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Table of Content

    16 October 2021, Volume 23 Issue 10
    Progress and Outlook of Agricultural Cooperation Mechanism in BRICS Countries
    REN Yufeng, TONG Yuhuan, DONG Bo, LI Zhemin,
    2021, 23(10):  1-9.  DOI: 10.13304/j.nykjdb.2021.0395
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    Improving the agricultural cooperation mechanism is an important way to promote sustainable agricultural development and cooperation between countries. The agricultural cooperation mechanism in BRICS (Brazil, Russia, India, China, South Africa) countries is one of the most important multilateral agricultural cooperation mechanisms in the world. This study systematically reviewed the background, significance and construction process of the establishment of the BRICS agricultural cooperation mechanism, and explored its effectiveness and problems, and prospected its future trend and put forward relevant suggestions. The study found that the agricultural cooperation of the BRICS countries had achieved a series of achievements: the international status had improved significantly, the internal agricultural trade volume had increased rapidly, and the ability to use foreign capital had been continuously enhanced. However, there were still problems such as political security risks, lack of landing platforms, and insufficient scientific and technological exchanges. It was recommended to establish a special fund to support agricultural technological innovation, improve agricultural information exchange platforms, and promote multilateral trade stability through bilateral agreements.
    Status and Suggestion of Construction of Agricultural Science and Technology Innovation Center in China
    YU Hui, Liu Xxianwu
    2021, 23(10):  10-14.  DOI: 10.13304/j.nykjdb.2021.0753
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    The Science and Technology Innovation Center (STIC) is the concentrated embodiment and important support of a countrys comprehensive science & technology strength, and also an important step for developed countries to make overall arrangements for scientific and technological innovation and drive industrial development. Under the background of comprehensively promoting rural revitalization and accelerating agricultural and rural modernization, it is of great theoretical and practical significance to discuss the development strategy of agricultural STIC in China. On the basis of deeply discussing the background  of the construction of STIC, this paper elaborated the connotation of agricultural STIC, analyzed the present situation in the construction of agricultural STIC at home and abroad and the existing problems in China, and put forward suggestions for future development from overall planning, clearing function, outstanding facilities leading, innovating in system and mechanism. It would provide support for optimizing regional innovation layout and building agricultural science and technology innovation highland.
    Advances in Genetic Researches and Molecular Regulation Mechanism of Leaf Angle in Maize
    ZHANG Quanyan, ZHANG Peigao, XU Chunxia, CONG Yining, LIU Li
    2021, 23(10):  15-24.  DOI: 10.13304/j.nykjdb.2021.0121
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    The major goal of  maize breeding  is to develop high yielding hybrids for various agro-ecological and socio-economic conditions. The leaf angle plays an important role in maize plant architecture. Understanding the formation of leaf angle, gene cloning and molecular mechanism controlling leaf angles are essential for the development of maize hybrids with high-yielding and tolerance to high density. This article summarized the progress on morphological formation, genetic basis, regulatory mechanism, and QTL mapping and gene cloning of the leaf angle in maize. The unexplained genetic and biochemical bases were clarified and some suggestions for the investigation in genetics and molecular regulation mechanism of leaf angle of maize in the future were provided, which were useful for the development of hybrids with tolerance to high density via marker-assisted selection to improve the yield potential in maize breeding program.
    Identification and Evaluation Cold Resistance of the National Regional Test Winter Wheat Varieties in the Northern Part of Huang-Huai Winter Wheat Region
    GUO Jiahui, BAI Xionghui, WANG Aidong, LI Ruijie, SHI Xiaoxin, SHI Yongfeng, LI Ailian, WANG Xicheng, WANG Hongfu, GUO Jie
    2021, 23(10):  25-34.  DOI: 10.13304/j.nykjdb.2021.0473
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    Winter wheat freezing injury is one of the main climatic disasters affecting food production security in China. The research on wheat freezing injury is of great significance. The seedling phenotypes (dead stem rate, number of tillers per plant before winter and number of secondary roots per plant before winter) of 46 winter wheat varieties in the national regional test in the northern part of Huang-Huai winter wheat region were analyzed in three environments, namely Dingxiang and Taigu in Shanxi and Zunhua in Hebei to screen the cold-resistant varieties and provide guidance for the cold identification test based on the winter performance of each test site. The results showed that the average dead stem rate of varieties in Dingxiang environment was highly significantly different from the remaining two environments (P<0.01), while there was no significant difference between Taigu and Zunhua environments. The number of tillers per plant before winter and the number of secondary roots per plant before winter were highly significantly different (P<0.01) in all three environments. Based on the clustering analysis of the varieties dead stem rate under the three environments, the participating varieties were classified into three categories: strong cold resistance (categoryⅠ), poor cold resistance (categoryⅡ) and moderate cold resistance (categoryⅢ). Seven varieties with lower dead stem rate were selected under three environments. To sum up, the Taigu and Zunhua environments were suitable as the test site for variety cold resistance identification in the winter wheat area of the northern part of Huang-Huai winter wheat region. This study provided theoretical basis and guidance for the cold resistance identification test of new winter wheat varieties of the national regional test in the northern part of Huang-Huai winter wheat region.
