to analyze dwarf culm.Inheritance mode of genes; construct a targeting population, perform high-throughput sequencing with BSA method, conduct preliminary mapping of dwarf genes, and perform allelic identification of dwarf materials with known positioning intervals to clarify target genes and known genes relationship. The results showed that the plant height of d8227 increased by 9.35%, the ear position increased by 31.50%, the leaves of d8227 decreased, and the length of stem nodes increased.dwarf-12 increased by 52.21%, 5.26%, 23.76%, 6.93%, 12.02%; using the paraffin section method, observe the characteristics of transverse and longitudinal cells on the upper, ear and lower ear of d8227 and dwarf-12 with a microscope, and d8227 was longitudinally sectioned.The cells were loosely arranged and the cells were obviously elongated;the dwarf-12 cells were arranged regularly and compactly.After measuring the cell area, ear and lower ear cell area of the d8227 were significantly increased than that of the dwarf-12, which was mainly caused by the elongation of the d8227 cells. Through genetic analysis, the dwarf stalk gene was a single recessive gene, and the gene was preliminarily located.The dwarf stalk gene were located at 190-215 Mb of chromosome 1.The dwarf maize that had been located in the interval was selected for allelic identification.The two-year planting results showed that d8227 and 123d, Na360 were not alleles, but may be alleles with 125d and 123d, which needed follow-up fine mapping and in-depth research. On the whole, d8227 is a medium dwarf material with excellent characters and has breeding potential, but further studies such as fine positioning are needed to judge its utilization value.

In order to further analyze the genetic basis regulating the protein content of super sweet corn stalk,this study used the BLINK model to locate the major SNP loci and predict candidate genes controlling the trait,based on the maize 56K gene chip.The results showed that during the harvest period of super sweet corn,the protein content of stalk ranged from 12.63 to 30.29 g/kg,with an average of 20.76 g/kg,showing a normal distribution.Six significant SNP loci regulating the protein content of super sweet corn stalk were identified by GWAS.These loci were distributed on chromosomes 1,4 and 6,and their contribution rates ranged from 10.07% to 18.17%.Among them,Affx-115330268 on chromosome 6 had the highest contribution rate.A total of 184 candidate genes were detected in the 200 kb confidence interval between the upstream and downstream of the significant association sites,of which 34 were annotated genes,accounting for 18.48%.Through GO functional annotation and KEGG pathway enrichment analysis,candidate genes were mainly involved in biological processes such as biological regulation,cellular processes,and catalytic activity,and were enriched in steroid biosynthesis,tryptophan metabolism,photosynthesis-antenna protein and other pathways.Based on the literature search and comparison,it was found that six key genes (GRMZM2G141473, GRMZM2G007854, GRMZM2G111319, GRMZM2G121024, GRMZM2G010353, GRMZM2G049547) that regulate the protein content of super sweet corn stalk,which are mainly involved in protein and enzyme synthesis.

In order to study the synergistic regulation characteristics of plant growth regulators on canopy-root traits of spring maize and to further reveal the lodging resistant mechanism of the plants,in 2021—2022,with the maize varieties Dika 159(DK159)and Xianyu 335(XY335)as experimental materials,at two planting densities of 75 000,90 000 plants/ha,plant growth regulator treatment (PGR) and water control (CK) were set up to analyze and compare the canopy structure,stem basel internode characters,root morphological characteristics and physicochemical properties of root bleeding sap under different treatments.The results showed that PGR had regulatory effects on both the maize canopy and roots.After PGR treatment,plant height,ear height and center of gravity height decreased,the mean leaf tilt angle above ear increased,light transmittance of ear layer increased by 23.59% on average,light transmittance of basel layer increased by 18.60% on average,and stem quality of basal internode was significantly improved.At the same time,the total root number,root length and root dry weight of PGR treatment increased,the root width at 10 cm below the surface increased,the root bleeding sap flow and nutrient flow increased,and the root morphological characteristics and transport capacity were obviously optimized.The flow of CTK and IAA in the root bleeding sap increased,while the flow of GA decreased.PGR effectively reduced the occurrence of stem lodging and root lodging through the synergistic regulation of canopy and root system,the field lodging rate of maize decreased from 13.43% to 6.47%,and the average yield of maize increased by 16.10%,thus achieving stable and high yield.

In order to explore the photosynthetic physiological response mechanisms of three summer maize varieties (Xundan 20, Jinbei 288 and Dika 667) which were commonly cultivated in arid and semi-arid areas to drought stress, these three varieties were treated under different drought stresses (including non-drought treatment (CK), light drought (LD) and heavy drought (HD)). Responses of net photosynthetic rate to light intensity (Pn-PAR) and net photosynthetic rate to intercellular CO₂ concentration (A-Ci) were estimated by the portable photosynthesis system Li-6400, and responses of chlorophyll fluorescence parameters to light intensity were measured by portable modulation chlorophyll fluorescence meter MINI-PAM, respectively. The results were as follows. As for all these three varieties, the response modes of Pn and stomatal conductance (Gs) to PAR were similar among these three maize varieties, and the responses of Pn to Gs shifted to left along the drought stress gradient. The initial chemical efficiency (CE) and photosynthetic capacity (Amax) were significantly lower under heavy drought treatment than under the other two treatments for each of the three varieties. Compared with the results under CK treatment, the non-photochemical quenching coefficient (qN) and the quantum yield of the regulatory energy dissipation (Y (NPQ)) were lower and the quantum yield of non-regulated energy dissipation (Y(NO)) was higher under LD or HD treatment for the two varieties of Jundan 20 and Dika 667; and the photochemical quenching coefficient (qP) was lower under HD treatment for the variety of Jinbei 288. Compared with the results under CK treatment, the maximum net photosynthetic rate (Pmax) and initial quantum efficiency (AQY) were a little higher under LD treatment for the variety of Jinbei 288. Compared with the other two varieties, the Pmax and AQY showed higher tolerance to drought stress by keeping relatively lower qQ and lower Y(NO) for the variety of Jinbei 288, and these results not only showed the greater tolerance of Jinbei288 to drought stress, but also provided reference for the screening of crop varieties for drought tolerance.

