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Table of Content

    15 April 2020, Volume 22 Issue 4
    System Construction of Poverty Alleviation Asset Management to Help Poverty Alleviation
    LI Shufeng1, REN Jinzheng2, LI Huiquan1, MAO Shiping1*
    2020, 22(4):  1-9.  DOI: 10.13304/j.nykjdb.2019.0750
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    With the investment increasing in poverty alleviation funds in recent years, a certain scale of poverty alleviation project assets have been formed in various regions, so improving the efficiency of poverty alleviation asset management and optimize the poverty alleviation asset management process has become an important breakthrough point to consolidate the quality of poverty alleviation. Based on the general asset management process, the poverty alleviation asset management process was constructed. By clearly registering the poverty alleviation asset identity information to provide a basis for optimizing asset management, the responsible entity was defined to improve management efficiency, standardize income distribution, help poverty alleviation and stimulate endogenous motivation, and build the supervision system enables poverty alleviation assets to operate in the sun. After fully understanding the implementation of poverty alleviation asset management in China, we should reasonably estimate the project asset return rate, profoundly explore the poverty alleviation mechanism for poverty alleviation assets, establish and improve the poverty alleviation asset supervision and inspection system, and lay a foundation for the establishment of a longterm poverty alleviation mechanism, which were helpful for poverty alleviation and smooth implementation.
    New Progress in Management Measures of the South Indian Ocean Fisheries Agreement and China’s Response Strategies
    XU Bo1,2, ZHANG Heng1, 2, 3, 4*, ZHANG Yingying1,2, FENG Chunlei1,2*
    2020, 22(4):  10-23.  DOI: 10.13304/j.nykjdb.2019.0668
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    The Indian Ocean is one of the main fishing grounds in the world. Since
    〈the Southern Indian Ocean Fisheries Agreement (SIOFA)〉 came into force, the organization has enacted 16 fisheries management measures that have been continuously updated to manage and conserve fisheries in the Southern Indian Ocean. At present, there are few studies on it in our country. This paper closely tracked the latest management trends and implementation requirements of the Southern Indian Ocean Fisheries Organization. It expounded the organizational framework, the impact of the latest management measures on China, the current fishing situation and resource assessment status of the agreement area, so as to provide references for China to join the organization in due course. The research results showed that, at the sixth conference of the parties in July 2019, SIOFA revised conservation management measures for interim management of bottom fisheries; standards for data collection, submission, verification and exchange; fishing authorization and notification of conservation and management measures; fishery monitoring, conservation and management measures. Five new conservation and management measures had been added to cover the duties of high seas boarding and inspection procedures, the mitigation of seabird bycatch, management of sharks, management of demersal stocks, and amendment terms of reference for the PAEWG or new CMM. Up to now, the group had set up five reserves, including Atlantis bank, Coral feature, Fool’s flat feature, Middle of What feature, and Walter’s Shoal feature, to evaluate the resources of bottomfish species, such as alfonsino, orange roughy, and Patagonian toothfish. However, the results of alfonsino evaluation had not been overfished. Orange roughy and P. toothfish had not been evaluated. The management measures of this fishery organization were more rigorous and comprehensive than those of China, while Chinese fishing boats shall strictly comply with the management requirements of this fishery organization. At present, the organization is still improving relevant conservation and management measures. Joining the organization as soon as possible will be helpful for the sustainable, healthy and orderly development of China’s deepsea fishery, and reflect the international influence and image of a responsible fishery country.
    Mechanism Research Advances in Plant Abiotic Stress Resistance Regulated by Hydrogen Sulfide
    LI Ziwei1, CHEN Simeng1, WANG Fazhan1, ZHANG Haoyang1, ZHANG Li2*, XU Zicheng1*
    2020, 22(4):  24-32.  DOI: 10.13304/j.nykjdb.2019.0342
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    Plants are inevitably subjected to various biotic or abiotic stresses during their growth and development. As a cell signal molecule, hydrogen sulfide (H2S) plays an important role in resisting various abiotic stresses, such as cold and heat, heavy metals, salt and drought, and interaction with other signal substances. In this paper, the mechanism of H2S resistance to abiotic stress in plant by gene regulation, alteration of enzyme activity and protein expression, s\|sulfhydrylation, mitigation of oxidative stress and interaction with signal substances were reviewed, the mechanism of H2S resisting abiotic stress in plants was also prospected.