    Gene Structural Characteristics and Regulation Prediction of SNAC Transcription Factors Against Stresses in Maize
    LUO Ping, PANG Bo, CUI Jinxin, YU Shuang, WANG Xiaonan, CHENG Ming, CHEN Yong, GAO Wenwei, HAO Zhuangfang
    2021, 23(10):  35-44.  DOI: 10.13304/j.nykjdb.2020.0657
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    NAC proteins are  plant-specific transcription factors, which play important roles in plant development and response to various abiotic stresses. In order to better reveal the stress tolerance function of the maize SNAC (stress-responsive NAM, ATAF1/2, CUC2) family,  the structural characteristics and possible regulatory mechanisms of the genes was predicted. This paper identified 16 SNAC family genes in maize by bioinformatics, and analyzed the physical and chemical properties, gene structure, potential phosphorylation sites, protein secondary structure, gene evolution relationship, amino acid sequence characteristics and promoter binding elements of each protein family. The results showed that 16 SNAC  genes in maize had no transmembrane structure, and all had N-terminal conservative domain and highly variable C-terminal domain. Most closely related members in the same subgroup had similar gene structure. There were a large number of phosphorylation sites in SNAC genes by the analysis of phosphorylation, and many cis-acting elements in the promoter region of SNAC genes. The prediction of secondary structure showed that the transcriptional regulatory region of SNAC in maize had high internal flexibility. Promoter analysis showed that there were a large number of cis-acting elements in the promoter region of SNAC gene family. These results provided candidate genes for the study of maize stress tolerance,  and were of great significance to the advancement of the functional analysis of maize SNAC family.
    Identification of Verticillium Wilt Resistance of Core Collection of Upland Cotton and Screening of Elite Resistant Germplasm
    CHEN Bin, SHI Rongkang, WANG Zhicheng, LIU Song, LI Qing, LIU Zhengwen, SUN Zhengwen, WANG Guoning, WU Jinhua, MA Zhiying, ZHANG Yan, WANG Xingfen
    2021, 23(10):  45-51.  DOI: 10.13304/j.nykjdb.2021.0170
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    Cotton Verticillium wilt, caused by Verticillium dahliae Kleb., is a soil borne disease, which could  cause serious damage in the cotton production. The core germplasm represents the genetic diversity of the entire resource population. In this study, 419 core germplasm of upland cotton varieties (lines) were identified for Verticillium wilt resistance and selected for excellent varieties by quantitative injection of V. dahliae in hexagonal plastic bowl in an environment controlled artificial growth chamber. The results showed that there were a few resistant varieties in this 419 core collection, only 12 resistant varieties were identified, the disease index ranged from 21.67 to 25.00; 253 varieties displayed tolerant and the disease index ranged from 25.47 to 50.00, other varieties were susceptible to disease; there was no variety with immunity and high Verticillium wilt resistance; Verticillium wilt resistance of the modern varieties (the average disease index was 43.75) was better than that of middle-stage varieties (48.60) and early-stage varieties (51.55); the resistance of the varieties from the Yellow River cotton-growing areas(the average disease index was 43.21) were better than those of other cotton-growing areas or geographic origins. The screening of disease-resistant varieties in this study provided excellent germplasm resources for genetic improvement of cotton Verticillium wilt resistance breeding.