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

Preliminary transcriptomic analysis identified ZmRAV1 as a candidate gene involved in maize's response to drought stress. To further investigate its function, this study cloned the ZmRAV1 gene, conducted bioinformatics analysis of its coding sequence, and overexpressed this gene in Arabidopsis thaliana. The function of ZmRAV1 was validated by assessing the phenotypes and physiological and biochemical indices of the transgenic Arabidopsis lines under drought conditions. The results showed that the ZmRAV1 gene had a total length of 1 176 bp and encoded 389 amino acids.It had the highest proportion of irregular coils in its secondary structure and was a hydrophilic protein that did not contain signal peptides and was non transmembrane.Subcellular localization indicated that the protein was located in the nucleus.ZmRAV1 exhibited high conservation across different species.Phylogenetic analysis indicated that ZmRAV1 shares the closest evolutionary relationship with its homolog in Miscanthus sinensis, showing a high degree of homology. After drought stress treatment,the root length of Arabidopsis thaliana lines overexpressing ZmRAV1 during germination was significantly higher than that of wild-type (WT)lines.In the seedling stage,WT showed withering or even death after drought stress,while the survival rate was lower than that of overexpressing lines.Moreover,the POD and SOD activities of ZmRAV1 overexpressing lines were higher than those of WT after drought treatment,indicating that overexpression of ZmRAV1 gene could enhance Arabidopsis thaliana's resistance to drought stress.

To clarify the effects of different tillage methods on soil moisture dynamics changes and maize yield under the condition of straw return to field in the black soil area along the foothills of Daxing'anling,based on six consecutive years of tillage positioning experiments,this study analyzed the effects of seven types of tillage methods,namely,full-crushing and deep-tillage (SCD),full-crushing and shallow-tillage (SSS),full-crushing and deep-tillage (SCS),full-crushing and re-harrowing (SCR),full-crushing and rotary tillage (STR),full-crushing and no-tillage (NTS),and conventional tillage without returning straw to the field (CK)on soil moisture characteristics,water consumption,water use efficiency,and agronomic traits and yield of maize in the 0—60 cm soil layer at different growth stages of maize in each treatment.The results showed a bimodal pattern of soil quality moisture content in 2022 and 2023.0—10 cm soil layer soil quality moisture content was significantly higher than that of CK,and the NTS treatment had the highest soil quality moisture content in several periods.10—20 cm soil layer soil quality moisture content was lower than that of CK in the SSS and NTS treatments at the jointing stage,and soil quality moisture content was higher than that of CK in the 20—40 cm and 40—60 cm soil layers in 2022 and 2023 for all the treatments.In 2022 and 2023,maize plant height in all treatments except NTS treatment was significantly higher than CK at different growth stages.The SCD treatment was the tallest and the NTS treatment was the shortest at mature stage.Leaf area index (LAI) varied little among treatments at seedling stage of maize,STR treatment had the highest LAI after the jointing stage,and all treatments had significantly higher LAI than NTS treatment at the big trumpet stage.Dry matter accumulation in all treatments except for the SCS,NTS treatment was significantly higher than in CK,and dry matter accumulation was highest in the SCD treatment and lowest in the NTS treatment at mature stage.All tillage treatments increased maize yield and water use efficiency compared with CK,but the SCD treatment was significantly higher than CK.Comprehensive analysis of the indexes showed that the two tillage methods of full-crushing and deep-tillage and full-crushing and shallow-tillage were favorable to improve soil structure,maize yield and water use efficiency in the black soil area along the foothills of Daxing'anling.

The mechanism of the effect of phosphorus application rate on the growth,yield formation and phosphorus fertilizer utilization rate of high-yield maize in Xinjiang under the condition of drip irrigation and fertilizer integration was clarified,in order to provide a theoretical basis for the high and stable yield of maize in Xinjiang and the green sustainability of fertilizer reduction and efficiency increase.The experiment was carried out in the maize high-yield demonstration base of Qitai Farm in Xinjiang from 2023 to 2024.Under the condition of drip irrigation and fertilizer integration,six phosphorus application levels were set up:no phosphorus fertilizer(P₀),pure phosphorus 60 kg/ha (P₆₀),90 kg/ha(P₉₀),120 kg/ha (P₁₂₀),150 kg/ha (P₁₅₀)and 180 kg/ha(P₁₈₀,CK).The changes of leaf area index(LAI),photosynthetic potential(LAD),dry matter accumulation,harvest index(HI),ear traits,yield and yield components of maize with water and fertilizer integration of dense planting drip irrigation were analyzed,and the effect of phosphorus application rate on yield and phosphorus fertilizer utilization rate of maize with dense planting drip irrigation in Xinjiang was clarified.The results showed that under the condition of drip fertigation and phosphorus application,the maize yield increased first and then tended to be stable with the increase of phosphorus application in the two years,and the yield was the highest(18.79—20.94 t/ha)at P₁₂₀ treatment.The amount of phosphorus application significantly affected the 1000-grain weight and grain number per ear of maize.The amount of phosphorus application mainly affected the length of maize ear bald tip.Compared with P₁₅₀ and P₁₈₀ treatments,the difference of ear bald tip length was not significant.During the critical growth period of corn,LAI showed a trend of first increasing and then stabilizing with increasing phosphorus fertilizer application rates.The LAI of maize under P₁₂₀ treatment at silking stage was 7.56—7.81,which was not significantly different from P₁₅₀ and P₁₈₀ treatments,but was significantly reduced by 21.54% under P₀ compared with P₁₂₀.In addition,the dry matter accumulation before and after anthesis of maize treated with P₁₂₀ was not significantly different from that of P₁₅₀ and P₁₈₀ treatments,which was 37.91% and 93.88% higher than that of P₀,respectively.In summary,drip fertigation and phosphorus application significantly affected LAI,LAD,pre-anthesis and post-anthesis dry matter accumulation and HI,shortened bald tip length,increased grain number per spike and 1000-grain weight,and then increased maize yield and phosphorus utilization efficiency,and realized the synergistic improvement of maize yield and phosphorus fertilizer utilization efficiency.

