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    16 August 2022, Volume 55 Issue 16
    CROP GENETICS & BREEDING·GERMPLASM RESOURCES·MOLECULAR GENETICS
    Mining of Genetic Locus of Maize Stay-Green Related Traits Under Multi-Environments
    CHANG LiGuo,HE KunHui,LIU JianChao
    Scientia Agricultura Sinica. 2022, 55(16):  3071-3081.  doi:10.3864/j.issn.0578-1752.2022.16.001
    Abstract ( 470 )   HTML ( 269 )   PDF (2062KB) ( 562 )   Save
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    【Objective】 Functional stay-green is generally considered a desirable trait in major crop varieties including maize. Finding new loci and candidate genes related to stay-green, and providing new theoretical basis for the genetic research on stay-green. 【Method】Using 150 recombinant inbred lines (RIL) populations derived from the cross between Xu 178 and K12, QTL mapping of three stay-green related traits (visual stay green (VSG), green leaf number at silking stage (GLNS) and green leaf number at mature stage (GLNM) were performed by the composite interval mapping(CIM)method of Windows QTL Cartographer V2.5. Besides, an association population, which composed of 139 natural materials genotyped with 50790 high-quality SNP markers, was used to dissect genetic locus of three traits by genome-wide association study (GWAS) based on the mixed linear model MLM). 【Result】Based on CIM, three traits (GLNM, GLNS and VSG)were mapped using phenotypic values in a single environment and best linear unbiased prediction (BLUP) value. A total of 37 QTLs were detected on all chromosomes except Chromosome 10, and the LOD score ranged from 2.58-11.36, with a phenotypic variation contribution rate of 4.34%-22.40%. Among them, 14, 12 and 11 loci were detected for GLNM, GLNS and VSG traits, respectively. Four of the QTLs, qGLNS2-1, qVSG1-1, qVSG1-2 and qVSG7-1, were genetically stable and were detected simultaneously in three or more different single environments. GWAS was performed on three stay-green related traits using MLM, and a total of 44 significant SNPs above the threshold line were detected. According to the physical position of SNP markers in the B73 reference genome, a total of 15 SNP were found to fall into the QTL interval mapped by linkage analysis. 【Conclusion】Combined with the results of QTL mapping and genome-wide association study, a total of 4 genetically stable colocalization genetic regions were detected (the corresponding physical position intervals on the B73 reference genome version 4 are 6.2-8.2 Mb on chromosome 1, 209.1-221.4 Mb on chromosome 2, 96.8-102.1 Mb on chromosome 6, and 4.9-11.4 Mb on chromosome 7), and four important candidate genes (Zm00001d006119, Zm00001d018975, Zm00001d006535 and Zm00001d036763) related to photosynthesis and stress response were mined.

    The Functional Analysis of High Mobility Group MsHMG-Y Involved in Flowering Regulation in Medicago sativa L.
    ZHANG YunXiu,JIANG Xu,WEI ChunXue,JIANG XueQian,LU DongYu,LONG RuiCai,YANG QingChuan,WANG Zhen,KANG JunMei
    Scientia Agricultura Sinica. 2022, 55(16):  3082-3092.  doi:10.3864/j.issn.0578-1752.2022.16.002
    Abstract ( 396 )   HTML ( 235 )   PDF (2298KB) ( 235 )   Save
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    【Objective】Flowering is an important signal indicating the transformation from vegetative growth to reproductive growth and has a significant effect on plant biomass. Alfalfa is one of the upmost forage crops worldwide, its yield and quality are closely related to flowering time. The optimum harvest time for alfalfa is during the early flowering stage, which could give the highest yield and the best quality. In the current study, an alfalfa flowering related gene, Medicago sativa High Mobility Group Y (MsHMG-Y), was cloned. The gene structure and expression pattern of MsHMG-Y were studied. Function of MsHMG-Y in alfalfa flowering regulation was analyzed. This work could provide theoretical support for mechanism study underlying flowering regulation. 【Method】MsHMG-Y was cloned by homology cloning strategy and the amino acid sequence was analyzed by multiple sequence alignment. The phylogenetic tree was also constructed. qRT-PCR analysis was used to detect the expression level of MsHMG-Y in different tissues and different flowering stages. The expression pattern of MsHMG-Y under light, gibberellin (GA3), salicylic acid (SA) or methyl jasmonate (MeJA) treatment were analyzed. The phenotype of MsHMG-Y-overexpressing alfalfa was analyzed, and the expression levels of flowering activators and suppressors were also analyzed. 【Result】Phylogenetic analysis showed that MsHMG-Y has the closest relationship with MtHMG-Y in Medicago truncatula. Spatial expression pattern analysis showed that MsHMG-Y was expressed in flowers, stems and leaves, with the highest expression level in flowers and the lowest expression level in leaves in both paternal and maternal alfalfa. In paternal alfalfa with early flowering phenotype, the expression level of MsHMG-Y was the highest at early flowering stage. The highest expression level of MsHMG-Y was detected at flower bud differentiation stage in maternal alfalfa with late flower phenotype. Photoperiod analysis showed that MsHMG-Y was down-regulated after 16-hour light treatment. After 28 hours of light treatment, the expression level of MsHMG-Y was continuously lower than that in the control group, indicating that MsHMG-Y was down-regulated after light treatment. After 50 μmol·L-1 GA3, 100 μmol·L-1 SA or 100 μmol·L-1 MeJA treatment, the expression level of MsHMG-Y was up-regulated compared with the mock treatment. In detail, the expression level of MsHMG-Y was the highest at 1 h under GA3 treatment, which was 3.5 folds higher than control. Under SA treatment, the expression level of MsHMG-Y was the highest at 6 h, which was 24 folds higher than the mock treatment. The expression level of MsHMG-Y was the highest at 3 h under MeJA treatment, which was 11 folds higher than the control. These results indicated that the expression of MsHMG-Y was inducible by the above three hormones. MsHMG-Y-overexpressing alfalfa has late flowering phenotype. The expression levels of flowering activator genes were down-regulated in MsHMG-Y-overexpressing alfalfa, while the expression levels of flowering inhibitor genes were up-regulated. Among these genes, expression of flowering activator genes MsPHYA, MsGI and MsFTa1 was significantly down-regulated by 4.9 folds, 3.9 folds and 2.8 folds respectively, and the expression level of flowering inhibitor genes MsTEM and MsSVP was increased by 2.5 folds and 1.9 folds, respectively. 【Conclusion】The expression of MsHMG-Y is inducible by photoperiod and exogenous hormone treatment, including GA3, SA and MeJA. Overexpression of MsHMG-Y in alfalfa resulted in delayed flowering time. MsHMG-Y plays an important role in regulatory mechanism underlying late flowering in alfalfa.

