Table of Content

15 April 2022, Volume 24 Issue 4

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AGRICULTURAL INNOVATION FORUM

Proposal Application， Peer Review and Funding of the Basic Agriculture and Crop Science Discipline of National Natural Science Foundation in 2021

Shanshan WEI, Xingfeng LI, Jing LUO

2022, 24(4):  1-10.  DOI: 10.13304/j.nykjdb.2022.0130

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In order to continuously promote the reform of science funds， facilitate the balanced and coordinated sustainable development of discipline， the proposal application， review and funding conditions under the new application code of the basic agriculture and crop science discipline of National Natural Science Foundation in 2021 were analyzed. The category-specific application and review based on the 4 types of scientific natures were also analyzed， and main problems and suggestions existing in the project application were proposed.

Research Progress of Histone Modification in Rice

Tao YANG, Xiaoqian MA, Quan ZHANG, Hongliang ZHANG

2022, 24(4):  11-20.  DOI: 10.13304/j.nykjdb.2021.0497

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As an important type of epigenetics， histone modification plays an important role in maintaining eukaryotic genome stability， gene expression regulation， and chromatin structure. Rice is an important food crop and a model plant for scientific research. Recent studies have found that histone modifications involved in the regulation of many important biological phenomena in rice， including growth and development， stress response， yield and quality formation. Therefore， clarifying the genetic and regulatory mechanisms of histone modifications in rice is of great significance to the genetic improvement of rice. In this paper， the mechanism of histone modification and the research progress in rice were reviewed， and the research prospects of histone modification in rice were further prospected， which can provide reference of rice breeding.

BIOTECHNOLOGY & LIFE SCIENCE

Genetic Composition of Taishan 22 Using High-density 90K SNP Array

Ruixia WANG, Xiaoling ZHAI, Yugang LI, Qiuhuan MU, Yingying SUN, Xianyin SUN, Yong MI, Guangde LYU, Hongmei GE, Zhaoguo QIAN

2022, 24(4):  21-29.  DOI: 10.13304/j.nykjdb.2021.0721

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In order to explore the effect of breeding selection on genome of wheat， this study evaluated the inheritance from Lumai 18 （mother） and Lumai14 （father）to Taishan 22 using 90K SNP array. The results showed that Taishan 22 inherited a little more SNP loci from Lumai 18 （51.87% ） than from Lumai 14 （ 48.13% ）. In Taishan 22， chromosomes 1A， 1B， 2A， 3B， 4A， 6A， 7A， 7B and 7D harbored more than 50% SNPs from Lumai 14， over 85% SNPs on 3B， 6A and 7A. Whereas， the remaining 12 chromosomes carried more than 50.00% SNPs from Lumai 18， over 98.00% SNPs on 2B and 5B especially. The parental genetic compositions were present mainly in large chromosomal segments in Taishan 22 on 1B， 2D， 4A， 5A， 5B， 6B and 7A chromosomes. Phenotyping investigation in multi-locations across years indicated that Taishan 22 was higher than Lumai 18 in plant height， internode length below spike， length from flag leaf pulvinus to spike base and days from sowing to heading. The yield related traits of spikelet number per spike， grain number per spike and 1 000-grain weight were between in the parents under rained conditions， while higher than Lumai18 in under other conditions. Grain length of Taishan 22 was higher than that of Lumai 18 under the 3 conditions， while grain width and grain thickness were between in the parents. Those results analyzed the genetic contribution from parental generation to filial generation， exhibited the influence of hybridization and artificial selection on agronomical traits and genome.

Changes of Agronomic Traits， Biomass Yield and Quality of National Silage Maize Combinations （Varieties）

Guanglei CHENG, Jun QIU, Xiaoguang WANG, Tianjun XU, Chuanyong CHEN, Chunyuan ZHANG, Qianqian XIA, Yuanqi WU, Jiuran ZHAO, Ronghuan WANG