In order to study the function of pollen lethal gene ZmAA1 and create tansgenic male sterile materials. ZmAA1 and its specific promoter Pg47 were found according to GenBank,designed to plus restriction endonuclease on the downstream and inserted them into an cloning vector puc57,construction of vector pCAMBIA3300-Pg47-ZmAA1-35S-bar used traditional construction methods digested connection.A maize inbred line Zheng 58 was infected by Agrobacterium tumefacfaciens with the vector pCAMBIA3300-Pg47-ZmAA1-35S-bar, 94 PPT-resistant seedlings were obtained and 47 plants were PCR positive.The pollen sterility in greenhouse RT-PCR assay for gene bar in the transgenic plant leaves and immuno strip test suggested that pollen lethal gene ZmAA1 had been integrated into the maize genome,and protein was expressed.

To investigate the effects of partially substituting chemical fertilizer with biochar-based organic fertilizer derived from cattle manure on N₂O emissions in summer maize fields and the underlying regulatory mechanisms,a field plot experiment was conducted from 2023 to 2024 at the Dishang Experimental Station of the Institute of Cereal and Oil Crops,Hebei Academy of Agriculture and Forestry Sciences.Four fertilization treatments were set up:CF(conventional nitrogen-phosphorus-potassium fertilizer),and COF1,COF2,and COF3,which replaced 15%,30%,and 45% of the chemical nitrogen in CF with an equivalent amount of nitrogen from biochar-based organic fertilizer derived from cattle manure,respectively.The study analyzed the effects of different fertilization regimes on N₂O emissions,plant nitrogen uptake,soil physicochemical properties,abundance of nitrogen-cycle-related functional genes,and grain yield.The results showed that:(1)Compared with CF,the cumulative N₂O emissions under COF1,COF2,and COF3 treatments were significantly reduced by 39.4%,42.5%,and 43.8%,respectively.While reducing emissions,COF1 and COF2 increased plant nitrogen uptake by 45.9% and 24.5%,and yield by 10.6% and 11.7%,respectively.(2)COF1 and COF2 significantly promoted the formation of water-stable aggregates(WSA)(increased by 12.7% and 16.5% compared with CF,respectively)and reduced the abundance of key denitrification functional genes(norB,norC,narH),while enhancing the expression of genes related to dissimilatory nitrate reduction to ammonium(DNRA)(napA,napB),thereby promoting the accumulation of soil nitrate and ammonium nitrogen.(3)COF1 and COF2 increased root biomass and the activities of nitrate reductase and glutamine synthetase in roots and leaves,synergistically improving plant nitrogen uptake and utilization.Correlation analysis further revealed that soil WSA formation was significantly negatively correlated with the abundance of key denitrification genes(norB/C,narH),while positively correlated with plant nitrogen uptake,root biomass,and nitrogen metabolism enzyme activities.In conclusion,replacing 15%—30% of chemical fertilizer with biochar-based organic fertilizer derived from cattle manure can directly inhibit the denitrification process and reduce N₂O emissions by promoting the formation of water-stable soil aggregates.Simultaneously,it indirectly reduces N₂O emissions by enhancing the DNRA pathway and plant nitrogen uptake capacity,which competes with denitrification for nitrate substrates.

In order to improve the nitrogen use efficiency and corn yield during the whole growth period of maize, it provides a reference for the high-yield nitrogen fertilizer operation model of maize in Heilongjiang Area. Ratio (CK:blank control; T1:50% base fertilizer+50% flowering fertilizer; T2:30% base fertilizer+40% jointing fertilizer+30% flowering fertilizer; T3:20% base fertilizer+60% jointing fertilizer+20% flowering fertilizer; T4:10% basal fertilizer+60% jointing fertilizer+30% flowering fertilizer) on the change of soil inorganic nitrogen content, nitrogen balance, nitrogen accumulation at different growth stages, nitrogen use efficiency and corn yield. The results showed that compared with the control group, T2, T3, and T4 effectively increased the inorganic nitrogen content of the soil plow layer during the filling stage and the mature stage; in terms of nitrogen balance, T2, T3, and T4 were significant difference than the T1 treatment. Reduced the apparent nitrogen loss, of which T4 apparent nitrogen loss was the lowest; compared with T1, reducing the ratio of nitrogen to topdressing significantly increased the nitrogen accumulation during the flowering-maturity period, and the nitrogen accumulation during the filling-maturity period T4 was the highest treatment; compared with T1, T2, T3, and T4 significantly increased the nitrogen absorption and utilization rate, agronomic utilization rate and partial productivity of maize, and the increase ranges was 16.66%-22.47%, 17.80%-35.76%, 4.93%-9.90% (Xianyu 335) and 6.55%-24.46%, 8.23%-36.94%, 2.02%-5.44% (Tiannong 9); reducing the ratio of nitrogen fertilizer to topdressing (T2, T3, T4) yields significantly higher than the traditional nitrogen application treatment T1, T3 had the highest yield, which was 9.90% (Xianyu 335) and 8.86% (Tiannong 9) compared with T1. In summary, under the experimental conditions, when the total nitrogen application rate was 210 kg/ha, 20% basal fertilizer+60% jointing fertilizer+20% flowering fertilizer was the best nitrogen basal dressing ratio.

