Table of Content

15 November 2019, Volume 21 Issue 11

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Comparative Advantages Analysis of Sino-US Agricultural Trade

LI Jinkai, CHEN Jueying, LIU Heguang*

2019, 21(11):  1-8.  DOI: 10.13304/j.nykjdb.2019.0058

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In recent years, Sino-US agricultural trade has shown a significant growth trend. The trade intensity in agricultural products between two countries has been continuously increasing, and the trade dependence of two countries has also become stronger. By comparing the advantage of export agricultural products in Sino-US agricultural trade, this paper used methods of revealed comparative advantage (RCA) index, trade competitive (TC) index to analyze the competitive advantage of agricultural exports. The results showed that: The United States′ export advantage agricultural products were mainly the land-intensive agricultural products and the resource-intensive agricultural products, such as soybean, pork and corn. The most typical agricultural product  of USA was the soybean, whose RCA index stayed above 5.0 and TC index stayed above 0.9 for a long time. Chinas export advantage agricultural products were mainly the labor-intensive agricultural products with aquatic products, fruit and vegetable products as the main categories. In 2017, the RCA index of aquatic products, fruit and vegetable products in China were 3.67 and 2.48, respectively, and the TC index were 0.94 and 0.75, respectively. Based on the above analysis, it was suggested to establish and improve Chinas agricultural products trade promotion system and support system, make full use of Chinas trade comparative advantage, improve the quality of agricultural labor force, and extensively seek trade partners to reduce import dependence.

Construction Experience  of Regional Agricultural Science and Technology Innovation Center in the Typical Developed Countries and Its Enlightenment to Beijing-Tianjin-Hebei Region

YANG Yanli, MA Hongkun, WANG Xiaojun, MAO Shiping*

2019, 21(11):  9-16.  DOI: 10.13304/j.nykjdb.2019.0206

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The coordinated development of Beijing-Tianjin-Hebei region has become a national strategy, and the construction of a regional agricultural scientific and technological innovation center in Beijing-Tianjin-Hebei region is an important link in the coordinated development of agricultural scientific and technological innovation in Beijing-Tianjin-Hebei region. However, the long-term linkage mechanism of regional agricultural science and technology innovation in Beijing-Tianjin-Hebei region has not yet been formed. This paper explored the successful experience of building regional agricultural scientific and technological innovation centers in Missouri, USA and Auvergne-Rona-Alps, France; and provided useful reference for the development of regional agricultural innovation centers in Beijing-Tianjin-Hebei region. To construct  regional agricultural scientific and technological innovation system and full play of market regulation mechanism and strengthen international cooperation were the important factors for the construction of agricultural scientific and technological innovation center. The Beijing-Tianjin-Hebei region should set up an agricultural scientific and technological innovation system with clear division of labor and collaborative innovation, promote agricultural enterprises to become the main body of agricultural scientific and technological innovation, perfect the service mechanism of agricultural scientific and technological innovation, and promote international cooperation. The comprehensive construction of regional agricultural science and technology innovation ecosystem would drive the overall progress of regional agricultural scientific and technological innovation level in Beijing-Tianjin-Hebei region and provide effective support for the coordinated development of regional agriculture in Beijing-Tianjin-Hebei region.

Seed Input-output Efficiency, Feed Grain Conversion Efficiency and Food and Nutrition Security

