Table of Content

15 June 2021, Volume 23 Issue 6

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Green Development Evaluation of Mariculture in China

YUE Dongdong, WU Fanxiu, FANG Hai, RUAN Wen, JI Weiwei

2021, 23(6):  1-12.  DOI: 10.13304/j.nykjdb.2020.0734

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The green development evaluation of mariculture is an important basis for judging the quality of industrial development, as well as a yardstick for identifying industrial transformation and upgrading. Based on the evaluation of agricultural green development, this paper constructed a green development evaluation index system for mariculture with 4 secondary indicators and 14 tertiary indicators, and made an applied evaluation of the mariculture development in 10 provinces or regions in 2019. The results showed that: the level of green development of mariculture in each province was low, with a median of 0.356 7, and Shandong had the highest score of 0.570 2, and Hebei had the lowest score of only 0.226 3. The results of the green development evaluation of mariculture in different dimensions were different, and the resource saving indicator average score was 0.102, the spatial expansion indicator average score was 0073, the environmentally friendly indicator average score was 0.132, the product green indicator average score was 0.057. The product green indicator was the main factor restricting the green development of mariculture, and the average contribution of this indicator in Hebei, Jiangsu, Fujian, Shandong, Guangdong and Hainan was only 10.89%. The established  evaluation index system was expected to provide a reference for the green development evaluation and application of mariculture, and put forward relevant suggestions based on the actual conditions of each province.

Extension Mode and Effect Evaluation of Organic Fertilizer Substituting Chemical Fertilizer Technology#br#

LIU Li, LIU Jing

2021, 23(6):  13-22.  DOI: 10.13304/j.nykjdb.2020.0233

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Based on the survey data in the pilot area of organic fertilizer substituting chemical fertilizer in apple planting project, this paper analyzed the promotion pattern and implementation effect of organic fertilizer substituting chemical fertilizer technology (OSCT) by the method of quantitative analysis and case analysis. The results showed that the promotion pattern of “fertilizer combination scheme & fertilizer products” limited the choice of fertilizer products as subsidized fertilizers. Farmers did not follow the recommended program for fertilization because the fertilizer products with subsidy were not familiar to them. The pattern had limited effect in promoting OSCT. The other pattern of “fertilizer supply enterprises & quota management” limited fertilizer companies that could supply subsidized fertilizers. The pattern was conducive to relax the choice of fertilizer products and obtained remarkable effect in promoting OSCT. So, more flexible promotion pattern was better adopted in OSCT. Currently there were some problems in OSCT promotion, such as the mismatch between technological supply and demand, the overlook of farmers′ demand for stable production and income increase in the policy objective constitution, and the oversimplification of the effect evaluation in process of policy implementation. The suggestions were proposed for improving the flexibility and feasibility of policy in OSCT promotion, such as reducing the purchase restrictions on alternative fertilizers, propelling the addition of organic fertilizer and reduction of chemical fertilizer step-by-step and evaluating the implementation effect of OSCT policy by a more comprehensive way. 

Global Small RNA Transcriptome Profiling of Rice Under Drought Stress

LIU Yuan, ZHANG Xiuyan, XU Miaoyun, ZHENG Hongyan, ZOU Junjie, ZHANG Lan, WANG Lei

2021, 23(6):  23-32.  DOI: 10.13304/j.nykjdb.2019.1079

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Small RNAs play important regulatory roles in response to environmental stress. However, miRNAs involve in the complex process of drought response and their regulatory mechanism remain to be further identified and explored. In this study, small RNA library of root, stem and leaf tissues from rice treated with drought was constructed and high throughput transcriptome was sequenced. The results showed that a total of 403 miRNAs were detected at genome-wide scale in all samples, including 352 known miRNAs and 51 new predicted miRNAs. There were 37, 35 and 56 miRNAs differentially expressed in roots, stems and leaves at 24 h after drought treatment, while 35, 62 and 65 miRNAs were differentially expressed in roots, stems and leaves at 96 h,  respectively. Moreover, 15 miRNAs were differentially expressed in each tissue at two time points after drought treatment, among which Osa-miR159f, Osa-miR164f, Osa-miR5082 and Osa-miR5493 were up-regulated during drought treatment. Thus, they might be key modulators in drought response. A total of 4 537 predicted target genes of miRNAs were obtained, and their functional annotation and GO/KEGG enrichment analysis were further carried out. Collectively, these results provided theoretical reference and data resource for the identification of new drought responsive miRNAs, and would contribute to the comprehensive mechanisms dissection of miRNAs involvement in drought tolerance regulation in plants.