    Exogenous 5Formyltetrahydrofolate Improves Rice Seedlings Growth  Under Limiting Nitrogen Condition
    YI Chen, ZHANG Chunyi, LIANG Qiuju*
    2020, 22(4):  33-43.  DOI: 10.13304/j.nykjdb.2019.0731
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    Folates, also known as vitamin B9, are essential cofacotors for growth and development of almost all organisms. Previously, it was found that the nitrogen metabolism was disturbed in Arabidopsis folatedefect mutants. However, the molecular mechanisms remain completely unknown. This study used rice (Oryza sativa L. Japonica) as material and explored the effect of 5formyltetrahydrofolate supplement on rice seedling growth and nitrogen metabolism under different nitrogen conditions and the molecular mechanism. The results showed as follows: under low nitrogen conditions, a slow growth and decrease in shoot length, fresh weight and chlorophyll content were observed in rice seedlings; exogenous 5formyltetrahydrofolate (200 μmol·L-1) could significantly promote the growth of rice seedlings and increase the shoot length, fresh weight and chlorophyll content under low nitrogen conditions; the content of folate derivatives, soluble protein, free amino acid were elevated with the addition of 5formyltetrahydrofolate; further analysis revealed that the enzymatic activity and gene transcription level of glutamate synthase were significantly increased. It predicted that folates could be involved in rice nitrogen metabolism by regulating the transcription and activity of glutamate synthase. These results were helpful for understanding the molecular mechanism underlying folates’ participation in plant nitrogen metabolism and provided new clues for the alleviation of lownitrogen stress and to increase plant nitrogen use efficiency.
     Effect of Exogenous Spermine on Growth and Physiological and Biochemical Indexes of Sweet Sorghum Seedlings
    under Drought Stress
    ZOU Fang, YANG Xiuliu, HUANG Siqi, WANG Zhiheng, WEI Yuqing*
    2020, 22(4):  44-52.  DOI: 10.13304/j.nykjdb.2019.0363
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    In order to explore the exogenous spermine (Spd) of sweet sorghum seedling growth under drought stress and the influence of the physiological and biochemical indicators, taking the sweet sorghum varieties Liaotian 1 as material under the indoor potted condition, this paper studied the effects of exogenous Spd on growth, photosynthesis, organic osmotic regulators and antioxidant protective enzymes of sweet sorghum seedlings under drought stress at three different concentration (0.6、1.2、1.8 mmol·L-1) of the Spd spraying processing in drought stress (15% PEG6000 simulation) of sweet sorghum seedling. The results showed that: Drought stress could significantly inhibit the growth and the physiological and biochemical indexes changes of sweet sorghum seedlings, while the spraying of Spd at different concentrations could improve the growth, photosynthetic efficiency, organic osmotic regulatory substance content and antioxidant protective enzyme activity of sweet sorghum seedlings under drought stress. Compared with drought stress treatment, the plant height of sweet sorghum seedlings sprayed with 1.2 mmol·L-1 Spd for 15 d increased by 31.62%, fresh weight increased by 58.29%, dry weight increased by 49.53%, leaf area increased by 30.96%, net photosynthetic rate increased by 135.40%, stomatal conductance (Gs) increased by 138.60%, transpiration rate increased by 158.54%, proline content increased by 71.16%, malondialdehyde content decreased by 53.17%, and superoxide dismutase activity increased by 39.69% under drought stress. This result indicated that under drought stress, the specific concentration (1.2 mmol·L-1) of exogenous Spd was beneficial to alleviate drought stress on sweet sorghum growth inhibition, increase the chlorophyll content of sweet sorghum seedling under drought stress and antioxidant enzyme activity, reduce the level of membrane lipid peroxidation, so as to relieve the drought stress to the injury of the sweet sorghum, sweet sorghum seedling drought resistance.