HUANG Zeying, GUO Yanzhi, SUN Junmao*

2019, 21(11):  17-26.  DOI: 10.13304/j.nykjdb.2019.0214

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The balance of feed grain supply and demand archieved by science and technology helps to ensure China food and nutrition security. This paper focused on seed and feed conversion technology and measured the long-term equilibrium coefficient of seed input-output efficiency and annual feed grain yield from 1981 to 2016 and the long-term equilibrium coefficient of feed conversion efficiency and annual livestock and poultry output from 1992 to 2016 in China by using error correction model. The results showed that when the seed input-output efficiency increased by 1, the annual increase in feed grain yield of rice, wheat, corn and soybean was 0.91×104, 127.33×104, 9.46×104  and 68.51×104 t, respectively, which substituted grain import volume from 2012 to 2017 with average increase of 447.71, 2.74, 39.39 and 108.14. When the feed grain conversion efficiency increased by 1, the annual output increase in pork, beef, mutton, chicken, eggs and milk were 748.69×104, 643.08×104, 148.30×104, 437.69×104, 606.33×104 and 241.89×104 t, respectively. The feed grain conversion efficiency of the layer and the cow still need to be improved by 1.74 and 12.13  to reach the 2020 nutrition program goal. The  deficiency intakes of protein, calcium, zinc and vitamin A for residents needed to be improved by 5.52  of the cattles feed grain conversion efficiency, 89.40  of the cows feed grain conversion efficiency, 3.10  of the cattles feed grain conversion efficiency and 14.80  of the layers feed grain conversion efficiency.

Screening of Dwarf Mutants and Identification of Candidate Genes in Maize

WANG Wenxiu, ZHENG Hongyan, XU Miaoyun, ZOU Junjie, ZHANG Lan, WANG Lei*

2019, 21(11):  27-34.  DOI: 10.13304/j.nykjdb.2019.0141

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Exploring dwarf genes is very important for maize breeding to increase plant dense. In this study, a series of maize dwarf mutants were obtained by screening  mutant library, which was constructed from inbred line Zheng 58 treated with ethyl methylate (EMS). Height of the dwarf mutants decreased by 10%~45%, the spike height decreased by 10%~65%, and the number of internodes of some mutants was also changed. All of the dwarf mutants cell were shortened by 25%~75%. Height of dwarf mutants was not only decided by cell shorting, also by cells number. To isolate dwarf candidate genes of mutants, five mutants were selected to construct the F2 segregation population. Combining BSR high-throughput sequencing and bioinformatics analysis, candidate genes of five mutants were obtained. These results provided an effective analytical method  and new maize dwarf resource for dwarf gene isolation from mutants.

Transgenic Potato Plant with GhABF2 and Its Drought Tolerance Analysis

PEI Huaidi1, LI Zhongwang1, CHEN Yuliang2, LUO Junjie1*

2019, 21(11):  35-42.  DOI: 10.13304/j.nykjdb.2018.0687

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The transcription factor GhABF2 is homologous to AREB1/ABF2. The drought resistance of plants are improved by overexpressing GhABF2. In order to create the drought-resistant germplasm resources of potato, GhABF2 gene was transferred into potato plantlet of cultivar “Atlantic” and mediated by Agrobacterium tumefaciens and 12 lines of kan-resistant seedlings were obtained. By using PCR、RT-PCR and Southern-blotting, this paper screened out eight transgenic lines with high GhABF2 expression, and investigated their physiological biochemical indexes and growth characteristics under drought conditions. The results showed that the biomass, chlorophyll content, soluble sugar content, proline content,  superoxide dismutase (SOD) and peroxidase (POD) activities of transgenic plants were significantly higher than those of the control under PEG-6000 stress. It was suggested that the drought tolerance of potato was improved by overexpressing GhABF2. The present research provided important genetic resources for drought-tolerant new variety breeding, and had important theoretical and practical significance.

Functional Analysis of BS2 Gene in Tobacco

LI Xia1,2, FAN Xin2, LIANG Chengzhen2, WANG Yuan2, ZHANG Rui2, MENG Zhigang2*, LIU Xiaodong1*, SUN Guoqing2*