Chloroplast Genome Structure Characteristic and Phylogenetic Analysis of Mulgedium tataricum

SU Yue§, LIU Juanjuan§, WAN Bin, ZHANG Pengju, CHEN Zhenggen, SU Junji, WANG Caixiang

2021, 23(6):  33-42.  DOI: 10.13304/j.nykjdb.2020.1116

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Mulgedium tataricum is a Compositae, Mulgedium plant, which contains natural flavonoids, including heat-clearing and detoxification, anti-tumor, and anti-oxidant, etc. Chloroplast genome contains a large number of functional genes, which play important roles in species identification and phylogeny. In this study, the chloroplast genome DNA was sequenced using high-throughput sequencing technology to obtain the full-length chloroplast genome sequence, and the chloroplast genome was assembled, annotated and characterized. Phylogenetic analysis of chloroplast genomes from 32 Compositae species and Arabidopsis thaliana was performed. The results showed that the whole length of Mulgedium tataricum chloroplast genome was 152 401 bp, showing a typical cyclic tetrad structure containing a pair of inverted repeats (IRa and IRb), large single copy (LSC), and small single copy (SSC), and the lengths were 25 010, 83 833 and 18 548 bp, respectively. A total of 132 genes  including 8 ribosomal RNA genes, 37 transfer RNA genes and 87 predicted genes were identified. SSR site analysis revealed that the genome sequence contained 21 dispersed palindromic repeats and 197 tandem repeats. The boundary analysis showed that some differences in the boundary genes among Mulgedium tataricum and other five Lactuceae species, and six Lactuceae species showed obvious expansion and contraction in IR/SC region. Phylogenetic analysis showed that 33 species from 14 genera of Compositae were grouped into two branches: the first branch included Mulgedium, Lactuca, Taraxacum, Sonchus, Anaphalis, Leontopodium, Chrysanthemum, Artemisia, Aster and Helianthus, among them, Mulgedium was most closely related to Lactuca. The second clade included Cirsium, Carthamus, Saussurea and Atractylodes. The results of this study laid the new evidence and material foundation for species identification, phylogenetic evolution and resource exploitation and utilization of Mulgedium tataricum.

Growth and Physiological Index of Tamarix leptostachys Bunge Seedlings Under Soil Drought Stress

HU Yang, LI Gangtie, LI Xing, JIA Shouyi

2021, 23(6):  43-50.  DOI: 10.13304/j.nykjdb.2019.1002

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In order to study the mechanism of drought-resistance in Tamarix leptostachys Bunge, this paper took the seedlings of Tamarix leptostachys Bunge with 2 a panicles as materials, and measured the growth and physiological traits of Tamarix leptostachys Bunge seedlings under different drought stresses. The results showed that: the growth of Tamarix leptostachys Bunge seedlings was inhibited by drought stress, including plant height and ground diameter, and its growth rate  decreased gradually. The relative water content, water potential and chlorophyll a/b content in leaf  gradually decreased with the increase of drought stress, while the relative electrical conductivity, malondialdehyde, proline, soluble protein and soluble sugar in leaves  increased significantly. The activity of superoxide dismutase and peroxidase in leaf of Tamarix leptostachys Bunge seedlings showed an increasing trend, and the activity of catalase first increased and then decreased. To sum up, drought stress had significantly affected activities of protective enzymes and content of osmotic adjustment substances in Tamarix leptostachys Bunge seedlings. So Tamarix leptostachys Bunge could be planted and popularized in dry areas due to high drought resistance.