    TILLAGE & CULTIVATION·PHYSIOLOGY & BIOCHEMISTRY·AGRICULTURE INFORMATION TECHNOLOGY
    Consistency Analysis of Classification Results for Single and Double Cropping Rice in Southern China Based on Sentinel-1/2 Imagery
    YANG JingYa,HU Qiong,WEI HaoDong,CAI ZhiWen,ZHANG XinYu,SONG Qian,XU BaoDong
    Scientia Agricultura Sinica. 2022, 55(16):  3093-3109.  doi:10.3864/j.issn.0578-1752.2022.16.003
    Abstract ( 385 )   HTML ( 10 )   PDF (12532KB) ( 277 )   Save
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    【Objective】Due to the abilities of all-time and all-weather data acquisition, the microwave remote sensing holds great potentials to identify rice in regions dominated by cloudy and rainy weather. The aim of this study was to analyze the consistency of classification results for single and double cropping rice by using optical and SAR remote sensing data, and then to explore the optimal SAR imagery features for rice classification. 【Method】In this study, using the object-based random forest classifier on the Google Earth Engine platform, Sentinel-1 and Sentinel-2 images were adopted to extract the single and double cropping rice from four typical rice growing areas in the Dongting Lake Plain. To analyze the optimal SAR features for the single and double cropping rice identification and the consistency of classification results based on Sentinel-1 and Sentinel-2 images, nine scenarios were established by the combination of different sensors and features and compared the performances of different scenarios. Furthermore, the R2 and DTW distance between the NDVI time series and the SAR backscatter coefficient time series (VH, VH/VV) were calculated, respectively. 【Result】 The overall accuracy of single and double rice cropping identification by using VH, VV and VH/VV time series was 90.42%, 82.08% and 88.33%, respectively. Moreover, the combination of VH and VH/VV time series could achieve a better performance (91.67%) for mapping single and double cropping rice. The derived R2 and DTW distance between VH (VH/VV, VV) time series and NDVI time series were 0.870 (0.915, 0.986) and 4.715 (1.896, 5.506) for single cropping rice, as well as 0.597 (0.783, 0.673) and 2.396 (1.839, 3.441) for double cropping rice, respectively. Higher R2 and lower DTW distance suggested that VH/VV time series, like NDVI, was more sensitive to the rice growth cycle. Furthermore, the flooding signals in rice transplanting phase could be well captured by VH time series. Additionally, the overall accuracy of single and double cropping rice classification based on optical and SAR features (S-2: NDVI, EVI, LSWI; S-1: VH, VH/VV) in six time windows was 91.25% and 90.00%, respectively, and their consistency was high, with the area correlation of 95.70%.【Conclusion】There was high consistency of classification results for single and double cropping rice based on optical and SAR imagery. Thus, Sentinel-1 imagery held great potentials to identify rice area in cloudy and rainy regions. Specifically, VH and VH/VV backscatter coefficient were optimal features for mapping rice. This study provided vital technical supports for feature optimization by using SAR imagery in cloudy and rainy regions to identify single and double cropping rice accurately.

    Mechanisms Analysis on Yield Gap and Nitrogen Use Efficiency Gap of Winter Wheat in Shandong Province
    HAN ShouWei,SI JiSheng,YU WeiBao,KONG LingAn,ZHANG Bin,WANG FaHong,ZHANG HaiLin,ZHAO Xin,LI HuaWei,MENG Yu
    Scientia Agricultura Sinica. 2022, 55(16):  3110-3122.  doi:10.3864/j.issn.0578-1752.2022.16.004
    Abstract ( 337 )   HTML ( 14 )   PDF (684KB) ( 337 )   Save
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    【Objective】 Four planting patterns were designed based on survey data to simulate four different yield levels of winter wheat to quantify the yield gap and nitrogen use efficiency gap in Shandong province, to analyze the relationship between yield gap and nitrogen use efficiency gap, and to clarify the contribution of the environment, cultivation conditions and physiological parameters to the yield gap, so as to explore possible ways to synergistically narrow yield gap and increase resource utilization efficiency. 【Method】 This experiment was carried out in Jining, Dezhou, Yantai and Zibo in Shandong from 2016 to 2020. Four treatments were set through comprehensive management measures, such as selection of varieties, fertilizer input, planting density, and irrigation level, which were super-high yield level (SH), high-yield and high-efficiency level (HH), farmer level (FP), and basic yield level (ISP). The yield gap and nitrogen use efficiency gap between different yield levels were analyzed quantitatively to explore the influencing factors of yield gap and nitrogen use efficiency gap and the way to narrow yield gap and increase nitrogen use efficiency. 【Result】 The yield gap between the current high-yield record of wheat in Shandong and SH, SH and HH, HH and FP, FP and ISP were 2 729.1, 674.3, 1 042.9 and 4 349.8 kg·hm-2, respectively. The partial production efficiency gap of nitrogen between SH and HH, HH and FP were -13.54 and 15.67 kg·kg-1, respectively. There was a quadratic equation between the yield and the partial production efficiency of nitrogen. The contribution rate of the current uncontrollable factors (precipitation, temperature, etc.) and controllable factors (resource input, etc.) to the yield gap were 31.16% and 68.84%, respectively. The results showed that the gap of mean leaf area index (MLAI), mean net assimilation rate (MNAR), ear number per unit area (EN) and grain weight (GW) were significantly positively correlated with the yield gap between SH and HH (YG). The gap of harvest index (HI), grain number per spike (GN) and grain weight (GW) were positively correlated with the yield gap between HH and FP (YG). SH and HH treatments had higher aboveground biomass, number of ears per plant and percentage of earring-tillers than FP treatment. 【Conclusion】 At present, the yield level of winter wheat of farmers in Shandong had only achieved 64.34% of the highest recorded yield. Cultivation measures, such as optimizing fertilizer and water input, increasing the proportion of topdressing, and increasing the application of organic fertilizer and zinc fertilizer, could reduce the yield gap by 23.46%, and increase the partial production efficiency of nitrogen by 56.99%. The post-anthesis material production capacity was still the limiting factor for wheat yield improvement. However, when ensuring the light contract after anthesis, increasing the re-transportation of pre-anthesis stored dry matter to improve the harvest index was an effective measure to synergistically improve yield and nitrogen use efficiency.