2019, 21(11):  43-50.  DOI: 10.13304/j.nykjdb.2019.0369

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BS2 protein is derived from Bacillus subtilis B111 with strong resistance to Verticillium wilt. It can inhibit the spore germination of Verticillium dahliae and destroy its mycelial growth. The full length of BS2 gene is 1 566 bp, and it has 522 codons. Because of the difference of preferred codons,  if it is directly introduced into plants without optimization it will result in low or no expression of genes. The BS2 was optimized according to plant optimal synthesis, and 332 codons were optimized. The bioinformatics analysis showed that 1～28 amino acids composed a N-terminal signal peptide ; the mature BS2 protein was composed of amino acids 224～521 and was a neutral zinc metal peptidase. The subcellular localization maped the BS2 protein to the cell membrane. By Oxford Cup method,  the crude protein extract of transgenic tobacco lines showed strong antibacterial activity. It was founded that the  control group without infestation of Verticillium dahliae, the growth of the wild type and transgenic plants was basically the same, the phenotype was not significantly different, while under infection group of Verticillium dahliae V991, the phenotypic traits of transgenic tobacco were significantly better than wild type, the activity of SOD, CAT and content of SA, ABA in transgenic tobacco were higher than those in wild type tobacco. So, the BS2 gene could significantly improve the resistance of transgenic tobacco to Verticillium wilt.

Effects of Exogenous Melatonin on Growth and Physiological Characteristics of Reed Seedlings under Salt Stress

FAN Haixia1, GUO Ruoxu1, XIN Guoqi2, LI Fengqin3

2019, 21(11):  51-58.  DOI: 10.13304/j.nykjdb.2018.0697

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In order to reveal the physiological mechanism of exogenous melatonin improving the resistance to salt stress of Phragmites communis L.,  0.01 mmol/L exogenous melatonin was applied to P. communis seedlings stressed with 150 mmol/L NaCl. The physiological characteristics, including dry matter accumulation, photosynthetic characteristics, antioxidant enzyme activities, osmotic adjustment content and malondialdehyde (MDA) content of P. communis seedlings were tested. The results showed that salt stress inhibited the growth and dry matter accumulation of P. communis seedlings, and caused serious physiological damage to seedlings. Spraying exogenous melatonin could increase the chlorophyll content and photosynthetic performance of P. communis seedling leaves, and increase the activities of superoxide dismutase (SOD), peroxidase (POD), catalase (CAT) and the content of osmotic adjustment substances, such as proline and soluble protein, reduce the content of reactive oxygen and MDA. Therefore, foliage application of melatonin could increase antioxidant enzymes activity and the accumulation of osmotic adjustment substances in the leaves of P. communis under salt stress, and effectively remove excess reactive oxygen species, alleviate oxidative damage and enhance the salt tolerance of P. communis seedlings.

Research Progress on Technology and Equipment of Ramie Fibre Stripping and Processing in China

XIANG Wei1, MA Lan1, LIU Jiajie1, XIAO Le2, LONG Chaohai1, WEN Qinghua1, LYU Jiangnan1*

2019, 21(11):  59-69.  DOI: 10.13304/j.nykjdb.2018.0783

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Mechanized decorticating and processing of ramie fiber is one of the important segments to realize ramie industry development, and also a key and difficult point of the whole process of ramie production mechanization. This paper described the basic structure, ramie fiber harvest process and  present research situation of  ramie physical mechanical properties; analyzed the research progress on ramie decorticating and processing technology and equipment at home and abroad; summarized the operating principles and characteristics of 4 kinds of ramie decorticator, including manual decorticator, manual reverse-drawing decorticator, directly-feeding and transverse-feeding decorticator; and discussed the development trend of ramie decorticating  technology and equipment in China. In future, the key R & D directions for ramie mechanization were improving and perfecting the existing ramie decorticator, coexisting and developing the portable and large scale ramie decorticator, studying the intelligent and efficient ramie decorticating technology, and capturing the processing technology of integrating ramie harvesting with decorticating.