    Identification of Drought Tolerance During Whole Growth Period in Cotton Germplasm Resources and Resistance Index Screening
    LI Jinglin, LIU Shaodong, ZHANG Siping, CHEN Jing, LIU Ruihua, SHEN Qian, LI Yang, MA Huijuan, ZHAO Xinhua, PANG Chaoyou
    2021, 23(10):  52-65.  DOI: 10.13304/j.nykjdb.2020.1084
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    To identify drought-resistant cotton varieties and screen the identification index  during the whole growth period, 238 cotton varieties with different drought resistance were treated with normal irrigation and drought stress during the whole growth period. The indexes of plant height, boll number, boll weight and soluble sugar content were selected, and drought resistance coefficient, principal component analysis, correlation analysis and cluster analysis were used to comprehensively evaluate the drought resistance of 238 cotton  resources and screen the drought resistance index. The results showed that drought stress had a significant effect on the growth of cotton during the whole growth period. Taking drought resistance (D value) as the main parameter, weighted drought resistance coefficient (WDC) and comprehensive drought resistance coefficient (CDC) as auxiliary parameters, 238 cotton variety resources could be divided into 5 grades, including 10 of typeⅠ (high drought resistance), 61 of typeⅡ (drought resistance), 84 of typeⅢ (moderate drought resistance), 78 of typeⅤ (sensitive type) and 5 of typeⅤ (highly sensitive type). Plant height, boll weight, lint percentage and soluble sugar content were more sensitive to drought stress than other indexes, which could be used as indicators for evaluating drought resistance of cotton variety resources during the whole growth period. Above results provided theoretical basis and basic materials for the breeding of new drought-resistant cotton varieties.
    Effects of Different Ratios of LED Red and Blue Continuous Light on the Photosynthetic Characteristics, Yield and Quality of Lettuce Before Harvest
    ZHANG Yubin, LIU Wenke, YANG Qichang, SHAO Mingjie, ZHA Lingyan, ZHOU Chengbo, LI Baoshi, WANG Qi
    2021, 23(10):  66-73.  DOI: 10.13304/j.nykjdb.2020.0445
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    In order to explore the effect of continuous light quality on the yield and quality of hydroponic lettuce (Lactuca sativa L.), five treatments of different red (R) and blue light (B) quality ratios (1R:4B, 1R:2B, 1R:1B, 2R:1B and 4R:1B) were set. The growth, photosynthetic characteristics, ascorbic acid (AsA) content and key enzyme activities of AsA metabolism were studied. The results showed that: the shoot fresh weights of lettuce increased by 38.82%~77.65% under different treatments of red and blue LED light, and the maximum shoot fresh weight of lettuce was 30.23 g under 2R:1B treatment. The root fresh weights were increased by 27.43%~73.14%, and the maximum root fresh weight was 3.03 g under 4R:1B treatment. The higher the ratio of red light, the bigger the leaf area, SPAD value and soluble sugar content of lettuce, but the change of nitrate content was not significant. Compared with other treatments, the net photosynthetic rate, transpiration rate, intercellular CO2 concentration and stomatal conductance of lettuce were the highest under 1R:4B treatment. The content of AsA and the activity of monodehydroascorbic acid reductase (MDHAR) in lettuce  significantly increased with increasing the ratio of blue light to continuous light. Under 1R:4B treatment, the content of AsA in leaf was the highest level of 3.22 mg·g-1, and the activity of MDHAR in lettuce leaf significantly increased by 0.81 U·mg-1 FW. In conclusion, the decrease of the ratio of blue light to continuous light before harvest could significantly improve the yield of lettuce and the content of soluble sugar. Increasing the ratio of continuous light to blue light before harvest could significantly increase the content of AsA and the activity of MDHAR.
    SSR Genetic Diversity Analysis of Yangtze River Delta White Goats from Conservation Populations
    LI Danyang, SUN Lingwei, WU Caifeng, ZHANG Shushan, ZHANG Defu, DAI Jianjun
    2021, 23(10):  74-81.  DOI: 10.13304/j.nykjdb.2020.0748
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    Yangtze River Delta white goat is a local goat breed with excellent skin, meat and hair. In order to provide data support for the germplasm resources protection and breeding improvement, this study analyzed the genetic diversities and genetic structures of two purebred white goat populations and one hybrid population from Yangtze River Delta region by simple sequence repeat (SSR)  markers. The genetic diversity of Haimen goat (HM), Chongming white goat (CM) and hybrid white goat (ZY) from Chongming region were detected by PCR amplification and capillary electrophoresis with 30 microsatellite markers. Different genotypes at different SSR loci and population were analyzed. In HM, CW and ZY populations, the total numbers of alleles were 205, 191 and 147, the average effective alleles (Ne) were 4.012, 3.812 and 3.092, the average numbers of expected heterozygosity (He) were 0.683, 0.668 and 0.617, and the average polymorphism information contents (PIC) were 0.647, 0.630 and 0.567, respectively. The total inbreeding numbers (Fit), mean genetic differentiation coefficients (Fst) and mean gene flows (Nm) of three populations were 0.011 0, 0.050 7 and 4.680 6. The genetic distance of ZY was closer to CM  than with HM. UPGMA analysis showed that CM and ZY were gathered together. Two purebred white goat populations from conservation goat farms and hybrid population from Chongming all showed high heterozygosity, high polymorphism, moderate genetic differentiation, gene exchange, little influence by inbreeding degree, and had high utilization value and potential, which could be used for the conservation and utilization of germplasm resources.
