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    15 June 2020, Volume 22 Issue 6
    Effect of COVID-19 Epidemic on Beef Cattle Production and Countermeasures in China
    ZHAO Chunping, ZAN Linsen*
    2020, 22(6):  1-5.  DOI: 10.13304/j.nykjdb.2020.0122
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    To investigate the effect of COVID-19 on beef cattle production in China, in February 2020, 263 beef cattle farms in 21 provinces of China were surveyed, covering the main areas of beef cattle production. The results showed that COVID-19 had a serious impact on Chinese beef cattle industry. In forage stock, 48% of the beef cattle farms had surpluses for 1 month; 45% had less than 2 months of forage, and 95% had run out of by-products, such as distillers grains. In fattening production, 95% of fattening cattle farms cannot buy stocker cattle as planned. The delay to sell fattening cattle increased the consumption of feed and forage. The markets for live cattle were closed, causing the decrease of cattle prices. In reproduction, brood cows missed one or two estrus cycles. In disease prevention and control, 70% of cattle farms almost ran out of medicines, and immunities cannot be carried out as planned. To solve these prominent problems, it was suggested that beef cattle farms should seriously implement the prevention and control requirements to ensure safety; prepare alternative plans for epidemic prevention and control in advance; improve the fine feeding and management system and standardized workflow, adjust the business strategy, etc. Additionally, it was also suggested that all layers of governments should open green channels for the farms to ensure the transportation of production means and products, supply special subsidy policies, and provide loans to help farm enhance confidence and resume production.
    Impact of COVID-19 Epidemic on Chinas Pig Industry #br# and Countermeasures
    WANG Zuli
    2020, 22(6):  6-11.  DOI: 10.13304/j.nykjdb.2020.0344
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    The impact of COVID-19 epidemic on Chinas pig industry was analyzed from pig production, pork consumption and pig prices. The results showed that the epidemic led to the poor circulation of feed and livestock products, the increase of operating costs of breeding enterprises, the difficulty of starting work of feed enterprises and slaughtering enterprises, etc., which significantly hindered the recovery process of pig production capacity, and affect the realization of the goal of pig production capacity recovery throughout the year; the total consumption and outdoor consumption of pork decreased significantly, but the proportion of pork consumption added indirectly With the consumption of poultry meat and eggs increased, the price of pigs increased in general and the regional price gap widened. In the short term, the pig industry wouldface the problems of the situation that prevention of Africa swine fever was still severe and the support policies fall into the “difficulties of grass-roots implementation”, and so on. Based on this, policy suggestions were put forward.
    Influence of COVID-19 Epidemic on Chinas Grain Industry
    SONG Lili§, ZHANG Lin§, YANG Yantao§, HOU Liwei, WANG Guogang
    2020, 22(6):  12-16.  DOI: 10.13304/j.nykjdb.2020.0359
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    The COVID-19 epidemic has caused different effects on Chinas grain production and peoples lives. In order to promote the orderly development of grain production and ensure food security, this paper studied the impact of the COVID-19 epidemic on Chinas grain industry. It was found that under the epidemic situation, agricultural employment was difficult, the supply of agricultural materials was tight, traditional technology services to the countryside stagnated, and cross regional farming was blocked. In addition, diseases and insect pests were reappearing, and the international situation was more complex and changeable in this year. The pressure and challenge to stabilize grain production  increased. Therefore, this paper suggested that food security should be taken as the top priority. In order to further ensure Chinas food security, we showed recover spring tillage production and area  double cropping rice, ensure the smooth passage of important materials, provide multiform agricultural science and technology services, improve the early warning mechanisms of domestic and international markets, and build a new support system for grain production.