Calibration and Experiment of Contact Parameters of Rice Grain Based on Discrete Element Method

LIU Yuping, ZHANG Tuo, LIU Yu*

2019, 21(11):  70-76.  DOI: 10.13304/j.nykjdb.2018.0730

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The credibility of simulation results was directly affected by the accuracy of rice grain parameter setting when EDEM coupling with FLUENT to simulate rice separation. In this paper, combined the measured and simulation test of rice grain response angle, two main contact parameters between rice grain models, static friction coefficient and rolling friction coefficient, were calibrated based on discrete elements. A response angle measuring device was designed to form two kinds of response angles  using collapse and injection, which could reduce the measurement error caused by non-simultaneous formation,  create a discrete element model of rice grain, combine the actual test and simulation test of the stacking angle, and establish the binary equation regression between two main contact parameters and two response angles. The measured results of the two kinds of response angles of rice grains were used as the correction index to solve the equations, and obtained the static friction coefficient and the rolling friction coefficient of the rice grain model were 0.433 6 and 0.161 5, respectively. The throwing test was designed to verify the calibrated parameters. The length and width of the throwing, and a response angle neared the spray point in experiment were compared with them in simulation, and the result showed that the relative error was less than 5.7%. These results indicated that the simulated motion trajectory of the particles was basically consistent with the actual trajectory. The discrete element model of the rice particles and the contact parameters obtained by the calibration can provide reference for the EDEM-FLUENT simulation of the rice cleaning process.

Development and Validation of Critical Nitrogen Dilution Curve for Spring Maize in Northeast China

LU Xianju1,2, GUO Xinyu1,2*, WEN Weiliang1,2, YU Zetao1,2

2019, 21(11):  77-83.  DOI: 10.13304/j.nykjdb.2018.0588

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Excessive nitrogen fertilizer application is a common phenomenon in maize cultivation. Nitrogen nutrition index (NNI) based on the critical nitrogen dilution curves is an important means to diagnose nitrogen deficiency. This study collected and analyzed the data of four experiment site under different N application rates in Northeast China and developed critical nitrogen dilution curve. And on this basis, the nitrogen nutrition index model and nitrogen demand model were established. The results showed that there was a negative power function between aboveground biomass and critical N concentration in Northeast China. The critical nitrogen dilution curves were validated using other independent data. The results showed that the nitrogen nutrition index model could be used for accurating diagnosis of maize nitrogen status and nitrogen demand calculation. The critical nitrogen dilution curve of spring maize in Northeast China developed in this study  provided better theoretical and technical guidance for nitrogen diagnosis and dynamic regulation of spring maize in this region.

Growth Conditions Optimization of Antagonistic Bacteria Against Powdery Mildew of Rosa roxburghii Tratt and Its Fermentation Broth Antibacterial Stability

RAN Jiping1,2, YAN Yan2*, LI Cen 1, MAO Yutao3, XIAO Yu4, FENG Tingting5

2019, 21(11):  84-93.  DOI: 10.13304/j.nykjdb.2018.0718

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In order to research the optimal culture solution of antagonistic bacteria against the Rosa roxburghii powdery mildew, this study carried out in vitro control experiment on leaves of R. roxburghii. The results showed that the concentration of antagonistic bacteria was positively correlated with the control effect of powdery mildew. The growth conditions of antagonistic bacteria JK-6 were optimized by 3-factor and 3-level response surface methodology. Meanwhile, the effects of temperature, pH, ultraviolet light, protease and different storage period on the stability of JK-6 fermentation broth for inhibiting powdery mildew were investigated. The results showed that the optimal medium formula of JK-6 was glucose 2 g/mL, peptone 1 g/mL, and NaCl concentration 0.8%; the best culture conditions was temperature 33.6 ℃, pH 7.6, liquid volume 40 mL, shaker speed 160 r/min. Under these conditions, the OD600 of the antagonistic bacteria JK-6 fermentation broth was 1.418. When the fermentation temperature was over 40 ℃, and the pH was acidity and alkalinity, the inhibitory effect of JK-6 fermentation broth on germination of powdery mildew spores decreased. The tolerance of fermentation broth to ultraviolet light and protease were higher, and under room temperature for one month, the fermentation broth still had high antibacterial activity. The present research suggested that JK-6 could significantly inhibit R. roxburghii powdery mildew and had certain guiding significance for the prevention and control of R. roxburghii powdery mildew.