    Application of Agricultural Digital Twin System in Crop Production System
    GU Shenghao, LU Xianju, WANG Yongjian, GUO Xinyu,
    2021, 23(10):  82-89.  DOI: 10.13304/j.nykjdb.2020.0364
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    The deep integration of the digital twin with agriculture will provide a new driving force for the digital transformation and upgrading of agriculture. Based on the data flow generated by the agricultural production system, the digital twin system can achieve intelligent management and regulation of the crop production system through real-time situational awareness, ultra-real-time virtual deduction and interactive feedback throughout the whole process. This paper  overviewed  the development of crop production system and its cognitive approaches, clarified the background, concept, connotation, basic components, and technical advantages of agricultural digital twin system, and raised the application scenarios and development strategies for the agricultural digital twin system, which provided reference for promoting the smart crop production in China.
    Particle Molding Simulation and Structural Parameter Optimization of Pellet Mill Based on Orthogonal Experiment
    YANG Taotao, ZHOU Xingyu, LU Xiaoli, QIAN Shanhua, YU Jinghu
    2021, 23(10):  90-96.  DOI: 10.13304/j.nykjdb.2020.0694
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    Pellet mill is one of the important equipment in the feed industry, and its structural parameter has impact on feed molding. In order to further optimize the granulation performance, this article used COMSOL finite element analysis software to analyze and simulate the extrusion process of the material, and designed a set of orthogonal experiments of L9 (34) to study the influence of the inner diameter of the ring die, die hole length, pressure roll diameter and die roll gap on forming performance, then used the weight matrix analysis to obtain a better parameter combination and verified it. The results showed as follows: ① the simulation of the internal model of the granulator could effectively reflect the movement state of the material in actual work. ② The order of the structural factors that affected the granulation performance from large to small was die roll gap, die hole length, pressure roll diameter, ring die inner diameter. ③ The optimal combination of granulation was ring die inner diameter 425 mm, die hole length 54 mm, pressure roller diameter 178 mm, die roller gap 1.5 mm. Compared to before optimization, the molding rate of the pellet mill had been improved. It was concluded that the simulation test and optimization method adopted in this paper had certain practical effects, which provided method reference for the internal molding simulation analysis of the granulator and the subsequent structural design and parameter optimization. 
    Experimental Study on the Shape Optimization of Soil Opener for Rapeseed Pot Seedling Transplanter
    QUAN Wei, WU Mingliang, GUAN Chunyun, LUO Haifeng
    2021, 23(10):  97-106.  DOI: 10.13304/j.nykjdb.2020.0914
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    In order to reduce the soil opening resistance of soil opener and the soil return coefficient in the hole section of rapeseed pot seedling transplanter,according to the agronomic requirements of rapeseed pot seedling transplanting and characteristics of vertical soil opening, the shape optimization of soil opener was studied.The shape of soil opener for rapeseed pot seedling transplanter(square cone, cylindrical, square rhomboid), bottom size of soil opener, and soil opening depth were chosen as the experiment factors and discrete element method was used for simulation analysis of soil opening process. The longitudinal section size and top size of the hole formed by the soil opener were compared and analyzed, and the influence of various experiment factors on the quality of the soil opening operation was analyzed by taking the soil entry resistance and the soil return coefficient of the internal section of the soil opener as evaluation indexes.The simulation results showed that among the three kinds of soil opener shape, the optimal one was cylindrical, followed by square cone and square rhomboid. The upper size of the holes formed by the cylindrical soil opener was 72 mm, the effective depth was 43 mm, the soil entry resistance during the soil opening process was 62.8 N, and the soil return coefficient of the internal section of the holes formed was 0.07.Combined with the soil groove verification experiment and the soil entry resistance experiment of the soil opener on the universal testing machine, the operation performance of the soil opener was verified. The test results showed that the error values between the test results and the simulation results of the hole upper size, effective depth, and soil return coefficient of the internal section were 57%, 6.9%, 5.3% and 22.2%, respectively. The experimental results showed the optimized of soil opener shape and the combination of parameters were reasonable, and the holes that met the design requirements.