    Cloning and Functional Analysis of Ghuhrf1 Gene and Promoter from Gossypium hirsutum
    YANG Jiangtao1,2,WANG Xujing1*,HASI Agula2,WANG Zhixing1*
    2020, 22(6):  17-25.  DOI: 10.13304/j.nykjdb.2019.0115
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    The absence of excellent gene and promoter is one of the main factors to restrict the development of genetic engineering in cotton fiber improvement. By analyzing the differential expression profiles in transcriptome databases, it was found that Ghuhrf1 was the dominant expressed at 0 DPA (days post anthesis) flowering in ovules, so it was speculated to be involved in the synthesis of cotton fibers. The fulllength cDNA of Ghuhrf1 gene was cloned by RACE techniques according EST sequence. Realtime PCR analysis indicated that Ghuhrf1 was significantly expressed at the initial stage of fiber cell differentiation. 1 417 bp sequence of Ghuhrf1 promoter was cloned according to the homologous sequence. There were lots of cis-acting factors and the tissue specific regulation elements, such as GCbox, CAATbox, CATbox, CCGTCCbox and ACGTmotif. Based on the distribution of the regulatory elements, four truncations of Ghuhrf1Pro were obtained and transformed into tobacco and Arabidopsis thaliana through Agrobacterium. The results of GUS histochemical staining indicated that the fulllength promoter Ghuhrf1Pro and the truncations Pro1(-1 180~+226 bp), Pro2 (-867~+226 bp), and Pro3 (-726~+226 bp) could specifically drive the gus gene to express in the differentiated and vigorous growth sites of the leaf tip and petiole base of the transgenic Arabidopsis thaliana, which indicated the meristem expressionrelated CATbox and CCGTCCbox elements played important roles in Ghuhrf1 promoter. At the same time, the promoter deletion analysis further indicated that the Ghuhrf1 gene might not be directly involved in the synthesis of cotton fiber, but indirectly involved in the regulation of the initiation of cotton fiber primitive cell differentiation. Above results provided reference for understanding Ghuhrf1 and regulatory elements for genetic engineering of cotton fiber quality improvement.
    QTL Mapping and Function Analysis of Candidate Genes  Related to  Plant Height in Flax
    SONG Xiaxia1, WANG Limin2, ZHANG Jianping2, ZHANG Tianbao1, LIU Caiyue1, LONG Yan1*, PEI Xinwu1
    2020, 22(6):  26-32.  DOI: 10.13304/j.nykjdb.2020.0142
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    Linseed flax (Linum usitatissimum L.) is one of the main oil crops in China, with strong drought tolerance, cold resistance and resistance to poverty characteristics. Plant height not only affects the yield of flax, but also relates to plant lodging and seed quality. This study used a recombinant inbred line population  consisting of 155 lines as experimental materials, which was constructed with Macbeth and Heiya 14 as parents, to analyze the plant height traits in Lanzhou and Jingtai at Gansu province, Yuanmou at Yunan province and Langfang at Hebei province. The QTL-seq based on high-throughput sequencing and the traditional QTL localization method were used to locate the QTL of flax plant height, and a main effect gene of plant height, LuCWINV1-1, was obtained. It belonged to the cell wall invertase of acid invertase and contained the conserved domains NDPNG, RDP and MWECP. There was mutation  in genome sequence of LuCWINV1-1 between the parents, which resulted the 21st glutamate and 523rd isoleucine in Macbeth were glycine and alanine in Heiya 14, respectively. By transformed into Arabidopsis, it was found that the plant height overexpressed LuCWINV1-1Mac became higher, while the plant height overexpressed LuCWINV-11 Hei became lower, which indicated that the gene controlled the plant height in flax. Those results laid a foundation for analyzing the mechanism of plant height in flax, and also explored that QTL-SEQ could be used to clone QTL candidate genes quickly and effectively in this small genome crop, which provided technical support for the subsequent identification of genes controlling the important agronomic characters of flax.
    Plant Growth-Promoting Activities of Endophytic Nitrogen-Fixing Bacteria Isolated From Seedlings of Faba Bean (Vicia faba L.)
    WANG Xinnan1, LUO Jiahao1, HAO Junjie2, ZHANG Xiaoyan2, LIU Lu1, FU Liping1, WANG Jialin1, HAN Yanhong3, LIU Quanlan1*
    2020, 22(6):  33-39.  DOI: 10.13304/j.nykjdb.2019.0439
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    In order to study plant growth-promoting activities of endophytic nitrogen-fixing bacteria in faba bean tissues, the related bacteria were isolated from leaves and roots of faba beans’ seedling and analyzed the relationship between the ability of dissolving phosphate and potassium and the ability of nitrogen fixation, cellulase production and pectinase production of these bacteria to identify potential strain that promote plant growth through.  8 strains were isolated from the seedling, in which 7 strains could dissolve inorganic phosphorus, 2 strains could dissolve potassium, 4 strains could product cellulose and 2 strains could product pectase. Sl24-3 from leaves had the highest activity of nitrogenase, and the secretory ability of cellulase and pectinase; SR23-1 had the ability of dissolving inorganic phosphorus and potassium. These results showed that nitrogen fixing bacteria in Vicia faba seedlings obviously promoted the growth, among which SL24-3 and SR23-1 were potential dominant growth promoting bacteria. This study  excavated the potential excellent growth promoting bacteria, which provided the theoretical basis for the in-depth study of endophyte promoting plant growth, and had practical value and significance.