    Effects of Row Spacing and Plant Density on Grain Yield and Quality of Grain-Feeding Sorghum
    WANG JinSong,DONG ErWei,LIU QiuXia,WU AiLian,WANG Yuan,WANG LiGe,JIAO XiaoYan
    Scientia Agricultura Sinica. 2022, 55(16):  3123-3133.  doi:10.3864/j.issn.0578-1752.2022.16.005
    Abstract ( 448 )   HTML ( 15 )   PDF (517KB) ( 418 )   Save
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    【Objective】This study was conducted to clarify effects of different row spacings and planting densities on the development, yield, grain quality and NPK (nitrogen, phosphorus and potassium) accumulation of grain-feeding sorghum, and to identify the optimal cultivation mode in agro-pastoral ecozone of Shanxi, so as to provide the theoretical basis for the grain-feeding sorghum cultivation. 【Method】A new grain-feeding sorghum variety Liaoxialiang No. 1 was selected for this study. Field experiments were conducted during 2018 and 2019. Three row spacings were set, i.e. 30, 50, and 60 cm, respectively. And there were four planting densities (13.5×104, 16.5×104, 19.5×104 and 22.5×104 plants/hm2) at each row spacing. The plant height and biomass at heading stage, grain yield, NPK accumulation at harvest and grain quality in different row spacings and planting densities were analyzed. 【Result】There were significantly effects of row spacing, planting density and their interaction on the grain-feeding sorghum growth, nutrient accumulation, grain yield and quality. As plant density increased, the plant height, biomass and NPK accumulation at heading stage were increased. However, the biomass produced after heading, biomass and NPK accumulation at harvest, along with yield, increased first and then decreased with the increase of density under row spacing with 50 and 60 cm; Actually, the grain yield of feeding sorghum was positively correlated with biomass and N accumulation at harvest and the biomass produced after heading. The average grain yield, N and P accumulation and biomass after heading in row spacing of 50 cm were higher than those of 60 and 30 cm. Among the 12 treatments, the treatment with row spacing of 50 cm, planting density of 16.5×104 plants/hm2 had improved biomass and N accumulation at harvest, which were increased by 3.6%-12.8% and 3.6%-18.6%, respectively, relative to the average value of the total 12 treatments. The grain yield with row spacing of 50 cm and planting density of 16.5×104 plants/hm2 was the highest among all treatments, and they were 10 814 kg·hm-2 in 2018 and 12 434 kg·hm-2 in 2019, respectively. Starch and protein content of grain decreased with planting density increasing, but the influence of row spacing variation on them were less. Grain tannin content was significantly increased with planting density adding, while the row spacing increase also promoted tannin content. The influence of row spacing and planting density on tannin content was obvious, compared with those on starch and protein. Those treatments with row spacing of 50 cm and density of 16.5×104 plants/hm2 had similar tannin content with the average value of different treatments. 【Conclusion】Both N accumulation and biomass production after heading were important for high grain yield of feeding sorghum. The appropriate plant spacing under different row spacings could improve feeding sorghum grain yield, but affect grain quality, especially the tannin content. Row spacing of 50 cm and density of 16.5×104 plants/hm2 was recommended in agro-pastoral ecozone in Shanxi (with variety of Liaoxialiang No.1) in terms of grain yield and quality of feeding sorghum.

    PLANT PROTECTION
    Identification and Functional Analysis of StSCD Family in Setosphaeria turcica
    HAO YuBin,LI HaiXiao,ZHANG Sai,LIU Ning,LIU YingZi,CAO ZhiYan,DONG JinGao
    Scientia Agricultura Sinica. 2022, 55(16):  3134-3143.  doi:10.3864/j.issn.0578-1752.2022.16.006
    Abstract ( 289 )   HTML ( 49 )   PDF (3556KB) ( 191 )   Save
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    【Objective】Scytalone dehydratase (SCD) is a key enzyme in melanin synthesis. The objective of this study is to identify the StSCD gene family of Setosphaeria turcica, and to analyze the differences in the expression of StSCD gene family during the appressorium development of S. turcica and the effect of SCD inhibitors on melanin synthesis, which will lay a foundation for further study on the important role of StSCD gene family in melanin synthesis and appressorium development. 【Method】Using the whole genome data of the wild-type strain 01-23 of S. turcica, the complete sequence of the StSCD gene family was obtained, and the protein sequences were compared with the SCD of Cochlibolus heterostrophus, Pyricularia oryzae, Colletotrichum lagenaria and other fungi. Materials from different appressorium developmental stages were collected for qRT-PCR analysis to obtain the expression levels of different StSCD genes at different stages, so as to determine the important dehydratase genes closely related to pathogen infection and appressorium melanization. Carpropamid, an inhibitor of SCD, was used to treat S. turcica, and the colony growth rate, melanin production and appressorium turgor pressure were measured, so as to determine the important function of SCD in appressorium development. 【Result】Four StSCD genes were found by searching the whole genome of S. turcica, the encoded protein of them has SCD conserved domain and conserved catalytic and substrate binding amino acid residues. StSCD3 protein has high homology with the functionally redundant SCD2 protein of Botrytis cinerea, and StSCD4 has high homology with SCD protein of Corynespora cassiicola. By analyzing the expression levels of StSCD genes at different stages during the growth and development of the pathogen, it was found that the expression levels of four StSCD genes were all up-regulated at the appressorium stage, and the expression levels of StSCD3 and StSCD4 were particularly up-regulated. The expression levels of StSCD3 and StSCD4 in the regenerated hyphae of the appressorium were significantly decreased, and the expression levels of StSCD4 were higher during the whole period of appressorium induction. The melanin synthesis was blocked and the appressorium turgor pressure was significantly reduced after carpropamid treatment. 【Conclusion】There are four StSCD genes in S. turcica. It is speculated that StSCD4 is involved in the synthesis of DHN melanin, and then affects the accumulation of appressorium turgor pressure.