Identification and Genome Analysis of a Cellulose Degrading Strain from the Intestinal Tract of Protaetia brevitarsis Larva

HUANG Wanqiu, SHI Dongdong, CAI Hongying, YU Dali, MENG Kun, YANG Peilong,

2021, 23(6):  51-58.  DOI: 10.13304/j.nykjdb.2019.0891

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There are abundant ellulose degrading bacteria in intestinal tract of larvae of Protaetia brevitarsis and they are capable of digesting and utilizing a large amount of lignocellulose. By using the Congo red staining method and filter paper degradation methods, Cellulomonas sp. strain h9 with strong cellulose degrading ability was isolated and identified by 16S rRNA analysis. The activity of the bacteria and its related enzymes were studied under different culture conditions, the results showed that strain h9 reached the stable growth state period after 120 h fermentation in liquid CMC-Na medium, and the maximum CMC enzyme activity was 0.19 U·mL^-1. The complete genome sequence of the strain h9 was obtained by genomic de novo sequencing, and the BLAST software was used to conduct a comparison analysis with the protein sequences in COG and CAZy databases. Key genes and pathways involved in the cellulose degradation, such as β-endoglucanases, β-glucosidases, and exoglucanases, were indentified. This study  provided the theoretical basis and experimental material for cellulose degrading enzymes and constructing cellulose degrading engineering bacteria.

Design and Research on “Space-Air-Ground” Integrated Monitoring System for Intelligent Orchard

RAO Xiaoyan, WU Jianwei, LI Chunpeng, XIONG Xiaofei, HUO Hongyan,

2021, 23(6):  59-66.  DOI: 10.13304/j.nykjdb.2020.1038

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In view of the problems in traditional apple orchard like imperfect data monitoring system, lack of scientific data for management decision and so on, this paper explored a kind of apple orchard “space-air-ground” integrated monitoring system, which integrated modern information technologies and intelligent equipment technologies such as satellite remote sensing(RS), unmanned aerial vehicle(UAV), agricultural internet of things(IOT), artificial intelligence(AI), etc., and integrated orchard information collection equipment suite, and built orchard data center based on SSM framework (Spring MVC, Spring, Mybatis). Through the integration and innovation of the new generation information technology collection system and the application of AI based image recognition of apple diseases and insect pests，the three-dimensional monitoring service function covering orchard soil, ecological environment, individual and group of fruit trees were realized, the efficiency and reliability of apple orchard monitoring were improved. It was of great significance of new form of business to promote the apple orchard production management to scientific, digital and intelligent.

Application of Grain In-bin Drying Based on Liquid Desiccant Dehumidification Driven by Heat Pump

PENG Donggen, NIE Jiangtao, SUN Wanfu

2021, 23(6):  67-76.  DOI: 10.13304/j.nykjdb.2020.0039

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Based on liquid desiccant dehumidification driven by heat pump, a system of grain in-bin drying was designed to achieve grain drying and storage process safely and efficiently, and the models of grain in-bin drying and each component in this system were established in this paper. This paper simulated the process of drying 200 t grain with initial moisture content of 22% and temperature of 20 ℃ to safe moisture content in Nanchang area in autumn. The influence of air flow rate on drying time and energy consumption were analyzed when the liquid desiccant dehumidification system was adopted for drying, and the optimal air flow rate with the lowest energy consumption was obtained. A hybrid drying system combining natural ventilation and liquid desiccant dehumidification was proposed, under adopting the optimal air flow rate to dry grains, and the influences of natural ventilation drying time on drying time and energy consumption of the system were analyzed. The changes of grain moisture content and COP (coefficient of performance) during drying process under only natural ventilation, liquid desiccant dehumidification and hybrid drying were studied. Simulation results show the liquid desiccant dehumidification system has the lowest energy consumption when the air flow rate is 200 m3·h-1·t-1, and the drying time far lower than the safe drying period is 200 h. The average COP range during drying is 4.3. The moisture of grains couldnt reduce to the requirements of storage in safe drying period when only natural ventilation drying is adopted, and the COP during the drying process was relatively low. The limitation of safe drying period on natural ventilation time should be considered and selecting reasonable natural ventilation time is beneficial to save energy under hybrid drying system. Hybrid drying system could make full use of natural ventilation drying ability in the early stage of drying, and adopt the liquid desiccant dehumidification in the later drying stage to reduce grains to safe moisture content. Above results provided an alternative system for realizing a safe, efficient and energy-saving grain in-bin drying process.