2022, 24(4):  30-37.  DOI: 10.13304/j.nykjdb.2021.0453

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Silage corn， with its unique advantages， occupies an important position in modern agriculture. The changes of agronomic traits， biological yield and quality of 394 silage maize combinations （varieties） tested in the national corn variety regional trials from 2003 to 2019 were systematically analyzed in this paper to provide instructive information for the development of Chinese silage maize industry and variety breeding. The results showed that： ① the average growth period of silage maize combinations （varieties） was 111.8 d from 2003 to 2019， the spring sowing combinations （varieties） was 109.3 d， which was 9.7 d longer than that of summer sowing. The average growth period of the spring sowing combinations （varieties） prolonged， while the summer sowing combinations （varieties） shortened gradually. ② The average plant height and ear height of silage maize combinations （varieties） was 300.5 and 132.3 cm respectively and both increased gradually from 2003 to 2019. The plant height increased by 12.5 cm， while the ear height only increased by 2.1 cm during the recent decade. ③ The average biological yield of the tested silage maize combinations （varieties） was 19 477.5 kg DW·hm^-2 from 2003 to 2019， with the trend of first decreasing and then increasing. The biomass dry weight yield from 2011 to 2019 increased by 721.8 kg·hm^-2 compared with that of 2003 to 2010. ④ The average content of neutral detergent fiber （NDF） and acid detergent fiber （ADF） content of the silage maize combinations （varieties） were 46.7% and 21.5% respectively from 2003 to 2019， with the trend of first increasing and then decreasing. The NDF and ADF content from 2011 to 2019 decreased by 6.8 and 5.5 percentage point respectively than that of 2003 to 2010. ⑤ The average crude protein content of the tested silage maize combinations （varieties） was 8.7% （2003—2019）， with less variation among years. The average starch content was 31.0% （2014—2019）， with the trend of increasing and concentrating gradually. The consecutive 17 year national silage maize regional trials showed that， the growth period of silage maize combinations （varieties） indicated the trend of the spring sowing prolonged， while the summer sowing shortened gradually； the plant height increased， but the ear height had little change； the quality improvement achieved remarkable progress， NDF and ADF content decreased significantly， the starch content increased obviously， the crude protein content remained stable； and the biological yield increased.

Mining SSR Loci and Analysis the Genetic Diversity of Tartary Buckwheat Based on the Whole Genome Sequence

Xixi ZUO, Yingjie SONG, Xinyan MA, Yunhui YANG, Yifei WANG, Zeguang GUO, Xiongzhi ZHU, Yue LIU

2022, 24(4):  38-51.  DOI: 10.13304/j.nykjdb.2021.0521

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Tartary buckwheat （Fagopyrum tataricum） is an important minor crop. In this study， molecular markers of the simple sequence repeat （SSR） were mined from 8 chromosomes sequence of tartary buckwheat in GenBank database. SSR primers were designed by primer 3.0 software and those with high polymorphism were employed to evaluate the genetic diversity. A total of 51 485 SSR loci were screened with average frequency of 114.07 Mb^-1. Among these SSR motifs， dinucleotide repeat was the main type accounting for 78.20%， followed by trinucleotide repeat （17.76%）. There were 361 types of repeat motifs， while AT/AT （69.60 %）， AAT/TTA （2.49%） and AGA/TCT （2.10%） were the main repeat types. The SSRs length ranged from 12 to 228 bp， and the ratio of SSRs with length ranging from 12 to 20 bp was 57.93%， the ratio with length above 20 bp was 42.07%. It was found that the SSR types detected were specific to the chromosomes. Based on the type of SSR loci， 156 pairs of primers were designed and 17 pairs of primers were screened with high polymorphism to analyze the genetic diversity of the 42 local varieties of tartary buckwheat. The diversity of black tartary buckwheat samples in Meigu County was the highest. The diversity of samples in Butuo County was significantly lower than that in the other two counties. It was of great significance to identify and analyze tartary buckwheat germplasm resources and molecular marker-assisted breeding through a large number of SSR mining， especially the chromosome specific SSR loci mining. In this study， a large number of SSRs were mined， especially the chromosomal specific SSR sites were mined， which was of great significance for the identification and analysis of tartary buckwheat germplasm resources and the molecular marker-assisted breeding of tartary buckwheat. Genetic diversity analysis also revealed the availability of SSR markers and the level of genetic diversity of tartary buckwheat， which provided a new approach for the study of the conservation of genetic diversity of tartary buckwheat.