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

Based on the long-term located fertilization experiment of Laiyang, Shandong Province, China, began in 1978, to study the transport and accumulation characteristics of nitrate nitrogen and ammonium nitrogen in the Fluvo-aquic soil and its relationship with the summer maize yield.The test set organic fertilizer(M), nitrogen fertilizer(N)2 factors, 3 levels, 9 treatment;3 levels of organic fertilizer(M):M₀(0 t/ha), M₁(30 t/ha), M₂(60 t/ha), and 3 levels of nitrogen fertilizer(N):N₀(0 kg/ha), N₁(138 kg/ha), N₂(276 kg/ha).After summer corn harvest in 2014 and 2015, the contents of nitrate nitrogen and ammonium nitrogen in soil 0-20, 20-40, 40-60, 60-80 and 80-100 cm were measured respectively, the accumulation of nitrate nitrogen, ammonium nitrogen in different soil depth of 0-100 cm and the summer corn yield were calculated.The results showed that the amount of nitrate nitrogen, ammonium nitrogen and its accumulation amount in soil could be improved by applying organic fertilizer or nitrogen fertilizer.In the 0-100 cm soil layer, the vertical migration trends of nitrate nitrogen of different treatments were different, but the vertical migration trend of ammonium nitrogen were basically the same.Compared with chemical fertilizer, application of organic fertilizer could slow nitrate to the deep soil leaching, but both of ammonium nitrogen to influence the trend of migration in deep soil was not obvious.Long-term application of organic fertilizer, nitrogen fertilizer on nitrate nitrogen, ammonium nitrogen accumulation amount of the impact of extremely significant level, there was extremely significant interaction effect on the accumulation of nitrate nitrogen in soil.Compared with the M₀N₀(CK), the accumulation of nitrate nitrogen and ammonium nitrogen in the addition of fertilization treatments were significantly respectively increased by 112%-396% and 69%-259% at P<0.05.In 0-20, 0-40, 0-60, 0-80, 0-100 cm in each soil layer, the nitrate nitrogen accumulation and the ammonium nitrogen accumulation had different linear relationship with summer maize yield.Research showed that rational application of organic and inorganic fertilizers could reduce the accumulation of nitrate nitrogen and ammonium nitrogen in soil and the leaching, and it is advantageous to improve the yield of crops, maintain the stability of the soil ecosystem, promote the sustainable development of agriculture and protect the groundwater resources.

To clarify the genetic characteristics of total leaf number and leaf number above the ear in maize,and reveal their regulatory effects on maize yield potential,biomass accumulation,and lodging resistance,experiments on QTL mapping and gene mining for controlling maize leaf number were conducted.By using SLAF-seq technology for high-throughput sequencing of Chang 7-2,PHB1M,and 138 F_2∶3 families,combined with two planting density treatments(E1:60 000 plants/ha;E2:120 000 plants/ha)QTL mapping was performed on leaf number phenotypic data,and gene mining was performed on the mapping results.The results showed that two total leaf number QTLs distributed on chromosome 8 were the main effect QTLs,contribution rates were 16.96% and 23.08%,respectively,and the additive effect value was negative;the QTL for the leaf number above the ear distributed on chromosomes 2 and 4,with a positive additive effect value.the two QTLs distributed on chromosome 4 were the main effect QTL,contribution rates were 10.18% and 14.75%,respectively;the QTLs for total leaf number and leaf number above the ear were distributed in different chromosomal regions and might be subject to relatively independent genetic regulation.Gene functional analysis revealed genes screened involvement in carbohydrate metabolism,plant hormone signal transduction,and selected some transcription factors.The results of this study provide richer theoretical support for further revealing the genetic basis of maize leaf number and offer targets for marker-assisted breeding.

To determine the optimum strip configuration for the intercropping of soybean and maize with different border-row advantages,the field experiments were carried out in two distinct ecological regions,Jian'an District of Xuchang City and Shangshui County of Zhoukou City,Henan Province.The experimental materials included two maize varieties with strong border-row advantage(MC121 and Denghai 3206(DH3206)),and two with weak border-row advantage(Haoyu 16(HY16)and MY73),previously screened,and one soybean variety Jindou 99(JD99).Two strip intercropping patterns were established∶6 rows of soybeans alternating with 4 rows of maize(6S4M)and 4 rows of soybeans alternating with 2 rows of maize(4S2M).Sole cropping of soybeans(CKS)and maize(CKM)were set as the controls.This study investigated the variations in maize agronomic traits,dry shoot weight,yield and its components of each row under different strip patterns,and compared the differences of land equivalent ratio(LER).The results showed that the LER was greater than 1 in 12 of the 16 treatments formed by two strip configurations for four maize varieties in the two ecological regions,and the LER of maize varieties HY16 and MY73 was greater than 1 under each strip configuration at two sites.The LER of MC121 and DH3206,with strong border-row advantage,was higher in strip type of 4S2M than that of 6S4M.In contrast,the LER of HY16,with weak border-row advantage,was higher in strip type of 6S4M than that of 4S2M,while it was opposite for MY73.Under 6S4M planting pattern,stem diameter,canopy light transmittance,chlorophyll a and chlorophyll b contents in ear leaf and leaf below the ear of maize variety DH3206 decreased with the increase of border row order;bottom light transmittance,chlorophyll b content in ear leaf and leaf below the ear of maize variety MC121 decreased with the increase of border row order in two experimental sites.The yield of maize varieties MC121 and DH3206 with strong border-row advantage in Jian'an District and Shangshui County decreased by 23.71%,27.00% and by 20.03%,9.05%,respectively.The dry shoot weight per plant of the edge row-2 at maturity decreased by 15.87%,19.93% and by 13.82%,24.56%,respectively,compared with the edge row-1.In contrast,there was no significant change in yield and dry shoot weight per plant at maturity between the edge row-1 and the edge row-2 of maize varieties with weak border-row advantage.In conclusion,the average LER of varieties with weak border-row advantage is higher than those with strong border-row advantage under the same strip configuration,and maize yield difference between intercropping and monoculture is seriously affected by variety type.Therefore,screening and matching suitable maize varieties is essential for improving the yield and benefit of soybean-maize strip intercropping system.