Effect of Inoculating Fusarium oxysporum on Seedings Growth and Leaf Free Amino Acids of Resistant and Susceptible Cucumbers

LI Yali, HOU Dong*, YUE Hongzhong, ZHANG Dongqin

2019, 21(11):  94-102.  DOI: 10.13304/j.nykjdb.2019.0086

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In order to clarify the cucumber resistant mechanism to Fusarium oxysporum, this paper inoculated F. oxysporum to both resistant and susceptible cucumber materials  taking inoculated sterile water as the control, and analyzed the differences in biological characteristics of the resistant and susceptible materials after inoculation, and dynamic variation rule of free amono acids in leaves. The results showed that: ① At 20 d after inoculation, the plant height, stem width, leaf area, total root length, total root area, total root volume, ratio of root to cap, healthy seedling index of the resistant materials had non-significant differences with those of the control. But in susceptible materials, those index were remarkably lower than those of the control. Among them, the total root length was the most obvious, which in susceptible materials was reduced 51.02% than that of the control. ② After inoculated F. oxysporum, the total free amino acid of resistant material decreased, while that in susceptible material inceased, showing a rising trend. At 8, 12, 16 and 20 d after inoculation, the total free amino acid content of resistant materials was almost not affected by F. oxysporum. While, those of susceptible materials increased by 14.05%, 32.54%, 56.29% and 149.10%, respectively. ③ Among the tested 34  free amino acids, 16 had remarkable different variation rules between resistant and susceptible materials. Citruline and alanine in resistant materials after inoculation were less than or equal to those of the control. But in susceptible materials, they were more than those of the control. The contents of tyrosine, taurine, methionine, leucine, β-aminoisobutyric, ornithine, lysine and proline were the opposite. With seedling growth after inoculation, the contents of citruline, asparagine, phosphoserine, urea, β-alanine, histidine, ornithine and arginine in resistant materals showed a downtrend, but those in susceptible materials showed  uptrend. It was speculated that citrulline, alanine, asparagine, serine phosphate, urea, β-alanine, histidine and arginine were bacterial promoting amino acids; tyrosine, taurine, methionine, leucine, β-aminoisobutyric acid, lysine and proline were bacteriostat amino acids. These results  provided reference frame and theoretical basis for cucumber resistant breeding to F. oxysporum.

Influence of Ginsenoside on the Feeding, Detoxifying Enzyme and Acetyl Cholinesterase Activity of Myzus persicae

LI Haitao1, HUANG Ximan1, LI Yu1, LIU Guangna1, XI Guangsheng2*

2019, 21(11):  103-110.  DOI: 10.13304/j.nykjdb.2018.0674

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This paper determined the detoxifying enzyme and acetyl cholinesterase (AChE) activity of Myzus persicae after feeding on ginsenoside by leaf impregnation method, and compared the effects of Rg1 and Rb1 on the enzyme activity  by using ginsenoside Rg1 and Rb1 as the experimental materials and M. persicae as the experimental insect. The results showed that: Rg1 and Rb1 significantly inhibited the feeding of M. persicae, and the detoxifying enzyme activity of M. persicae at a lower concentration. After treatment for 24 h, Rg1 significantly inhibited glutathione -S- transferase (GSTs), multi-function oxidase (MFO), carboxylesterase (CarE) and AChE. After treatment for 48 h, Rb1 significantly inhibited the MFO, CarE and AChE of M. persicae. Moreover, the inhibition of Rg1 on detoxifying enzyme of M. persicae was more significant than that of Rb1; Rg1 and Rb1 could induce the enhancement of enzyme activity and break the balance of detoxifying enzyme activity of M. persicae. These results could provide reference for biological control of plant pests and the development of new pesticides.

