China Agricultural University Research Articles

Early-Life Supplementation of Grape Pomace Extracts Lastingly Promotes Polyphenol Metabolism and Optimizes Gut Microbiota

Background: Previous investigations have reported that nutritional supplementation in a critical developmental window can strikingly influence health level and metabolic status in adult life. Grape polyphenol harbors many physiological properties, especially in regulating metabolic status. In the present study, we aimed to investigate whether the GPE supplementation in a vital window plays an important role in metabolic and health status in adult life, by promoting the polyphenol metabolism and optimizing host gut microbiota. Methods: One group of 3-week-old mice and one group of 6-week-old mice were given GPE by gavage for 12 days, and the other group of 3-week- or 6-week- old mice were given by normal saline as control. We detected polyphenol metabolites in the plasma by UPLC-MS/MS. We also used Real-time quantitative RT-PCR to examine mRNA expression levels of genes related to polyphenol metabolism. Furthermore, we analysed the structure of gut microbiota and the correlation between the mRNA expression levels of polyphenol metabolism related genes and gut microbiota. Findings: There were a considerably more abundance of polyphenol metabolites in plasma of 3-week-old mice than that in plasma of 6-week-old mice. Consequently, much higher mRNA expression levels of polyphenol metabolism related genes were observed in intestine of 3-week-old mice. Moreover, after GPE supplementation, the gut microbiota of 3-week-old mice was characterized by a drastic expansion of Akkermansia and Lactobacillus, and a remarkable inhibition of norank_f__Lachnospiraceae, unclassified_f__Lachnospiraceae, Mucispirillum, in comparison with that of 6-week-old mice. In addition, Akkermansia and Lactobacillus had the positive connections with the mRNA expression levels of genes related to polyphenol metabolism in jejunum, such as LPH, SGLT1, SULT1A1, UGT1A1, UGT1A4, UGT1A6. Interpretation: GPE supplementation in a critical developmental window promoted polyphenol absorption and modulated gut microbial community structure, which might contribute to metabolic status and the long-term health. Funding Statement: National Key Research and Development Plan during the 13th five-year plan period (No. 2017YFD0400504). Declaration of Interests: The authors declare no conflict of interest. Ethics Approval Statement: The animal study was approved by the China Agricultural University Laboratory Animal Welfare and Animal Experimental Ethical Committee (Beijing, China).

Azotobacter bryophylli sp. nov., isolated from the succulent plant Bryophyllum pinnatum.

A Gram-stain-negative, aerobic, nitrogen-fixing bacterium, designated strain L461T, was isolated from leaves of Bryophyllum pinnatum growing at the South China Agricultural University. Phylogenetic analysis of the 16S rRNA gene sequence indicated it as a member of the genus Azotobacter closely related to Azotobacter beijerinckii JCM 20725T (97.82 % similarity) and Azotobacter chroococcum ATCC 9043T (97.34 %). Its major fatty acid components were C16 : 1 ω9c and C16 : 0. Its predominant isoprenoid quinone was Q-9. Its major polar lipids were phosphatidylethanolamine, phosphatidylglycerol, aminophospholipid, phospholipid and one unknown lipid. Its DNA G+C content was 64.9 mol% (Tm). DNA-DNA relatedness values between strain L461T and the reference strains of A. beijerinckii and A. chroococcum were 46.43 and 28.23 %, respectively. Biological and biochemical tests, protein patterns, genomic DNA fingerprinting, and comparison of cellular fatty acids distinguished strain L461T from the closely related Azotobacter species. Based on these data, the novel species Azotobacter bryophylli sp. nov. is proposed, with the type strain L461T (=KCTC 62195T=GDMCC 1.1250T).

Design and construction of the new library at China Agricultural University

A new, world-class library has been built at China Agricultural University in Beijing, the oldest agricultural higher education institute in China. The new building’s attractive natural stone facades reflect both old and new, from bamboo writing slips to barcodes, while the dramatic internal space is user-friendly, energy-efficient and flexible. During construction, an innovative hybrid diaphragm walling solution was adopted due to the high groundwater level and restricted site. Building information modelling technology was also successfully used throughout design and construction, helping to improve construction quality and safety management.

Getting that sugar, one way or another.