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 nutrient expert (NE) management on nitrogen (N) use efficiency and soil organic carbon (SOC) sequestration in the wheat-maize rotation system and improve its management practices, a long-term experiment was set up in 2009 to compare NE management with farmer's practice (FP) management. Through 9-years experiment, the crop yield, N use efficiency, SOC content, SOC sequestration rate and SOC sequestration efficiency were measured and analyzed. The advantages of long-term NE management in wheat-maize crop rotation system were evaluated. The results showed that long-term NE management reduced the amount of N fertilizer application rate, compared with FP management, but maintained the crop yields (no significant difference with FP). Compared with FP management, the average accumulative recovery efficiency of N, agronomic efficiency of N, and partial productivity of N in NE management system increased by 7.4 percentage points, 39.7%, and 28.4% in maize production system, and increased by 8.0 percentage points, 28.9%, and 32.8% in wheat production system, respectively After 9-years experiment, both NE and FP increased the SOC contents, with NE management increased faster than FP. The annual SOC contents rise rates of NE treatment in 0-5 cm, 5-10 cm and 10-20 cm soil profile were 0.28, 0.27, 0.34 g/(kg·a), respectively, which were 7.7%, 68.8% and 126.7% higher than those of FP treatment. The average annual carbon input of NE and FP treatment from straw returning were 8.5, 8.7 t/(ha·a), respectively, and the SOC sequestration rates were 1.35, 0.68 t/(ha·a),respectively, and the SOC sequestration efficiencies were 18.6% and 0.4%, respectively, which shown a significant difference. NE management could improve N use efficiency and increase SOC sequestration. Long-term NE management is one of the important measures for fertilizer saving, efficiency strengthen and SOC pool richen in wheat-maize rotation system. It would play a crucial role in ensuring food security and realizing agriculture green development.

This study investigated the accumulation and distribution of dry matter,nitrogen(N)and zinc(Zn)of summer maize under N and Zn fertilization,to provide a basis for reasonable application of zinc fertilizer and combined fertilization.Split-split design was used with three N rates(90,180,225 kg/ha N)as the main factor,two Zn rates(0,4.5 kg/ha ZnSO₄·7H₂O)as the second factor,two varieties(ZD958 and GSY66)as the third factor.The effect of N and Zn application on the grain yield,dry matter accumulation dynamic and N and Zn absorption,accumulation and distribution of each organ of different maize varieties by field experiment.The results showed that the grain yield achieved 9.77,10.42 t/ha under the N rates of 180,225 kg/ha,respectively,increased by 18.0% compared with 90 kg/ha.The treatment of 225 kg/ha N had the highest plant dry matter accumulation after silking,while the treatment of 90 kg/ha had higher ratio of cob and grain dry matter at the mature stage.Highest N concentration in each organ,Zn concentration in the stem and N and Zn accumulation in the leaf and grain were obtained in the treatment of 225 kg/ha,while highest Zn concentration in the sheath,bract and grain and ratio of grain N and Zn were found in the treatment of 90 kg/ha.No effect was found in the grain yield and dry matter accumulation and distribution under two Zn treatments.Zn application significantly increased N and Zn concentration and accumulation but decreased distribution ratio of grain N and Zn by 6.93,6.86 percentage points,respectively.Relative to GSY66,ZD958 had higher grain yield and dry matter ratio,and increased dry matter by 29.2% at maturity.Besides this,ZD958 decreased grain N and Zn concentration by 8.9% and 5.3%,respectively,but improved grain accumulation and distribution ratio.Correlation analysis showed that grain yield and N concentration in the stem,leaf and grain were significantly positively correlated.There was also a significantly or extremely significantly positive correlation between Zn concentration in the leaf and N concentration in the sheath and grain,between Zn concentration in the cob and N concentration in the sheath,cob and bract.These results suggested that combination of N and Zn fertilizers could increase yield and plant dry matter accumulation,enhance the N and Zn absorption and accumulation in each organ especially grain,but decrease distribution ratio of N and Zn in the grain.

To investigate the phosphate-solubilizing effects of different combinations of phosphate-solubilizing bacteria(PSB)and their impact on maize growth and phosphorus uptake,a pot experiment was conducted using three bacterial strains with distinct taxonomic classifications and phosphate-solubilizing capacities:Pseudomonas frederiksbergensis P4-5,Arthrobacter oryzae P5-41,and Bacillus aryabhattai P3-50.A non-inoculated treatment served as the blank control(CK),and the experimental treatments included:single inoculation with P4-5(Pf),single inoculation with P5-41(Ao),single inoculation with P3-50(Ba),dual inoculation with P4-5 and P5-41(Pf×Ao),dual inoculation with P4-5 and P3-50(Pf×Ba),dual inoculation with P5-41 and P3-50(Ao×Ba),and combined inoculation with P4-5,P5-41,and P3-50(Pf×Ao×Ba).The effects of these inoculation treatments on maize root morphology,shoot growth,phosphorus uptake,and indole-3-acetic acid(IAA)secretion capacity by the bacterial strains were analyzed.The results indicated that,compared to the CK,all PSB inoculations significantly increased maize stem diameter,leaf SPAD value,shoot biomass,and phosphorus uptake.Furthermore,they also significantly enhanced rhizosphere alkaline phosphatase activity(except for single inoculation with Pf and Ba,respectively)and reduced soil available phosphorus content(except for single inoculation with Ba).Among these treatments,the combined inoculation of Pf×Ao×Ba exhibited the best overall performance.This treatment secreted high concentrations of IAA,optimized maize root morphology(increasing root length,volume,surface area,and number of root tips),and significantly increased rhizosphere alkaline phosphatase activity,thereby promoting the mineralization of soil organic phosphorus and consequently enhancing maize growth and phosphorus uptake.In conclusion,the combined inoculation of Pf×Ao×Ba significantly promoted maize growth and improved phosphorus nutrition through a dual mechanism:optimizing root morphology by increasing root length,volume,surface area,and root tip number through IAA secretion,and effectively mineralizing soil organic phosphorus by enhancing alkaline phosphatase activity.

