Table of Content

15 June 2022, Volume 24 Issue 6

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AGRICULTURAL INNOVATION FORUM

Bipartite Intelligent Design of Crops—Intelligent Combination of Natural Variation and Intelligent Creation of Artificial Variation

Hai WANG, Jinsheng LAI, Haiyang WANG, Xinhai LI

2022, 24(6):  1-8.  DOI: 10.13304/j.nykjdb.2022.0391

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We are witnessing a profound and far-reaching revolution in crop breeding. Intelligent design of crops，driven by interdisciplinary integration of biotechnology（BT）and information technology（IT），is now outperforming and replacing traditional breeding methods. Future intelligent design of crops should be bipartite. Intelligent cross breeding is based on large-scale genomic，phenotypic and environmental data platforms，as well as statistical models built upon them. These will facilitate the design of optimal combinations of natural genomic variants，and realization of such design by the fastest breeding scheme. Intelligent biological breeding，on the other hand，will harness the power of artificial intelligence （especially generative models）and synthetic evolution to design genomic components or proteins of agronomic importance，placing genome editing and synthetic biology at the center of crop genetic improvement. This viewpoint discussed the theoretical basis，cutting-edge technologies and future directions of both branches of intelligent crop design. Limiting factors from public and private sectors that are making the bottlenecks in intelligent design of crops were also discussed.

International Experience and Enlightenment on Development of Smart Agricultural Information Services

Jianhua ZHENG, Ruixue ZHAO, Hua ZHAO, Sijing LI, Guogang WANG

2022, 24(6):  9-18.  DOI: 10.13304/j.nykjdb.2021.0764

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The combinations of emerging technologies，such as big data， internet of things， cloud computing， intelligent equipment and agriculture promote the development of agriculture to intelligence. In the context of global modernization of agriculture， smart agricultural information service can support the efficient and precision agricultural production. Regarding the current problems of agricultural information services development in China， such as imperfect service system， blocked service channels， regional differences in agricultural informationization， unbalanced information supply and demand， and lack of information service talents， it is of great significance to clarify the solutions. The agricultural information service system construction， service mode and intelligent development in the United States， Western European countries， Japan and the Republic of Korea were reviewed， according to the requirement of smart agriculture development in China， 6 enlightenments to smart agricultural information service development in China were suggested， which were to pay attention to the leading position of the government， strengthen the construction of laws， regulations and standards， enhance the construction of infrastructure， build the smart information service pattern， improve information literacy of farmers and agricultural related enterprises and develop socialized agricultural information service system.

Practical Experiences of Veterinary Antibiotics Reduction at Abroad and Enlightenment to China

Mengmeng CHEN, Xiaofeng LI, Hongbo XIAO

2022, 24(6):  19-26.  DOI: 10.13304/j.nykjdb.2021.0345

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Veterinary antibiotics reduction is of great significance for the green and healthy development of livestock and poultry breeding industry in China. Due to the late start of the veterinary antibiotics reduction in China， there is no specific action guide at present， and the large difference in livestock and poultry breeding environment causes the difficulty of comprehensive promotion. Therefore， based on the practical experience of international organizations and developed countries in animal husbandry， combined with the development status of livestock and poultry breeding industry in China， this paper put forward corresponding suggestions： popularizing safe drug use knowledge， improving the system of laws and regulations， adding the label of “reduced resistance， no resistance” for animal products， carrying out risk assessment of animal food and veterinary drug residues， establishing a network of breeding farms and veterinarians， guiding farms to do a good job in biosafety prevention and control， and improving the monitoring and management network for the use of veterinary drug. These suggestions will provide reference for the promotion of veterinary antibiotics reduction actions in China.

BIOTECHNOLOGY & LIFE SCIENCE

Research Progress on the Regulation Mechanism of Exogenous Selenium on Heavy Metal Stress in Plants

Juntao MA, Wen ZHOU, Jinghao LI, Yizhuo JING, Dan HAN, Huifang SHAO

2022, 24(6):  27-35.  DOI: 10.13304/j.nykjdb.2021.0645

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Selenium is a beneficial trace element for plants， and it plays an important role in plant growth and resistance. More and more studies have found that exogenous addition of selenium could effectively alleviate plant heavy metal stress， and related research have gradually deepened. This article summarized the relevant research on the absorption and transport accumulation of selenium by plants and the mechanism of selenium alleviating heavy metal stress in recent years， and compared the similarities and differences of selenium to different types of heavy metal stress mitigation mechanisms， and it can provide the theoretical basis for improving the ability of plants to resist heavy metal stress.

