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Yield gap and resource utilization efficiency of three major food crops in the world——A review 被引量:5
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作者 RONG Liang-bing GONG Kai-yuan +5 位作者 DUAN Feng-ying LI Shao-kun ZHAO Ming HE Jianqiang ZHOU Wen-bin YU Qiang 《Journal of Integrative Agriculture》 SCIE CAS CSCD 2021年第2期349-362,共14页
Yield gap analysis could provide management suggestions to increase crop yields,while the understandings of resource utilization efficiency could help judge the rationality of the management.Based on more than 110 pub... Yield gap analysis could provide management suggestions to increase crop yields,while the understandings of resource utilization efficiency could help judge the rationality of the management.Based on more than 110 published papers and data from Food and Agriculture Organization (FAO,www.fao.org/faostat) and the Global Yield Gap and Water Productivity Atlas (www.yieldgap.org),this study summarized the concept,quantitative method of yield gap,yield-limiting factors,and resource utilization efficiency of the three major food crops (wheat,maize and rice).Currently,global potential yields of wheat,maize and rice were 7.7,10.4 and 8.5 t ha^(–1),respectively.However,actual yields of wheat,maize and rice were just 4.1,5.5 and 4.0 t ha^(–1),respectively.Climate,nutrients,moisture,crop varieties,planting dates,and socioeconomic conditions are the most mentioned yield-limiting factors.In terms of resource utilization,nitrogen utilization,water utilization,and radiation utilization efficiencies are still not optimal,and this review has summarized the main improvement measures.The current research focuses on quantitative potential yield and yield gap,with a rough explanation of yield-limiting factors.Subsequent research should use remote sensing data to improve the accuracy of the regional scale and use machine learning to quantify the role of yield-limiting factors in yield gaps and the impact of change crop management on resource utilization efficiency,so as to propose reasonable and effective measures to close yield gaps. 展开更多
关键词 food crops YIELD yield gap resource utilization efficiency yield-limiting factor
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The Relationship between Water Resources Use Efficiency and Scientific and Technological Innovation Level: Case Study of Yangtze River Basin in China
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作者 Guangming Yang Qingqing Gui +2 位作者 Junyue Liu Fengtai Zhang Siyi Cheng 《Journal of Environmental & Earth Sciences》 2023年第2期15-35,共21页
The Yangtze River Basin’s water resource utilization efficiency(WUE)and scientific and technological innovation level(STI)are closely connected,and the comprehension of these relationships will help to improve WUE an... The Yangtze River Basin’s water resource utilization efficiency(WUE)and scientific and technological innovation level(STI)are closely connected,and the comprehension of these relationships will help to improve WUE and promote local economic growth and conservation of water.This study uses 19 provinces and regions along the Yangtze River’s mainstream from 2009 to 2019 as its research objects and uses a Vector Auto Regression(VAR)model to quantitatively evaluate the spatiotemporal evolution of the coupling coordination degree(CCD)between the two subsystems of WUE and STI.The findings show that:(1)Both the WUE and STI in the Yangtze River Basin showed an upward trend during the study period,but the STI effectively lagged behind the WUE;(2)The CCD of the two subsystems generally showed an upward trend,and the CCD of each province was improved to varying degrees,but the majority of regions did not develop a high-quality coordination stage;(3)The CCD of the two systems displayed apparent positive spatial autocorrelation in the spatial correlation pattern,and there were only two types:high-high(H-H)urbanization areas and low-low(L-L)urbanization areas;(4)The STI showed no obvious response to the impact of the WUE,while the WUE responded greatly to the STI,and both of them were highly dependent on themselves.Optimizing their interaction mechanisms should be the primary focus of high-quality development in the basin of the Yangtze River in the future.These results give the government an empirical basis to enhance the WUE and promote regional sustainable development. 展开更多
关键词 Water resource utilization efficiency(WUE) Scientific and technological innovation level(STI) Coupling coordination Interactive response Yangtze River Basin
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Photosynthetic Carbon Gain, Allocation and Resources-Use Efficiency in Invasive Eupatorium Adenophorum and Its Native Congener E. Japonicum under Different Light and Nutrient Conditions
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作者 Jiye QIANG Ruifang WANG 《Agricultural Science & Technology》 CAS 2017年第10期1832-1840,共9页
Invasion is often facilitated by high resources availabilities and suppressed under low resources habitats. However, a number of invasive plants can successfully establish and dominate in resource-poor and (or) the ... Invasion is often facilitated by high resources availabilities and suppressed under low resources habitats. However, a number of invasive plants can successfully establish and dominate in resource-poor and (or) the understory of closed forests, indicating the plant's performances are habitats-dependent and species-specific. It is therefore necessary to explore the ecophysiological characteristics associated invasiveness for one invasive species across multiple resources availabilities whilst taking the relatedness into these comparative studies. In this study, invasive Eupitorium adenophorum and its native congener E. japonicum grew under different resource gradients in terms of light levels and soil nitrogen additions to identify the functional significance morphological and physiological traits associated closely with invasion and to examine their comparative responses. Photosynthetic carbon gain, biomass allocation