To explore the function of key genes in photosynthesis, a functional knockout mutant (zmC₄nadp-me) of ZmC₄NADP-ME, the gene encoding the rate-limiting enzyme of the dark reaction of photosynthesis in maize, was obtained. Evolutionary tree analysis showed that ZmC₄NADP-ME and its homologous genes exist in multiple copies in most plants, with diverse expression patterns. Phenotypic analysis revealed that the entire zmC₄nadp-me plant was yellow-green, and its seedling-stage leaves dried up and died rapidly under light. Chlorophyll fluorescence analysis indicated that Y(Ⅱ) and electron transport rate ETR(Ⅱ) of photosystem Ⅱ (PSⅡ) in zmC₄nadp-me decreased significantly, with little change in Y(NPQ), while the Y(NO) increased notably. Measurement of the absorption capacity (P700) of photosystem Ⅰ (PSⅠ) found that both the electron transport rate (ETR(Ⅰ)) and the actual photoelectron efficiency (Y(Ⅰ)) of zmC₄nadp-me dropped substantially, and the gap widened with increasing light intensity. Under specific light intensities, Y(ND) and Y(NA) of zmC₄nadp-me were greater than those of the wild type (WT). In conclusion, ZmC₄NADP-ME is essential for plant growth and development. Disruption of this gene severely stresses PSⅡ, and the plant can't alleviate this stress by increasing Y(NPQ). Meanwhile, at low light intensities, the inhibition of PSⅠ may originate from the electron donor side of PSⅠ, and as the light intensity increases, the inhibition from the electron acceptor side of PSⅠ becomes a key factor.

The objective of this study was to investigate the transcriptome differences after and before high temperature stress during maize anthesis stage, and to explore the key genes and proteins which are contributed to the high temperature resistant. The pollen activities of maize inbred lines Chang 7-2 and Zheng 58 were detected by Ampha^TM Z30 pollen activity analyzer (Amphays, Switzerland), firstly. RNA-sequencing, construction library and quality assessment were carried out for two periods before and after high temperature treatment using the Illumina Hiseq2000^TM sequencing platform, then the sequencing results were analyzed by bioinformatics. The differential expression genes (DEGs) were analyzed using edegR software. Key different expression genes and proteins with high temperature resistance were analyzed by VENN mapping, GO functional enrichment, KEGG pathway method and transcription factors analysis.The pollen activity of Chang 7-2 grown in normal condition was 42.89% and the pollen activity which was treated by high temperature during anthesis stage was 24.37%. The pollen activity of Zheng 58 which was grown in normal condition was 64.83% and the pollen activity treated by high temperature was 35.57%. The results showed that 4 176 significant DEGs were detected in Chang 7-2 inbred under normal growth condition and high temperature treatment. 5 487 significant DEGs were detected in Zheng 58 inbred under normal growth condition and high temperature treatment. KEGG pathway enrichment analysis showed that 2 062 differentially expressed genes in Zheng 58 were enriched in 399 related pathways. KEGG pathway enrichment analysis showed that 1 943 DEGs in Chang 7-2 were enriched in 352 related pathways. A total of 55 transcription factor families were obtained by the transcription factor analysis, of which 45 transcriptional factors contained more than 10 differentially expressed genes. In conclusion, Comparing the RNA-sequencing after and before high temperature treatment of Chang 7-2 and Zheng 58, many DEGs were obtained. The differences of response mechanisms between Chang 7-2 and Zheng 58 to anthesis high temperature stress were comparatively analyzed. The three gene families (Hsfs, IAA and PIP₂) and the Hsps proteins are playing significant roles in the regulation of high temperature stress in maize.

In order to explore the effect of grain size and sowing depth on emergence and seedling growth,determining suitable grain size and sowing depth in mechanization of summer maize production of Southwest Hilly Area.In the split-plot design,using Zhenghong 505 as the test material,3 kinds of grain size was assigned to the main plot,and 3 sowing depth(2,6,10 cm) to the subplot,emergence rate of maize,seedling quality,yield and yield components have been investigated in drought condition.The results showed that compared with small grain,large grain had higher emergence rate,the seedling was more haleness and grew better in drought,and there was a certain effect of increasing yield ultimately;Shallow sowing(2 cm) was conducive to the emergence,and the growth vigor of the seedlings of 6 cm sowing depth was best just when emerging,then the 10 cm depth of the seedling grew gradually strong,and obviously better at the 5 leaf period(large and medium grain)-7 leaf period(small grain) than shallow sowing treatment,which also showed a certain increase in yield.Therefore,in the dry land or dry season,choosing large grain and suitable sowing depth in maize production can effectively better sthong seedlings,improve the resistance of drought,and achieve the purpose of producing income insurance.