    Prediction on the Vegetation Coverage of Tribulus terrestris L. Based on the Continuous Wavelet Transform
    LIU Xin, YANG Guang, LIN Qun, ZHANG Longying, CHEN Haoyu, WANG Ning, LIU Feng, LIU Chen
    2021, 23(10):  107-116.  DOI: 10.13304/j.nykjdb.2020.0268
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    The vegetation coverage is one of the most effective indicators to evaluate the desertification of land, and also is an important indicator for monitoring vegetation. Hyperspectral estimation of vegetation coverage can provide an important basis for vegetation monitoring. Tribulus terrestris L. fixed sand in the semi arid zone Togtoh County was as the research object, the spectral curve features of different vegetation coverages were analyzed; the correlation between the original spectral vegetation index of two wave bands and the vegetation coverage was extracted, and the optimal wave band combination was selected. The spectral reflectance ratio of vegetation was decomposed at the different scales by the continuous wavelet transform (CWT), and the optimal wave bands at the different decomposition scales were extracted. The vegetation coverage estimation models were established using the partial least square method (PLSR) and support vector machine (SVM) with the different independent variables. The results showed that: ① there was significant correlation between the original spectrum vegetation index and vegetation coverage with all the correlation coefficients above 0.55, and the optimal band combinations were DI (2 260 and 2 210 nm), RI (1 410 and 660 nm), NI (1 470 and 670 nm),RDVI(1 770 and 670 nm) and MSR(1 410 and 660 nm), respectively. ② There was also good correlation between the wavelet coefficient and vegetation coverage, which the correlation coefficients in the 1~10 scales of original spectral were high than 0.72 with the maximum correlation 0.788 9 in the sixth decomposition scale at the band 630 nm. The maximum correlation between the wavelet coefficient extracted from the first-order differential spectrum and the vegetation coverage was 0.806 9, and the correlations between the wavelet coefficient of 1~10 scale extracted from the second-order differential spectrum and the vegetation coverage were above 0.6 with the maximum correlation 0.781 8. ③Among the models established by using the original spectral vegetation index and wavelet coefficient extracted by CWT as the independent variables, the PLSR model input the second-order differential wavelet coefficient showed best precision and stability, which R2 was 0.905 9 and RMSE was 0.035 6, respectively. These results showed that the CWT algorithm could improve spectral characteristic information, which provided a technical method for the estimated inversion of vegetation coverage.
    Problems and Countermeasures in Substrate Utilization of Spent Mushroom Substrates
    ZHOU Wanlai, YANG Rui, ZHANG Dongdong, LIN Wei, CHEN Xuejiao, WANG Hong, LI Jie, QI Zhiyong
    2021, 23(10):  117-123.  DOI: 10.13304/j.nykjdb.2020.0814
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    There are a huge amount of spent mushroom substrates (SMS) in China, meanwhile, there is a huge market demand for horticultural substrate. Therefore, utilizing SMS as horticultural substrate is of great significance. SMS has great potential for substrate utilization as it has unique physical and chemical properties, as well as rich nutrients. However, the substrate utilization of SMS is still insufficient. In view of this situation, this paper summarized the main problems existing in the substrate utilization of SMS, including the physicochemical properties of SMS varied greatly, while the research on uniformization technique was weak; the electrical conductivity (EC) value of SMS was generally high, while efficient salt-reduction technology was lack; the existing substrate utilization technology of SMS was mainly through fermentation, which failed to fully utilize the potential of SMS. This paper also put forward some countermeasures for substrate utilization of SMS, with the purpose to provide guidance for efficient substrate utilization of spent mushroom substrates.