Identification of a Bacillus Strain and its Inhibiton Activity to the Synthesis of Aflatoxin Precursor

WANG Zhuo1*, YUAN Kebo1, LI Zengxu1, YAN Peisheng2*

2019, 21(11):  111-120.  DOI: 10.13304/j.nykjdb.2018.0676

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In order to develop biological preservatives that can effectively improve the resistant ability of peanut and other agricultural products to aflatoxin contamination, an isolated biocontrol strain was identified with 16S rDNA and its anti-mold and anti-aflatoxin characteristics were studied. The results showed that it was a Bacillus subtilis, the ability to produce anti-aflatoxigenic effective components was not affected by subculture quantity. The fungi strain could produce antia-flatoxigenic effective components in wide fermentation temperature range. The initial pH value of the optimal culture medium for the strain was 6, and the optimal culture time for the generation of anti-aflatoxigenic effective components was 6 d. The yield of anti-aflatoxigenic effective components extracted by methanol from strain fermentation supernatant was the highest and the activity was the strongest. The mold infection of peanuts indicated that the inhibition rate for norsolorinic acid (NA) accumulation reached 84% or more when 0.2～3.2 mg/mL anti-aflatoxigenic effective components were added, which was higher than that of sodium diacetate (SDA) used. The anti-aflatoxigenic effective components palyed  good roles in the anti-mildew and anti-virus treatment of peanut. The results showed that the anti-aflatoxigenic effective components exacted from B. subtilis Hitwh-B05  improved anti-mildew and anti-virus abilities of agricultural products, and prevented the mildew and virus infection from the source. Its use can decrease the harm of chemical preservatives to environment and human.

Effects of Cotton Stalk Biochar Application on Greenhuse Gas Emissions in the Farmlands of North China Plain

LIU Hongyuan1, ZHANG Aiping1, WANG Yongsheng2, YANG Shiqi1, XING Lei1, YANG Zhengli1*

2019, 21(11):  121-129.  DOI: 10.13304/j.nykjdb.2018.0556

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Taking winter wheat and summer maize crop rotation farmland in Northern China Plain as research object, this paper studied the influence of 4 different doses cotton stalk biochar \[CK(control group), C1(2.25 t/hm2 biochar), C2(4.5 t/hm2 biochar), C3(9.0 t/hm2 biochar)\] on soil physical and chemical properties and greenhouse gases (CH4 and N2O) flux in the case of conventional fertilization; and evaluated the impact of different treatments on global warming potential (GWP) and greenhouse gas intensity (GHGI) combining with the production. The results showed that biochar addition could not obviously affect the cumulative CH4 cumulative emission in soil. In summer maize season, only C2 and C3 treatments could remarkably reduce soil N2O emission fluxes by 37.19% and 48.58%, respectively. In winter wheat season, all adding biochar treatments could remarkably reduce the N2O emission fluxes in soil by 24.26%~48.02%. The path analysis results indicated that soil NH+4-N content was the major factor influencing soil N2O emission flux. In summer corn season, C2 and C3 treatments could remarkably increase corn yields by 9.46% and 10.99%, respectively. In winter wheat season, only C3 treatment could remarkably increase wheat yield by 7.13%. Moreover, adding 4.5 t/hm2 and 9 t/hm2 biochar treatments could evidently reduce the GWP and GHGI, while adding 2.25 t/hm2 biochar treatment could only dramatically lower the GWP and GHGI in winter wheat season. To sum up, the conversion of cotton stalk into biochar in farmland in Northern China Plain could not only increase crop yield, but also reduce greenhouse gas emissions.

Influences of Adding Biochar on Loss of Nitrogen and Phosphorus and Yield of Rape in Soil