Identification of Cold-related Co-expression Modules in Cotton Cotyledon by WGCNA

Yuqing ZHOU, Yongfei YANG, Changwei GE, Qian SHEN, Siping ZHANG, Shaodong LIU, Huijuan MA, Jing CHEN, Ruihua LIU, Shicong LI, Xinhua ZHAO, Cundong LI, Chaoyou PANG

2022, 24(4):  52-62.  DOI: 10.13304/j.nykjdb.2020.0783

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Weighted gene co-expression network analysis （WGCNA） is substantially used to identify gene modules related to the trait of interest in multi-sample transcriptome data. Transcriptome data of Xinluzhong 16 and Xinluzhong 32 were assessed to prospect molecular mechanisms under 4 ℃ stress to study the mechnism of cotton’s response to cold stress. Ultimately， the co-expression matrix containing 22 083 expressed genes was fabricated after the genes of low expression level were filtered. And them WGCNA identified 9 modules， among them 2 modules remarkably linked with cold resistance such as brown positively associated with 9 and 12 h， while blue positively associated with 0， 1 and 3 h. KEGG and GO enrichment perusal were evaluated on these 2 modules which could be enriched with GO terms， i.?e. modulation of stress response. Hub genes were screened by estimating gene connectivity in their corresponding networks which might play key roles in abiotic stress resistance. Above results would assist in understanding the regulatory mechanism of cold tolerance in cotton.

Identification of COI Family Genes and Their Expression in Gossypium hirsutum L. Under Drought and Salt Stress

Meili LI, Junji SU, Yonglin YANG, Jianghong QIN, Xianxian LI, Delong YANG, Qi MA, Caixiang WANG

2022, 24(4):  63-74.  DOI: 10.13304/j.nykjdb.2021.0926

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COI1 （COR-insensitive 1） and Skp1-Cullin-F-box protein constitute the SCF^COI1 complex，a core component of jasmine signal transduction， which plays an important role in plant growth development and response to stress. A total of 48 COI genes were identified in Gossypium hirsutum L.， which were unevenly distributed in 21 chromosomes and mainly located in the nucleus and cytoplasm. According to the phylogenetic relationship， the GhCOI genes were divided into 3 subgroups （Ⅰ~Ⅲ）. Collinearity analysis showed that COI genes expanded by segmental duplication in upland cotton. The GhCOI genes contained 1 ~ 9 exons， and there were 6 stress response elements in their promoter regions. The transcriptome data showed that 66.7%， 56.25%， 68.8% and 27.1% of genes were highly expressed under NaCl， PEG， heat and cold stress， respectively， and some genes responded to multiple abiotic stresses simultaneously. The qRT-PCR results showed that GhCOI5-A06 was a candidate gene with strong response to NaCl and PEG stress， which showed that GhCOIs involved in response to abiotic stress. Above results laid foundation for further analysis of this family genes function in cotton.

Analysis of Codon Usage Bias and Phylogenetic of Chloroplast Genome in Nymphaea

Xiang HUANG, Guangming CHU, Xinkai ZHENG, Jintao CHENG, Jianhao CHEN, Yingchun XU, Qijiang JIN, Meihua YANG

2022, 24(4):  75-84.  DOI: 10.13304/j.nykjdb.2021.0768

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Nymphaea is primitive angiosperm with important economic， medicinal and ornamental value. The characteries analysis of codons in the coding region of chloroplast genome is of great significance for chloroplast genetic engineering and species phylogeny. The codon usage profiling of chloroplast genomes in Nymphaea was systematically analyzed， and the phylogenetic relationship was decoded among the 22 Nymphaea plants. The results showed that the codon adaptation index of chloroplast genome from total 22 Nymphaea ranged from 0.168 to 0.170， and the effective codon number ranged from 51.301 to 51.577， which indicated weak codon preference in Nymphaea. The GC contents of bases at different positions of codon were 46.26% （GC1）， 38.67% （GC2） and 32.54% （GC3）， respectively， indicating that A and U used in chloroplast codons were rich in Nymphaea. The analysis of ENC plot， PR2 plot and neutral plot showed that the codon bias in the chloroplast genome was mainly affected by selection pressure. Correlation analysis showed that ENC value was significantly correlated with GC2 and GC3 （P<0.05）， which indicated that the composition of bases in the 1^st and 2^nd had great influence on codon using pattern. The optimal codon analysis showed that there were quantitative differences of the optimal codons among these species （5~11）， and two optimal codons （CCA and AAU） were determined. Phylogenetic analysis showed that the classification results based on relative synonymous codon usage （RSCU） value were consistent to those based on chloroplast gene sequences （matK， trnL?trnF and coding sequence）， which indicated that the codon using characteristics among related species of Nymphaea were similar， and the classification results based on codon RSCU value divided Nymphaea into 3 subgenera， which provided a theoretical basis for the phylogeny， species classification and chloroplast genetic engineering of Nymphaea.