Overexpression of a Cotton Glucuronokinase Gene GbGlcAK Promotes Cell Elongation in Arabidopsis thaliana

Nan WU, Jun YANG, Yan ZHANG, Zhengwen SUN, Dongmei ZHANG, Lihua LI, Jinhua WU, Zhiying MA, Xingfen WANG

2022, 24(6):  36-46.  DOI: 10.13304/j.nykjdb.2021.0806

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Fiber quality improvement is an important objective for cotton breeding. A differentially expressed gene GlcAK （glucuronic acid kinase/glucuronokinase） between sea island and upland cotton was identified based on RNA-seq data from different stages of fiber development. In this study， GbGlcAK （Gossypium barbadense GlcAK） with 1 101 bp of ORF was cloned from the fibers of sea island cotton Pima 90-53， which encoded 366 amino acids. GbGlcAK had the structure domain of GHMP kinases N and C domain and belonged to the GHMP superfamily. GbGlcAK was a soluble and non-secretory protein. In terms of phyletic evolution， GbGlcAK was most closely related to GlcAK from A.thaliana. Subcellular localization results showed that GbGlcAK was distributed in the cytoplasm. Compared with the wild type， the transgenic A.thaliana lines possessed significantly longer leaf trichomes， hypocotyls， hypocotyl cells and roots. The expression of uridine diphosphate-D-glucuronic acid （UDP-D-GlcA） metabolic related genes were upregulated， and the pectin content was also significantly increased in the transgenic lines. These results suggested that overexpression of GbGlcAK in A. thaliana up-regulated UDP-D-GlcA metabolic pathway， thereby increased pectin content and promoted cell elongation. Our study provided references for further exposing the function of GbGlcAK in cotton fiber development.

Isolation of Endophytic Bacteria in Soybean and Its Action Effect

Zhenxiang TIAN, Wei DING, Zhuo CHENG, Hangyu DAI

2022, 24(6):  47-57.  DOI: 10.13304/j.nykjdb.2021.0631

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In order to explore the use of endophytic bacteria to promote the growth and development of soybean and thus to obtain environmentally friendly bioregulators， the dominant endophytic bacteria were isolated from soybean seeds and their effects on the growth and physiological indexes of soybean were investigated. Soybean seeds were put into non-woven bags and buried in the soil for 10 days. After disinfection of the surface of the seeds， 8 strains of endophytic bacteria were isolated around the radicle， two dominant endophytic bacteria KC-1 and MD12-2 were obtained through preliminary screening. They were identified as Brevibacillus laterosporus and Bacillus subtilis， respectively. They had the ability to produce IAA and dissolve organic phosphorus. KC-1 and MD12-2 significantly promoted seed germination when the concentration was 2.5×10⁷ cfu·mL^-1. Pot experiment showed that the plant height， plant dry weight， chlorophyll content， root activity， nitrate reductase activity and nodule nitrogenase activity of soybean were significantly increased after soaking seeds with KC-1 and MD12-2 at the concentrations of 10×10⁷ and 5×10⁷ cfu·mL^-1 （P<0.05）.

Microbial Community Structure of Potato Rhizosphere Soil and Its Response to Drought Stress

Lili WANG, Congpei YIN, Feng LI, Zhimin YANG, Fangming LIU, Baisong LIN, Xiaojing LIU, Haijun LIU, Jing SUN, Dongdong SHAN, Jianghui CUI, Zhenqing ZHANG