Design and Experiment of Pneumatic Double-side Fertilizer Devices for Ratoon Rice

LIU Dezhu, ZHOU Yong, ZHANG Guozhong, ZHANG Mengyue, KE Huibin, YANG Quanjun

2021, 23(6):  77-85.  DOI: 10.13304/j.nykjdb.2019.1052

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In order to resolve the problems of uneven fertilization and inaccurately fertilization rate in ratoon rice topdressing, a kind of double-side pneumatic fertilizer device was designed in this paper. the quadratic regression rotation-orthogonal combination experiment was carried out to research the effects of rotation speed of outer fluted roller, working length of outer grooved wheel, and the angle of the fertilizer distributor on the fertilizer device performance. And the regression mathematical models of total quantity of the fertilizer discharging stability coefficient of variation and row fertilizer quantity consistently coefficient of variations was established. The results showed that the factors affecting total quantity of the fertilizer discharging stability coefficient of variation were the rotation speed, the working length, and the angle in sequence. The factors affecting row fertilizer quantity consistently coefficient of variations were the rotation speed, the angle, and the working length in sequence. The optimal parameter combination was determined by Design-Expert 8.0 with the rotation speed of 16 r·min-1, the working length of 22 mm, and the angle of 114°. Under the optimal parameter, the total quantity of the fertilizer discharging stability coefficient of variation and the row fertilizer quantity consistently coefficient of variations were 1% and 2.45%, respectively. The fertilizer device could meet the requirements of ratoon rice dressing and fertilizer excretion performance was good.

Design and Test Verification of Two-stage Jet Mixer Based on CFD

ZHOU Shuxian, SHI Yixin, JIANG Ping

2021, 23(6):  86-96.  DOI: 10.13304/j.nykjdb.2020.0708

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In order to solve the problems of small mixing ratio and inaccurate mixing ratio of jet mixer, a two-stage injection jet mixer was designed. The method of computational fluid dynamics was used to numerically simulate the fluid flow characteristics of the two-stage injection jet mixer. According to venturi pipe design standards and combing with CFD to simulate and calculate the different nozzle diameters, best mixing diameters were obtained, which were 9 and 21 mm, respectively. Using a four-factor and four-level simulation design, the influence of different throat lengths, expansion tube short axis lengths and diffuser tube angle  on the uniformity of the mixer outlet surface were explored. The simulation results showed that when the length of the primary throat was 45 mm, the length of the secondary throat was 80 mm, the short axis length of the primary jet expansion tube was 26 mm, and the angle of the secondary jet diffusion tube was 7°, the coefficient of variation was the smallest and the best mixing uniformity. And then the influence of different mixing ratios on the mixing coefficient of variation of the mixer was simulated and analyzed, and it was concluded that the two-stage mixer  achieved the same mixing effect under different mixing ratios. According to the optimized simulation results, the test data of different flow rates and mixing ratios were selected to compare the mixers. The test results showed that the maximum error between the test value and the actual value of the same mixing ratio was 3.5%, and the mixing coefficient of variation was all below 0.041 2, which indicated that the mixer could achieve a better mixing effect when the mixer was from 300∶1 to 3 000∶1. The maximum error between the simulated value and the experimental value of the same mixing ratio was 12.1%, which proved that the two-stage injection jet mixer meets the design requirements.

Design and Experiment of Microwave Vacuum Drying Equipment with CO₂ Cold Trap

SHI Yangjie, XI Xiaobo, YUAN Rican, SHAN Xiang, ZHANG Qi, ZHAO Qidong, ZHANG Ruihong