Effects of Different Light Qualities on Growth， Physiological Characteristics and Flavonoids Accumulation of Epimedium koreanum

Ailin DAI, Yonggang ZHANG, Qiang AI, Xichao TENG, Limin YANG

2022, 24(4):  85-92.  DOI: 10.13304/j.nykjdb.2021.0676

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In order to study the effects of different light quality treatments on the growth， physiological characteristics and flavonoid accumulation of Epimedium koreanum， and determine the suitable light quality conditions for the cultivation and production of E. koreanum， 4 kinds of LED light source （white， red， yellow， blue） were set， and the white light treatment was as control （CK）. The growth indicators， physiological indicators and the content of flavonoids of E. koreanum under different light treatments， such as plant height， stem diameter， leaf area， leaf fresh weight， leaf dry weight， chlorophyll content， photosynthetic parameters， antioxidant enzyme activity， etc. were determined. The results showed that the leaf area， leaf fresh weight， leaf dry weight and chlorophyll content of E. koreanum significantly increased under blue light treatment. And the net photosynthetic under blue light treatment rate was higher than those under other light treatments. The blue light treatment promoted the accumulation of flavonoids in the leaves of E. koreanum. Compared with the white light treatment， the contents of total flavonoids， icariin and total flavonol glycosides under blue light treatment increased by 12.9%， 14.3% and 8.6%， respectively.Red and yellow light treatment were not conducive to the accumulation of flavonoids in the leaves of E. koreanum. Therefore， the leaf yield and flavonoid content of E. koreanum could be increased by covering the blue film or supplementing the LED blue light source at night during the cultivation of E. koreanum.

INTELLIGENT AGRICULTURE & AGRICULTURAL MACHINERY

Research Progress of Agricultural Machinery Scheduling Technology Based on Time Window

Huang HUANG, Yanyan CHEN, Pengyu CHEN, Rui LUO, Yadong LIU, Wei HU

2022, 24(4):  93-106.  DOI: 10.13304/j.nykjdb.2021.0723

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The construction of cross-regional multi-agricultural machinery scheduling service system can reduce the cost of traditional agricultural machinery allocation， avoid the blind flow of multi-regional agricultural machinery， and improve the efficiency of agricultural machinery. At present， cross-regional multi-agricultural machinery scheduling service is the main operation mode of agriculture in China， and intelligent scheduling model and optimization algorithm are widely used in agricultural machinery scheduling. Aiming at the characteristics of agricultural machinery intelligent scheduling technology based on time window， the differences between agricultural machinery scheduling and traditional vehicle scheduling， and the research on the current situation of agricultural machinery intelligent scheduling by domestic and foreign scholars were introduced. And problems of hard time window， soft time window and fuzzy time window in the field of vehicle scheduling were also expounded. Models of agricultural machinery intelligent scheduling optimization problem were sorted out and classified， and hybrid algorithms of single intelligent algorithm and multiple algorithms for agricultural machinery scheduling problems were summarized. The status of agricultural machinery scheduling problems on job focus， model building and scheduling algorithm were summarized， and the future development direction was prospected.

Performance Simulation and Experiment of Stirred and Bunch Rice Seeding Device

Nanrui TANG, Yong ZHOU, Guozhong ZHANG, Fang LIANG, Huibin KE

2022, 24(4):  107-115.  DOI: 10.13304/j.nykjdb.2020.0975

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Aming at the problems of poor fluidity and the difficulty of filling seeds in the filling area resulted by rough surface of rice seeds， a double-cavity rice precision seeding and bunch seeding device with filling and stirring function was designed. The device stired the filling area’s seeds through the stirring type holes protruding from the seed plate to increase the seeds fluidity in the filling area. Besides， the stirring side plate was placed in the first stage of the stirring type holes to direct the seed flow and assist the seed filling. The results of EDEM simulation showed that the stirring holes increased the seeds fluidity of the filling area and assist with the seed filling. This three-factor and three-level orthogonal test was conducted taking the rice seed “Guangliangyou 100” with bud as the test object and the stirring hole depth， the seeding plate rotation speed and the seeding layer height as test factors. Additionally， bench test was conducted on the bunch seeding device’s performance on the JPS-12 test stand. The experimental results showed that when the hole depth was 7 mm， the seeding layer height of the filling area was 50 mm， and the rotation speed of the bunch seeding plate was 30 r·min^-1， the performance of the bunch seeding device was optimal. At this time， the qualified rate of the hole number was 85.7%， the seeding omission index was 1.8%， and the qualified rate of hole spacing was 96.4%. This study provided reference for the design and improving seeding performance of mechanical seeding device.