    Function of Sugar Transport Protein SlSTP2 in Tomato Defense Against Bacterial Leaf Spot
    LI YiMei,WANG Jiao,WANG Ping,SHI Kai
    Scientia Agricultura Sinica. 2022, 55(16):  3144-3154.  doi:10.3864/j.issn.0578-1752.2022.16.007
    Abstract ( 312 )   HTML ( 37 )   PDF (2666KB) ( 140 )   Save
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    【Background】In recent years, tomato diseases occur frequently in open field and protected cultivation due to the suboptimal environmental conditions. Tomato bacterial leaf spot caused by Pseudomonas syringae pv. tomato (Pst) is a common bacterial disease, which severely affects the yield and quality of tomato. Sugar is an important signaling molecule as well as nutrient substance in plants. When plants are subjected to pathogen attack, sugar not only functions as a signal to regulate the plant defense, but also provides energy for immune responses as a main carbon source. Sugar transport protein (STP) family is responsible for the sugar transport, and plays an important role in plant growth, development and defense. 【Objective】The objective of this study is to clarify whether STP family is involved in the regulation of plant defense against bacterial leaf spot. 【Method】CR (Solanum lycopersicum cv. Condine Red) was used as the wild-type (WT) background in this study. The responses of STP gene family to Pst DC3000 were determined by Pst DC3000 inoculation. The SlSTP2, which was up-regulated most significantly after Pst DC3000 inoculation, was selected for further investigation. The Slstp2 homozygous mutant and overexpression materials were generated. To explore the role of SlSTP2 in plant defense against bacterial leaf spot, WT and Slstp2 mutants, OE:SlSTP2 plants were inoculated with Pst DC3000, then the disease symptoms were assessed by disease-associated cell death and bacterial growth as well as the photochemical efficiency. In order to explore the potential mechanism of SlSTP2 in the disease resistance, the interacting proteins were screened by bimolecular fluorescence complementary (BiFC) assay. The mutant and overexpression materials of candidate interacting protein were generated and inoculated with Pst DC3000 to investigate its role in plant defense against bacterial leaf spot. 【Result】After inoculation with Pst DC3000 on tomato plants, the expressions of SlSTP1 and SlSTP2 were up-regulated. SlSTP2 was up-regulated most significantly, so it was selected for further investigation and its mutant and overexpression materials were generated. WT and Slstp2 mutants, OE:SlSTP2 plants were subjected to Pst DC3000 inoculation. Compared with WT plants, Slstp2 mutants showed significantly increased susceptibility, as evidenced by more severe disease symptoms, increased disease-associated cell death, an enhanced bacterial population and a decreased photochemical efficiency in the leaves. On the contrary, OE:SlSTP2 plants showed enhanced defense against Pst DC3000 compared with WT plants. It was further found that SlSTP2 interacted with the G protein β subunit SlAGB1 using BiFC assay. Similar to the Slstp2 mutants, the Slagb1 mutants also showed significantly increased susceptibility to Pst DC3000 compared with WT plants, and OE:SlAGB1 plants showed enhanced defense against Pst DC3000 as OE:SlSTP2 plants. 【Conclusion】SlSTP2 is significantly induced by Pst DC3000 inoculation, and positively regulates the defense against bacterial leaf spot in tomato. SlSTP2 interacts with SlAGB1, which also plays a positive role in defense against bacterial leaf spot, suggesting that SlSTP2 associated with SlAGB1 regulate tomato resistance to bacterial leaf spot.

    SOIL & FERTILIZER·WATER-SAVING IRRIGATION·AGROECOLOGY & ENVIRONMENT
    Response of Wheat Yield and Grain Nitrogen, Phosphorus and Potassium Concentrations to Test-Integrated Potassium Application and Soil Available Potassium in Northern Wheat Production Regions of China
    MA Yue,TIAN Yi,MU WenYan,ZHANG XueMei,ZHANG LuLu,YU Jie,LI YongHua,WANG HaoLin,HE Gang,SHI Mei,WANG ZhaoHui,QIU WeiHong
    Scientia Agricultura Sinica. 2022, 55(16):  3155-3169.  doi:10.3864/j.issn.0578-1752.2022.16.008
    Abstract ( 295 )   HTML ( 45 )   PDF (575KB) ( 220 )   Save
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    【Objective】It is of great importance to clarify the relationships of changes in wheat grain yield and grain nutrients absorption and distribution to test-integrated potassium (K) fertilizer application and soil available K, for the purpose of high yield, high quality, green production of wheat and saving K resources in northern wheat production region of China. 【Method】In this research, a 43-site field experiment was conducted in northern wheat region of China from 2018 to 2020, to investigate effects of test-integrated K application on grain yield, yield components, grain nitrogen (N), phosphorus (P), and K concentrations, and nutrients uptake and absorption of wheat at different soil available K levels. 【Result】The insufficient and excessive K application occurred widely in northern wheat production region. With the increase of soil available K level, the wheat yield increased significantly and reached the maximum value of 6 340 kg·hm-2 at the available K of 150-180 mg·kg-1. Excessive soil available K was not able to further increase the grain yield, and it significantly decreased to 5 409 kg·hm-2 when soil available K was higher than 180 mg·kg-1. Compared with the farmers’ fertilizer application rate (FF), the recommended K fertilizer rate (RF) by the test-integrated fertilizer application was decreased at the soil available K level of 150-180 mg·kg-1, and increased at the other levels. The RF was found to have increased the wheat yield in comparison to FF with the yield increase significant at soil available K lower than 90 mg·kg-1 and higher than 180 mg·kg-1. When the soil available P was higher than 30 mg·kg-1 and the soil available K was at 120-150 mg·kg-1 or higher than 180 mg·kg-1, the wheat yield of no K application (RF-K) showed a tendency to decrease in comparison to RF. With the increase of soil available K level, wheat grain N concentration increased significantly, but no significant difference was observed in the grain N, P, and K concentrations between FF and RF. Compared with RF, the grain N, P, and K concentrations under RF-K significantly decreased when the soil available K was higher than 180 mg·kg-1. When the soil available K was higher than 180 mg·kg-1, the K partial factor productivity and K fertilizer uptake efficiency under RF were significantly higher than those under FF. 【Conclusion】The reasonable fertilization could get high wheat yield when the soil available K was at 150-180 mg·kg-1, but the wheat yield might be reduced without K fertilization when the soil available P was higher than 30 mg·kg-1. Therefore, the K fertilizer rate should be recommended based on the target wheat yield and soil available P and K levels, for the purpose of yield stabilization, quality improvement, and efficiency increase in the northern wheat production regions of China.