2021, 23(6):  97-104.  DOI: 10.13304/j.nykjdb.2020.0356

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In order to optimize the technology of microwave vacuum freeze drying, a microwave vacuum dryer with CO2 cold trap was developed based on the principle of microwave vacuum freeze-drying, and the main structure, working principle and working process of the device were introduced. It innovatively used  liquid CO₂ as a refrigerant, and achieved the recycling of CO₂ through a reasonable layout. Based on the principle  liquid CO₂ spray pre-freezing, the structure of spray device was designed, and the rotating speed of rotary table was calculated to improve the effect of material pre-freezing. The finned cold trap tube was designed, and according to the formula of heat transfer coefficient of fin type cold well tube, the specific size of the cold well tube was determined. The convective heat transfer process with phase change in the cold well was analyzed, the gas in the cold well was located in the slipstream zone by calculation, and the evaluation index of convective heat transfer intensity in the cold well was Nu≈4.3, indicating that the heat transfer efficiency was good. Taking white radish as an example, the effect of spray flow and microwave power on drying rate was tested. The results showed that in case of no frostbite on materials, the larger the spray flow was, the better the material pre-freezing effect was; in a certain range, the material drying rate had a positive correlation with the spray flow and microwave power, and both show a trend of fast first and then slow.

Purification of Polyphenols from Sweet Tea by the Macroporous Resins and Its Inhibitory Activity on α-glucosidase and DPPH·

WU Jie, GONG Jiangning

2021, 23(6):  113-119.  DOI: 10.13304/j.nykjdb.2020.0804

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In order to fully utilize sweet tea  resource and screen out active ingredients for hypoglycemic treatment and antioxidance, this paper optimized the HPD-826 resin from four different polarities of macroporous resins by comparing their static adsorption and desorption performances on sweet tea polyphenols; and discussed its conditions of dynamically purified process. Then, the polyphenols after purification were extracted with HPD-826 resin by using organic solvents with different polarities, and the effects of hypoglycemic treatment and antioxidance were determined. The results showed that the optimal conditions of sweet tea polyphenols purified by HPD-826 resin were followed: sample with 2.0 mg·mL-1 mass concentration of solution, 50 mL volume, and 2 BV·h^-1 flow rate, eluent ethanol with 60% volume fraction, 250 mL volume, and 2 BV·h^-1 eluent rate. Under these optimized conditons, the mean purity of polyphenol was up to 81.2%. There were positive correlations between mass concentrations of solvent extracts and inhibition rate of α-glucosidase and clearance rate of DPPH·. The ethyl acetate-soluble fraction from polyphenol purified by HPD-826 resin had the strongest inhibition to α-glucosidase and DPPH·, which showed good value of medicinal development.

Research Progress on the Current Status of Reactive Nitrogen Losses from Cropland Soil and the Regulation Pathways of Biochar Amendment

HU Chaohua, LIU Yueming, PANG Ziqin, YUAN Zhaonian

2021, 23(6):  120-129.  DOI: 10.13304/j.nykjdb.2021.0113

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N₂O emission and NO^-3-N leaching from cropland are major pathways of reactive N losses in soils, and important sources of global reactive N pollution, resulting in a serious threat to global climate and water environment security. The producing process of cropland reactive N losses is closely related to soil nitrification and denitrification. There exists significant difference regarding to soil nitrification and denitrification under different cultivation systems. Particularly, in our country, long-term and high input of nitrogen fertilization is widespread in continuous cropping farmland of economic crops (e.g., sugarcane), leading to accelerate large-scale soil acidification, and enhance the soil nitrification significantly, which directly affect the change trend and controlling strategy of agriculture-derived reactive N losses. In recent years, as a kind of multi-functional and char-based soil conditioner, biochar has great potential in application for regulating reactive N transformation processes, improving farmland soil, as well as increasing or maintaining crop yield. In this paper, research progress on the status of agricultural soil reactive N losses was reviewed, followed by its main influencing factors and key microbial processes. Furthermore, the potential pathways of biochar amendment to regulate reactive N transformation and nitrogen recycling utilization in cropland were explored, and then the future research direction was also prospected correspondingly, aiming to provide new ideas for the research on the control of reactive N pollution in farmland, efficient utilization of N fertilizers, as well as the development of high-efficiency, green and sustainable agriculture in China

Effect of Increasing Temperature in Different Growth Stages on Rice Yield and Quality in Cold Regions

JIANG Shukun, WANG Lizhi, YANG Xianli, CHI liyong, LI Zhongjie, LI Mingxian, ZHANG Xijuan, ZHAO Qian, LI Rui, JIANG Hui, LI Wenhua