Research on Mechanical Characteristics of Clamping Conveyor for Leafy Vegetables

Qi LIU, Bin CHEN, Songlin SUN, Mingtao XIAO, Chaoran SUN

2022, 24(4):  116-125.  DOI: 10.13304/j.nykjdb.2021.0759

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In order to determine the mechanized harvesting parameters of leafy vegetables， Pakchoi at the harvest period was taken as the research object， and the critical force test of clamping parts damage was carried out to determine the non-destructive clamping force of Pakchoi. Aiming at the shortcomings of the current universal testing machine for compression testing， a testing platform for measuring clamping parameters was designed. This testing platform could adjust the relevant parameters of the clamping and conveying operation， and record the operation process in real time with the help of sensors.Taking clamping angle （15°～25°）， clamping height （2.0～4.0 cm）， and clamping material （rubber timing belt， pattern conveyor belt， blue cloth sponge belt） as the influencing factors， damaging the critical force and damaging compression as the evaluation index， the response surface test method was used to carry out the optimization test of the comprehensive influencing factors of the clamping and conveying in the harvesting process of Pakchoi， the regression equation between the test influencing factors and the test evaluation index was established and the influence of the test influencing factor combination on the gripping conveyance of Pakchoi was explored. The results showed that when blue cloth sponge belt was used as clamping material， the minimum damage critical force and damage compression were used as the goal， the damage critical force and damage compression at this time were 16.95 N and 18.03 mm in order， at a clamping angle of 15° and the clamping height of 2.0 cm. In the actual harvest， the clamping force should be between the minimum clamping force and the critical damage force， then the harvest could reduce the damage rate of the Pakchoi Harvest.

BIO-MANUFACTURING & RESOURCE AND ECOLOGY

Study on Dynamic Effects of Organic Materials on Soil Carbon， Nitrogen and Microbial Biomass

Yue GU, Jinggui WU

2022, 24(4):  126-133.  DOI: 10.13304/j.nykjdb.2021.0228

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In order to explore the effects of different sources of organic materials returning to the field under the condition of long-term mulching drip irrigation， 4 treatments were set up including no exogenous material （CK） and maize straw （MS）， forage grass （FG）， sheep manure （SM）. The contents of carbon and nitrogen in soil were determined during the whole growth period of maize. The results indicated that， due to the application of organic materials， the contents of soil organic carbon （SOC） and total nitrogen （TN） increased by 2.78%~19.83%， and the contents of soil biomass carbon （MBC） and soil biomass nitrogen （MBN） increased by 6.64%~39.91% and 4.05%~112%， respectively. And the quotient of microbial biomass carbon （qMBC） and quotient of microbial biomass nitrogen （qMBN） in organic materials treatments were higher than those in CK treatment， which indicated that the application of organic materials increased the microbial biomass carbon and nitrogen in soil. The soil metabolic quotient showed the fluctuating change with the growth of maize. MS treatment improved soil qMBC and qMBN， and increased the contents of MBC and MBN； while SM treatment showed the lower qMBC and qMBN， and the higher contents of SOC and TN. In general， the applying of organic materials return to the field could conducive to the storage of carbon and nitrogen in the soil.

Bench-scale Study on Operation Effect and Power Generation Performance Treatment of Dairy Farms Wastewater by Microbial Fuel Cell

Lu LIU, Xiuping TAO, Jianchao SONG, Bin SHANG, Wenqian XU, Hongmin DONG, Yangyang CAI

2022, 24(4):  134-143.  DOI: 10.13304/j.nykjdb.2021.0852

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In order to investigate the feasibility of applying microbial fuel cell （MFC） to dairy farm wastewater treatment technology， a dual-chamber and a single-chamber MFC reaction device were constructed. Dairy farm wastewater was used as the anode reaction liquid， and its electrical performance and degradation effect of main pollutants in sewage were studied. The results showed that both single-chamber and dual-chamber MFC could operate stably with electricity， the average maximum output voltage was 563.8 and 390.8 mV， the maximum power density was 48.5 and 21.7 mW·m^-2， and the apparent internal resistance was 346.4 and 489.5 Ω， respectively， and the single-chamber MFC had better power generation performance than the dual-chamber MFC. The average removal rates of chemical oxygen demand （COD） in daily farm wastewater by single-chamber MFC and dual-chamber MFC were 79.3% and 77.4%， respectively. The average removal rates of total phosphorus （TP）， total nitrogen （TN） and ammonia nitrogen （NH{}_{\mathrm{4}}^{+}-N） by single-chamber MFC were 70.9%， 65.4% and 78.9%， respectively. The corresponding removal rates were 101.4%， 24.3% and 21.0% higher than those of dual-chamber MFC， respectively， the pollutant removal rate of single-chamber MFC was superior to the dual-chamber MFC. MFC as a new method of wastewater treatment is technical feasibility for dairy wastewater treatment， it can generate electricity while degrading organic matter， nitrogen and phosphorus pollutants in dairy wastewater， and has broad prospects in achieving energy saving， carbon peaking and carbon neutrality.