    Effects of Salt Stress on Seed Germination and Seedling Physiological Characteristics of Hemiptelea davidii
    YANG Ying1, WANG Yuelin2, YAN Jingqiuzi1, LI Gangtie1*
    2020, 22(4):  53-60.  DOI: 10.13304/j.nykjdb.2019.0108
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    In order to study the response of Hemiptelea davidii seeds and seedlings to salt stress, seed germination of H. davidii was carried out on the petri dish and the seedling culture was carried out by pot experiment. Germination rate, germination potential, germination index, vigor index, relative salt damage rate of H. davidii seed were tested under treatments with NaCl、Na2SO4、Na2CO3 and NaHCO3, as well as malondialdehyde (MDA), superoxide dismutase (SOD) and peroxidase (POD) of H. davidii seedlings. The results showed that:① Under salt concentration range of present work, the seeds of H. davidii can germinate normally under the salt stress treatments of NaCl concentration <30 mmol·L-1, Na2CO3 concentration <10 mmol·L-1, Na2SO4 concentration <20 mmol·L-1 and NaHCO3 concentration <20 mmol·L-1. NaHCO3 and Na2CO3 were more harmful than neutral salts of NaCl and Na2SO4. ②The relative salt damage rate of H. davidii seeds was all greater than 0. The four salts all inhibited seed germination, but the extent was different and showed a tendency of NaCl<Na2SO4<NaHCO3<Na2CO3. ③During the growth of seedlings, MDA content in leaves of different treatments increased gradually. The activities of SOD and POD increased first then decreased with the increase of salt concentration. However, MDA content and activities of SOD and POD of H. davidii seedlings did not change significantly, when NaCl concentration <30 mmol·L-1, Na2CO3 concentration <10 mmol·L-1, Na2SO4 concentration <10 mmol·L-1 or NaHCO3 concentration <20 mmol·L-1. It was suggested that seed germination and seedling growth of H. davidii had certain tolerance to low level salt stress, but high level salt stress will inhibit seed germination and hinder seedling growth of H. davidii. The present work provided theoretical basis for the cultivation and promotion of H. davidii in saline-alkali soil.
    Physiological Characteristics of Three Mulberry #br# Species in Response to Salt Stress
    HU Bo, YAN Wei*, LIU Yu, HAO Yanling
    2020, 22(4):  61-67.  DOI: 10.13304/j.nykjdb.2019.0374
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    Taking Morus alba cv. Tortuosa, Morus australis Poir. var. Australis, Morus mongolica Schneid. as experimental material, this paper explored the effects of the three different concentrations (0, 100, 200, 300, 400 mmol·L-1) on malondialdehyde (MDA), chlorophyll, soluble sugar (SS), peroxidase (POD), superoxide dismutase (SOD).The content of MDA in three mulberry plants increased with the increase salt concentration. And MDA content in Morus mongolica Schneid. was higher than that in other two mulberry varieties.The content of chlorophyll gradually decreased with the increase of salt concentration, and Morus alba cv. Tortuosa, Morus australis Poir. var. Australis, Morus mongolica  Schneid. reached the minimum values of 6.75, 12.61 and 8.93 mg·g-1 at 400 mmol·L-1 salt concentration. Activity of SOD, POD and the content of SS increased first and then decreased with the increasing salt concentration.  The theoretical basis was provided for the evaluation of salt tolerance of different mulberry varieties planted in saline areas of Western China by the determination of each index.
    Analysis of Seed Characteristics and Plant Growth Status of Bupleurum chinense From Different Geographical Provenances
    QI Wentao1, LI Jianchao1, WANG Chen1, LUO Rong1,2, LIU Changli2*
    2020, 22(4):  68-77.  DOI: 10.13304/j.nykjdb.2019.0968
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    Bupleurum chinense DC. is widely distributed in China and planted in many provinces, but the source of seeds, planting technology and management mode are different, which lead different characteristics, unstable quality and uncontrollable medicinal properties of Radix Bupleuri. The geographical variation, morphologica characteristics and plant growth status of the B. chinense seeds from 10 locations in 7 provinces of China were measured and analyzed, and the correlation of the variation of B. chinense seeds and plants were discussed. The results showed that there were significant differences in the seed length, width, thickness, 1 000grain weight and water content of B.chinense seeds from different locations (P<0.05). The 1 000grain weight was positively correlated with longitude;there was a significant positive correlation in water content and annual rainfall. The correlations between other geographical ecological factors and seed characteristics were not significant. The growth status of aboveground and underground parts of B. chinense plants showed significant differences (P<0.05), plant stem diameter was positively correlated with the latitude, and the root dry weight was significantly positively correlated with the annual average sunshine. Euclidean distance cluster analysis showed that the B.chinense seeds from 10 locations were clustered into four categories and there were difference between catedories.