Getting that sugar, one way or another.

Meet the First Authors.

Meet the First Authors.

H3N2 canine influenza virus and Enterococcus faecalis coinfection in dogs in China

BackgroundIn May 2017, 17 dogs in a German Shepherd breeding kennel in northern China developed respiratory clinical signs. The owner treated the dogs with an intravenous injection of Shuang-Huang-lian, a traditional Chinese medicine, and azithromycin. The respiratory signs improved 3 days post-treatment, however, cysts were observed in the necks of eight dogs, and three of them died in the following 2 days.Case presentationQuantitative real-time PCR was used to detect canine influenza virus (CIV). All of the dogs in this kennel were positive and the remaining 14 dogs had seroconverted. Two of the dogs were taken to the China Agricultural University Veterinary Teaching Hospital for further examination. Two strains of influenza virus (A/canine/Beijing/0512–133/2017 and A/canine/Beijing/0512–137/2017) isolated from the nasal swabs of these dogs were sequenced and identified as avian-origin H3N2 CIV. For the two dogs admitted to the hospital, hematology showed mild inflammation and radiograph results indicated pneumonia. Cyst fluid was plated for bacterial culture and bacterial 16 s rRNA gene PCR was performed, followed by Sanger sequencing. The results indicated an Enterococcus faecalis infection. Antimicrobial susceptibility tests were performed and dogs were treated with enrofloxacin. All 14 remaining dogs recovered within 16 days.ConclusionsCoinfection of H3N2 CIV and Enterococcus faecalis was detected in dogs, which has not been reported previously. Our results highlight that CIV infection might promote the secondary infection of opportunistic bacteria and cause more severe and complicated clinical outcomes.

L-Arginine Enhances Intestinal Stem Cell Function

Background: L-arginine preserves intestinal barrier integrity from injury, but underlying mechanisms remain unknown. Methods: In this study we utilized mice and small intestinal (SI) organoid models to clarify the role of L-arginine on epithelial differentiation of intestinal stem cells (ISCs). Findings: Here we show that L-arginine significantly increased expansion of ISCs, and Paneth cells in vivo and in vitro. Importantly, L-arginine stimulated ISC proliferation through Wnt/β-catenin signals of Paneth cells. Pre-treatment with L-arginine protected SI organoids in response to damage provoked by murine TNF-α and mice in response to gut injury provoked by a chemotherapy drug (5-FU). Interpretation: Our results demonstrate that L-arginine stimulated ISCs proliferation through Wnt/β-Catenin pathway activated by Wnt3a secreted by Paneth cells to protect the intestinal epithelial barrier. Funding Statement: This work was supported by National Key R&D Program of China (2018YFD0500600), the State Key Laboratory of Animal Nutrition (2004DA125184), National Natural Science Foundation of China (31502024), National Basic Research Program of China (973 program 2013CB127302), A Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD). Declaration of Interests: There are no conflicts of interest (financial, professional or personal) related to this manuscript. Ethics Approval Statement: All procedures were performed in accordance with institutional and national guidelines and regulations and were approved by the China Agricultural University Animal Care and Use Committee.

Estimates on nitrogen uptake in the subsequent wheat by above-ground and root residue and rhizodeposition of using peanut labeled with 15N isotope on the North China Plain

Leguminous crops play a vital role in enhancing crop yield and improving soil fertility. Therefore, it can be used as an organic N source for improving soil fertility. The purpose of this study was to (i) quantify the amounts of N derived from rhizodeposition, root and above-ground biomass of peanut residue in comparison with wheat and (ii) estimate the effect of the residual N on the wheat-growing season in the subsequent year. The plants of peanut and wheat were stem fed with 15N urea using the cotton-wick method at the Wuqiao Station of China Agricultural University in 2014. The experiment consisted of four residue-returning strategies in a randomized complete-block design: (i) no return of crop residue (CR0); (ii) return of above-ground biomass of peanut crop (CR1); (iii) return of peanut root biomass (CR2); and (iv) return of all residue of the whole peanut plant (CR3). The 31.5 and 21% of the labeled 15N isotope were accumulated in the above-ground tissues (leaves and stems) of peanuts and wheat, respectively. N rhizodeposition of peanuts and wheat accounted for 14.91 and 3.61% of the BG15N, respectively. The 15N from the below-ground 15N-labeled of peanuts were supplied 11.3, 5.9, 13.5, and 6.1% of in the CR0, CR1, CR2, and CR3 treatments, respectively. Peanut straw contributes a significant proportion of N to the soil through the decomposition of plant residues and N rhizodeposition. With the current production level on the NCP, it is estimated that peanut straw can potentially replace 104 500 tons of synthetic N fertilizer per year. The inclusion of peanut in rotation with cereal can significantly reduce the use of N fertilizer and enhance the system sustainability.