2022, 24(6):  58-69.  DOI: 10.13304/j.nykjdb.2021.0692

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To study the microbial community structure of potato rhizosphere soil and its response to drought stress， the pot experiment was performed， and the rhizosphere soils of potatoes with different drought stress were as materials. The potatoes rhizosphere soil （planted soil） and CK soil were collected at flowering stages. Then the microbial DNA was isolated， and the V3~V4 region of bacteria was deep sequenced by Illumina Miseq. The characteristics of microbial community structure was analyzed. The results showed that a total of 1 263 889 effective sequences were identified， among which 6 785 OTUs belonged to 33 phyla， 94 classes， 267 orders， 462 families， 919 genera， and 1 930 species. Compared with CK soil before planted potato， Proteobacteria， Actinobacteria， Acidobacteria， Chloroflexi， Bacteroidetes， Firmicutes and Gemmatimonadetes were the dominant phyla in the rhizosphere soil after planted potato， and the relative abundance of Actinobacteria increased significantly. Drought stress increased the relative abundances of Proteobacteria， Bacteroidetes， Gemmatimonadetes and Pseudomonas. Principal coordinates analysis （PCoA） showed that potatoes planted and drought stress were the main causes of variation in soil bacterial community structure. Phylogenetic investigation of communities by reconstruction of unobserved states （PICRUSt） profiling indicated that sequences related to metabolism， signaling transduction， defense mechanism and basic vital activity were enriched in the drought-treated rhizosphere soil， which might be important for plant survival and drought tolerance， and provided new insights for the researches of improving drought tolerance of potatoes by soil microorganisms.

Sequencing Analysis of Fungal Diversity in Rhizosphere Soil of Cynanchum bungei Decne

Jie LI, Ying LIN, Meiyu XU, Fei WANG, Lingchuan XU

2022, 24(6):  70-81.  DOI: 10.13304/j.nykjdb.2021.0963

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To understand the structure and composition of rhizosphere soil microbial community of Cynanchum bungei Decne， and make full use of rhizosphere microbial resources， the fungal community richness and diversity in rhizosphere soil （at 10 and 20 cm deep） of Cynanchum bungei Decne form Lianhuashan of Laiwu City （LW）， Lixia （LX） and Changqing （CQ） of Jinan City of Shandong Province were analyzed by Illumina MiSeq high throughput sequencing technology. The results showed that 1 589 OTUs were obtained from 6 samples， belonging to 11 phyla， 35 classes， 84 orders， 142 families and 237 genera. Ascomycota and Mortierellomycota were the common dominant bacteria of 6 samples at phyla level. Sample CQ20 had the highest community abundance and diversity， and sample LX20 had the most uniform distribution of fungal community. With the deepening of underground rhizome depth， the abundance and diversity of fungal microbial community increased， which provided theoretical basis for optimizing the rhizosphere growth-promoting bacteria and improving the planting technique of simulating wild.

Characteristics of the Growth of Rhodococcuspyridinivorans Rp3 and Ability to Degrade Skatole

Yuhong WU, Rongjun GUO, Guizhen MA, Shidong LI

2022, 24(6):  82-89.  DOI: 10.13304/j.nykjdb.2021.0139

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To obtain an optimal medium for the growth of Rhodococcuspyridinivorans strain Rp3 and clarify the influence of different factors on its ability to degrade skatole， the fermentation medium was optimized by single factor and orthogonal experiments， and the skatole content in the medium was analyzed by high performance liquid chromatography to determine the effects of optimal carbon and nitrogen， metal ions， temperature， and continuous subculture on the growth of strain Rp3 and its ability to degrade skatole. The results showed that strain Rp3 could utilize skatole as the sole carbon for its growth. The growth of strain Rp3 promoted by organic carbon and nitrogen was as following： yeast extract powder>beef extract>sucrose. The optimal carbon and nitrogen were sucrose 16 g·L^-1， beef extract 14 g·L^-1 and yeast extract 6 g·L^-1. Skatole couldn’t be degraded in the medium without Mg²⁺， and its degradation significantly reduced when Mg²⁺ was replaced by Fe²⁺， Mn²⁺ and Zn²⁺. The skatole degrading ability of strain Rp3 increased with the raised temperature. The degrading efficacy could reach 82.9%~95.5% when cultured at 28~40 ℃ for 24 hours. The carbon and nitrogen source and continuous subculture didn’t affect the skatole degradation by strain Rp3. The above results indicated that Rhodococcuspyridinivorans Rp3 was a potential strain to be developed further due to its convenient and stable culturing characteristics.