Effects of Slow-released Fertilizer Compound Humic Acid Instead of Urea on Grain Yield and Population Quality in Xumai New Varieties

Yuan YI, Huiyun ZHANG, Liwei LIU, Jing WANG, Xuecheng ZHU, Na ZHAO, Guohua FENG

2022, 24(4):  144-153.  DOI: 10.13304/j.nykjdb.2021.0041

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In order to explore the promoting effects of slow-released fertilizer （SRF） compound humic acid instead of urea on grain yield. A three-factor split block was designed， and Xumai 2023 and Xumai 38 were selected as main plot， slow-released fertilizer and urea as 2 base fertilizer types and five treatment （A1， A2， A3， A4， A5） were set according to different nitrogen topdressing methods. To explore the effects of different nitrogen application on grain yield and its components， leaf area index （LAI）， stem and tiller number， earbearing tiller percentages， dry matter accumulation， and harvest index （HI）. Meanwhile， the correlation analysis between grain yield and population quality characteristics was also detected. The results showed that grain yield was significant positively with total setting kernels， dry matter accumulation after anthesis， harvest index and grain/leaf area（P<0.05）. The yield of the 2 varieties was the lowest under A1 treatment， and the yield increasing potential of slow-release fertilizer was higher than that of urea； among the topdressing methods， the topdressing of slow-release fertilizer at the regreening stage had the best yield increase effect. Compared with the conventional fertilization mode of farmer （urea was applied to both base fertilizer and jointing fertilizer）， the application of slow-release fertilizer twice before sowing and regreening period increased the yield of Xumai 2023 and Xumai 38 by 2.86% and 3.06%， respectively， indicating that this fertilization mode has high yield increasing potential and application value in production.

Effects of Sodium Dinitrate with Bacillus Sbutilis Complex on Growth and Physiological Indexes of Tobacco Seedlings

Tianwei PENG, Huiya XIE, Sijun LI, Yixuan LIU, Kaifeng SHUAI, Yuanyuan PENG, Qing WANG, Diqin LI

2022, 24(4):  154-161.  DOI: 10.13304/j.nykjdb.2021.0128

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In order to study the effects of different concentrations combination of plant growth regulators and microorganism agents on quality of tobacco seedlings， new flue-cured tobacco strain 20619 with floating seedlings as the experimental material， different concentrations mixture of sodium nitrophenolate & Bacillus subtilis agent was sprayed on 4 leaves 1 heart of tobacco seedlings， and determined and analyzed main growth and physiological indexes of tobacco seedlings with 8 leaves & 1 heart. The result showed that in 8 leaves 1 heart of tobacco seedlings after sprayed compound of sodium nitrophenolate & Bacillus subtilis agent， its dry matter accumulation content， root activity， chlorophyll content and nitrate reductase activity were better than that of the control， and dry weight （4.98 g·plant^-1）， ratio of dry to fresh weight， roots activity （93.01 μg·g^-1·h^-1）， chlorophyll content （0.548 5 mg·g^-1） & nitrate reductase （1.434 U·g^-1） of tobacco seedlings were the highest of the treatment of spraied compounding agents of sodium nitrophenolate 20 mg & Bacillus subtilis agent 7.5 g， and activities of catalase， superoxide dismutase， peroxidase and malondialdehyde in leaves were the highest. It showed that spraying the mixture of sodium nitrophenolate & Bacillus subtilis agent on tobacco seedlings is beneficial to improve the quality of tobacco seedlings and cultivating strong seedlings.