Assessing the performance of different irrigation systems on lettuce (Lactuca sativa L.) in the greenhouse.

Lettuce (Lactuca sativa L.) is a very important leafy vegetable in China and is commonly grown using furrow irrigation. In order to improve production efficiency, greenhouse experiments were conducted at Experimental Station, China Agricultural University, Beijing, China using furrow irrigation (FI), micro-sprinkler irrigation (MS), plastic film mulching irrigation (PF) and a combined plastic film mulching–micro-sprinkler irrigation system (PF+MS) to study their effects on soil physical characteristics, water distribution, root morpho-physiological traits, nutrition absorption, lettuce yield and water use efficiency for a spring crop and autumn crop in 2015 (Fig 1). Root length, root surface area, and root density were significantly higher under PF and PF+MS than under FI. Moreover, these traits were higher under MS than under FI but these differences were not significant. The soluble protein, soluble sugar, and Vitamin C content of lettuce decreased in the order PF+MS > PF > MS > FI in both crops. In the spring crop, the biological yield of MS, PF, and PF+MS was 7.22%、36.77%、43.20% higher than FI, respectively. In the spring crop, biological water use efficiency (BWUE) of FI, MS, PF and PF+MS was 20.93, 25.24, 36.81 and 38.54 kg m−3, respectively. The BWUE of MS, PF, and PF+MS was 20.59%, 75.87% and 84.14% higher than FI. Economic water use efficiency (EWUE) of FI, MS, PF and PF+MS was 17.06, 21.31, 31.11 and 32.31 kg m−3, respectively. The EWUE of MS, PF, and PF+MS was 24.91%, 82.36% and 89.39% higher than FI, respectively. The autumn crop achieved a higher WUE than the spring crop. The results suggested that the combined plastic film mulching-micro-sprinkler irrigation was the most suitable irrigation approach for increasing lettuce yield.

First person – Yunlong Li

ABSTRACTFirst Person is a series of interviews with the first authors of a selection of papers published in Biology Open, helping early-career researchers promote themselves alongside their papers. Yunlong Li is first author on ‘The ATPase TER94 regulates Notch signalling during Drosophila wing development’, published in BiO. Yunlong is a graduate student in the lab of Junzheng, Zhang at China Agricultural University, Beijing, P. R. China, investigating the regulatory mechanisms of developmental signalling pathways in Drosophila melanogaster.

Big data analytics for MOOC video watching behavior based on Spark

The purpose of this study is to measure the effectiveness of courses delivered using MOOCs in China Agricultural University. Video watching is considered to be the most important way to disseminate knowledge in Massive Open Online Course (MOOC). Its mission is to understand the degree of students’ learning engagement and to provide suggestions for teachers to construct courses. This paper proposes the analysis methods of students’ video watching behavior in MOOCs platform and verifies it with the data of the cauX platform. Initially, a detailed statistical analysis of video watching data and behavior was performed. Later, data preprocessing algorithms based on Spark platform were developed and used to calculate the number of video watching behaviors in every hour and every minute. Then, the entropy weight method was used to calculate the weight of pause video, seek video and speed change video. Finally, we analyze and discuss the results of experiment. The results show that the proposed method based on Spark platform can quickly and accurately analyze the characteristics of video watching behavior.