    Isolation of Endophytic Cultures From Sesbania cannabina Seeds and Their Effects on Germination
    ZHANG Kaiye1,2, LIU Xiaolin2, DONG Xiaoyan2,3, LIU Runjin4, HE Liheng1*, XIE Zhihong2,3*
    2020, 22(6):  40-48.  DOI: 10.13304/j.nykjdb.2020.0127
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    Plant-microorganism combined bioremediation is important for saline-alkali land remediation, and the key  is to obtain effective microbial strain. In order to obtain more resources of plant growth promoting bacteria (PGPB), the cultivable endophytes of S. cannabina seeds were used to isolate endophytic culture. 79 strains were isolated from S. cannabina seeds, belonging to Bacillus, Azorhizobium, Cellulosimicrobium. Six strains producted IAA were selected to measure the phosphate solubilization and siderophore production. SC45, SC59, SC60 had phosphate solubilization, among them, SC60 had the highest production with (207.9±14.29) mg·L-1, and SC45 had siderophore production. Germination experiment showed that six strains could promote germination potential and seed vigor. SC45, SC60, SC59 and SC17 increased the vigor coefficient of S. cannabina seeds by 13.3%, 14.1%, 29.9% and 26.7%, respectively. Soaking seeds with SC60 and SC17 strains also promoted radicle development, and the radicle ratios increased by 29.5% and 13%. Above results showed that SC60 had the IAA activity and phosphate solubilizing activity, and could be used as plant growth-promoting bacteria to promote plant radicle development and increase seed vigor, so it could be as potential PGPB to promote S. cannabina growth.
    Identification and Optimization of Fermentation Conditions of the Bacillus amyloliquefaciens HNU1 in Tropical Soil
    FU Kexin1,2, YANG Ye2*, ZENG Gengdi1
    2020, 22(6):  49-59.  DOI: 10.13304/j.nykjdb.2019.0077
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    Heavy metals are highly toxic, nondegradable, sustainable in the environment and can accumulate in the soil through food chain which result in a serious threat to the health of organisms. Although the microbial remediation has advantages of low economic cost, high efficiency and no secondary pollution, there are several disadvantages including exogenous microorganisms not easy to survive and reproduce in soil. Therefore, this study identified the strain of HNU1, an enriched copper ion bacterium, which was isolated and preserved in  previous study. The strain HNU1 was identified as Bacillus amyloliquefaciens through morphological observation, physiological and biochemical test and the analysis of 16S rDNA. Based on single factor experiment and orthogonal experimental, the optimum fermentation conditions were designed: the optimal medium contained 2 g·L-1 sucrose, 4 g·L-1 yeast extract, 6 g·L-1 tryptone, and 5 g·L-1 MgSO4. The optimum condition was pH 8.0, temperature 37 °C, inoculation quantity of 0.1%, rotation speed of 180 r·min-1, liquid volume of 25 mL and a 50 mL shake flask. In this study, the strain HNU1 was identified as Bacillus amyloliquefaciens with good properties of copper ions adsorption. Therefore, the strain HNU1 could be further developed into microbial fertilizer for the remediation of copper contaminated soil, which was of great significance for the remediation of heavy metal contaminated soil.
    Estimation of Organic Matter Content in Southern Paddy Soil Based on Airborne Hyperspectral Images
    GUO Han1, ZHANG Xu1*, LU Zhou2, TIAN Ting3, XU Feifei2,LUO Ming2, WU Zhenggui3, SUN Zhenjun5
    2020, 22(6):  60-71.  DOI: 10.13304/j.nykjdb.2019.0645
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    Organic matter spectra in paddy soils are often influenced by soil background such as water and straw. In order to weaken and remove the influence of nonorganic matter components, an estimation model of organic matter in paddy soils in southern China was constructed. In this paper, Airborne Hyperspectral (GaiaSkyMini2VN) was used as data source to extract onedimensional characteristic spectra by single and combined transformation of the original reflectance (continuum removal, inverse, logarithmic, firstorder differential, secondorder differential single transformation and inverse firstorder differential, logarithmic firstorder differential, reciprocal logarithmic combined transformation); twodimensional characteristic spectra were extracted by ratio and normalization processing of the transformed spectra; linear (multiple linear regression, partial least squares) and nonlinear(back propagation neural network and support vector machine) organic matter prediction models based on characteristic spectra were constructed to monitor the organic matter of paddy soils in Southern China. The results showed that onedimensional spectral transformation could significantly enhanced the sensitivity of spectral response to organic matter. Twodimensional spectral transformation fully mined spectral information, enhanced the intrinsic relationship between organic matter and spectrum, and improved the modeling accuracy. Nonlinear models (BPNN, SVM), especially BPNN, had good fit for soil organic matter and high modeling accuracy. The BPNN model based on the original reflectance ratio indexhad the best modeling effect, with modeling accuracy of 0952 and testing accuracy of 0889. Above results were applicable to the monitoring of organic quality of paddy soils in southern China. It could provide important reference in feature band extraction and modeling method selection of soil organic monitoring by airborne hyperspectral spectroscopy and put forward new ideas for the management of modern agricultural development.