2021, 23(6):  130-139.  DOI: 10.13304/j.nykjdb.2019.0983

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Global warming and climate change make hot temperature become one of the main climatic factors limiting rice production in cold regions. Open hexagonal glass house was used to simulate high temperature in daytime in this study, with a tolerant high-yield variety Longdao 21 and a susceptible high-quality variety Longdao 18 as materials, to research the effect of high temperature in different growth stages on rice yield and grain quality in the cold region. The results showed that heating facilities could increase an average daily temperature by 1.2 to 2.6 ℃. High temperature during the whole growth period increased the yield of Longdao 21 and Longdao 18 by 7.4 and 4.5 t·hm^-2, respectively. Yield-increasing was mainly achieved by high biomass, more effective panicles and  greater spikelet’s number per panicle. The yield of Longdao 21 increased 1.2, 3.9, 0.8 and 1.1 t·hm^-2 by high temperature at tillering stage, jointing stage, heading stage and grain-filling stage, respectively. The yield of Longdao 18 increased 1.5, 2.5 and 1.8 t·hm^-2 by high temperature at jointing stage, heading stage and grain-filling stage, respectively. The yields of Longdao 21 and Longdao 18 decreased 0.2 and 1.2·t hm^-2 by high temperature at the booting stage. High yield was mainly achieved by high biomass, more effective panicles and  greater spikelet number per panicle at tillering stage, jointing stage, heading stage and grain-filling stage. The yield response of different heat-resistant varieties to high temperature was mainly affected by the seed setting rate. At the same time, it was also found that the temperature increasing had a negative effect on 1 000-grain weight. The brown rice rate and milled rice rate were increased by high temperature at tillering stage and jointing stage, while the brown rice rate and milled rice rate were increased at booting stage, heading stage and grain-filling stage. The chalky kernel and chalkiness increased by high temperature at booting stage, heading stage and grain-filling stage. The effects of high temperature on rice taste value, protein content and amylose content were small. In the future, if high temperature occurs at the early growth stages in cold regions, the harm would be relatively weak, and there would be some beneficial effects. However, if the high temperature occured at the booting stage, heading stage and grain-filling stage, it would be more harmful to the production of high-quality rice in the cold region. The research of high temperature on rice in the late growth stage and breeding high temperature resistant varieties should be further strengthened in the future.





Influences of Selenium Fertilizer on Millet Yield and Grain Selenium Enrichment

LI Ran, LIU Yuhang, LIANG Shan, ZHANG Min,

2021, 23(6):  140-146.  DOI: 10.13304/j.nykjdb.2020.0250

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In order to guide the rational use of selenium fertilizer in the production of selenium-enriched millet and to explore the effects of organic selenium fertilizer (bioselenium-enriched synergist) and inorganic selenium fertilizer (sodium selenite) on the growth of millet and selenium absorption in grains, the effects of different selenium fertilizers（15、30、60、120 g·hm^-2） on ear characteristics, grain selenium content, selenium existing form and lutein content of millet were analyzed by spraying different concentrations of organic selenium fertilizer and inorganic selenium fertilizer, sodium selenite, on the leaf surface of millet. The results showed that the leaf spraying of two kinds of selenium fertilizers could increase  grain yield and grain selenium content, and the effect of inorganic selenium fertilizer was better than that of organic selenium fertilizer. The millet yield treated with inorganic selenium fertilizer of 60 g·hm^-2 reached to 92.80%, and the selenium content reached to 1.09 mg·kg^-1. The analysis on  selenium morphology showed that selenium in millet grain was mainly in the organic form including selenocystine and selenomethionine. The content of organic selenium in the inorganic selenium fertilizer treatment was higher than that in the organic selenium fertilizer one. No significant effect was found of selenium on the lutein content of millet grains. The results showed that, compared with the organic selenium, sodium selenite was a better selenium fertilizer for producing selenium-enriched millet.