    Effects of Exogenous Chromium on Physiological Indexes and Antioxidant System Changes of Corydalis yanhusuo
    SHENG Li1,2, CHENG Fulong1, YU Shunhui1, WANG Baihui3, LU Zenghui4, PAN Jie1*
    2020, 22(4):  78-84.  DOI: 10.13304/j.nykjdb.2019.0733
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    In order to explore the changes of physiological indexes and antioxidant system of Corydalis yanhusuo under different concentrations of exogenous Cr6+, the chromium contents, plant height, biomass and antioxidant system of C. yanhusuo were determined. The results showed that: the accumulation of Cr6+ in C. yanhusuo increased with the increase of soil Cr6+ concentration in the range of 67.32~323.32 mg·kg-1 Cr6+ treatment. The plant height and the biomass of C. yanhusuo were increased first and decreased afterwards. When the concentration of Cr6+ in the soil was less than 131.32 mg·kg-1, the growth of C. yanhusuo was promoted, and this effect was concentration-dependent: when the concentration of Cr6+ in the soil was lower than 131.32 mg·kg-1,  SOD still had higher activity to disproportionated superoxide radical into H2O2. At this time, POD and CAT activities were increasing, and H2O2 was decomposed, so the growth of C. yanhusuo was promoted; when the concentration of Cr6+ in the soil reaches 195.32 mg·kg-1, the percolation of C. yanhusuo was severe, SOD activity had a large reduction, and superoxide radical was accumulated in the plant, so the growth of the C. yanhusuo was inhibited.
    Research Progress on Hyperspectral Remote Sensing Monitoring of Crop Environmental Stress
    YANG Feifei, LI Shijuan*, LIU Shengping, LYU Chunyang, LIU Dazhong, XIAO Shunfu, LIU Hang
    2020, 22(4):  85-93.  DOI: doi:10.13304/j.nykjdb.2019.0489
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    Frequent crop environmental stress not only seriously affects regional food production and ecological security, but also threatens social and economic stability and sustainable development. Hyperspectral remote sensing can monitor crop environmental stress in real time and accurately, which has great advantages over traditional monitoring methods. This paper firstly introduced the theoretical basis of hyperspectral remote sensing for monitoring crop environmental stress, focusing on direct monitoring based on spectral response characteristics and indirect monitoring based on agronomic parameters and physiological information inversion. The research progress of hyperspectral remote sensing in monitoring crop pests and diseases and water stress was summarized. On this basis, the insufficiency of this technology in the field of crop environmental stress monitoring was pointed out, such as the lack of specific knowledge of spectral response characteristics, the low accuracy and universality of inversion model, and the limited use of data. The development direction of hyperspectral remote sensing in crop environmental stress monitoring was discussed in order to provide reference for crop environmental stress monitoring and early warning.
    Study on Crown Prediction Model of Main Tree Species in Songshan Nature Reserve in Beijing
    WANG Yuan1, WANG Xiulan1*, FENG Zhongke1, SUN Sufen2, ZHANG Lang3,4, LIU Peibin5
    2020, 22(4):  94-101.  DOI: 10.13304/j.nykjdb.2018.0722
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    As a key factor in forestry research, the research on crown width is of great significance for the development of precision forestry. In order to better use crown width to predict other factors of trees, 14 common tree species such as Pinus tabulaeformis Carr., Tilia tuan Szyszyl., Quercus mongolica Fischer ex Ledebour in Songshan Nature Reserve of Beijing were selected to establish the DBHcrown model and tree hightcrown model. Based on the six regression equations and the measured data of plots, the filtered optimal equations for each species were tested for accuracy. The results showed that the model of 14 tree species displayed good fitting accuracy, most of decision coefficients(R2) were greater than 0.5. Among them, the highest R2 belonged to Juglans regia Linn. DBHcrown model which was 0.951, and the R2 of Juglans regia Linn. height model was 0.887. The lowest R2 belonged to Quercus mongolica Fischer ex Ledebour tree height model which was 0.506 and also more than 0.5. The accuracy evaluation index of these models in this study provided esstatistical significance and important reference value for the prediction of largearea forest parameters in Songshan area of Beijing.