    Effects of Green Manure Turning Over and Nitrogen Reducing on Rice Yield, Quality and Soil Fertility
    LIANG Qin, ZHOU Zehong, MA Xueqing, QI Yan, JIANG Jin, HAN Wenbin, QUAN Ziman, MO Kun, LI Sheng, CAO Weidong
    2021, 23(10):  124-130.  DOI: 10.13304/j.nykjdb.2020.0587
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    In order to explore the effect of reducing the application of N fertilizer in green manure Lathyrus sativus on rice yield,  quality and soil fertility, six treatments were set up including winter fallow + 100% N fertilizer (CK), Lathyrus sativus + 60% N fertilizer (GM+N60), Lathyrus sativus + 70% N fertilizer (GM+N70), Lathyrus sativus + 80% N fertilizer (GM+N80), Lathyrus sativus + no fertilizer (GM) and winter fallow + no fertilization (NF). The results of three years field experiments showed that, compared with CK, Lathyrus sativus combined with reducing N fertilizer application could increase rice yield, GM+N70 and GM+N80 treatments significantly increased rice yields, which increased by 13.84% and 7.25%, respectively. And Lathyrus sativus combined with reducing N fertilizer application could improve brown rice rate, milled rice rate, head rice rate and protein content; reduce chalkiness, chalkiness grain rate and amylose content of rice. The head milled rice rate of GM+N70 treatment was the highest (78.02%), the chalkiness grain rate was the lowest (18.11%). The amylose content of GM+N80 treatment was the lowest (14.26%). The combined application of Lathyrus sativus and N fertilizer could significantly increase the contents of soil organic matter, total nitrogen, alkali hydrolyzable nitrogen and available potassium. In conclusion, Lathyrus sativus and reducing N fertilizer application by 20%~30% should be beneficial to rice yield, quality and improvement of soil fertility, which provided theoretical basis for scientific application of N fertilizer after turning over Lathyrus sativus in Sichuan region.
    Analysis of Spatial Distribution and Influencing Factors of Plant Communities in the Lower Reaches of Tarim River
    LIU Xinghong, ZHANG Qingqing, ZHANG Guangpeng, LI Hong
    2021, 23(10):  131-144.  DOI: 10.13304/j.nykjdb.2020.0321
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    In order to explore the spatial distribution of plant communities and their influencing factors in the lower reaches of Tarim River, 36 sample plots and important values of plant species surveyed in the field were used to classify the number of plant communities by the two-way indicator species analysis method (TWINSPAN), and the distributions of plant communities and influencing factors were analyzed by detrended correspondence analysis (DCA), canonical correspondence analysis (CCA) and detrended canonical correspondence analysis (DCCA). The results showed that: ①among all the plots investigated, T. ramosissima had the highest frequency, accounting for 8611% of the total plots. P. euphratica accounted for 41.67% of the total plots. P. aviculare, H. caspica, C. physodes, S. pellucida and K. scoparia had the lowest frequency, accounting for 2.78% of the total plots. ②TWINSPAN classification classified all samples into 9 plant clusters, and the performance of their spatial distribution showed that P. euphratica, T. ramosissima and P. australis were mainly dominant species within 50 m reaches from the river. P. euphratica, A. sparsifolia, H. halodendron, T. ramosissima and P. australis were the dominant species within 150—500 m reaches from the river. P. euphratica and T. ramosissima were the dominant species within 500—1 050 m reaches from the river. ③ The cumulative contribution rates of the first two principal component factors on environmental factors reached more than 50%. The contribution rate of each factor and the significance analysis showed that the total salt content and the depth of groundwater were main influence factors on the spatial distribution of plant communities in the lower reaches of Tarim River, which had great significance for studying the quantitative characteristics of plant communities, vegetation protection and ecological restoration in the lower reaches of Tarim River.
    Study on Nitrogen Reduction and Efficiency Increase Technology Under Water-fertilizer Integration of Summer Maize in Central Region of Shandong Province
    WU Guangjun, HUANG Zhiyin, ZHANG Chao, LU Duxu, ZHAI Naijia, QIAO Jian, LIU Weixia, WANG Ningning, WANG Guangming
    2021, 23(10):  145-152.  DOI: 10.13304/j.nykjdb.2020.0434
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    In order to study the influence of water-fertilizer Integration on growth of summer maize in Central Region of Shandong province, five treatments were conducted including non-nitrogen (CK), reduction of nitrogen of water and fertilizer integration (W1N1), normal nitrogen of water and fertilizer integration (W1N2), reduction of nitrogen of conventional fertilizer and water management (W2N1), normal nitrogen of conventional fertilizer and water management (W2N2). The growth, nitrogen absorption and utilization of maize were investigated under different treatments. The results showed that: the grain yield, panicle number and 1 000-grain weight of maize in fertilization treatments were higher than those in no fertilization treatment. Under the same nitrogen application rate, the treatments of water and fertilizer integration could significantly increase corn grain yield, shoot biomass and total nitrogen accumulation of maize. The accumulation of dry matter, the absorption and accumulation of nitrogen after flowering in W1N2 treatment were significantly increased . The nitrogen transport amount and nitrogen transport rate in W1N1 treatment were increased. Compared with CK, the nitrogen transportation amount and transportation rate of nitrogen in W1N1 treatment were increased by 120.51% and 72.78%, respectively. In W1N1 treatment, the grain yield was higher, and the nitrogen transport efficiency, nitrogen partial productivity and nitrogen agronomic utilization efficiency were improved. So, the suitable reduction of nitrogen rate under water-fertilizer integration could not only enhance nitrogen use efficiency, but also high yield.