and resource-use efficiency are evaluated in this pot experiment. Across treatments, E. adenophorum exhibited consistently higher values for most of the morphological variables including plant stature, relative growth rate (RGR), leaf root ratio (LRR), leaf area ratio (LAR), total leaf area, and lower root: shoot ratio (RSR). Significantly higher Pmax corresponded with higher photosynthetic nitrogen use efficiency (PNUE) and photosynthetic energy use efficiency (PEUE) especially in low light and (or) unfertile condition. Higher Gs and Pmax but lower photosynthetic water use efficiency (WUE) indicated the trade-off relationship between WUE and PNUE for E. adenophorum. Final biomasses were higher for E. adenophorum in nutrient and(or) light limited conditions, in which higher leaf construction cost(CC) compared with E. japonicum could be over-compensated by its significantly higher assimilation rates. The effects of light levels on these plant attributes were stronger than soil nutrient contents. The responses of these two congeneric species to light and nitrogen availabilities were similar, but the differences were magnified in resources limited conditions, indicating the better performancer at acquiring and at using limited resources of E. adenophorum over its co-occurring native flora. Our study presented the distinctive advantages of E. adenophorum in resources-poor environments, indicating conventional strategy of managing resources levels to control the invasion and expending of exotic species may not be as effective as expected. 展开更多
关键词 INVASIVENESS Biomass allocation resource utilization efficiency Construction cost PHENOLOGY
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Urban development and resource endowments shape natural resource utilization efficiency in Chinese cities 被引量:1
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作者 Yanbing Liu Fei Lu +1 位作者 Chaofan Xian Zhiyun Ouyang 《Journal of Environmental Sciences》 SCIE EI CAS CSCD 2023年第4期806-816,共11页
Improving the efficiency with which natural resources are utilized is an indispensable for achieving sustainable development and carbon neutrality. By analyzing the utilization efficiency of energy, water, and land, w... Improving the efficiency with which natural resources are utilized is an indispensable for achieving sustainable development and carbon neutrality. By analyzing the utilization efficiency of energy, water, and land, we established a comprehensive natural resource utilization efficiency index(NRUEI). We then calculated the 2016 index for 165 cities in China,and investigated what caused it to vary. We found three main results:(1) the NRUEI varied greatly across China and there were significant positive correlations between urban energy utilization efficiency(EUE), water utilization efficiency(WUE) and land utilization efficiency(LUE);(2) the NRUEI showed a significant positive correlation with a city’s population size,economy(Gross Domestic Product(GDP)), and the level of urban social development(GDP per capita);(3) cities in East China have the highest natural resource utilization efficiency,while cities in Northeast China have the lowest. These results indicate that China’s increasing urban development is associated with rising natural resource utilization efficiency and that the city’s endowment of natural resources is an important factor affecting that efficiency. Further, the results showed that the determinants of a city’s NRUEI differed in large and small cities. Lastly, our results suggest that improving EUE is key for improving NRUEI in urban China, and different efficiencies can be improved intertwined. A major takeaway of this study is that there is great potential for improving natural resource utilization efficiency in Chinese cities and we include city-specific suggestions for efficiency improvements. 展开更多
关键词 Urban development resource endowment resource utilization efficiency Sustainable city
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Water resource utilization efficiency and spatial spillover effects in China 被引量:30
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作者 SUN Caizhi ZHAO Liangshi +1 位作者 ZOU Wei ZHENG Defeng 《Journal of Geographical Sciences》 SCIE CSCD 2014年第5期771-788,共18页
Based on provincial panel data of water footprint and grey water footprint, and with the help of data envelopment analysis model considering and without considering the unde- sirable output, this paper estimates the w... Based on provincial panel data of water footprint and grey water footprint, and with the help of data envelopment analysis model considering and without considering the unde- sirable output, this paper estimates the water resources utilization efficiency in China from 1997 to 2011. The spatial weighting matrix based on economy-spatial distance function is established to discuss spatial autocorrelation of water resources utilization efficiency. With the help of absolute/3-convergence model, this paper concludes that there exists/%convergence in the water resources utilization efficiency. Under the conditions of considering and without considering the undesirable output, it takes about 52.6 and 5.6 years respectively to achieve the extent of half of convergence. By mean of the spatial Durbin econometric model, this paper studies spatial spillover effects of the provincial water resources utilization efficiency in China. The results are as follows. 1) With considering and without considering the undesir- able output, there is significant spatial correlation in provincial water resource efficiency in China. 2) Under the two cases, the spatial autoregressive coefficients (p) are 0.278 and 0.507 respectively, at 1% significance level. There exist the spatial spillover effects of provin- cial water resources utilization efficiency. 3) With considering the undesirable output, these factors of the education funds, the transportation infrastructure, and the industrial and agri- cultural water consumption proportion have positive impacts. These factors of foreign direct investment, the industry value-added water consumption per ten thousand yuan, per capita water consumption, and the total precipitation have negative impacts. 4) Without considering the undesirable output, the factor of GDP per laborer has a greater positive significant influ- ence on the water resources utilization efficiency. However the facts of industry value-added water consumption in ten thousand yuan and the transportation infrastructure have no sig- nificant influence. 5) Regardless of undesirable output of water resources utilization efficiency the assessment of the present real water resources utilization in China will be distorted and policy-making will be misled. The water efficiency measure considering environmental factors (such as gray water footprint) is more reasonable. 展开更多