    Study on a Straw Carbonizing Furnace with Two Chambers by Indirect Heating of Flue Gas
    WANG Lie, FAN Qizhou*, WU Wei, LIU Bichen
    2020, 22(4):  102-110.  DOI: 10.13304/j.nykjdb.2019.0026
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    In order to resolve the problem of treating crop straws for smallscale farmers in rural areas, this paper designed twobox flue gas indirect heating fixedbed biomass carbonizing equipment with a builtin combustion chamber and two rectangular boxes as carbonizing chambers for carbonizing bundles of crop straws. The device utilized external heating and high temperature heating assisted by flue gas to improve the uniformity of carbonization temperature distribution and reduce heat loss. Taking corn straw as raw material, the fixed carbon content, carbon yield and final carbonization temperature were used as indicators to investigate the influence of inlet air volume, heating time and bundle diameter of corn straw on the index through orthogonal test. The results showed that the equipment worked well, and the air intake, heating time and bundle diameter had significant effects on the fixed carbon content; the bunch diameter had the greatest influence on the carbon yield and the final carbonization temperature. The optimal parameters combination were a fan speed of 2 800 r·min-1, the heating time of 4 h and the bundled diameter of 35 cm. At this time, the overall yield of equipment carbon was the highest.
    Habitat Suitability for Wheat Yellow Mosaic Disease in HuangHuaiHai Region Based on the Maximum Entropy Model
    HAN Xiaochao1, MING Yanfang1*, JI Zhonglin2, WANG Kai1
    2020, 22(4):  111-119.  DOI: 10.13304/j.nykjdb.2019.0487
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    The scientific prediction of the suitable growing area of wheat yellow mosaic disease in HuangHuaiHai area is of great significance to control the spread of the disease and ensure wheat production. Based on the data of the distribution of wheat yellow mosaic disease and the environmental factors, the MaxEnt model was used to predict the suitable area of this disease, and the contribution rate and ROC curve of ecological factors were analyzed to explore the main ecological factors affecting wheat yellow mosaic disease. The results showed that AUC of the area under the ROC curve was 0.955, and the model was reliable. The precipitation of the driest month and the warmest month, the highest temperature, altitude, clay and the wettest month had important effects on the distribution of this disease. The suitable growing areas mainly distributed in existing areas (Weihai, Yantai, Qingdao, Weifang, Zibo, Jinan, Tai’an, Rizhao, Linyi, Jining, Zaozhuang, Pingdingshan, Zhumadian, Zhoukou, Kaifeng and Fuyang) and the predicted area (Laiwu, Heze, Xinyang, Shangqiu, Huainan, Huaibei, Suzhou, Xuzhou, Suqian Lianyungang and Bengbu). The predicted proper area was wide, so it was suggested to add yellow mosaic disease of wheat as a national agricultural phytosanitary pest, and set up epidemic detection points in highfitness areas, and strengthen field management according to main environmental factors.
    A New Subtype of Calmodulinlike TaCML25/26 in Wheat Regulate Resistance to Leaf Rust
    LIU Peng1,WEI Jie1,YANG Yiqing1, ZHANG Na1,WEN Xiaolei1,2, FAN Xuefeng1,YANG Wenxiang1*,LIU Daqun1*
    2020, 22(4):  120-128.  DOI: 10.13304/j.nykjdb.2019.0596
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    Wheat leaf rust is an important disease in wheat production, and the utilization of resistant varieties is a safely, efficient and economical method to control the disease. It is clear that the role of leaf rustrelated genes in leaf rust resistance is of great significance for the effective control. The Ca2+ CaM/CML messenger system plays an important role in disease resistance, and different CaM subtypes may regulate different resistance pathways. Previous studies showed CaM/CML sequences significantly differentially expressed in diseaseresistant and susceptible transcription. Based on this, this study cloned the open reading frame (ORF) of this differentially expressed sequence in wheat nearisogene line TcLr19. Through Blastx and sevral kinds of software, the structural properties were preliminarily determined. The gene encoded a novel CML isoform with 458 bp in length and 147 amino acids and contained no transmembrane region, no signal peptide, located in other organelles rather than mitochondria, and had an EFhand_8 and multiple EFh conservative domains. The amino acid sequence of this gene shared 99% identify with CML25/26 from Aegilops tauschii. The gene was tentatively designated as TaCML25/26. SWISSMODEL was used to construct a threedimensional model of CML to initially determine its structural characteristics. The differential expression of CML gene under leaf rust infection was detected by realtime fluorescence quantitative PCR (qRTPCR). The gene was expressed in different levels in roots, stems and leaves. It was induced by Puccinia triticina, and the peak time of expression was significantly different in wheat leaf rust resistance nearisogenic line TcLr19 and the susceptible mutant Mu19. And the peak time was 96 h earlier in TcLr19 than that in susceptible mutant. The exogenous phytohormone salicylic acid and abscisic acid induced TaCML25/26 upregulated expression in TcLr19. The results laid a foundation for the future analysis of the potential biological function of wheat calmodulin gene in plant wheat leaf rust resistance.