    Estimating Wheat Planting Density Based on Multiple Ridge Regression
    LIU Zhe, WU Wei, ZHANG Shanwen, CUI Qianqian, LI Ruiyang
    2020, 22(6):  72-80.  DOI: 10.13304/j.nykjdb.2019.0608
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    Planting density has a great impact on wheat yield, and reasonable planting density is of great significance for increasing wheat yield. Therefore, it is particularly critical to quickly and accurately estimate the wheat planting density.  This paper proposed a method for estimating wheat planting density based on multi-ridge regression. Firstly, the method transfered the acquired color image of  wheat seedling from RGB to Lab, and used the improved K-means clustering algorithm to segment the wheat seedling in the Lab color space. Secondly, 50 images of known seedling density were selected as training samples and normalized, and then the standard difference the area of the image features and contour features and LBP texture features was calaulated. The 3 characteristic parameters and known features were obtained. As training input, the density of wheat seedlings was used to obtain the functional mapping relationship between wheat seedling density and characteristic parameters. Finally, the image of the wheat seedling to be tested was processed according to the above steps, and 3 characteristic parameters of the test wheat seedling image were obtained as inputs, and substituted into the mapping function to obtain the density value of the tested wheat seedling image. The experimental results showed that when estimating the planting density of 4 different varieties of wheat, the average accuracy of wheat seedling density in single image of field wheat seedlings was 93.99%, and the average relative error was 6.01%. Compared with the existing methods of estimating wheat planting density, the estimating accuracy of this method was significantly improved.
    Study on Estimation Model of Eucalyptus Accumulation in Guangxi Based on Decision Tree Integrated Learning
    LI Xiaowei1,WU Baoguo1*,SU Xiaohui1,CHEN Yuling1,PENG Yiqin2,YU Yonghui2, FAN Xiaohu2
    2020, 22(6):  81-90.  DOI: 10.13304/j.nykjdb.2019.0900
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    Stand accumulation is an important index to measure the productivity of small stand. Taking peak forest farm in Guangxi fastgrowing eucalyptus as the research object, and two stand factors of age and density, and the slope direction, slope, slope, soil etc-site factor as the independent variables, and ha accumulation as dependent variable, this paper compared and analyzed nine choose optimal decision tree model forecast eucalyptus accumulation of different ages using the construction integration, integration, learning methods decision tree model. The results showed that: ① the ensemble learning decision tree model was more accurate than the nonensemble model, and the serial ensemble model boosting was more accurate than the parallel ensemble model bagging. In the serial ensemble model, XGboost model had the best evaluation index, and the training set R2was 081, RMSE was 044, and test set RMSE was 048, MAE was 034. ② the proportion of the importance of the independent variable in the optimal model XGboost was greater than 1%, followed by age (78%), elevation (49%), soil thickness (38%) and density (32%), in which age was much higher than the sum of the importance of other variables, the influence of vertical elevation was greater than that of horizontal slope in spatial position, and the influence of afforestation density was lower than that of soil factors. ③ the model results showed that the generalization test accuracy R2 of the same species in other areas of guangxi was 0785, and the P value was 22E-16, which met the test standard, indicating that the model had better effect in predicting the productivity of fastgrowing eucalyptus species in some areas of Guangxi, and provided a basis for forested harvest prediction of forest farms.