北京市平原区土壤有机碳垂直分布特征

PDF HTML阅读 XML下载 导出引用 引用提醒 北京市平原区土壤有机碳垂直分布特征 DOI: 10.5846/stxb201801090067 作者: 作者单位: 中国农业大学资源与环境学院,中国农业大学,中国农业大学资源与环境学院 作者简介: 通讯作者: 中图分类号: 基金项目: 北京市自然科学基金重点项目（8151001）；国家自然科学基金面上项目（41771561） Vertical distribution of soil organic carbon in plains areas of Beijing Author: Affiliation: College of Resources and Environmental Science, China Agricultural University,China Agricultural University, Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:研究土壤有机碳垂直分布特征规律对精确测算土壤有机碳储量具有重要意义。通过野外调查实地挖取北京市平原区40个典型土壤剖面共169个样品数据，研究土壤有机碳垂直分布特征。结果表明：1）北京市平原区0-150 cm土壤平均有机碳含量为（5.98±2.62）g/kg，垂直分布上，随剖面深度增加土壤有机碳含量逐渐降低，且在浅层（≤ 60 cm）下降速度显著快于深层（ > 60 cm）；2）各发生层次不同土壤质地的有机碳含量差异整体上均表现为粉粒及黏粒含量比例越高，即质地越黏重，土壤有机碳含量越高；3）不同土体构型的平均土壤有机碳含量大小关系为通体砂 < 通体壤 < 上壤下黏 < 夹黏，通体砂型土壤有机碳含量垂直变化相对平缓，上壤下黏型土壤有机碳含量在垂直方向呈"降-升-降"趋势，通体壤及夹黏型则均呈先快速下降后缓慢下降趋势；4）耕地和园地土壤平均有机碳含量高于荒草地，耕地在整个剖面中土壤有机碳含量均居于三种土地利用类型之首，耕地和园地的土壤有机碳含量在0-20 cm和40-60 cm之间下降速度高达40.10%和55.92%，剖面深度超过60 cm后下降速度显著放缓，受人类活动直接影响相对较少的荒草地在垂直方向上变化相对平缓。 Abstract:Understanding the vertical distribution of soil organic carbon (SOC) is of great significance for precisely assessing SOC storage. In this paper, data from 169 samples of 40 typical soil profiles in the plains areas of Beijing were excavated in the field and analyzed to investigate the vertical distribution characteristics of SOC. The results showed:1) The average SOC content in the 0-150 cm depth in the plains areas of Beijing was 5.98 ±2.62 g/kg. SOC content gradually decreased with depth, and the rate of decrease in the shallow (≤ 60 cm) SOC was significantly faster than that in deep (> 60 cm) SOC. The average SOC contents in the depths of 0-20, 20-40, 40-60, 60-80, 80-100 cm and 100-150 cm were 8.49, 6.47, 4.78, 4.94, 4.61 g/kg and 3.87 g/kg, respectively. 2) The differences in the SOC of different soil textures at different profile layers generally showed that the higher the proportion of powder and clay content, namely, the more viscous the texture, the higher the content of SOC. 3) The trend of average SOC contents along different soil profile configuration patterns was sand-sand-sand < loam-loam-loam < loam-loam-clay < loam-clay-loam. The average SOC of sand-sand-sand was significantly lower than that of the other soil profile configurations, and its vertical variation was relatively gentle. The SOC content of loam-loam-clay showed a vertical trend of "decline-rise-decline", while the SOC content of loam-loam-loam and loam-clay-loam showed a trend of rapid decrease and then slight decrease. 4) The average SOC contents of cultivated land and orchard land were higher than that of grassland, and the cultivated land in each profile level ranked the first among the three kinds of land use types. The SOC content of cultivated land and orchard land decreased by 40.10% and 55.92%, respectively, between the depths of 0-20 cm and 40-60 cm, and the rate of decrease slowed down significantly in the profile depths deeper than 60 cm. Compared with the cultivated land and orchard land, which were more directly affected by human activities, the SOC contents of grassland changed relatively gently in the vertical direction. 参考文献 相似文献 引证文献