    Application Prospect of EM Bacteria in Agricultural Production of Guizhou Karst Region
    TANG Xiaopeng, CHEN Lei, XIONG Kangning*
    2020, 22(4):  129-138.  DOI: 10.13304/j.nykjdb.2019.0134
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    Karst rocky desertification is a kind of ecosystem degradation phenomenon, which can lead to soil degradation, land nutrient reduction, low land productivity, water pollution and other ecological environment problems, so it seriously threaten the ecological and environmental safty and social economic development of karst areas in China. This paper introduced the characteristics of agricultural production in Guizhou karst region, a typical karst region in southwest China, and reviewed the application of effective microorganisms (EM) in the unconventional feed resources development, animal husbandry, aquaculture and planning industry, and looked forward to the application prospect of EM bacteria in agricultural production in karst region of Guizhou with aimto provide some references for the sustainable development of ecological agriculture in karst region of Guizhou.
    Cotton Stalk Biochar Retarding Stress of Cadmium on Growth of Rice
    LIU Shidou1, ZHU Xinping1,2*, ZHAO Yi1, WANG Boyan1, HAN Yaoguang1, YANG Beibei1, LU Zhi1, JIA Hongtao1,2
    2020, 22(4):  139-146.  DOI: 10.13304/j.nykjdb.2019.0453
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    In order to investigate the effect of cotton stalk biochar on retarding cadmium stress on the growth of rice (Oryza sativa L.), an outdoor pot experiment was conducted with ‘Tefengyou 2’ rice as test material. Adding cotton stalk biochar with concentrations of 0% (C0), 1% (C1), 2.5% (C2.5) and 5% (C5) into the paddy soil with cadmium concentration of 0, 1, 4, 8 mg·kg-1. The effects of application of biochar on plant height, leaf SPAD value, photosynthetic characteristics, leaf water use efficiency and other physiological and yield indexes were analyzed in rice jointing stage, booting stage, filling stage and ripening stage. The results showed that: ① under the condition of C0 treatment, cadmium stress treatment decreased plant height, leaf SPAD value, photosynthetic capacity, leaf water use efficiency and yield, and these indexes decreased with the increase of cadmium concentration (P<0.05). ② Under cadmium stress treatments, C1 treatment could significantly increase rice plant height, leaf water use efficiency and rice yield (P<0.05). Under four cadmium concentration of 0, 1, 4, 8 mg·kg-1, compared with C0, the yield per pot of C1 was increased by 45.45%, 30.63%, 22.20% and 12.98%, respectively. In general, cadmium had a stress effect on rice growth, reducing photosynthetic physiological capacity and yield of rice, however the application of 1% biochar can effectively retard cadmium stress on rice and increase rice yield.