    Study on the Key Factors of Heat Treatment Disinfection of Pathogenic  Microorganisms in Digested Slurry From Swine Manure
    CHEN Teng, DONG Hongmin*, ZHANG Wanqin, YIN Fubin
    2020, 22(6):  91-99.  DOI: 10.13304/j.nykjdb.2019.0671
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    Farmland application and backwash of pig house are the main ways to utilize  swine manure based digested slurry from swine manure. However, the potential risk of pathogenic microorganisms exists in digested slurry produced by psychrophilic and mesophilic biogas digesters. Referring to the pasteurization technology after anaerobic fermentation in the European Union, the heat treatment disinfection method was used to disinfect the digested slurry from swine manure. In order to optimize heat treatment disinfection parameters of digested slurry, the number of coliform bacteria and fecal coliform were used as indicators to evaluate the key factors and disinfection effects of heat treatment. Based on the preliminary test of heating temperature of 50~80 ℃, the experiments were carried out using digested slurry with 3 total solids (TS) content (2%, 4%, 6%), 4 heating temperatures (525, 55, 575, 60 ℃), 3 heating time (the time from 35 ℃ to heating temperature, 15 min, 30 min), respectively. The Results showed that the heating temperature and heating time had an significant influence on the disinfection efficiency of swine manure digested slurry (P< 001), while the TS of digested slurry had no significant effect (P>005). In addition, the temperature growth rate of digested slurry decreased with the increase of total solids content in digested slurry. For digested slurry from swine manure used in this study, the average group number of coliform and fecal coliform in digested slurry were less than 1 CFU·mL-1 and 003 MPN·mL-1 after continuous heating time for 15 min at 60 ℃, respectively, which could meet the requirements of reclaimed water quality standard (SL368-2006) for pathogenic microorganisms disinfection in the reuse of reclaimed water for agriculture. The present research provided a reference for the development of disinfection technology of digested slurry from swine manure.
    Effect of Complex Antagonistic Bacteria on Controlling Strawberry Root Rot
    WANG Mengyuan1, DU Yanquan2, CAI Weiwei1, WANG Zihao2*, ZHU Jianqiang1*
    2020, 22(6):  100-110.  DOI: 10.13304/j.nykjdb.2019.0952
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    In order to obtain the antagonistic bacteria to Neopestalotiopsis clavispora, three strains of antagonistic bacteria were identified, namely Bacillus velezensis-17, Bacillus amyloliquefacen-27 and Bacillus subtilis-Y1-7, and the plate confrontation test of indoor target pathogens and the broad-spectrum verification test of biocontrol effect were performed in this paper. The microscopical observation of 10×4  and 10×10 times of the edge mycelium of the bacteriostatic circle was carried out to detect whether the metabolites of the three biocontrol bacteria contained the promoting biomass and lipopeptide active antiviral substances such as indoleacetic acid (IAA) and iron carrier. The pot and field experiments were designed to detect the effects of disease prevention, growth promotion and production increase. The results showed that: the three biocontrol strains had antagonistic effects on the target pathogens and other six pathogens, such as Botrytiscinerea Pers., and the mycelia on the edge of the inhibition zone appeared deformities such as thinning, twisting and increasing branches. The results of color test of fermentation broth showed that IAA and iron carrier were produced by the tested strains, and the crude extracellular extract of the tested strains had the effect of antagonizing N. clavispora. The above results preliminarily proved that the three biocontrol strains had the potential of promoting growth and disease resistance. Pot experiments showed that the prevention effect was better than the therapeutic effect, and the prevention effect of complex antagonistic bacteria was better than each single one, the control effect could be 73.68%. Field experiments showed it was better on both disease control and yield increasing with complex bacteria, the control effect reached 57.18%~66.00% and the yield increase of per hectare reached 12.97%~37.99%. Pot and field experiments showed that the three strains of biocontrol bacteria had the effect of promoting growth, disease control and increasing production respectively, and the compound effect of three strains of biocontrol bacteria was the best.
    MLST Analysis of Salmonella Isolates From Different Animal Sources in Yanqi County of Xinjiang
    WANG Kai, LIN Yajun, WANG Shufeng, LI Shuxian, XIANG Zhiyu, XIA Lining*
    2020, 22(6):  111-122.  DOI: 10.13304/j.nykjdb.2019.0204
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    In order to understand the drug resistance of Salmonella spp. from different animal sources to commonly used antibiotics and the distribution of drug-resistant genes in Yanqi County, Xinjiang province, as well as the relationship between drug-resistant Salmonella from different animal sources, anal swabs of chicken, cattle, pig and sheep from several farms in Yanqi County, Xinjiang were sampled, the minimum inhibitory concentration of 13 antimicrobial agents on Salmonella isolated from samples were performed using agar dilution method,and PCR was used to detect the drug-resistant strains. Then MLST method was used to analyze the relationship of Salmonella from different animals. Results showed that:  ① 110 strains of Salmonella were isolated from chicken (27.5%, 110/400), 63 strains of Salmonella were isolated from cattle (64.9%, 63/97) and 40 strains of Salmonella were isolated from swine (10.0% 40/400), 17 strains of Salmonella were isolated from sheep (6.8%, 17/250). ② The resistance rate of Salmonella isolates from cattle to ampicillin, kanamycin and florfenicol was above 50.0%, and the resistance to 7 antibiotics was the main trend, the percentage was 33.3%. The resistance rate of Salmonella from pigs to tetracycline was higher than that from other animals in  tested region, the isolates showed multiple-drug resistance with resistance to 0~7 multi-drug. ③ Carrying rate of blaTEM, blaOXA, oqxA, oqxB, aac(6′)-Ib-cr, ant(3″)-Ia, aadA2 and tetB genes in Salmonella from cattle and sheep were higher than those in chicken and pig. However, blaCMY-2, qnrB, qnrS and tetA genes were detected only in Salmonella from pig. ④ MLST analysis suggested that 8 strains of Salmonella from different animal sources were all ST34. Phylogenetic tree analysis suggested that there was a close genetic relationship between them. It was suggested that Salmonella were isolated from all animal feces in the farms investigated in Yanqi County. There was difference of resistance to the tested antibiotics between Salmonella isolates. The multi-drug resistance genes were coexistent, and  clonal transmission  existed among resistant Salmonella strains from different animal sources.