INTELLIGENT AGRICULTURE & AGRICULTURAL MACHINERY

Research Review on Crop Digital Twin System for Monitoring Growth Status and Environmental Response

Wei LI, Deli ZHU, Qing WANG, Shaohua ZENG

2022, 24(6):  90-105.  DOI: 10.13304/j.nykjdb.2021.0235

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At the digital and intelligent stage of agricultural production， people need to comprehensively and accurately understand crop growth status and farmland environment in real-time， and make corresponding analysis， feedback， and decision through relevant information. Aiming at this problem， this paper drew on the concept of the industrial digital twin system and summarized the interactive system between the synchronization of actual crop growth and simulated growth， the real-time status of crops， and the real-time management strategy of crops as a crop digital twin system. Based on the research at home and abroad， this paper pointed out that the crop digital twin system included the stages of acquiring and transmitting data， building models， and visualization interaction； its key technologies included sensor technology， image segmentation technology， modeling technology， and visualization technology. In addition， this paper considered that the research in this field could be carried out from the aspects of basic crop data， system model capabilities， and multi-platform collaborative interaction. The related research on crop digital twin system for monitoring growth status and environmental response had greater practical significance for intelligent and digital agricultural production， and also had greater application value in theory and application.

Design and Experiment of Pneumatic Fertilizer Collecting and Discharging Device for Ratooning Rice

Huibin KE, Yong ZHOU, Guozhong ZHANG, Wen LYU, Yan LIU, Lin HUANG

2022, 24(6):  106-114.  DOI: 10.13304/j.nykjdb.2021.0483

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To solve the problems of uneven fertilization and low utilization rate in traditional topdressing of ratooning rice， a pneumatic fertilizer collecting and discharging device was designed. In this study， the main factors affecting the fertilization performance were tested with the tool of quaternary quadratic regression orthogonal rotation combination， and a regression model was established using the uniformity variation coefficient of each row’s fertilizer discharging volume as the evaluation index to study the of influence angle of the fertilizer inlet， height of the fertilizer inlet， length of the bellows and the speed of the fertilizer discharging shaft on the uniformity of fertilizer discharging in each row. The results showed that the main factors affecting the device’s uniformity variation coefficient of the fertilizer discharging volume were ranked with the speed of the fertilizer discharging shaft， the angle of the fertilizer inlet， the length of the bellows， the height of the fertilizer inlet. Using Design-Expert10.0 software， the optimal combination of the parameters was obtaing the angle of the fertilizer inlet was 54°， the height of the fertilizer inlet was 216 mm， the length of the bellows was 200 mm， the speed of the fertilizer discharging shaft was 47 r·min^-1. Under these conditions， the uniformity variation coefficient of the fertilizer discharging volume of each row is 1.71%， which could sufficiently meet the topdressing requirements of ratooning rice.

Design and Optimization of Single Row In-line Cassava Planter

Tingting SHI, Yulan LIAO, Xuyou PENG, Chenyu YUAN

2022, 24(6):  115-122.  DOI: 10.13304/j.nykjdb.2021.0869

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Cassava is widely planted in tropical and subtropical areas， where the soil is cohesive and the weather is more rainy，which leaded to problems such as high labor intensity and low labor efficiency in cassava planting. Combined with the management requirements of intercropping， fertilization and weeding and the agronomic requirements of cassava planting， this paper designed a single row cassava in-line planter with seven link mechanism. The power of cassava planter comed from the tractor power output shaft， which provided power for the seed separation device and seven link mechanism through 2 groups of sprockets. The length of seven bar component and the installation position angle θ of duckbill planter were used to construct parametric model through the auxiliary software Solidworks.And then the modeling was imported into Adams for simulation analysis to obtain the motion trajectory of the planter mechanism by changing the parameter length of the main rod mechanism. The main parameters related to performance were optimized using ADAMS software to obtain the design meeted single line in-line cassava planter.