Effects of Different Straw Biochar Substrate on the Physiological Properties of Cosmos bipinnatus

HUANG Qingyang, JIANG Chao, YU Yuanchun, XIE Zubin

2021, 23(6):  147-153.  DOI: 10.13304/j.nykjdb.2020.0077

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In order to study the effect of straw biochar compound substrate on the growth of Cosmos bipinnatus, peat, vermiculite, pearlite and soil with the proportion of 4∶1∶1∶4 (volume ratio) were set as a control, and straw biochars of soybean, wheat, rice, corn and aged corn were chosen as test materials and replaced the peat in control group according to different proportion until the peat was completely replaced for determining the best type and dosage of straw biochar in Cosmos bipinnatus cultivation. The results showed that, compared to control group, straw biochar substrates promoted the growth of the Cosmos bipinnatus. According to the straw biochar types and dosages, straw biochar substrates significantly affected germination rate, biomass, malondialdehyde content, catalase activity, chloroplast pigment concentration and root activity. When rice straw biochar compound substrate (biochar 20%, peat 20%, perlite 10%, vermiculite 10%, soil 40%) was used to cultivate the Cosmos bipinnatus, the germination rate was the highest, and the biomass, catalase activity and root activity were significantly increased compared with the control group. Chloroplast pigment concentration and malondialdehyde content were not significantly different from the control group.

Study on the Transformation of Nutrients in Kitchen Waste by Black Soldier Fly

YIN Jingkai, GONG Xiaoyan, SUN Lina, HAN Mengqi, YANG Yuan, XU Xiaoyan, WANG Xiaobo

2021, 23(6):  154-159.  DOI: 10.13304/j.nykjdb.2020.0263

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In order to evaluate the resource utilization of black soldier fly to kitchen waste，the best production performance of  black soldier fly larvae to treat kitchen waste was screened, and the conversion of black soldier fly to kitchen waste under the best production performance was analyzed. The results showed that: the production performance of treatment of 3.6 kg kitchen waste by 100 g 7-day-old black soldier fly larvae was the best, the dry matter reduction rate of kitchen waste was 74.0%, and the dry matter conversion rate was 33.9% after 8 d coversion of kitchen waste. The content of crude protein and fat in worm was 45.1% and 48.1% respectively, which was 61.2% and 640% of the total protein and fat in the original kitchen waste. 61.3% of N and 71.4% of K in kitchen waste were transferred into the worm, 60.0% of P and 50.4% of Na were transferred into the feces. The pH, EC and organic matter content of the feces were 22.5%, 32.4% and 28.9% higher than that of the original kitchen waste, respectively, and the contents of N, P and Na were 13.5%, 130% and 92.9% higher, respectively. There was no significant change in K content. The pH, organic matter and N, P, K nutrient content of the feces meet the requirements of China's organic fertilizer standards. These results showed that the biotransformation of black soldier fly was a feasible and efficient way to treat kitchen waste.

Progress on Genetic Engineered Vaccines for Fish Diseases

JIANG Shuiqing, LI Ting, ZHANG Yinan, HUANG Xiaohong

2021, 23(6):  160-170.  DOI: 10.13304/j.nykjdb.2020.0555

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Chemicals used for the prevention and control of fish diseases have brought about the deterioration of water quality, excessive drug residues in aquatic products and increased drug resistance of pathogens. With the development of the fish immunology and molecular biological technology, genetically engineered vaccines for fish diseases have been given considerable attention. This paper systematically summarized the background, significance, types and research status of fish genetic engineered vaccine, clarified challenges and proposed some suggestions for further development, which would provide reference for the development and application of the fish vaccines in the future.