Effect of TS-PAA Water Retaining Agent on Growth and Photosynthetic Characteristics of Cigar under Drought Stress

Fangling WANG, Mingyue ZHANG, Yaru ZHOU, Qinglin GUAN, Xinyan LI, Qiu ZHONG, Mingqin ZHAO

2022, 24(4):  162-172.  DOI: 10.13304/j.nykjdb.2020.0970

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In order to explore the effects of the TS-PAA water-retaining agent on the growth and photosynthetic characteristics of cigar under drought stress， a pot experiment was carried out with Dexue 3 cigar as material， and 5 water-retaining agent dosages were set. The soil moisture content， cigar growth and development index， leaf active oxygen content， antioxidant enzyme activity and photosynthetic characteristics were measured under different dosages of water-retaining agents. The results were as followed： ① with the aggravation of drought stress， the application of this water-retaining agent could effectively increase soil moisture content， cigar root activity， dry/fresh weight of the shoots and roots of cigar； ②under drought stress， the application of TS-PAA water retaining agent increased the activity of superoxide dismutase （SOD）， peroxidase （POD）， catalase （CAT） and soluble protein content of cigar leaves， and decreased the content of malondialdehyde （MDA）， hydrogen peroxide （H₂O₂） and superoxide anion， but the effects were different with different dosages； ③the application of TS-PAA water retention agent under drought stress increased the photosynthetic pigment content and photosynthesis of cigar tobacco leaves， and the chlorophyll content， net photosynthetic rate （P_n）， transpiration rate （T_r）， stomatal conductance （G_s） and water use efficiency （WUE） increased firstly and then decreased with the increase of the amount of TS-PAA， while the intercellular CO₂ concentration （C_i） and foliar water pressure deficit （VPD） showed the opposite trend. Therefore， the application of TS-PAA water retaining agent enhanced drought stress tolerance of cigar under drought stress. In this study， the effect of water retaining agent was optimal at 0.24% （the ratio of water retaining agent quality to soil dry weight）.

Sensitivity Differences of Shrub Seedlings to Cadmium Toxicity

Xiaoqing ZHANG, Zhuangzhuang LI, Shibao CHEN, Yu MENG, Dajun REN, Shuqing ZHANG

2022, 24(4):  173-184.  DOI: 10.13304/j.nykjdb.2021.0070

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In order to explore the sensitivity differences of shrub seedlings and different test endpoints to cadmium （Cd） poisoning， 12 common shrubs were selected for hydroponic experiment of Cd toxicity to shrub seedlings， and the seedlings growth parameters （apparent toxicity symptoms， plant height， fresh and dry weight of shoots， root growth state） under different concentrations of Cd treatments ［0（CK）， 0.5， 1.0， 2.0， 4.0， 8.0， 16.0， 32.0 mg·L^-1］ were determined to compare the stability of different test endpoints. Meanwhile， the species sensitivity distributions （SSD） were made using the Burr-Ⅲ model to analyze the sensitivity of different shrub seedlings to Cd. All the studied plant seedlings showed toxicity symptoms in Cd concentrations ranges of 1.0~4.0 mg·L^-1. The discrapency of Cd toxicity thresholds on different toxic endpoint of plant shoots and roots growth was large. Toxicity thresholds corresponding to 10% （EC₁₀） and 50% （EC₅₀） inhibition of shoot dry weight values ranged from 0.11 （Pittosporum tobira） to 1.30 mg·L^-1 （Fatsia japonica） and 2.58 （Ligustrum japonicum ‘Howardii’） to 10.90 mg·L^-1 （Fatsia japonica）， and the difference multiple reached 11.8 and 4.2 times， respectively. The EC₁₀ and EC₅₀ values of root branch number ranged from 0.08 （Ligustrum japonicum ‘Howardii’） to 1.27 mg·L^-1 （Fatsia japonica） and 2.40 （Ligustrum japonicum ‘Howardii’） to 10.30 mg·L^-1 （Fatsia japonica）， and the difference multiple reached 15.8 and 4.3 times， respectively. The toxicity sensitivity for different test endpoints were as following： root branch number> total root length> total root surface area> total root tip number> shoot dry weight> plant height> shoot fresh weight. It indicated that the root elongation indexes are more sensitive to Cd toxicity than other endpoints. The SSD based on EC₅₀ of shoot dry weight and root branch number showed almost consistant sensitivity distribution for most plants，among them， Ligustrum japonicum ‘Howardii’ and Pittosporum tobira were sensitive plants to cadmium toxicity and Fatsia japonica were proved to be tolerant plant to cadmium toxicity. At the same time， the thresholds HC₅ of ecological risk to protect 95% plant quality without cadmium toxicity were derived according to SSD.