    Drug Sensitivity Analysis and Molecular Typing of Cronobacter sakazakii Isolated From Food
    ZHANG Caixia1,2, CHEN Ying2, HU Antuo3, WANG Ping2*, WANG Hongxun1*
    2020, 22(6):  123-129.  DOI: 10.13304/j.nykjdb.2019.0149
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    Cronobacter is a gram-negative bacterium, and it is the main pathogen that threatens the health of infants and children. In recent years, there have been reports of drug-resistant strains of Cronobacter in dairy products and foods. The emergence of drug-resistant strains poses great challenges for clinical treatment. In order to explore the correlation between PFGE type and drug resistance phenotype, this paper tested 68 strains of Cronobacter sakazakii for antibiotic susceptibility by BD PhoenixTM-100 automatic bacterial identification and drug susceptibility analysis system, and selected a total of 19 antibiotics, and used PFGE for molecular typing. The results showed that: 4 strains of Cronobacter sakazakii were drug-resistant, and the resistance rate was 5.88%. Among them, 3 were resistant to cefazolin, 1 to tetracycline. 18 strains showed intermediary, 16 were intermediary to cefazolin and 2 to chloramphenicol. All strains were sensitive to the remaining 16 antibiotics. 68 strains of Cronobacter sakazakii were divided into 58 PFGE type, of which PT037, PT050, PT054, PT007, PT043 and PT046 contained 4, 3, 3, 2, 2, 2 strains respectively, and the remaining 52 types each contain 1 strain, and the type was more dispersed. 3 strains of cefazolin-resistant strains contained 3 PFGE types, 18 strains of intermediate strains contained 16 PFGE types. The resistance rate of Cronobacter sakazakii food isolates detected in this study was low, and no multidrug-resistant strains were found. There was a high degree of genetic polymorphism, and no significant correlation between PFGE type and drug resistance.
    Changing Patterns of Composition and Thermodynamic Property of locust and linden honey after crystallization
    GUO Nana1§, MI Xin2§, LUO Qihua3, ZHAO Yazhou1*
    2020, 22(6):  130-137.  DOI: 10.13304/j.nykjdb.2019.0181
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    To establish a practical method for evaluating the characteristics and quality of honeys, this paper analyzed the compositions of honeys from different nectar plants (Tilia tuan and Robinia pseudoacacia)in different physical states (amorphous or crystalline), and determined the thermodynamic properties of different honeys by differential scanning calorimetry (DSC). The results showed that: Glucose and fructose contents between Tilia tuan honey and Robinia pseudoacacia honey, at either crystalline or amorphous states, were significantly different. The water activity of Tilia tuan honey samples was more favorable to yeast growth, compared with that of Robinia pseudoacacia honey. The glass transition temperature (Tg), endothermic peak temperature (Tpk) and endothermic peak enthalpy change (ΔH) could be used to effectively evaluate the crystallization degree of honeys. The thermodynamic properties of honey were significantly affected by its physical state (amorphous or crystalline), rather than its nectar plant of origin. Overall, the growth of microorganisms, especially yeast, in honey could be controlled by monitoring the water activity of honey. Thermodynamic parameters including Tg, Tpk and ΔH could be employed to determine the degree of crystallization of a specific honey.