将GEP纳入生态补偿绩效考核评估分析

PDF HTML阅读 XML下载 导出引用 引用提醒 将GEP纳入生态补偿绩效考核评估分析 DOI: 10.5846/stxb201809252081 作者: 作者单位: 中国农业大学人文与发展学院,中国农业大学人文与发展学院,中国农业大学人文与发展学院 作者简介: 通讯作者: 中图分类号: 基金项目: 亚洲开发银行技术援助项目（ADB TA-9040PRC） Evaluation of the incorporation of gross ecosystem product into performance appraisals for ecological compensation Author: Affiliation: College of Humanities and Development Studies,China Agricultural University,College of Humanities and Development Studies,China Agricultural University,College of Humanities and Development Studies,China Agricultural University Fund Project: ADB technical assistance project 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:随着十八大以来我国生态文明建设进程的加快，生态补偿的实践也在快速推进，在生态补偿机制不断完善的过程中，对生态补偿机制的实施效果进行考核评估是确保机制运行效率的核心问题。对将GEP纳入生态补偿绩效考核的必要性和可行性进行了研究。研究表明：现有的生态补偿绩效考核机制存在一定缺陷，而基于GEP的生态补偿绩效考核能够激发受偿主体在生态系统服务供给方面的创新潜力；从与基于生态系统服务产出的其他绩效考核的相容性来看，GEP对于生态系统服务评估的扭曲程度更低，可以作为县域环境考核的优化指标；从与基于活动类型的绩效考核的相容性来看，将GEP纳入生态补偿绩效考核体系并不是简单否定基于活动类型的绩效考核体系的作用。将GEP纳入生态补偿绩效考核需要将其与现有绩效考核体系有机结合，它特别适用于生态综合补偿机制下生态补偿绩效考核。 Abstract:With the promotion of ecological civilization in China, since the 18th CPC National Congress, eco-compensation practices have advanced rapidly. Evaluation of implementation effectiveness is the core issue to ensure continuous improvement in the efficiency of the eco-compensation mechanism. This study analyzes the necessity and feasibility of incorporating gross ecosystem product (GEP) into the performance appraisal for ecological compensation. The existing performance appraisal mechanisms need to be further improved. The performance appraisal of eco-compensation based on GEP is a direct appraisal based on the output of ecosystem services. An appraisal based on GEP can unlock the innovation potential of subjects that receive compensation from the supply of ecosystem services. GEP has less distortions of the evaluation of ecosystem services, and thus, can be used as an optimization index for county-level environmental appraisals. However, we cannot include GEP in the performance appraisal system of eco-compensation, as this would deny the role of the performance appraisal system based on types of activities. Several policy recommendations are proposed based on these findings, such as organically combining GEP with the existing performance appraisal system, exploring the establishment of comprehensive eco-compensation mechanisms, and reducing the loss of eco-compensation efficiency through the improvement of appraisal and incentive mechanisms 参考文献 相似文献 引证文献

Water-related land cover data products for geospatial analysis and modeling of infectious disease transmission risks

Event Abstract Back to Event Water-related land cover data products for geospatial analysis and modeling of infectious disease transmission risks Xiangming Xiao1*, Geli Zhang2, JInwei Dong3, Zhenhua Zou1, Xinxin Wang4 and Marius Gilbert5 1 University of Oklahoma, United States 2 China Agricultural University (CAU), China 3 Institute of Geographic Sciences and Natural Resources Research (CAS), China 4 Fudan University, China 5 Free University of Brussels, Belgium Transmission of many zoonotic infectious diseases is associated with the spatial-temporal changes in habitats, hosts, and vectors. One example is the highly pathogenic avian influenza viruses (HPAIV), and its transmission is closely related to the spatial distribution and movement of domestic ducks and wild water fowls which use water-related land cover types (e.g., open surface water body, natural wetland, and rice paddy) as their habitats. In the past decades, land use change and climate change have substantially and rapidly altered the spatial distribution and temporal dynamics of water-related land cover types, which calls for accurate and timely updated data, information, and knowledge of those water-related land cover types across the local, regional, national, and global scales. In this presentation, we will provide an update on water-related land cover data products from analyses of satellite images over years, including open surface water body, natural wetland, and rice paddy in China, USA, monsoon Asia, and the globe. We will also introduce the case studies that use these geospatial datasets in risk assessment and modeling of infectious diseases. We hope that this presentation will stimulate more discussion and collaboration between the geospatial science community, which focuses on the use of satellite images to track and monitor land use and land cover changes, and the animal and human health science community, which focuses on the epidemiology and ecology of infectious diseases that affect both animal and human health. Acknowledgements The research was supported by the National Institutes of Health (NIH) NIAID grant (1R01AI101028-01A2). Keywords: Surface water, aquaculture, wetlands, Rice paddies, remote sensing, avian influenza Conference: GeoVet 2019. Novel spatio-temporal approaches in the era of Big Data, Davis, United States, 8 Oct - 10 Oct, 2019. Presentation Type: Regular oral presentation Topic: Spatial data sources, open data, accessibility and information integration Citation: Xiao X, Zhang G, Dong J, Zou Z, Wang X and Gilbert M (2019). Water-related land cover data products for geospatial analysis and modeling of infectious disease transmission risks. Front. Vet. Sci. Conference Abstract: GeoVet 2019. Novel spatio-temporal approaches in the era of Big Data. doi: 10.3389/conf.fvets.2019.05.00052 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 07 Jun 2019; Published Online: 27 Sep 2019. * Correspondence: Prof. Xiangming Xiao, University of Oklahoma, Norman, United States, xiangming.xiao@ou.edu Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Xiangming Xiao Geli Zhang JInwei Dong Zhenhua Zou Xinxin Wang Marius Gilbert Google Xiangming Xiao Geli Zhang JInwei Dong Zhenhua Zou Xinxin Wang Marius Gilbert Google Scholar Xiangming Xiao Geli Zhang JInwei Dong Zhenhua Zou Xinxin Wang Marius Gilbert PubMed Xiangming Xiao Geli Zhang JInwei Dong Zhenhua Zou Xinxin Wang Marius Gilbert Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