MARINE AGRICULTURE & FRESHWATER FISHERIES

Acoustic Investigation Methods for Dosidicus gigas Fishery in Gulf of California

Fenghua TANG, Zuli WU, Jialiang YANG, Hongliang HUANG, Keji JIANG

2022, 24(4):  185-192.  DOI: 10.13304/j.nykjdb.2021.0003

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Acoustic method has become an important mean for marine biological resources assessment. The analysis method of acoustic data is the key in the qualification and quantification of fisheries resources. Based on the analysis of target intensity， noise elimination and species discrimination during data processing， the method of hydroacoustic investigation of Dosidicus gigas resources was explored in the Gulf of California， Mexico， and a foundation for systematically understanding and grasping the amount of economic species resources was laid in the Gulf of California fisheries. The survey was carried out by the boat R.V. BIP-XI in the cruise of China-Mexico joint survey and the data were collected by the Simrad EK60 system in the Gulf of California. Transducers were all precomputed using the standard sphere method before the cruise. After the background noise was removed by integrating threshold and SNR estimation method， it was found that the noise removal effect of high frequency signal was effective and the image variation of 120 kHz echo was more obvious than that of 38 kHz. The overall noise removal effect of the former was better than that of the latter. Combined with the method of subtracting background noise from dummy variables and optimizing integral threshold， most noise data were eliminated and data complexity was reduce. After the elimination of sea bottom and sea surface signals， noise elimination and frequency difference identification， most of the irrelevant noise signals in the survey area were eliminated， and finally the signal of target fish species was extracted by frequency difference method. Through the analysis of the acoustic survey method in the Gulf of California， the preliminary progress in the acoustic assessment of oceanic squid had been made， and the direction and foundation for the later resource investigation had been pointed out.

Relationship Between Fishing Grounds of Yellowfin Tuna （Thunnus albacares） and Dissolved Oxygen in the Western and Central Pacific

Zhen ZHAO, Aoran SUN, Chunling ZHANG, Guoping ZHU, Song HU

2022, 24(4):  193-202.  DOI: 10.13304/j.nykjdb.2021.0743

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The vertical structure of dissolved oxygen is an important factor affecting the vertical activities of yellowfin tuna （Thunnus albacares）. In order to better understand the distribution characteristics of dissolved oxygen in Seine yellowfin tuna fisheries and its impact on Seine fishery production in the Central and western Pacific， the vertical structure characteristics of dissolved oxygen concentration of fishery area and the relationship between dissolved oxygen and fish catch spatial or temporal distribution were analyzed. A statistical model of the relationship between dissolved oxygen vertical structure and fishery catch was given. The data adopted was the WOA18 three-dimensional dissolved oxygen dataset and yellowfin tuna fishery production data in the Central and Western Pacific from 2008 to 2017. The results showed that higher catch per unit effort （CPUE） value of yellowfin tuna was mainly concentrated in the western tropical Pacific of 5°S—5°N. The dissolved oxygen concentration in the fishing area decreased with the increase of depth. The concentrations of dissolved oxygen in surface and 50 m depth of the fishery areas were about 195~210 μmol?kg^-1 and 192~199 μmol?kg^-1， respectively. CPUEs were concentrated in the areas of 150 and 300 m depth with 147 and 120 μmol?kg^-1， respectively. There was a negative correlation between the CPUE and the vertical gradient of dissolved oxygen， especially above the thermocline. The model showed that the relationship between the distribution of fishing ground and the dissolved oxygen change at different depths obeyed the gaussian function distribution， which provided a theoretical basis for understanding the level and characteristics of dissolved oxygen in fishery area and establishing a more accurate fishery prediction model.

INNOVATIVE METHODS AND TECHNOLOGIES

Conditions Optimization of Selenium-enriched Suspension Culture for Protocorms of Dendrobium officinale

Suju HAN, Chuang MEI

2022, 24(4):  210-217.  DOI: 10.13304/j.nykjdb.2020.1102

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In this study， the growth index， polysaccharide， alkaloid， total protein， selenium content and other indexes of Dendrobiumcandidum Procorms Se-enriched suspension culture were evaluated to optimize the conditions of Se-enriched suspension culture of Dendrobium candidum， providing theoretical basis and material basis for the development of Se-enriched Dendrobium candidum products. The results showed that the optimal Se-enriched suspension medium for protocorms of Dendrobium officinale was MS+2.0 mg·L^-1 6-BA+ 0.50 mg·L^-1 NAA+30g·L^-1 sucrose +0.05 mg·L^-1 Na₂SeO₃， inoculation amount was 100 g·L^-1， pH was 5.8. When the subculture period was 30 days， the selenium content of protocorms was up to 4.01 mg·kg^-1， polysaccharide content was 34.79%， alkaloid content was 0.026%， and total protein content was 28.25%. The suspension culture system of selenium-enriched suspension culture for protocorms of Dendrobium officinale was established successfully.