Yield and nitrogen accumulation of maize will decline under soil acidification,but the physiological mechanism is not clear.Field experiment was conducted with four different soil acidity gradients:nautral acid(pH=7,CK),weak acid(pH=6,T1),medium acid(pH=5,T2)and strong acid(pH=4,T3),comparing yield,nitrogen accumulation,grain protein content,nitrogen metabolism-related enzyme activities,gene expression,nitrate nitrogen,ammonium nitrogen,soluble protein,free amino acid content in leaf and stem of maize.The results showed that compared with CK,the yield of T1,T2 and T3 treatments declined by 4.2%,30.7% and 52.3%,respectively.Grain number per spike decreased by 1.8%,28.1% and 42.8%;grain protein content showed a downward trend with T3 treatment significantly reduced by 14.5%.At the big flare stage,with the increase of soil acidity,nitrogen accumulation in leaves showed a downward trend,it was significantly decreased in T2 and T3 treatment by 28.1% and 56.2%,respectively.In stem,the nitrogen accumulation increased firstly and then decreased.Compared with CK,T1 treatment was significantly increased by 33.1%,and T3 treatment significantly decreased by 65.4%.At the big flare stage, the activities of nitrate reductase, glutamate dehydrogenase and glutamate synthase in leaf and stem under T3 treatment were significantly higher than those in CK, while the activities of glutamine synthase in leaf were significantly decreased. The amino acids in stem decreased first and then increased.With the increase of soil acidity,the expressions of ZmGln2 and ZmFd-GOGAT were up-regulated,which promoted the assimilation of {{\mathrm{NH}}_4}^{+} released by photorespiration and {{\mathrm{NH}}_4}^{+} produced by {{\mathrm{NO}}_3}^{-} reduction;the down-regulated expression of ZmGln1.2-ZmGln1.4, ZmNADH-GOGAT2 in leaf and ZmNADH-GOGAT1 in stem decreased the assimilation of {{\mathrm{NH}}_4}^{+} released by catabolism.By up-regulating or down-regulating the expression of relevant genes,maize could promote the production of more free amino acids and soluble proteins during nitrogen metabolism to resist acidification stress,but also reduced the nitrogen accumulation,resulting in lower yield and grain protein content.

This study to Laiyang in Chao Soil Region long-term positioning straw of wheat-maize rotation as research object,applying nitrogen fertilizer were studied under the condition of straw returning and the single application organic fertilizer on wheat and maize yield and grain quality of influence.At the same level of nitrogen fertilizer,the two crop straw returning to field application of nitrogen fertilizer (WCN) treatment of wheat,corn grain crude fat content compared with a quarter of straw to field nitrogen fertilizer (WN) treatment significantly increased by 5.72% and 9.49%.The proportion of straw was more conducive to improve the crude fat content of grain.WCN processing wheat,corn grain protein content than those of the other two season straw (WC) treatment significantly improved 32.53%,72.44%,showed that the proportion of nitrogen bigger was beneficial to improving the protein content.Single application of organic fertilizer and two season straw returning to field application of nitrogen fertilizer could significantly improve the yield of wheat and maize.Different straw returning treatment on wheat grain lysine,cystine acid,alanine had little effect,the corn grain cystine acid,glutamic acid,glycine has little effect,except for aspartic acid,leucine,valine,lysine lysine,cystine acid,alanine,long-term different straw also fields of other amino acids.To sum up,the application of nitrogen fertilizer on the basis of straw returning to the field can get higher yield and improve grain quality.

In order to study the effects of loss control and ordinary fertilizers on nutrient accumulation and growth and development of summer maize,field experiments were conducted at the Xinji experimental station of Agricultural University of Hebei during 2014-2015.Maize morphology and physiology characters and nutrient uptake efficiency were studied using maize hybrid Zhengdan 958 as material.The results showed that with the same nutrient amount (N 144 kg/ha,P₂O₅ 72 kg/ha,K₂O 72 kg/ha) of loss control and ordinary fertilizer applied,there were significant changes on maize growth and development,dry matter accumulation and nutrient accumulation,and the effects of loss control fertilizer treatment were significantly better than those of ordinary fertilizer.Compared with ordinary fertilizer,the 1 000 grains weight,dry matter and yield of maize of loss control fertilizer could be increased by 12.3%,12.8% and 6.9%,respectively.The content of nutrient elements in organs of loss control fertilizer treatment was higher than that of the ordinary fertilizer.Maize leaf area index and photosynthetic rate at kernel filling stage were enhanced by loss control fertilizer treatment.Stalk thickness and puncture resistance of basal internodes of loss control fertilizer treatment maize were also enhanced,so the lodging resistance ability was increased.As a new type of fertilizer,loss control fertilizer would play an important role in improving the yield of maize,increasing the efficiency of fertilization and protecting the environment.

The aims were to study the effect of maize straw returning on soil fertility and productivity under wheat-maize rotation system in North China,and to explore the best way and suitable amount of maize straw returning.From 2021 to 2023,a field split-plot experiment was conducted in Quzhou County,Hebei Province to compare the effects of different maize straw returning methods and amounts on wheat growth,yield composition and soil organic matter content.There were two treatments in the main area,which were cutting and crushing.The sub-area was the amount of straw returning to the field,4 levels,which were 0,0.5,1.0,and 1.5 times of the amount of maize straw in the year.The results showed that compared with straw crushing,the yield of wheat increased by 4.3% under straw cutting treatment,the number of spikes increased by 7.6%,and the harvest index increased by 1.4%,with all significant difference in 2023.The N content of wheat straw was significantly increased by 0.04 percentage points,the N and P uptake of wheat aboveground were significantly increased by 10.8% and 14.3%,respectively(2022),but the K content of wheat straw was significantly reduced by 0.13 percentage points(2023).Cutting treatment could significantly promote the growth of wheat before and after winter,and the NDVI value at jointing stage significantly increased by 11.9%(2022).Soil pH increased by 0.22 units(2023).With the increase of maize straw returning amount,wheat yield and NDVI value at jointing stage showed parabolic model of first increased and then decreased,the N,P and K absorption of above ground wheat showed a significant downward trend,and soil organic matter showed a continuous significant increase trend.Based on the growth potential and yield of wheat,the suitable returning ratio of straw cutting treatment was 58%—62%,and the suitable returning ratio of crushing treatment was 29%—42%.Under the conditions of this experiment,maize straw cutting returning has obvious advantages in promoting wheat growth,and increasing wheat yield.It can be popularized and applied in wheat-maize rotation areas that 58%—62% maize straw is returned into the soil.