    Temporal and Spatial Characteristics of Resources Input and Environmental Effects for Maize Production in the Three Provinces of Northeast China
    CHEN XuHao,GAO Qiang,CHEN XinPing,ZHANG WuShuai
    Scientia Agricultura Sinica. 2022, 55(16):  3170-3184.  doi:10.3864/j.issn.0578-1752.2022.16.009
    Abstract ( 279 )   HTML ( 43 )   PDF (541KB) ( 198 )   Save
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    【Objective】The total production of maize is the highest among the three staple grain crops in China, ranking second position in the world. The planting area of maize in the three provinces of northeast China accounts for 39% of China, while the investment of resources is relatively low. The purpose of this study is to clarify the temporal and spatial characteristics of resources input and environmental effects for maize production in the three provinces of northeast China. 【Method】 In this paper, based on the life cycle assessment (LCA) method, the reactive nitrogen loss model suitable for maize production in the three provinces of northeast China was used to quantitatively evaluate the resources input (fertilizer, pesticide and diesel oil, etc.) and related environmental risks such as reactive nitrogen losses and GHG emissions of maize production systems in Northeast China from 2007 to 2016. 【Result】The average total fertilizer application rate of maize production in Jilin Province was 400 kg·hm-2, the average yield per unit area was 7 065 kg·hm-2, the average GHG emissions per unit area was 2 965 kg CO2 eq·hm-2, all of the above were the highest in the three provinces, but the carbon and nitrogen footprint was low, and the average reactive N losses per unit area was in the middle level and changed little from year to year. The average nitrogen input of Liaoning Province was 184 kg·hm-2, the average N loss per unit area was 20.8 kg N·hm-2, and carbon and nitrogen footprint was 493 kg CO2 eq·Mg-1 and 3.53 kg N·Mg-1, respectively, all of which were the highest. The per unit yield of 5 966 kg·hm-2, was in the middle level, and the GHG emission did not change much from year to year. The average nitrogen application rate in Heilongjiang Province was 149 kg·hm-2 per unit yield, the average unit area N losses and GHG emissions were the lowest in the three provinces, while the carbon and nitrogen footprint were in the middle level. From 2008 to 2015, the planting area of maize in the three provinces of northeast China increased year by year, with a cumulative increase of 5.73 million hectares. In 2015, the total maize production of the three provinces was the highest, reaching 91.16 million tons, accounting for 32% of the country's ten-year (2007-2016) average production, of which Heilongjiang Province, Jilin Province and Liaoning Province accounted for 13.9%, 11.7%, and 6.7%, respectively. The ten-year average planting area accounted for 30% of the country, of which Heilongjiang Province, Jilin Province and Liaoning Province accounted for 14.7%, 9.3%, and 6.4%, respectively. The ten-year average maize grain yield in the three provinces of northeast China was 6 116 kg·hm-2, and the highest average yield was achieved in 2013, which was 6 824 kg·hm-2. During 2007 to 2016, the fertilizer input of maize production in the three provinces of northeast China showed an overall upward trend, nitrogen fertilizer decreased steadily, while phosphorus and potassium fertilizer increased year by year. From 2014 to 2016, the increase trend of fertilizers rate slowed down sharply and gradually became stable. The ten-year average rate of nitrogen, phosphate and potassium fertilizers were 177, 101, and 70.2 kg·hm-2, respectively. From 2007 to 2016, the pesticide input for maize production in Northeast China showed a steady upward trend, while the diesel input was relatively stable in the first four years, and then gradually increased. During the ten years of maize production in Northeast China, the average rate of pesticide used was 10.2 kg·hm-2, and that of diesel was 94.6 kg·hm-2. The average N losses and GHG emissions per unit area of maize production in 2007-2016 were 19.0 kg N·hm-2 and 2 770 kg CO2 eq·hm-2, respectively. The reactive nitrogen losses per unit area was stable from 2007 to 2016. The average GHG emissions of maize production showed a downward trend in 2007-2008 and 2009-2011, a steady upward trend in 2012-2016, and reached the highest with 3 045 kg CO2 eq·hm-2 in 2016. Ammonia volatilization caused by field application of nitrogen fertilizer was the main way of reactive nitrogen losses in maize production, followed by nitrate leaching loss, and nitrous oxide emission. The main emission sector of GHG emissions was fertilizer production, transportation and field application. During the past ten years, the average nitrogen footprint and carbon footprint of maize production in Northeast China were 3.16 kg N·Mg-1 and 459 kg CO2 eq·Mg-1, respectively. 【Conclusion】The resource inputs and environmental cost of maize production in the three provinces of northeast China were significantly different on the spatial scale. The average fertilizer input of Jilin Province was 124 kg·hm-2 higher than that of Heilongjiang Province, while the GHG emissions were 524 kg CO2 eq·hm-2 higher. In 2007-2016, the nitrogen input for maize production in the three provinces of northeast China ranged from 170 to182 kg·hm-2, N losses ranged from 18.4 to19.4 kg N·hm-2, which played a good demonstration role for the green development of agriculture in China. The carbon and nitrogen footprint of maize production mainly depended on the trade-off between resource input and yield per unit area, noticeably, the nitrogen fertilizer input had a greater impact. The spatial-temporal characteristics analysis of resource inputs and environmental effects for maize production in the three provinces of northeast China contributes to clarify the limiting factors and main controlling factors at present stage, and provides theoretical support for optimizing nutrient management to achieve win-win situation of food security and carbon emission reduction.