    Effect Evaluation of Field Experiment of Two Paenibacillus sp. Agents in WheatMaize Rotation Area
    2020, 22(4):  147-152.  DOI: 10.13304/j.nykjdb.2019.0556
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    The field application experiment of microbial agents has an important guiding significance for the development of microbial fertilizers suitablefor practical agricultural production. In this study, two Paenibacillus sp. agents screened in the previous study were used in the field experiment of wheatmaize rotation area, and the effect was evaluated. Compared with the control, the two kinds of microbial agents had no effect on bloom, ear setting time. The plant height and fresh weight of wheat at jointing and booting stage were significantly improved. Among the yield components of wheat, the agent 1 significantly increased the 1 000grain weight; the agent 2 significantly increased the number of ears. Both microbial agents significantly increased the total yield of wheat, and the highest yield reached (6 211.24±92.95) kg·hm-2, compared with the control, the yield increased by 16.23%. The yield of agent 2 under 15% reduction in nitrogen fertilizer reached (6 056.27±24.14) kg·hm-2, 23.20% higher than that of the control with 15% nitrogen reduction, and 13.84% higher than that of the normal control. The two agents also had different effects on plant height, leaf length and leaf width of maize. During the harvest period, the plant height and fresh weight of maize increased significantly. Compared with 15% nitrogen reduction, the two microbial agents significantly increased ear fresh weight, ear dry weight, ear length, ear width and 100grain weight. Compared with the control with 15% nitrogen reduction, the two agents significantly increased ear fresh weight, ear dry weight, ear length, ear width and 100grain weight. After
    treating with agent 1, the yield reached (8 566.27±157.87) kg· hm-2, and the agent 2 reached (8 602.70±122.79) kg· hm-2, which increased by 18.58% and 19.09%, respectively compared with the control of nitrogen reduction. Compared with the control with normal application of nitrogen fertilizer, yield increased by 9.3% and 9.77%, respectively. This study provided a basis for enriching the variety resources of microbial fertilizers in China, and provided research data for popularizing the field application technology of microbial fertilizers for wheat, maize and other crops.
    Effects of Three-year Mulching with Different Thicknesses of Plastic Film on Soil Water and Heat Effect, Maize Yield and Film Residues
    TANG Wenxue1, MA Zhongming2*
    2020, 22(4):  153-161.  DOI: 10.13304/j.nykjdb.2019.0102
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     In order to study the effects of three-year mulching with different thickness of plastic film on soil water and heat effects, maize yield and film residue, field experiments were conducted with three-year mulching of plastic film. In the field experiment, four thickness levels of the mulch (0.008, 0.010, 0.012, 0.015 mm) were randomly designed. The results showed that: ① The mulch film with thickness of 0.012 mm and 0.015 mm had good effect of increasing temperature and preserving the moisture of the soil after many years. Compared with one-year mulching CK, water consumption during the growth period of film mulching with thickness of 0.012 and 0.015 mm only increased by 1.96% and 1.14%, and the soil temperature from corn sowing to jointing stage only decreased by 0.74 and 0.71 ℃. ② Under three-year mulching, the growth of crops was affected, and the yield and water use efficiency of maize reduced. Yield and water use efficiency under 0.008 mm thickness mulch were significantly lower than that of CK, 13.24% and 18.12%, but the efficiency under the thickness of 0.010, 0.012 and 0.015 mm was close to that of CK, and only decreased by 2.27%~4.09%, 2.85%~8.36%. ③ Under three-year mulching, the input cost effectively reduced, and the ratio of output to input of maize significantly increased by 13.73%, 25.00%, 26.47% and 25.49% compared with CK. ④ Three-year mulching significantly reduced the film residues, which was 55.74%~61.42% lower than CK, but the film with thickness of 0.008 and 0.010 mm was fragile and difficult to recover, making the residual coefficient of plastic film as high as 35.60% and 32.97%. When the film thickness increased to 0.012 and 0.015 mm, the residual coefficient decreased to 21.99% and 19.81%. In conclusion, the application of plastic film with thickness greater than 0.012 mm in multi-year mulching could ensure maize yield, improve water use efficiency and the ratio of output to input, and effectively reduce residual film pollution.