Parameters Calibration of Discrete Element for Kitchen Waste Organic Fertilizer Bioconversion by Black Soldier Fly

Shisheng SONG, Songlin SUN, Qin FANG, Caiwang PENG, Ting ZHOU, Haiying ZHU

2022, 24(6):  123-132.  DOI: 10.13304/j.nykjdb.2021.0783

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When using the discrete element method to simulate and analyze the key aspects of the collection and transfer of kitchen waste organic fertilizer bioconversion by the black soldier fly， there were problems of lacking the intrinsic parameters of kitchen waste organic fertilizer and the contact parameters between kitchen waste organic fertilizer and equipment. The black soldier fly bioconversion kitchen waste organic fertilizer with a moisture content of 37.5% was used as the research object， and its discrete element simulation model parameters were calibrated by EDEM 2020 software. The optimal combinations of the parameters determined by the Plackett-Burman test， the steepest climb test and the Box-Behnken test were as follows： Poisson’s ratio 0.2， shear modulus 7 MPa， density 2 000 kg·m^-3， organic fertilizer-organic fertilizer collision recovery coefficient 0.46， organic fertilizer-organic fertilizer static friction coefficient 0.8， organic fertilizer-organic fertilizer rolling friction coefficient 0.15， organic fertilizer-steel collision recovery coefficient 0.51， organic fertilizer-steel static friction coefficient 0.65， organic fertilizer-steel rolling friction coefficient 0.09， JKR surface energy 0.1 J·m^-2， under this parameter combination， the relative error between the simulation test results and the physical test results was 3.63 %， which was proved that the data was reliable. The results of this study showed that the discrete element model of kitchen waste organic fertilizer and the parameters obtained after calibration was reliable， which provided some references for the discrete element study of black soldier fly bioconversion of kitchen waste organic fertilizer in terms of mechanical collection， transportation and separation.

ANIMAL AND PLANT HEALTH

Effects of Reductive Soil Disinfestation on Soil Bacterial Community Structure and Soil Enzyme Activity in Continuous Cropping of Ginseng

Ning YAN, Yu ZHAN, Xinyue MIAO, Ergang WANG, Changbao CHEN, Qiong LI

2022, 24(6):  133-144.  DOI: 10.13304/j.nykjdb.2021.0695

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Reductive soil disinfestation （RSD） and soil fumigation （SF） technologies can control soil-borne diseases more effectively and repair degraded soil quickly. In order to research the effects of 2 technologies on soil bacterial community of continuous cropping ginseng， 3 treatments were set up： reductive soil disinfestation plus soil fumigation （RSD+SF）， reductive soil disinfestation plus compound bacteria （RSD+F） and soil fumigation plus compound bacteria （SF+F）. IlluminaMiseq high-throughput sequencing technology was used to analyze and determine the soil bacterial community and soil enzyme activities by 3 soil modification methods. The results showed that the highest diversity and richness of bacterial community was found in RSD+F group， and those of the lowest was found in SF+F group， and 3 groups had 431 identical bacterial genera. The highest bacterial richness was Gemmatimonas with abundance of 9.17% in RSD+SF group， norank_f_noranko_Gaiellales had the highest bacterial richness with abundance of 8.72% in RSD+F group， and Bacillus had the highest bacterial richness with abundance of 9.16% in RSD+F group. Bacillus was the common dominant bacterial community of the top 10 dominant flora in the soil by 3 improved methods. Correlation analysis showed that the soil enzyme activity significantly correlated with soil bacterial community structure. With the increase of growth time， the soil enzyme activities of continuous cropping ginseng with different soil modification methods were significantly different （P<0.05）. In conclusion， 3 soil improvement methods could increase the richness of beneficial bacteria genus and improve soil enzyme activity to different degrees， and the number of beneficial bacteria genus and soil enzyme activity in RSD+SF group and RSD+F group were higher than those in SF+F group.