    Effects of Amendments on Soil Fauna Community Characteristics in a Fluvo-Aquic Sandy Soil
    YANG Jing,ZHANG He,LI ShuangShuang,LI GuiHua,ZHANG JianFeng
    Scientia Agricultura Sinica. 2022, 55(16):  3185-3199.  doi:10.3864/j.issn.0578-1752.2022.16.010
    Abstract ( 234 )   HTML ( 52 )   PDF (693KB) ( 128 )   Save
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    【Objective】 Soil fauna is an important component of terrestrial ecosystem, therefore, the studying of the relationship between soil fauna and amendments will help reveal the mechanism of amendments to soil fauna.【Method】During 2016-2019, the characteristics of the soil fauna community in the soil surface layer (0-20 cm) of wheat and maize rotation area with different amendments were investigated. There were four treatments, including no amendment (CK), organic amendment 15 t·hm-2 (YJ), inorganic amendment 2.25 t·hm-2 (WJ) and organic amendment 15 t·hm-2+inorganic amendment 2.25 t·hm-2 (YW). 【Result】During the study period, 4 351 soil fauna belonging to 8 classes, 20 orders, 41 families, and 44 classes were collected, of which 28 families were macrofauna, and the dominant groups were Asilidae and Myrmicinae, accounting for 62.9% of the total captured soil macrofauna. In another, 14 families soil meso-and micro-fauna were collected, and the dominant groups were Acarid and Oribatida, accounting for 93.0% of the total captured soil meso- and micro-fauna. Soil fauna mainly belonged to saprozoic and omnivores. The data indicated that the total number and taxa of soil fauna collected during the experiment was the highest under WJ, and the lowest under YJ. The number of Scutigerellidae, Sejidae and Japygidae decreased and their richness index decreased, while the mites increased, and the dominance index was high under amendments comparing with CK. There were significant differences in individual number and diversity index of small and medium animal communities among different years (P<0.05), and the number of individuals showed a gradually increasing trend; but the Jaccard index (q) of soil fauna was less than 0.50 among all treatments, and the similarity of macrofauna community was lower than that of meso- and micro- community. The ecological niche widths of meso- and micro- soil fauna, such as Acarid, Oribatida, and Onychiuridae, were higher than those of macrofauna, such as Myrmicinae. However, the niche overlap index was higher than 0.97, indicating that the application of amendments increased the common resources of soil fauna. The NMDS analysis showed that the soil animal community in wheat season 2018 was significantly different from that in other years, whereas, in maize season of 2016, 2018, and 2019, there were different. The results of RDA indicated that soil TN and AK were significantly correlated with Acarid, Oribatida, Onychiuridae, Enicocephalidae, Carabidaein wheat season (P<0.05); the soil organic matter and pH were main factors influencing Acarid, Enicocephalidae, Sciaridae, and Asilidae in maize season (P<0.05). The PRC analysis showed that the relative abundance of Uropodidae peaked in October 2017, and that of Asilidae and Myrmicinae peaked in October 2016 under YJ. The relative abundance of Onychiuridae, Acarid, and Oribatida reached a peak in October 2016 under the combined application of organic and inorganic amendments, and that of Phlaeothripidae and Enicocephalidae appeared in 2019 and peaked in October 2019, demonstrating the incongruity of soil fauna groups to the amendments. 【Conclusion】The variation of soil fauna community and diversity in different years were much more profound than amendments, and the amendments modified soil fauna community and diversity mainly by changing soil pH, SOM, and TN in a fluvo-aquic sandy soil.

    HORTICULTURE
    Screening and Functional Analysis in Heat-Tolerance of the Upstream Transcription Factors of Pepper CaHsfA2
    LIU RuiYao,HUANG GuoHong,LI HaiYan,LIANG MinMin,LU MingHui
    Scientia Agricultura Sinica. 2022, 55(16):  3200-3209.  doi:10.3864/j.issn.0578-1752.2022.16.011
    Abstract ( 397 )   HTML ( 41 )   PDF (2002KB) ( 219 )   Save
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    【Background】 Pepper is widely cultivated as a vegetable around the world. With the increasing frequency of extreme high temperature weather in recent years, the heat stress has become one of the main environmental factors affecting pepper productivity, due to its feature of warm-prone but heat-sensitive. Therefore, it is very important for pepper production to clarify its mechanisms supporting heat-tolerance and then to develop pepper varieties with heat tolerance. 【Objective】 Since the heat shock transcription factor HsfA2 plays important roles in plant heat tolerance, the upstream transcription factors of pepper CaHsfA2 were screened and functionally analyzed in heat-tolerance in this study, in order to provide the theoretical basis for further understanding the mechanisms of heat tolerance of pepper. 【Method】 The 955 bp promoter sequence upstream of start codon of CaHsfA2 was used as the bait, the yeast one-hybrid (Y1H) technology was applied to screen the upstream transcription factors of CaHsfA2, and their interactions were checked by Y1H point-to-point hybridization, dual-luciferase reporter system (Dual-Luciferase), and LUC assay (LCA). For the candidate upstream transcription factors of CaHsfA2, their dynamic expression under heat stress in pepper heat-tolerant line R9 were analyzed by qRT-PCR technology; the subcellular localization were fulfilled through the transient gene expression technology, and its functional analysis in heat tolerance were performed by using the virus-induced gene silencing technology (VIGS). 【Result】 CaBES1 was identified as the candidate upstream transcription factor of CaHsfA2, and their interactions were confirmed. By the analysis of Dual-Luciferase system and CaHsfA2 expression in CaBES1-silenced pepper plants, it was suggested that CaBES1 negatively regulated the transcription of CaHsfA2. The result of subcellular localization showed that CaBES1 was expressed in both cell membrane and nucleus. After heat stress treatment, the fluorescence signal in the nucleus was enhanced, which was consistent with the property of CaBES1 transferring from cytoplasm to nucleus when it performed its biological functions. By dynamic expression pattern analysis, under heat stress, the expression level of CaBES1 decreased firstly and then increased, which also indicated that CaBES1 could respond to heat signal and laid a foundation for the further functional study in heat tolerance. After CaBES1 was silenced in pepper, by comparing the phenotype, relative electrical conductivity and chlorophyll content of silenced plants and control plants, it was inferred that silencing of CaBES1 increased the expression of CaHsfA2 and enhanced the heat tolerance of pepper. 【Conclusion】 CaBES1 inhibited pepper heat tolerance by negatively regulating the expression of CaHsfA2.

    Genetic Relationship Among Citrus and Its Relatives as Revealed by cpInDel and cpSSR Marker
    YANG Cheng,GONG GuiZhi,PENG ZhuChun,CHANG ZhenZhen,YI Xuan,HONG QiBin
    Scientia Agricultura Sinica. 2022, 55(16):  3210-3223.  doi:10.3864/j.issn.0578-1752.2022.16.012
    Abstract ( 268 )   HTML ( 28 )   PDF (710KB) ( 116 )   Save
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    【Objective】The genetic diversity analysis of the chloroplast genome was performed to reveal the genetic evolution of citrus from the cytoplasmic level, so as to provide a reference for the collection, evaluation and utilization of citrus germplasm resources. 【Method】Taking the hypervariable region of Citrus sinensis chloroplast genome as reference, De Novo assemblies were carried out with next-generation sequencing data of representative Citrus and its related genera materials. The assembled sequences were aligned to discover site-variations, and cpInDel markers were designed on the basis of variation sites. SSR sites composed of two or more nucleotide repeats were located in the chloroplast genome of sweet orange, and SSR sites with length variations were adopted to design cpSSR markers. The newly developed markers and reported cpSSR markers were used to detect genetic diversity in 48 samples of Citrus and its relatives that are representative in taxonomy and/or origin through band typing and clustering analysis. 【Result】4 cpInDel markers and 13 cpSSR markers were developed successfully and they could produce clear polymorphic bands in all tested samples. The band pattern of cpIndel was relatively simple. Single marker could distinguish a specific genus or several genera. At species and/or above taxa level, the cpInDel markers gave more convenient and accurate discrimination effect. Similar clustering results were obtained with cpInDel and cpSSR markers, and minor differences were found in the relationship between the lower-rank taxa and the classification of a few genotypes. The cytoplasmic origins of P. trifoliate hybrids were found to be different from P. trifoliata, and those of lemon, limonia and lime hybrid were different from C. medica by both markers. Wangcang zhoupigan, a representative variety of C. speciosa, had a different cytoplasmic origin from other mandarin varieties. Ziyang xiangcheng and Korean xiangcheng, both classified as C. junos, might have different cytoplasmic origin. cpSSR markers classify mandarin, sweet orange and sour orange, ichang papeda and honghe papeda into three clusters, representing C. reticulata, C. sinensis and Papeda, while cpInDel markers showed that they were closely related and classified into one cluster. Indian wild mandarin were clustered into C. medica by cpInDel, and were put into a single cluster by cpSSR. 【Conclusion】Molecular marker analysis of chloroplast genome could reveal the genetic relationship of Citrus and its related genera and discover a different relationship from the view of nuclear genome. However, if combined with markers from nuclear genome, more comprehensive and accurate indentification and phylogenetic relationship revealing should be obtained for the citrus germplasm resources.