    Effects of Different Loose-leaf Baking Flue-curing Process on Tobacco Quality in Rainy Areas
    LIU Yong1, LI Lixin1, WU Jinfu2, ZHAO Shude2, HE Kuanxin1*
    2020, 22(4):  162-170.  DOI: 10.13304/j.nykjdb.2019.0672
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    In order to explore loose-leaf baking technology suitable for the rainy ecological conditions in Jiangxi Province, the airflow descent bulk curing barns was transformed. On the basis of the original bamboo air distribution plate and single bar, metal mesh wind deflector and H-shaped bar were optimized and improved, and different leaning loose-leaf baking flue-curing treatments were carried out and compared. The results showed that when tobacco leaves were stacked and loaded inclining to the direction of partition wall of tobacco curing barn by about 15°, and the loading density was reasonably controlled, the baked dry tobacco weight could be increased by 50.99%~62.88%, and the labor cost of loading, unloading tobacco could be reduced by 43.15%~46.84%. Compared with hang pole bulk curing, the average price of the middle and upper leaves of loose-leaf loading treatments was increased by 0.18~4.92 yuan·kg-1, and the sensory quality was improved by 0.2~3.9 points. Reducing the yellowing degree of middle warm layer tobacco leaves during yellowing period by 10%~20%, and decreasing the maximum temperature of stem-drying period by 2~3 ℃, tobacco leaves could be laid down in an orderly direction to the partition wall of tobacco curing barn, and it was successfully baked; the cured tobacco leaves shrunk obviously, the appearance quality such as structure, oil content and color of tobacco leaves were obviously improved, the phenomenon of thinning of tobacco leaves in low temperature area and scorched gas of tobacco leaves in upper layer tobacco leaves were alleviated; and the malpractice of leaves color in main vein and both sides in loose-leaf baking treatments was effectively improved.
    Effects of LED Red and Blue Light on Growth, Yield and Saponin Content of American Ginseng (Panax quinquefolius)
    2020, 22(4):  171-176.  DOI: 10.13304/j.nykjdb.2019.0539
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    In order to explore the effects of LED red and blue light on the growth, yield and quality of American ginseng plants, the seedlings of 2yearold were used as materials and experiments were carries out in an artificial light plant factory with controllable environment. Three red and blue light qualities, including 2R:1B (Q2∶1), 3R:1B (Q3∶1) and 4R:1B (Q4∶1), as well as 2 light intensities, including 50 (I50) and 80 μmol·m-2·s-1 (I80) were setup, and the effects of 6 treatments on the growth and quality of American ginseng were investigated. The results showed that the effects of different red and blue light on the photosynthesis of American ginseng were slightly different. Q3∶1I50 treatment had the largest number of American ginseng fruits and seeds. The fresh and dry weight of the root of American ginseng was the heaviest under Q2∶1I80 treatment. The content of total saponins under Q4:∶I80 treatment was significantly higher than that in the other treatments. In total, light intensity is an important factor affecting the growth, yield and saponin content of American ginseng. Low light intensity was beneficial to the shoot growth of American ginseng, and high light intensity is advantageous to the root growth of American ginseng. The results provided scientific basis for designation of LED red and blue light irradiation conditions based on yield and saponin content. It also provided technical support for plant factories to cultivate high valueadded crops such as American ginseng and promoted the development of plant factories industry.
    Association of Bryophytes with Site Factors and Indicator Species in  Agroforestry Ecotone of East Guangdong
    YANG Xuecheng, HUANG Runxia, ZHOU Qing, XU Mingfeng, TANG Qiming, SU Zhiyao*
    2020, 22(4):  177-186.  DOI: 10.13304/j.nykjdb.2019.0113
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    Bryophytes, as the most primitive higher plants, are small in individuals and often have large cushioned cluster communities, which are extremely sensitive to environment. In order to investigate the relationship between the surface bryophytes of subtropical forest and various habitats, and study the habitat-indicative role of bryophytes, data collected from 6 hm2 permanent plots in Guangdong Kanghe Provincial Nature Reserve were analyzed. We used Random forest analysis was used to test the predictive importance of different habitat factors on bryophyte, and used indicator species analysis was used to reveal the indicative species under different habitat gradients. The results showed that convexity and potential direct incident radiation were of high importance to the cover, richness, Simpson Index, evenness and Berger-Parker dominance of Moss and Liverwort, which indicated that convexity and potential direct incident radiation had great influence on bryophytes and were important environmental factors to limit the growth of bryophytes. The habitat factors such as slope and elevation also had different effects on the diversity index of bryophytes, which showed that the diversity pattern of bryophytes was not affected by a single factor, but influenced by many factors. The indicator species analysis showed that there were differences in the indicative species of bryophytes under different habitat gradients, and some bryophytes were able to indicate different habitat conditions at the same time. Pseudotaxiphyllum pohliaecarpum had significant indicative effect on the 2nd elevational gradient, the 3rd slope calss and the 1th convexity gradient, with wide ecological amplitude. Rhynchostegium pallidifolium had significant indication effect on the 1th elevational gradient, sunny aspect and 2nd convexity gradient, with high ecological amplitude and strong adaptability.