    Effects of Topographic Factors and Land Use on the Spatial Variability of Soil Nutrients in Maoshan Watershed
    QIN Fucang, NIU Xiaole, YANG Zhenqi, MA Xin, REN Xiaotong
    2020, 22(6):  138-148.  DOI: 10.13304/j.nykjdb.2019.0120
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    Soil nutrient is the material guarantee of plant growth. Topography and human activities will affect the spatial distribution of soil characters. Taking Maoshan watershed in the black soil region of Northeast China as an example, this paper analyzed the spatial characteristics of soil nutrients by using GIS technology and geostatistics method, and also explored the effects of topographic factors, land use types and their interaction. The results showed that: ①The distribution of soil nutrients in Maoshan watershed accorded with the normal distribution. The variation coefficients of soil organic matter, alkaline hydrolysis nitrogen, available phosphorus and available potassium were 1734% ~ 4081%. ②The spatial distribution of soil nutrients increased from northwest to southeast, and the content of soil nutrients in the middle of the basin was higher than that in the east and west. ③Elevation and slope factors were negatively correlated with soil organic matter, alkaline hydrolysis nitrogen, available phosphorus and available potassium. Soil nutrients had no significant correlations with slope aspect. ④Elevation factors and land use types interactively affected soil nutrient properties. Slope, aspect factors and land use types interactively had no significant effects on these soil nutrient properties.
    Impacts of Different Manure and Chemical Fertilizer N Input Ratios on Physiological Characteristics of Leaves and Yield of Rice under Doublecropping Rice Field
    TANG Haiming, LI Chao, XIAO Xiaoping*, TANG Wenguang, CHENG Kaikai, PAN Xiaochen, WANG Ke, LI Weiyan
    2020, 22(6):  149-160.  DOI: 10.13304/j.nykjdb.2019.0146
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    In order to explore the effects of different manure nitrogen (N) input ratios on the physiological characteristics in plant leaves and grain yield of early and late rice, this paper established a field experiment in Ningxiang county of Hunan province, and investigated the protective enzyme activities and photosynthetic characteristics of early and late rice leaves, and grain yield of early and late rice. The experiment included five different fertilization treatments: without N fertilizer input as a control (M0), chemical fertilizer (M1), 30% N of organic matter plus 70% N of chemical fertilizer (M2), 50% N of organic matter plus 50% N of chemical fertilizer (M3), and 100% N of organic matter (M4). The results showed that: The activities of superoxide dismutase (superoxide dismutase, SOD), peroxidase (peroxidase, POD) and catalase (catalase, CAT) in rice leaves of M1, M2, M3 and M4 treatments were increased when compared with M0 treatment at different main growth stages of early and late rice. Meanwhile, compared with M0 treatment, the malondialdehyde (malondialdehyde, MDA) and proline (Pro) contents in rice leaves of M1, M2, M3 and M4 treatments were decreased at different main growth stages of early and late rice, respectively. ANOV indicated that the activities of SOD, POD and CAT in leaves of rice plant with M1 and M2 treatments were significantly (P<005) higher than that of the M0 treatment, and the MDA and Pro contents in leaves of rice plant with M1 and M2 treatments were significantly (P<005) lower than that of the M0 treatment at different main growth stages of early and late rice, respectively. Meanwhile, the net photosynthetic rate, transpiration rate, stomatal conductance in leaves of rice plant with M1, M2, M3 and M4 treatments were significantly (P<005) higher than that of the M0 treatment at different main growth stages of early and late rice, respectively. In 2017 and 2018, the grain yield of early rice with M1 and M2 treatments were significantly (P<005) higher than that of the M0 treatment, and the grain yield of late rice with M1 and M4 treatments were significantly (P<005) higher than that of the M0 treatment, respectively. Compared with M0 treatment, the grain yield of M1 and M2 treatments were increased by 2 0408 and 1 9728 kg·hm-2 in early season in 2017 and 2018, the grain yield of M1 and M4 treatments were increased by 2 1724 and 2 0060 kg·hm-2 in late season in 2017 and 2018, respectively. As a result, it was an effective way for improving protective enzyme activities and photosynthetic characteristics in leaves of rice plant by taken manure N input practices, which was the physiological mechanism to obtain higher grain yield of rice.