    Study on Irrigation Mode and Water Consumption of Cotton Drip Irrigation Without Film in South Xinjiang
    WANG Hongbo, ZHAO Li, GAO Yang, WANG Xingpeng, CAO Hui,
    2021, 23(10):  153-160.  DOI: 10.13304/j.nykjdb.2020.0631
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    Based on the long-term consideration of soil environmental issues, the cultivation mode of cotton drip irrigation without film mulching should become an effective way to solve the residual pollution of film in cotton fields of southern Xinjiang. In order to explore the feasibility of the cotton drip irrigation without film mulching in southern Xinjiang, 5 treatments of drip irrigations without film mulching were set, including 27 (I1), 36 (I2), 45 (I3), 54 (I4) and 63 mm (I5), and the irrigation quota (36 mm, I6) of drip irrigation under the mulch drip irrigation was used as the control treatment. The responses of soil moisture distribution, cotton water consumption and yield under different irrigation quotas were studied. The results showed that the soil moisture content of drip irrigation without film mulching cotton field was lower than that of drip irrigation with the mulch when the irrigation quota was the same, while it was increased with the increase of irrigation quota under without film mulching cotton field. The soil moisture content of I5 treatment was increased with the increase of soil depth, while those of I1, I2, I3, and I4 treatments were gradually decreased after reaching a peak at 60 cm soil layer. When the irrigation quota was the same, the yield of seed cotton in the I2 treatment without film was significantly lower than that in the I6 treatment with film, a decrease of 14.25%. And under the cultivation mode of drip irrigation without film, the yields of seed cotton were increased firstly and then decreased with the increase of irrigation quota, while the utilization efficiencies of water were gradually decreased with the increase of irrigation quota. The yield of seed cotton in I4 treatment was the highest (5 999.49 kg·hm-2), which was no significant difference with I6. Therefore, combining with the yield of cotton, the suitable irrigation quota for cotton drip irrigation without film mulching was 54 mm, and the irrigation frequency was 10 times during the whole growth stages,  which provided theoretical basis for developing scientific cultivation mode of cotton drip irrigation without film mulching.
    Temporal and Spatial Variation of Drought Index and Its Impact on Potato Yield in Central Inner Mongolia
    YUE Kun, JIN Linxue, LI Yunpeng, JIANG Shaojie, NIU Dong
    2021, 23(10):  161-170.  DOI: 10.13304/j.nykjdb.2020.0503
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    In order to understand the degree of drought and impact on potato yield of main potato producing areas in central Inner Mongolia, the precipitation concentration degree (PCD), precipitation concentration period (PCP), standardized precipitation index (SPI), and standardized precipitation evapotranspiration index (SPEI) were calculated using precipitation data from 23 weather stations of the potato growing area in central of Inner Mongolia from 1961 to 2017. The indices were used to analyze the distribution of precipitation resources and the characteristics of drought in these regions, and establish correlations with yield reduction of potato. The results showed that the PCP in the study area had a negative correlation with the precipitation during the growing season and showed a significantly downward trend, and the PCD in the east was earlier than that in the west. The areas with severe drought were mainly located in the middle of the study area. Drought levels were eased in the northwest and increased in the southeast. Yield of potato might be reduced in the year with PCD>0.37, PCP>39, SPI<0.13, or SPEI<0.34; and  the year with PCD> 0.48, PCP> 41, SPI<-0.54 or SPEI<-0.29 might be a disaster.