樟树(Cinnamomum camphora)幼苗细根形态对氮磷添加和幼苗密度的响应

PDF HTML阅读 XML下载 导出引用 引用提醒 樟树(Cinnamomum camphora)幼苗细根形态对氮磷添加和幼苗密度的响应 DOI: 10.5846/stxb201809041884 作者: 作者单位: 华南农业大学林学与风景园林学院 作者简介: 通讯作者: 中图分类号: 基金项目: 中央财政林业科技推广示范项目（2015-GDTK-07） Responses of fine root morphology of Cinnamomum camphora seedlings to nitrogen and phosphorus additions and planting density Author: Affiliation: College of Forestry and Landscape Architecture,South China Agricultural University Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:全球氮沉降对森林生态系统结构和功能的影响已成为现代生态学研究热点之一，我国华南地区氮沉降的增长引起了土壤酸化和磷限制加剧等一系列生态问题。密度制约着植物个体对环境资源的吸收利用，是自然界中十分重要的选择压力之一。因此研究樟树（Cinnamomum camphora）幼苗的细根形态对氮磷添加和密度的响应，有利于了解亚热带树木根系对氮沉降和磷添加与林分密度的响应过程和机制，并为全球变化背景下樟树林生态系统的管理提供依据。本研究以1年生樟树幼苗为试验材料，选择氯化铵（NH4Cl）作为氮肥以模拟大气氮沉降，并且以二水合磷酸二氢钠（NaH2PO4·2H2O）模拟磷添加，氮磷处理设置4个水平，即对照、施N、施P和施N+P；种植密度设置10、20、40和80株/m2 4个水平。测定各处理樟树幼苗细根的根长、表面积、体积和根尖数，分析氮磷添加、密度和两者交互作用对樟树幼苗细根的影响。研究结果表明，与对照处理相比，N、P和N+P处理促进了幼苗细根长度、表面积、体积以及根尖数的增加。低密度条件下的N添加对幼苗根系形态的促进效果强于P添加。N+P处理对10、20、40株/m2幼苗根系形态的促进效果最佳，而各处理对80株/m2幼苗根系形态的促进效果均无显著性差异。随着种植密度的增大，幼苗细根长度、表面积、体积和根尖数均减少。樟树幼苗的细根长度、表面积、体积和根尖数在各密度间和不同氮磷添加处理间均有显著性差异，密度和氮磷处理间的交互作用对根系形态各指标均无显著影响。 Abstract:With the continuing deposition of atmospheric N and wide application of P fertilizer, N and P have become a major factor affecting the ecosystem C balance. Fine root morphological characteristics, such as the root length, surface area, volume, and tips, play a critical role in many functions, including nutrient absorption. Global N deposition and P addition induce changes in root morphology. Seedling density is an important factor affecting root morphology because of the enhanced resource competition among high density seedlings, which reflects the allocation ratio of photosynthetic C in the roots, and ultimately affects the overall plant C allocation balance. Understanding the effects of N and P additions and planting density on the fine root morphology is important to be able to improve fine root health. However, knowledge regarding the effects of N and P additions on the root morphology is limited, and it is still unclear how N and P additions and seedling density alter the fine root morphology of Cinnamomum camphora seedlings. In this study, the root morphology of C. camphora seedlings planted at different densities was evaluated, along with the root length, surface area, volume, and tips, in order to reveal the effects of N and P additions and plant density on the fine root morphological characteristics of this species. One-year-old C. camphora seedlings were used as test materials, and NH4Cl and NaH2PO4·2H2O were selected to simulate N deposition and P addition, respectively. N and P additions were performed with four different levels of treatment (control, N, P, and N+P), and seedlings were planted at four different densities (10, 20, 40, and 80 seedlings/m2). The results showed that the N, P, and N+P treatments increased the root length, surface area, volume, and tips of seedlings compared to those of the control treatment. The effect of N addition on root morphology was stronger than that of P addition under low planting densities. The N+P treatment had the greatest effect on the fine root morphology at densities of 10, 20, and 40 seedlings/m2, while there was no significant difference in the effect of each treatment at 80 seedlings/m2. With increased planting density, the length, surface area, volume, and tips of the seedling roots tended to decrease. The effects of different densities or treatments on the fine root length, surface area, volume, and tips of the seedlings were significantly different, but the interactive effect of density and N and P additions on the fine root morphology of the seedlings was not significant. 参考文献 相似文献 引证文献