A Receptor-like kinase(RLK)gene, OsSIK1,plays important roles in drought stress-tolerance in rice,through the activation of the antioxidative system.To make maize plants have much more drought resistance genes and further to obtain drought tolerance maize germplasm.In this study, OsSIK1 gene of rice was transformated into maize inbred Zheng 58 plants by pollen-mediated method.First,transgenic plants in T₁,T₂ and T₃ were detected by Kanamycin resistance screening,PCR and Southern Blotting,transgenic plants were obtained from T₁ and pure transgenic lines was obtained from T₃.Next,drought resistance analysis to transgenic maize plants and non-transformation control plants were conducted under the condition of 16.1% PEG drought stress.The results showed that compared with non-transgenic plants,the seedling leaf relative water content,chlorophyll content and SOD activity of transgenic plants were increased by 7.4%-19.8%,11.3%-106.9% and 45.8%-93.4%,respectively;furthermore,the relative conductivity and MDA content were decreased by 35.4%-58.1%,and 25.7%-50.4%,respectively.All the physiological indexes under the drought stress proved that transgenic OsSIK1 gene improved the drought resistance of transgenic maize plants,further analysis found that there were significant differences on drought tolerance between 5 transformed lines and their control groups,and their performance of field were superior to that of non-transgenic maize seedlings.At last,5 transgenic maize inbred lines were obtained,which suggested that genetically modified maize has improved the drought resistance by introducing foreign OsSIK1 gene of rice.

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.

In order to investigate the molecular mechanism of Mu gene transfer in sweet corn mutant, the flanking sequence of the insertion site of Mutator gene was isolated by Mu-AFLP method, and the authenticity of transposon insertions was verified by a pair of specific primers P1 and P2 designed according to the extension of the flanking sequences.Meanwhile the genetic biological information of the insertion site was analyzed.The results showed that the flanking sequence was 299 bp, which was located on the third chromosome.The full length of the mutant gene was 5 746 bp, encoding 592 amino acid.The theoretical molecular weight of the encoding protein was 67.5 kDa, the hydrophobic amino acid content was 42.06%, which had 10 transmembrane.It belonged to hydrophilic membrane protein.This result laid a foundation for the better use of Mutator to create new germplasm of sweet corn and it was very important for the development of endosperm and starch synthesis in maize.

To increase crop yields,reduce the application of chemical fertilizers,and improve nutrient utilization efficiency,N-efficient maize cultivars were screened and popularized. An understanding of nitrogen uptake,utilization,and field balance in maize cultivars with contrasting nitrogen efficiency response to N management is essential for efficient breeding and cultivation of maize to produce fodder and bio-energy. To determine the effects of N management on these factors during maize cultivation,a two-year field experiment was conducted in 2015 and 2016 in a subtropical semi-humid climate zone. The results showed that the proportion of N in the stem plus sheath and leaves in ZH311 during VT and R6 was significantly higher than that of XY508. In addition,the N accumulation into grain post-silking(NAG)and contribution of NAG to grain(CNAG)of ZH311 were significantly higher than those of XY508,while the N redistribution rate(NRR)and contribution of NRA to grain yield(CNRA)of ZH311 were significantly lower than those of XY508. The higher proportion of N in the vegetative organs of a N-efficient cultivar,ZH311,led to a significantly higher N accumulation in each stage than that observed for the N-inefficient cultivar XY508. The N accumulation advantage of ZH311 was higher after silking than before silking. The high post-silking N accumulation of ZH311 inhibited the pre-silking N transport that determines the N transport rate and contribution rate to grain of pre-silking N accumulation,which were significantly lower than those of XY508. Meanwhile,the N uptake efficiency,N recovery efficiency,and N partial productivity of ZH311 were significantly higher than those of XY508. Compared with that of XY508,the root system of ZH311 could more effectively absorb and utilize inorganic N in the 40-80 cm soil layer,reduce N deposition,and significantly decrease apparent N losses. The differences in apparent N losses between the two cultivars were mainly elicited post-topdressing. In summary,ZH311 has not only a higher yield per unit area than XY508,but also lower N losses,consequently reducing environmental risks.

In order to investigate the effect of fertilizer reduction combined with organic fertilizer on the yield and quality of silage corn and soil nutrient,in 2019 and 2020,the effects of fertilizer reduction and organic fertilizer on agronomic traits,yield, quality,soil nutrient content and fertilizer utilization rate of silage corn were studied.As a result,the yield of silage corn was significantly affected by different fertilization treatments,and the yield of mixed application of organic fertilizer and slow control fertilizer reached 55 084.75 kg/ha,dry matter production reached 24 192.11 kg/ha.There was no significant difference in yield between slow controlled fertilizer constant and slow controlled fertilizer reduction of 20%,that was,excessive fertilization had no significant effect on yield.The accumulation of N,P and K under T2 treatment was 234.83,173.75,35.72 kg/ha,and significantly higher than other treatments.The maximum nitrogen fertilizer productivity of silage corn under T4 treatment was 166.46 kg/kg,and the maximum nitrogen fertilizer utilization efficiency under T1 treatment was 0.80 kg/kg,which indicated that the mixed application of organic fertilizer and inorganic fertilizer could improve the productivity of silage corn.After T4 treatment,the crude fat content of silage corn was the highest,and the application of organic fertilizer could increase the crude fat content of silage corn,and also increase the content of acid washing fiber.The yield of silage maize was correlated with urease,catalase and available phosphorus content,the correlation coefficients were 0.845,0.798,0.784.The results showed that fertilizer reduction and organic fertilizer application in Southwest China could significantly improve the yield and quality of silage corn,which was beneficial to the protection of farmland ecological environment and the sustainable utilization of soil fertility.