Allelopathic Effects of Organic Acids and Saponins in Ginseng Root Exudates on Pathogenic and Biocontrol Bacteria

Li YANG, Li YU, Zhuo SUN, Tongyu ZHANG, Yang ZHANG, Limin YANG

2022, 24(6):  145-155.  DOI: 10.13304/j.nykjdb.2021.0303

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To investigate the allelopathic effects of ginseng root exudates on pathogenic bacteria and biocontrol bacteria of pathogenic bacteria， the allelopathic effects of organic acids （benzoic acid， phthalic acid， adipic acid， succinic acid） and saponins （ginsenoside Rb2， Rd， Rc Rg1， Re） in root exudates of Panaxginseng on these microorganisms were studied in vitro. The results showed that the allelopathic effects of organic acids and saponins on microorganisms were characterized by multiple receptors， low threshold （1 μg·L^-1）， wide concentration range （1 μg·L^-1~1 mg·L^-1）， but no obvious concentration effect. Allelopathy of organic acids and saponins ranged from -132.94% to 31.33%， the promotion effect of these substances on biocontrol bacteria was greater than that on pathogenic bacteria， and the direct inhibitory activity on the growth of some pathogenic bacteria was observed， these metabolites separated from ginseng root exudates showed certain harmful/beneficial effects on pathogenic bacteria and biocontrol bacteria. Ginsenosides Rd and Re had the function of inhibiting pathogenic bacteria and promoting biocontrol bacteria， which meant they were the important terpenoid defense substances in root exudates of ginseng.

BIO-MANUFACTURING & RESOURCE AND ECOLOGY

Effects of Mixed Applying of Controlled-release Urea and Conventional Urea on Yield，Water and Nitrogen Utilization of Maize in Dryland

Yi DANG, Jianjun ZHANG, Gang ZHAO, Tinglu FAN, Lei WANG, Shangzhong LI, Gang ZHOU

2022, 24(6):  156-165.  DOI: 10.13304/j.nykjdb.2021.0200

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To evaluate the impact of mixed applying between controlled-release urea and conventional urea on maize growth， yield and use efficiency of water and nitrogen in dryland， taking Xianyu 335 as material， and 3 mixed applying of conventional and controlled-release urea were set according to the ratio of 7∶3 （T1）， 5∶5 （T2）， 3∶7 （T3）， and no nitrogen fertilizer （CK1）， conventional urea only （CK2） and controlled-release urea only （CK3） were as controls. The changes of SPAD value， dry matter accumulation， water consumption， yield and use efficiency of water and fertilizer were determined. The results showed that T3 treatment had high SPAD value and dry matter accumulation during the whole growth period， which balanced the water consumption process and supply of nitrogen nutrients with the nitrogen use efficiency 38.8%. The yield and water use efficiency of T3 treatment were 13 354.5 kg·hm^-2 and 33.60 kg·hm^-2·mm^-1， respectively， which increased by 14.6%~30.1% and 6.8%~15.4% than other nitrogen treatments. And the grain number per spike and 100-grain weight of T3 treatment were 642.2 and 30.8 g， respectively， which increased by 2.0%~6.0% and 3.9%~12.0% than other nitrogen treatments. Therefore， the combination of 70% controlled release urea and 30% conventional urea could improve the growth of spring maize in dryland， and promote yield and water and fertilizer utilization.

Research on Characteristics of Nitrogen and Phosphorus Loss from Surface Runoff of Cotton Field in Northern Jiangxi Province of Poyang Lake Region

Lijuan ZHANG, Yukun QIN, Huihuang CHENG, Yongqi LI, Haihua LUO

2022, 24(6):  166-175.  DOI: 10.13304/j.nykjdb.2021.0374

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In order to clarify the characteristics of nitrogen and phosphorus loss from surface runoff of cotton fields in northern Jiangxi of Poyang Lake ecological region， and explore the effects of nitrogen fertilizer reduction and partial organic substitution on nitrogen and phosphorus loss， the field runoff pool method was used to monitor the loss for 4 consecutive years under natural rainfall conditions. The results showed that the rainstorm in the test area mainly occurred from May to July， which was high risk period of runoff occurrence. The annual cumulative loss of total nitrogen and total phosphorus in cotton field were 7.59~22.49 and 0.43~1.61 kg·hm^-2， respectively. Particulate nitrogen and soluble phosphorus were the main component of inorganic nitrogen loss. There was a very significant correlation between surface runoff， nutrient loss time， loss amount and rainfall， and there was a very significant power function correlation between runoff and the loss amounts of nitrogen and phosphorus under the conventional fertilization treatment. Compared with conventional fertilization， the fertilization measure of reducing nitrogen by 20% and applying 10% organic fertilization could reduce surface runoff， total nitrogen loss and runoff coefficient， which had no significant effects on phosphorus loss and yield of cotton.