Adaptation of Chinese and German maize-based food-feed-energy systems to limited phosphate resources—a new Sino-German international research training group

Phosphate is supplied to agriculture by mining and fertilizer production, followed by different steps of phosphate utilization, including primary production, feed and food consumption, and conversion of biomass, with accumulation in soils, but little recycling and severe environmental losses. Phosphate is a limited essential nutrient, however, with very uneven distribution worldwide. Closing the cycle and reducing primary phosphate consumption are fundamental future challenges. Maize has a relatively high phosphate requirement. China and Germany together cover the whole range of maize production systems. The new Sino-German international research training group “Adaptation of Chinese and German maize-based food-feed-energy systems to limited phosphate resources” (AMAIZE-P) was initiated in 2018 as a joint venture of the China Agricultural University (Beijing, China) and the University of Hohenheim (Stuttgart, Germany). The interdisciplinary and complementary research is driven by the hypothesis that under phosphate limited conditions, high productivity and high phosphate use efficiency can be achieved simultaneously by adapting phosphate cycling and availability (sources) to the multipurpose phosphate demands (sinks) in maize-based food-feed-energy systems. The educational program for doctoral researchers in China and Germany includes joint block seminars, thematic field trips, case studies, methodological courses, doctoral researchers’ conferences, intercultural training sessions and personal training.

Atomization characteristics of multi-type aerial nozzles in wind tunnel and low airflow velocity condition in manned agricultural helicopter

In order to explore the atomization characteristics of the LICHENG series nozzle for manned agricultural helicopter under medium and low airflow velocity conditions, droplet size tests on five sizes of nozzles 11002, 11003, 11004, 11006 and 11010 were carried out by laser diffraction device (LDD), based on the high-low speed composite wind tunnel for agricultural aviation designed by the National Center for International Collaboration Research on Precision Agricultural Aviation Pesticides Spraying Technology (NPAAC) of South China Agricultural University (SCAU). The results showed that under the three spray pressures of 30, 40 and 50 psi, the droplet sizes of the five types of nozzles expressed similar trends with the increase of airflow velocity. Among them, the droplet size variation of nozzles 11006 and 11010 with larger orifice size was the most significant, the largest range of D V0.1 was nozzle 11010, and the largest range of D V0.5 and D V0.9 was nozzle 11006. In addition, the changes of spray pressure would directly affect the quality of spray, especially the nozzles 11002, 11003 and 11004 with small orifice sizes were significantly affected. Under the condition of medium and low airflow velocity of 0-27.8 m/s, 89% of spread value (SV) by the five nozzles were in the range of less than 15%, but there were some test nozzles with poor spray stability during the test, which made the measurements of droplet size value larger, resulting in a maximum test deviation of up to 210.9 I¼m. The result also exposed the limitations exist in wind tunnel droplet size testing by using LDD, and an increase in airflow velocity resulted in a larger measurement droplet size. This phenomenon was particularly significant in the D V0.5 test results of various types of nozzles. This study can provide experimental data guidance for the optimization design and parameter selection of aerial nozzle for manned agricultural helicopter. Keywords: manned helicopter, aerial nozzle, wind tunnel, droplet size, agricultural application, spray classification DOI:  10.33440/j.ijpaa.20190201.0031  Citation: Yao W X, Lan Y B, Hoffmann W C,  Guo S, Chen S D, Wen S, et al.  Atomization characteristics of multi-type aerial nozzles in wind tunnel and low airflow velocity condition in manned agricultural helicopter.  Int J Precis Agric Aviat, 2019; 2(1): 9–17.