CHEN Qinghua1, XU Zhuo1, TANG Jichao1,2, JIN Weibin2, SUN Zhigui1, LU Bilin1*

2019, 21(11):  130-137.  DOI: 10.13304/j.nykjdb.2018.0585

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It is a key issue in biochar applying technology to clear and definite the effects of biochar in reducing nitrogen and phosphorus loss of soil and crop  yield. Using tube experiment, this paper added different portions biochar (0.5%, 1.0%, 1.5%) to 20 cm soil layer, simulated rainfall and collected the liquid inside the tube, then tested and analyzed nitrogen and phosphorus contents. By this way, the paper studied the effects of adding different proportions of biochar on soil nitrogen and phosphorus leaching and rapeseed growth. The results showed that: ① Compared with no biochar treatment, 1.5% biochar treatment significantly reduced TN leaching loss, TN leaching concentration ratio, NO-3-N leaching loss, NO-3-N leaching concentration ratio, TP leaching loss and TP leaching concentration ratio; there was no significant difference in the leaching loss of NH+4-N and PO2-4-P among the treatments. ② During rapeseed growing period, the leaching loss of TN and NO-3-N decreased with the increase of biochar application, taking NO-3-N leaching loss as the major part. Affected by fertilization and utilization during crop growth, the rules of leaching loss of NH+4-N, TP and PO2-4-P were not obvious. ③ Biochar application increased rapeseed yield, mainly reflected in the increase in effective branching number, efficient pod number per plant and seed number per fruit.

Monthly Dynamic Variation of Soil Seed Bank in Different Dune Types of the Yellow River Diversion Area

XIN Zhiming1,2, DONG Xue1*, LIU Minghu1, LI Xinle1,2, DUAN Ruibing1,2, HAO Yuguang1,2, LU Zhandong3

2019, 21(11):  138-148.  DOI: 10.13304/j.nykjdb.2018.0694

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Taking seed germination test, this paper studied the seasonal dynamic variation of soil seed banks at April (spring), July(summer), October(autumn)  in 3 different sand dunes (fixed dune, semi-fixed dune, mobile dune) of the Yellow River diversion area; and analyzed the water-level-fluctuating zone (including the flooded, non-flooded and control areas) and the relationship between standing vegetation and soil seed bank. The results showed that: at flooded area, the density of soil seed bank declined gradually with time flowing i.e. April (201 seeds/m2)>July (176 seeds/m2)>October (170 seeds/m2). At non-flooded area, the density of soil seed bank was in the following order: April (1 063 seeds/m2)>October (1 036 seeds/m2)>July (733 seeds/m2). The figure of each month was bigger than that of the control area, and the same monthly variation rule was. The soil seed bank density was fixed dune>semi fixed dune>moving dune with distinguish monthly variation i.e. April (1 002 seeds/m2)>October (903 seeds/m2)>July (609 seeds/m2). There were 23 species belonging to 8 families and 23 genera in soil seed banks of the Yellow River diversion area. Most of them belonged to Chenopodiaceae and Poaceae, accounting for 65%. Judging from the lifestyle, each month took annual herbage species as principal. In terms of species composition, the number of soil seed banks in July was obviously smaller than that of April and October. At the non-flooded area, a microecological environment was formed by alternating wetness and dryness. It was more favorable for foreign species to enter. Thus, the species in soil seed bank were more abundant. Species in soil seed bank at hydro-fluctuation belt was more than that in the standing vegetation. However the control section was relatively small. Their Jaccard similarity coefficients of species composition between the seed bank and standing vegetation were respectively 0.357, 0.333 and 0.289 in flooded area, non-flooded area and the control area. The results indicated that the similarity coefficients were flat.

Analysis of Ecological Benefit of “Rice-duck Farming” Model and Its Economic Benefit in Ecological Farm

ZHAO Jianshe1,2, YANG Qiaoyun1,2, XIE Kaiquan1,2, WU Chao1,2, JIANG Gaoming3,4, LI Xiaofang1,2, HU Bo5, GUO Liyue3,4*

2019, 21(11):  149-156.  DOI: 10.13304/j.nykjdb.2018.0733

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In order to make the ecological and economic benefits of “rice-duck farming” in ecological farm more clearly, and provide theoretical and technical support for improving the “rice-duck farming” technique and its application in ecological farm, this paper analyzed ecological benefit of “rice-duck farming” according to previous studies, and carried out a research according to actual production in an ecological farm, all of the inputs including pesticides, fertilizers, labors and the costs for management were comprehensively analyzed in “rice-duck farming” system and conventional rice cultivation process. The prospect of “rice-duck farming” production in ecological farm was also been analyzed. The results showed that: a lot of organic fertilizers, labors and biological pesticides were invested in the early time in “rice-duck farming” system, and the effective panicle number of rice was less, which led to the yield of rice decreased, eventually resulted in the price of rice reaching 8.20 yuan/kg without considering the cost of organic certification, which was much higher than that of conventional rice. However, the pesticides and chemical fertilizers in the “rice-duck farming” system were abandoned, so the soil and air environment were improved, and there were no pesticide residues in the rice which could be very easy certified as an organic production,  the net income was 76 000 yuan/hm2 which was much higher than that of ordinary rice cultivation (27 595 yuan/hm2).