Effect of Nitrogen Reduction on Agronomic Trait， Photosynthetic Characteristics and Yield of Sesame

Tongmei GAO, Feng LI, Xiaoyu SU, Dongyong WANG, Yuan TIAN, Pengyu ZHANG, Tongke LI, Zihao YANG, Shuangling WEI

2022, 24(6):  176-188.  DOI: 10.13304/j.nykjdb.2021.0944

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To study the effect of nitrogen reduction on agronomic traits， photosynthetic characteristics and yield of sesame， Zhengtaizhi 4 was as material and 4 treatments were set including no fertilizer （N0）， nitrogen reduction treatment （75 kg·hm^-2， N1）， routinely nitrogen treatment （150 kg·hm^-2， N2） and high-nitrogen treatment （225 kg·hm^-2， N3）. The leaf photosynthetic characteristics were measured in seedling stage， budding stage， initial flowering stage， full-bloom stage， final flowering stage and maturation stage， and finally agronomic trait， yield and quality indexes were investigated in the harvest period. The results showed that， compared with N2 treatment， N1 treatment did not show significant differences on capsule axis length， I.e.capsules per plant， I.e.seeds per capsule， 1 000-seed weight and yield per plant， while significantly decreased on plant height， and economic coefficient increased by 6.10%. Compared with N2 treatment， the plant height， capsule axis length， I.e.capsules per plant， I.e.seeds per capsule， 1 000-seed weight， yield per plant and economic coefficient of N0 treatment decreased by 15.89%， 12.70%， 25.67%， 6.38%， 10.00%， 40.15% and 16.43%， respectively. The dry matter accumulation showed， compared with N2 treatment， N1 treatment did not show significant differences on dry weight of root， leaf， stem， capsule peel， total matter and seeds capsule ratio of sesame， while N0 treatment decreased significantly on dry weight of root， stem， capsule peel， total matter and seeds capsule ratio of sesame， declined by 19.40%， 25.40%， 28.40 %， 27.57% and 9.83%， respectively. The photosynthetic characteristics indicated that， compared with N2 treatment， N1 treatment did not show significantly differences on net photosynthetic rate （P_n）， transpiration rate （T_r）， water use efficiency （WUE）， stomatal conductance （G_s） and intercellular CO₂ concentration （C_i）， while N0 treatment declined significantly on P_n and WUEby 8.15% and 8.52%， respectively. To sum up， nitrogen reduction had no significant effect on agronomic traits， photosynthetic characteristics and yield of sesame， which provided theoretical basis and technical support for high yield of sesame in the high-nitrogen stubble land.

Effect of Rape Straw Fiber on Pore Characteristics of Cement Mortar

Fan ZHANG, Yue GU, Chen CAO, Baohua LIU

2022, 24(6):  189-195.  DOI: 10.13304/j.nykjdb.2021.1107

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In order to explore the effect and mechanism of rape straw fiber on the performance of cement mortar， the treated rape straw fiber was mixed into cement according to 0， 1%， 2%， 3% and 4%. The standard water consumptions and setting times of cement with different straw fiber ratios were determined. The influence of rape straw fiber ratio on the porosity and pore characteristics of cement mortar at different ages （3， 7 and 28 d） was studied combining with microscanning. The results showed that the apparent density of cement mortar gradually decreased with the increase of straw ratio. Compared with the control group， the apparent density of straw ratio 4% treatment decreased by 9.27%. The pore size distribution of straw ratio 1% was similar to the control group. And the pore size distributions of straw ratio 3% and 4% were similar， and the proportions of harmful holes and multiple harmful holes reached 14.2%， 15.4% and 24.15%， 25.01% at 28 d age， respectively， which were about 3.5 times of the control group. With the increase of straw ratio， the maximum aperture of cement mortar decreased. And with the increase of age， the maximum aperture of cement mortar and the proportions of harmful holes and multiple harmful holes also decreased. The micromorphology analysis showed that the straw fiber and cement were bonded better in straw ratio 1% treatment， while the muiti-harmful holes and harmful holes significant increased and mainly appeared around straw fiber in straw ratio 3% and 4% treatments.