关键词 water resources utilization efficiency SBM model undesirable output spatial effect spatial Durbineconometric model spillover effects
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Performance evaluation of a WDM/OCDM based hybrid optical switch utilizing efficient resource allocation
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作者 Ahmed Nabih Zaki Rashed Abd-Elnaser A. Mohammed Osama M.A. Dardeer 《Chinese Optics Letters》 SCIE EI CAS CSCD 2014年第5期5-10,共6页
A hybrid optical switch (HOS) with physical layer of wavelength division multiplexing and optical code division multiplexing (WDM/OCDM) scheme is proposed. An additional feature to the HOS than optical cross conne... A hybrid optical switch (HOS) with physical layer of wavelength division multiplexing and optical code division multiplexing (WDM/OCDM) scheme is proposed. An additional feature to the HOS than optical cross connect (OXC) is that the controller can process requests for both circuit establishment and burst scheduling. In our study, the measurement criteria of HOS are the blocking probability, probability of error, and probability of outage. To simplify the analysis, no distinction is made between a circuit in progress and a burst in progress. Moreover, a minimum fit (MinF) resource allocation strategy is applied in order to increase the bandwidth efficiency and control the multiplexing interference of the OCDM. A 2D Markov model for the HOS is presented using the MinF strategy. Numerical results reveal that the code parameters and the resource allocation strategy greatly affect the performance. Certain periority can be achieved by assigning shorter codes to high periority users and longer codes to low periority users. Also, the probability of error and outage are reduced bv aonling the MinF strategy. 展开更多
关键词 WDM Performance evaluation of a WDM/OCDM based hybrid optical switch utilizing efficient resource allocation
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Multi-radio access based bandwidth allocation strategy for video communication in heterogeneous wireless networks 被引量:3
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作者 Zhu Xuewen Zhu Qi 《The Journal of China Universities of Posts and Telecommunications》 EI CSCD 2016年第2期6-14,共9页
In order to make full use of the radio resource of heterogeneous wireless networks(HWNs) and promote the quality of service(Qo S) of multi-homing users for video communication, a bandwidth allocation algorithm bas... In order to make full use of the radio resource of heterogeneous wireless networks(HWNs) and promote the quality of service(Qo S) of multi-homing users for video communication, a bandwidth allocation algorithm based on multi-radio access is proposed in this paper. The proposed algorithm adopts an improved distributed common radio resource management(DCRRM) model which can reduce the signaling overhead sufficiently. This scheme can be divided into two phases. In the first phase, candidate network set of each user is obtained according to the received signal strength(RSS). And the simple additive weighted(SAW) method is employed to determine the active network set. In the second phase, the utility optimization problem is formulated by linear combining of the video communication satisfaction model, cost model and energy efficiency model. And finding the optimal bandwidth allocation scheme with Lagrange multiplier method and Karush-Kuhn-Tucker(KKT) conditions. Simulation results show that the proposed algorithm promotes the network load performances and guarantees that users obtain the best joint utility under current situation. 展开更多
关键词 video communication heterogeneous wireless networks joint utility energy efficiency radio resource management
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Software defined Internet of vehicles:architecture,challenges and solutions 被引量:1
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作者 CHEN Jiacheng ZHOU Haibo +3 位作者 ZHANG Ning YANG Peng GUI Lin SHEN Xuemin 《Journal of Communications and Information Networks》 2016年第1期14-26,共13页
IoV(Internet of Vehicles)is a promising paradigm to the future of automobiles,which will undoubtedly boost the automobile market as well as accelerate innovation in Internet services and applications.The concept of SD... IoV(Internet of Vehicles)is a promising paradigm to the future of automobiles,which will undoubtedly boost the automobile market as well as accelerate innovation in Internet services and applications.The concept of SD-IoV(Software Defined IoV)is presented,which is capable of improving resource utilization,service quality,and network optimization in the harsh vehicular network environments.First,A generalized SD-IoV architecture as an intuitive big picture is presented.Then,the major functions realized by SD-IoV are elabrated on to illustrate how the current challenges are resolved.As the key enablers of SD-IoV,three possible implementation methods of the wireless control path are described and compared.Finally,the challenges and existing solutions of SD-IoV are disuessed and open issues are pointed out so as to shed light on future research. 展开更多
关键词 software defined networking Internet of vehicles network architecture heterogeneous network resource utilization efficiency vehicle-to-infrastructure vehicle-to-vehicle
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