    FOOD SCIENCE AND ENGINEERING
    Flavor Escape Behavior of Stewed Beef with Soy Sauce During Air-Cooling and Refrigeration
    QIANG Yu, JIANG Wei, LIU ChengJiang, HUANG Feng, HAN Dong, ZHANG ChunHui
    Scientia Agricultura Sinica. 2022, 55(16):  3224-3241.  doi:10.3864/j.issn.0578-1752.2022.16.013
    Abstract ( 229 )   HTML ( 26 )   PDF (1427KB) ( 119 )   Save
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    【Objective】This study clarified the escape behavior of key volatile compounds in stewed beef with soy sauce during air-cooling process and refrigeration, aiming to provide the theoretical basis for the flavor preservation and conformity of stewed beef with soy sauce. 【Method】 The volatile flavors in stewed beef with soy sauce were identified by the electronic nose (E-nose) and headspace solid-phase microextraction gas chromatography-mass spectrometry (HS-SPME/GC-MS) combined with odor activity value (OAV) and principal component analysis (PCA), which defined the dynamic change of flavors during cold air-cooling process (the central temperature was reduced from 50℃ to 10℃, the wind speed was 2 m∙s-1, and the cooling time was 90 minutes) and refrigeration (0, 6, 18, 30, 42 and 54 h at 4℃). Then the escape behavior of key flavor active compounds in stewed beef with soy sauce were revealed. 【Result】According to the E-nose analysis, the flavor profiles of stewed beef with soy sauce exhibited significant differences among the three stages (“out of the pot”, before air-cooling and after air-cooling). Nitrogen oxides, alcohols, aldehydes, ketones, aromatics and organic sulfides were considered the main compounds for the discrepancy. On the other side, the stewed beef with soy sauce after 0, 42 and 54 h refrigeration showed differential flavor profiles, which mainly caused by the variety in nitrogen compounds, alcohols, aldehydes and ketones. However, there was no significant difference in the flavor profiles among 6, 18 and 30 h refrigeration. The HS-SPME-GC-MS results showed that 39, 31 and 33 volatile compounds were identified in three cold air-cooling stages, and the contents were 13 636.18, 9 799.21 and 8 213.86 μg∙kg-1, respectively, with total amounts reducing by 39.8%. Morever, 36, 36, 34, 34, 31 and 29 volatile compounds were identified on different refrigeration periods, the contents were 7 712.65, 6 196.00, 5 319.42, 4 732.69, 5 295.05 and 4 281.82 μg∙kg-1, respectively, and the total contents decreased by 44.5%. Therefore, the flavor escape of stewed beef with soy sauce mainly occurred in the refrigeration stage. Besides, OAV analysis showed stewed beef with soy sauce in the cold air-cooling stage had 18 key active compounds, while eucalyptol, lauryl alcohol, valeraldehyde, and L-carvone were all lost before cold air-cooling, and acetoin, phenethyl alcohol, geranyl acetone, as well as linalool escaped severely, with their OAV values reducing by 81.3%, 64.0%, 63.7% and 55.1%, respectively. 15 key active volatile compounds were identified during refrigeration. Among them, isobutyl acetate and ethyl heptanoate were lost after 6 h. Anethole, eugenol, 4-allylanisole, and linalool were severely escaped, and the OAV values decreased by 63.9%, 63.8%, 58.1% and 53.9%, respectively. Refrigeration was the main stage for the loss and dissipation of flavor compounds in stewed beef with soy sauce; alcohols, ketones, esters and phenolic ethers were more susceptible to lose and escape during air-cooling and refrigeration; the loss and dissipation of flavor compounds were mainly derived from spices. 【Conclusion】This study revealed the escape behavior of flavor active compounds in stewed beef with soy sauce during air-cooling process and refrigeration, and provide the theoretical basis for stewed beef's flavor retention and regulation with soy sauce.