Broadcasting Winter Wheat Can Increase Grain Yield without Reducing the Kernels per Spike and the Kernel Weight

In North China, row spacing is the most common planting pattern used for winter wheat. Currently, there are three sowing and tillage methods for row spacing: rotary tillage sowing with straw return (RTS), subsoil tillage sowing with straw return (DTS), and no-tillage sowing with straw return (NTS). Recently, Hao proposed a new sowing pattern called uniform broadcast sowing with straw return (BSS) which could increase winter wheat yield. In this research, a field experiment was conducted during the growing seasons in 2011–2012 and 2012–2013. The winter wheat (Triticum aestivum L.) variety Jimai 22 was sowed with the four seeding and tillage methods—RTS, DTS, NTS, and BSS—at the China Agriculture University Wuqiao experimental station in the North China Plain. After tillage sowing and determining the sowing efficiency, the effective cover ratio of the seeds was measured, and the emergence ratio was calculated after emergence. In the two growing seasons, the growth and development stages were recorded. The dry matter accumulation (DMA), the yield, and the yield components (spikes per hectare, kernels per spike, and kernel weight) were also determined. We also measured the canopy structure leaf area index (LAI) and the stand uniformity. The results showed that BSS had the lowest emergence rate and lowest plant stands when compared with the other treatments. However, BSS had the highest grain yield at 7599.0 kg·ha−1 and 9763.3 kg·ha−1, which was 11.55, 16.17, 20.16% and 13.01, 15.68, 21.88% higher than DTS, RTS, and NTS in the 2011/2012 and 2012/2013 growing seasons, respectively. The improved grain yield of BSS was due to the increased productive tillers per hectometer-squared, which was attributed to the higher stand uniformity. More importantly, the increased tillers per hectare and grain yield were not accompanied by a reduction in grain number per spike or grain weight. The stand uniformity could facilitate canopy construction and population architecture and result in more even sunlight distribution, increased leaf area index (LAI) and sunlight interception, and enhanced photosynthetic activity. The stand uniformity also could increase both the pre-anthesis and post-anthesis DMA and promote the harvest index (HI). This study indicates that BSS is the most suitable sowing method for winter wheat production in North China.

National Center for International Collaboration Research on Precision Agricultural Aviation Pesticide Spraying Technology, South China Agricultural University

Inside Front Cover National Center for International Collaboration Research on Precision Agricultural Aviation Pesticide Spraying Technology, South China Agricultural University Inside Back Cover Precision Agricultural Aviation Application Technology Research Overseas Expertise Introduction Center for Discipline Innovation(111 Center), South China Agricultural University

Reasons that Affect the Interaction Among Students in Virtual Learning Environment

With the development of the technology, virtual learning environments are seeing wider application in college education. The research goal of this paper is mainly to explore the influence of the interaction between students and students in the virtual learning environment, and to improve students’ academic performance. The paper takes the online course of Canvas platform set by international college of China Agricultural University as an example, summarizes the interactive function of Canvas platform from the perspective of students and teachers, and conducts a questionnaire survey on students. Through analysis, the authors find that both teachers and students believe that the interaction in the virtual learning environment can improve students’ academic performance. And the gender and the major are key factors.