    Influence of Drought Stress on Growth and Quality of Silage Corn at Jointing Stage
    SONG Jinhui, WENG Qiaoyun, LYU Aizhi, YUAN Jincheng, LIU Yinghui*
    2020, 22(6):  161-167.  DOI: 10.13304/j.nykjdb.2019.0858
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    In order to clarify the effect of moderate and severe drought stress at jointing stage on growth character and quality of silage corn, using a grain and feed variety ‘Zhongyuandan 32’ as the experimental material, this paper performed water controlled experiments in rain shed to analyze the change trend of growth period, plant morphology, dry matter mass per plant and quality indexes of silage corn. The results showed that drought stress at the jointing stage delayed growth process of silage corn, extended the interval from jointing to silking by 2~6 d, and shortened the interval from silking to ripening by 1~4 d. Plant height and leaf area were inhibited, dry matter mass per plant, dry to fresh ratio and ear rate decreased. The content of crude protein, acid detergent fiber and neutral detergent fiber increased, the content of dry matter and starch decreased, the comprehensive evaluation indexes relative forage value and grading index decreased. The more severe drought stress was, the longer the drought stress was, the greater the impact on the above indexes of silage maize was. After rehydration, plant height and leaf area showed obvious compensation effect, but compared with normal water supply (T1), equivalent compensation could not be achieved. So drought stress at jointing stage results in slow growth decreased dry matter mass per plant and quality of silage corn.
    Impact of Millet and Soybean Intercropping on Their Photosynthetic Characteristics and Yield
    LI Zhi, WANG Hongfu*, WANG Yuyun, YANG Jing, YU Bingxing, HUANG Shanshan
    2020, 22(6):  168-175.  DOI: 10.13304/j.nykjdb.2019.0807
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    In order to explore a better intercropping model of millet with soybean, varieties ‘Nongda 8’ and ‘Jindou 25’, were selected as experimental materials for millet and soybean, on the basis of no nitrogen fertilizer, 5 treatments of intercropping ratio of millet to soybean, including 6:0 (T1), 2:4 (T2), 3:3 (T3), 4:2 (T4) and 0:6 (T5) were set up. Photosynthetic characteristics and yield of millet and soybean in different treatments were detected. The results showed that chlorophyll content of soybean in different treatments had no significant difference compared with single cropping mode. While chlorophyll content of millet in different treatments had a certain increasing trend, treatment T2 was the most increasing one. Net photosynthetic rate, transpiration rate and stomatal conductance of millet under intercropping treatments increased significantly, and treatment T2 was the best one; while these photosynthetic indexes of soybean decreased significantly. The intercellular CO2 concentration of millet under intercropping treatment decreased, while that of soybean increased. The yield of millet increased by 2%~9% in intercropping mode, while the yield of soybean decreased by 29%~33%. The intercropping treatment of millet with soybean was better than single cropping mode in whole. Among them, T2 treatment was the best one. The results had certain guiding significance for the intercropping practice of intercropping of millet with soybean.
    Effects of Nitrogen Fertilizer Application on Nutrient Accumulation, Yield and Quality of Flue-cured Tobacco
    YANG Chengcui1, XU Zhaoli2, SHI Puyou1, JIA Meng1, BAI Yuxiang1, ZHU Xuanquan1, CHENG Yadong1, YANG Huanwen1, WANG Ge1*
    2020, 22(6):  176-185.  DOI: 10.13304/j.nykjdb.2019.0325
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    To investigate the potential of reducing the amount of chemical nitrogen fertilizer on the basis of applying organic fertilizer in low fertility tobacco planting soil, the field experiment was conducted with local conventional fertilization as control (CK), different nitrogen reduction ratio + organic fertilizer treatments,  including chemical fertilizer nitrogen reduction 20% + organic fertilizer 3 300 kg·hm-2 (D1), chemical fertilizer nitrogen reduction 30% + organic fertilizer 4 950 kg·hm-2 (D2), chemical fertilizer nitrogen reduction 40% + organic fertilizer 6 600 kg·hm-2 (D3) were set up. The effects on dry matter accumulation, nutrient accumulation characteristics, yield and quality of tobacco leaves were studied. The results showed that compared with CK, in D1 and D2 treatments, the dry matter accumulation of tobacco plants was increased, the absorption of nitrogen, phosphorus and potassium and their transferring to tobacco leaves were promoted, and the apparent utilization rate of nitrogen was improved. In addition, D1 and D2 treatments significantly increased the yield of tobacco leaves and promoted the coordination of internal chemical components. The indexes of economic characters of D2 treatment were significantly higher than those of D1 treatment except for yield. And D3 treatment was significantly lower than other treatments in all aspects. In summary, under the condition of applying organic fertilizer in low fertility tobacco planting soil, nitrogen reduction of 20% + organic fertilizer 3 300 kg·hm-2 and nitrogen reduction 30% + organic fertilizer 4 950 kg·hm-2 were more beneficial for nutrient absorption and accumulation of tobacco plants. The treatment of 30% nitrogen reduction + 4 950 kg·hm-2 organic fertilizer was the most beneficial for the formation of yield and quality of tobacco leaves.