Relationships Between Soil Factors and Populus euphratica’s Sap Flow at Different Time Scales

Yaru HUANG, Yingbin MA, Yonghua LI, Xue DONG, Yuan LIU, Meng YU, Chunxia HAN, Kaimin JIAN, Haifeng MA

2022, 24(6):  196-205.  DOI: 10.13304/j.nykjdb.2021.0388

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In order to reveal the influence of soil factors on the sap flow at different time scale of Populus euphratica in Kumtag Desert， the sap flow of Populus euphratica and soil factors， such as soil water content （SWC） and soil temperature （Ts）， were observed synchronously for 5 months. The results were followed， on the monthly scale，SWC_200cm was the main factor influencing the sap flow of Populus euphratica， which could explain 94.9% of sap flow changes. On the daily scale， Ts_200cm， SWC_50cm， SWC_20cm and SWC_200cm had greater influence on the sap flow changes of Populus euphratica， which 93.2% of the sap flow changes of Populus euphratica was explained by these 4 factors， and Ts_200cm was the main influence factor， which could explain 90.3% of the sap flow changes of Populus euphratica. On the hourly scale，Ts_200cm was the biggest influence factor on the sap flow velocity， which could explain 51.6% of the sap flow change. With the expansion of time scale， the number of factors affecting the flow rate changed from more to less， and the reliability changed from small to large. It showed that， based on the soil water content and soil temperature， the predicting of hourly sap flow rate in Populus euphratica required more parameters and had the less reliability， while the predicting of monthly sap flow rate required fewer parameters and had the more reliable. It was more appropriate to predict the sap flow rate of Populus euphratica at a monthly scale.

Effects of Compound Fertilizer on Tea Yield， Quality and Fertility of Tea Garden Soil

Chenguang ZHAO, Siyun NIU, Xun CHEN, Li FANG, Haitao LI, Peixing WANG, Binbin SHEN, Yuanzhi SHI

2022, 24(6):  206-217.  DOI: 10.13304/j.nykjdb.2021.0304

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In order to analyze the effects of different fertilizer treatments on the growth of tea plant and the fertility of tea garden soil， the Longjing 43 tea tree was used as the test variety， and 6 treatments were set according to different fertilizer methods including T1 （no fertilizer treatment） ， T2 （controlled-release fertilizer treatment）， T3（carbon-based fertilizer treatment）， T4（urea-formaldehyde treatment）， T5（special fertilizer of tea tree treatment） and T6（habit fertilizer treatment）. The tea yield， tea nutrient element content， tea garden soil fertility and economic benefit of different treatments were analyzed. The results showed that the application of compound fertilizer could increase the yield of tea and the 100-bud weight of tea shoots. Compared with no fertilizer application， compound fertilizer application significantly increased the tea yieald tea， among which the effect of special fertilizer treatment was the most stable. Increasing the compound fertilizer could promote the germination of tea buds earlier， and it could be mined 1 week earlier than that without compound fertilizer， but there was no significant difference among the treatments. The application of compound fertilizer could increase the content of N in tea， at most 15% compared with no fertilizer application， but there was no significant difference the content of C among different compound fertilizer treatments. The application of compound fertilizer could significantly increase the content of available nutrient in tea garden soil， and the carbon-based compound fertilizer was better in preventing the leaching loss of fertilizer， followed by special fertilizer of tea tree and urea-formaldehyde compound fertilizer， all of which could improve the fertilizer utilization ratio， reduce environmental pollution. The application of compound fertilizer could improve the quality of tea， especially the special fertilizer of tea tree， which the economic benefit and nutrient use efficiency were the highest. By analyzing the effects of different fertilizers on the growth of tea tree and the soil fertility of tea garden， this study aimed to provide theoretical basis for the choice of fertilizers in tea garden in this area， which was expected to improve the economic benefit of tea garden.