    ANIMAL SCIENCE·VETERINARY SCIENCE
    Non-Starch Polysaccharide Enzymes Cocktail of Corn-Miscellaneous Meal-Based Diet Optimization by In Vitro Method and Its Effects on Intestinal Microbiome in Finishing Pigs
    DENG FuLi,SHEN Dan,ZHONG RuQing,ZHANG ShunFen,LI Tao,SUN ShuDong,CHEN Liang,ZHANG HongFu
    Scientia Agricultura Sinica. 2022, 55(16):  3242-3255.  doi:10.3864/j.issn.0578-1752.2022.16.014
    Abstract ( 478 )   HTML ( 40 )   PDF (861KB) ( 124 )   Save
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    【Objective】 The objective of this study was to optimize the non-starch polysaccharide (NSP) enzymes cocktail of the corn-miscellaneous meal-based diet for finishing pigs by using in vitro simulation method, and to analyze the effects of the optimal NSP enzymes cocktail (OEC) on dietary nutrient digestibility and intestinal microbial composition and structure of finishing pigs. Finally, it could provide data support and theoretical reference for efficient utilization of diets and precise feeding. 【Method】 In experiment 1, different levels of six NSP enzymes (xylanase, β-glucanase, cellulase, α-galactosidase, β-mannanase, and pectinase) were individually and respectively added to the corn-miscellaneous meal-based diet of finishing pigs. Then, in vitro ileal dry matter digestibility (IVIDMD) was determined by gastric-small intestinal simulation digestion method in vitro. When IVIDMD reached the maximum, the supplemental level of each NSP enzyme was the coding level of NSP enzyme 0. In vitro digestion experiments were carried out according to the six-element quadratic regression orthogonal rotation combination design. Meanwhile, the optimal NSP enzymes cocktail (OEC) of the corn-miscellaneous meal-based diet was selected by establishing the six-element quadratic regression equation between IVIDMD and the supplemental level of NSP enzymes. The in vitro dry matter digestibility (IVDMD), in vitro gross energy digestibility (IVGED) and in vitro digestible energy (IVDE) of diets before and after OEC addition were determined by gastric-small intestinal-large intestinal simulation digestion method in vitro to verify the effect of OEC. In experiment 2, 16 healthy castrated barrows (117.8 ± 1.66 kg) with similar body weight were randomly divided into two groups with eight pigs in each group. The pigs in the control group were fed the corn-miscellaneous meal-based diet, and the pigs in the enzyme-addition group were fed the basal diet supplemented with OEC. On the 18th day of the experiment, the fresh feces of pigs were collected by rectal wiping method, and the diversity and relative abundance of fecal microbiome were analyzed by high-throughput sequencing analysis of 16S rRNA gene, and the function was predicted. 【Result】 (1) Under the conditions of this experiment, the optimized NSP enzymes cocktail of corn-miscellaneous meal-based diet was as follows: cellulase 1 003 U·kg-1, xylanase 18 076 U·kg-1, β-glucanase 1 377 U·kg-1, β-mannanase 14 765 U·kg-1, α-galactosidase 337 U·kg-1, and pectinase 138 U·kg-1. (2) Adding NSP enzymes cocktail optimized by in vitro method in corn-miscellaneous meal-based diet significantly increased the IVDMD from 73.44% to 76.26% (P<0.01), the IVGED from 74.03% to 76.45% (P = 0.01), and the IVDE from 14.97 MJ·kg-1 to 15.58 MJ·kg-1 (P<0.01). (3) At the phylum level, a total of 12 phyla with relative abundances greater than 0.1% were selected, among which Bacteroidetes, Firmicutes, and Spirochetes were the dominant phyla, and the sum of these three phyla accounted for more than 96% in the group. (4) At the genus level, adding OEC in the diet significantly increased the relative abundance of Norank_F_F082, Norank_F_Bacteroidales_ RF16_group, Bacteroides and Roseburia (P<0.05), and Eubacterium_ruminantium_group (P = 0.083) had an increasing trend, while the relative abundance of Oscillibacter decreased significantly (P<0.05), and Clostridium_Sensu_Stricto_1 and Norank_F__Norank_O__ WCHB1-41 (P = 0.083) showed a decreasing trend (P = 0.052). 【Conclusion】 Dietary non-starch polysaccharide enzymes cocktail optimization by in vitro method increased in vitro digestibility of dry matter and energy and in vitro digestible energy of corn-miscellaneous meal-based diets in finishing pigs. It also increased the proportion of beneficial bacteria in intestinal microorganism, such as fiber decompose bacteria and butyric acid producing bacteria, and reduced the number of harmful bacteria to a certain extent, and optimized intestinal microecology.

    Preparation and Identification of Monoclonal Antibodies to P30 Protein and Establishment of Blocking ELISA to Detecting Antibodies Against African Swine Fever Virus
    ZHANG FengXi,XIAO Qi,ZHU JiaPing,YIN LiHong,ZHAO XiaLing,YAN MingShuai,XU JinHua,WEN LiBin,NIU JiaQiang,HE KongWang
    Scientia Agricultura Sinica. 2022, 55(16):  3256-3266.  doi:10.3864/j.issn.0578-1752.2022.16.015
    Abstract ( 551 )   HTML ( 52 )   PDF (1870KB) ( 187 )   Save
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    【Background】 African swine fever (ASF) first appeared in China in August 2018, causing great harm to the pig industry and heavy losses. At present, there is no safe and effective vaccine to prevent ASF, so the establishment of rapid and specific detection method provides an effective means for the prevention and control of ASF. 【Objective】To prepare specific monoclonal antibodies against African swine fever virus (ASFV) and establish a rapid and specific detection method for ASF. Provide technical means for the detection and prevention and control of ASF. 【Method】The expression vector pET-28a-P30 was constructed and the rP30 protein was obtained by prokaryotic expression system. The purified rP30 protein was used as antigen to immunize BALB/c mice. The specific hybridoma cell line of ASFV P30 protein was prepared by cell fusion and cell subcloning. The truncated expression of P30 protein was performed, and Western Blot and indirect enzyme-linked immunosorbent assay (iELISA) were used to identify the antigen epitope corresponding to the monoclonal antibody. The prepared monoclonal antibody was used to establish the detection method of blocking ELISA antibody for ASF. 【Result】 The results of double digestion and PCR showed that the recombinant vector pET-28a-P30 was constructed, and the sequence was not mutated by sequencing. After IPTG induction, the recombinant P30 protein was mainly expressed in the inclusion body with a molecular weight of about 33 kD. The purified P30 protein was mixed with 1﹕1 Freund's adjuvant to immunize mice. After three immunizations, the serum titer of mice reached 1﹕102 400, indicating that the expressed protein had good immunogenicity. Eight P30 protein-specific hybridoma cells were obtained by cell fusion and subcloning. The eight monoclonal antibodies obtained by Western Blot and indirect immunofluorescence assay (IFA) showed good reactivity. The superposition test showed that all the 8 monoclonal antibodies had the same antigenic sites. Different fragments of P30 protein were truncated, and the prepared 2-12B monoclonal antibodies were selected to react with different truncated P30 proteins, showing that the antigenic epitope region of the monoclonal antibodies was 187-194aa. The ASF blocking ELISA antibody detection method was successfully established by using 2-12B monoclonal antibody and optimizing the conditions. 190 clinical samples were detected and compared with commercial African swine fever ELISA antibody detection kit. The positive coincidence rate of the two methods was 90.91 %, and the total coincidence rate was 96.32 %. 【Conclusion】 In this study, ASFV P30 protein was successfully obtained. Eight specific monoclonal antibodies with good reactivity were screened by iELISA, Western Blot and IFA, and the antigen recognition epitopes were 187-194 aa. The monoclonal antibody was used to establish a high specificity and sensitivity ASFV blocking ELISA antibody detection method, which provided a means and support for the detection and prevention of ASF.