Impacts of Tropical Cyclones on Mussel Culture Area and Yield in Shengsi

WU Zuli, HUANG Liangmin, WANG Fei, ZHANG Shengmao, ZHANG Shouyu

2021, 23(6):  171-183.  DOI: 10.13304/j.nykjdb.2019.1044

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In order to study the effects of tropical cyclones on mussel cultivation facilities in Shengsi country Ma’an archipelago and provide basic data for the reasonable distribution of Shengsi mussel culture location, this paper used some data to analyze the effects of tropical cyclones on the changes of the marine environment field, location and area of Shengsi mussel culture. The data contained the track data of tropical cyclones in northwest pacific from 2000 to 2018, mussel culture area and yield data, the environmental elements in marine culture area measured data and remote sensing data, and mussel culture area status from remote sensing images. Based on  the statistical characteristics of historical tropical cyclone movement path and wind condition, the results of multi-year variation of mussel culture location in Ma’an archipelago, the types of sediment and the characteristics of geographical islands distribution in Ma’an archipelago, the suggestions for mussel culture location selection in Ma’an archipelago were put forward. The results showed that: a total of 38 tropical cyclones entered the affected area during 2000 to 2018. The annual average number of tropical cyclones was about 2, and high frequency of tropical cyclones were found in July to September, with frequency peaking in August. The paths of tropical cyclones could be divided into 2 types, 9 tropical cyclones of the first type path mainly were server tropical cyclones intensity and 29 tropical cyclones of the second type path mainly were tropical storm or typhoon intensity. The wind in the direction of south-southeast-eastsouth was rare throughout all the years, but the northwest-northeast north wind reached 9 to 11 grade produced by tropical cyclones sometimes happended in August. The mussel culture area in Shengsi was damaged in a large area under the impact of strong northeastward wind and rapid current caused by Muifa in the year 2011. Since 2011, the Shengsi mussel culture area had experienced three times of recovery and expansion, by now the main culture area tended to be saturated. It was proposed that a new mussel culture area could be established in the west of Huaniao island, Dongkushan island, Qiuzishan island, Zhuzhushan island and Sanhengshan island on arc-islands chain.

Phenotypic Identification and Combining Ability Effect Analysis of Mutants by Fast Neutron Irradiation

LIU Zhongxiang, YANG Yanzhong, WANG Xiaojuan, LIAN Xiaorong, ZHOU Wenqi, HE Haijun, ZHOU Yuqian, KOU Sirong

2021, 23(6):  184-194.  DOI: 10.13304/j.nykjdb.2020.0451

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In order to evaluate the combining ability effects and utilization value of  maize breeding, six mutants (fu18312, fu1603, fu17138, fu18321, fu18398 and fu18362) obtained by 252CF fast neutron irradiation were used as female parents, while Chang 7-2, Mo17, B73, LY0986 and LY162 were used as male parents. On the basis of the phenotypic characterization, 11 agronomic traits of 11 materials were divided into two groups according to NCII design (incomplete diallel cross design). And the combining ability effects of 30 cross combinations were analyzed. The results showed that the general combining abilities (GCA) of 6 mutants varied greatly in the same or different traits. The GCA effect of fu18312 (dwarf and low-spike mutant) were negative on plant height and ear height, which should be beneficial to the improvement of lodging resistance of hybrid combination. The GCA effects of fu1603 and fu17138 on traits of yield were mostly positive, which should be used to the breeding of new variety with higher stem, bigger ear and more grain number. Due to yellow leaf margins and lower yield compared with the wild type, fu17138 could be used as a marker in seed production for protecting intellectual property rights. A strong dominant hybrid combination (LY0986×fu17138) was screened through analyzing the combining ability of the main agronomic traits of 6 mutants, which provided germplasm resources for breed selection and  a theoretical basis for further improvement and utilization of fast neutron mutants.

Determination of Magnesium Content in Natural Rubber by Three Different Digested Methods

PAN Xiaowei, YE Jianzhi, ZENG Shaodong, LI Pei, LIN Liyun, ZHANG Jianguo, YANG Chunliang

2021, 23(6):  195-201.  DOI: 10.13304/j.nykjdb.2019.0912

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To study a suitable method for determining magnesium content in natural rubber, the digested effects of three methods were studied including dry ashing, microwave digestion and graphite digestion. The results showed that three methods could meet the basic requirements. Dry ashing method had little influence on the experimental data. When the concentration of samples was low, the sample size could be appropriately increased. The microwave digestion had simple operation and short detected time. Graphite digestion had not only simple operation but also higher efficiency, so it was convenient for analysing a bulk of samples. Moreover, compared with the other methods, the cost of equipment and consumables of the graphite digestion had the greatest advantages. The graphite digestion was recommended as the more suitable method to measure the content of magnesium in natural rubber.