Survival and Quality Change of Haliotis diversicolor in Slightly Acidic Electrolyzed Water

ZHANG Moyan1, CHEN Xue2, XIE Qingchao1,3, OU Jie1,3, XIE Jing1,3, PAN Yingjie1,3, ZHAO Yong1,3*, LIU Haiquan1,3,4*

2019, 21(11):  157-162.  DOI: 10.13304/j.nykjdb.2019.0383

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Slightly acidic electrolytic water (SAEW) has been widely used in fruit and vegetable preservation, instrument disinfection and other fields because of its broad-spectrum bactericidal effect, but the preservation of aquatic products is less. Variously colored abalone (Haliotis diversicolor) with an average body weight of about (34.3±1) g was reared in SAEW made of Wojie Intelligent Electrolyzer and sea water crystal at water temperature of (10±1)℃ for 2 d, and in the control group SAEW was not added. Survival rate and total colonies on the abalone were detected, and the quality changes of abalone after storage at 4 ℃ were analyzed by sensory evaluation andvolatile base nitrogen (TVB-N) value. The results showed that: At  9 d, the survival rate of abalone in electrolyzed water group was 66.7%, which was greater than seawater group  50%. In storage, after 9 d, the TVB-N value of seawater group was 19 mg/100 g, exceeding the limit value (15 mg/100 g), while the electrolyzed water group was not. At 12 d, the sensory score of the seawater group was 31, and the score of the electrolysis water group reached 54.5, which was better than that of the seawater group. After 15 d, the total number of abalone colonies in the electrolysis water group was 5.9 log10 CFU/g, and the total number of abalone colonies in the seawater group reached 7.24 log10 CFU/g, which exceeded the acceptable upper limit of food microorganisms by 7 log10 CFU/g, both groups were dominated by Pseudomonas and Shewanella. The findings indicated that SAEW had certain application potential in the preservation and preservation of fishery products.

Elements Analysis in the Muscle and Bone of Gymnocypris doubula and Schizothorax prenanti

WU Xiaohui1, LIU Yang1,2, XU Qianghua1,2,3,4*

2019, 21(11):  163-169.  DOI: 10.13304/j.nykjdb.2019.0035

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Gymnocypris dobula (GD) and Schizothorax prenanti (SP) are 2 types of mountain carps. The former grows at high altitude (>4 500 m) in the Qinghai-Tibet Plateau with low oxygen level; and the latter in the upper  Yangtze River at the lower altitudes (<1 000 m). In order to investigate the trace element differences inside fish body grown in differet altitude, this paper measured the macroelements (Na, Mg, Al, K, Ca, Fe and Zn) and microelements (V, Cr, Mn, As, Se, Sr, Sb and Ba) in muscle, vertebrae and skull tissues of both GD and SP, and conducted comparison and analysis on the contents of these elements. Results showed that significant differences were only existed in the Se and Sb contents between GD and SP muscles, and only As contents showed significant differences in the vertebrae of these 2 schizothoracine fishes. The extremely high concentrations of Se and Sb elements in GD muscle, and extremely high concentrations of As element in GD vertebra might relate to adapting the high altitude and low oxygen environment. This paper measured and analyzed for the first time in China the macroelement and microelemrnt in muscle and bone of schizothoracine fishes from different altitudes using microwave digestion methods; and effectively explored the elements differences of these 2 kinds of fishes. Therefore, the paper had provided basis for analyzing the physiological mechanism of these 2 fishes in adpting to low oxygen environment through tissue element analysis.