    Diversity of Fermentation Microbes and Changes of Hydrolytic Enzyme Activities of Cigar Leaf Raw Materials
    ZHANG Lei, LUO Zehua, YANG Mingchuan, LI Shigui, XIN Yuhua, CAI Bin, LIU Haobao, CENG Dailong, GU Jingang, DUAN Bihua
    2021, 23(10):  171-180.  DOI: 10.13304/j.nykjdb.2020.0534
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    Fermentation of tobacco leaves plays a key role in cigar quality and special favor. This paper studied the microbial diversity of tobacco leaves of two cultivars at different fermentation stages and the variation of three hydrolytic enzymes (protease, amylase and pectinase). It was found that the microbial floras were dynamic during the fermentation process. The microbial community of sample 1 was dominated by Staphylococcus at the early stage and changed to Enterobacter, Pseudomonas, and Brevibacterium at the end, while sample 2 had Staphylococcus and Tetragenococcus as the predominant species over the whole process. The enzyme activities changed a lot between cultivars and during the fermentation. For sample 1, the protease and amylase activities were maximal (165.95 U·g-1 and 0.34 U·g-1, respectively) at the end of fermentation, while the highest pectinase activity (1.30 U·g-1) was detected at the beginning. The protease activity (121.57 U·g-1) of sample 2 was the highest at the end, but lower than that of sample 1; and the pectinase and amylase activities in the middle reached to the peak,1.60 and 0.38 U·g-1, respectively, which were more than that of sample 1. Moreover, the pH of sample 1 changed significantly over the whole fermentation process, and changed to alkaline (pH 7.6) in the middle stage; and the pH of sample 2 changed little and kept acidic in three fermentation stages.
    Mechanism of Polyunsaturated Fatty Acids Biosynthesis and Metabolism in Marine Invertebrates: A Review
    WANG Heng, DING Jun
    2021, 23(10):  181-191.  DOI: 10.13304/j.nykjdb.2020.0690
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    Recently, people have paid more and more attention to the safety of aquatic products, high quality animal protein and healthy fat sources. Marine invertebrates are not only  good source of food protein, but also are  major source of polyunsaturated fatty acids (PUFA). The previous studies had shown that almost all PUFAs were originated from primary producers in aquatic ecosystems. PUFAs biosynthesized by microalgae in the ocean were caught by organisms at higher trophic levels of food chain for producing new PUFA through biotransformation or modification. A large number of studies on the pathways of PUFA biosynthesis and metabolism were reported in primary producers and vertebrates, however, little was known about PUFA biosynthesis and metabolism in  invertebrates. Therefore, this paper summarized the progress on PUFA biosynthesis and metabolism, as well as involved key enzymes and genes in five marine invertebrates (sponges, cnidarians, molluscs, crustaceans, and echinoderms), which provided valuable reference for understanding the synthetic metabolism and regulatory mechanism of PUFA in invertebrates.
    Effects of Thermocline and Space-time Factors on Yellowfin Tuna Fishing Ground Distribution in the Central and Western Pacific in Abnormal Climate#br#
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    ZHOU Weifeng, CHEN Liangliang, CUI Xuesen, ZHANG Heng
    2021, 23(10):  192-201.  DOI: 10.13304/j.nykjdb.2020.0280
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    In order to explore the impact of climate change on fishery resources, using the 2008—2017 Argo grid data (BOA_Argo) and the fishing log data of commercial fishing vessels during the same period, the temporal and spatial characteristics of the thermocline in the main fishing grounds of the yellowfin tuna purse seine in the western and central Pacific Ocean in La Ni’a and El Ni’o years were studied. Combined with GAM (generalized additive model) model, the variables affecting yellowfin tuna were analyzed. The results showed that, in the La Ni’a year, the CPUE moved westward as the high-value zone of the upper bound contracted westward, up to 145°E, and in the El Ni’o year, the CPUE was moved eastward to 165°E. Compared with normal years, the upper boundary depth difference of the thermocline on the east and west sides of the equatorial Pacific was larger than that of the normal year, and the upper boundary depth of 80~130 m was westward. The strength of the thermocline was generally weak in the west and strong in the east. The thickness of the thermocline was based on 15°N and 15°S, and each had a thick band-like distribution structure. The CPUE was distributed in 120—200 m thick. When the temperature range of the upper boundary of the thermocline was 27.5~29.5 ℃ and the intensity range was 0.08~0.13 ℃·m-1, the CPUE distribution was denser. The upper-bound temperature had the greatest impact on the CPUE. The eastward shift of the CPUE in El Ni’o and the westward shift of the CPUE in La Ni’a moved with the optimal parameter values of the fishing site in the thermocline. The factor of year had a fluctuating effect on the CPUE, and the influence of the La Ni’a year on the CPUE was closer. The areas with high abundance were 5°N—5°S, 150°E—175°E. From the above, the change of thermocline caused by abnormal climate had significant effect on CPUE.