Jingxin Xu

Nanjing University of Information Science and Technology

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Youfei Zheng

Nanjing University of Information Science and Technology

Mai Boru

China Meteorological Administration

Hanqing Kang

Xi'an University of Architecture and Technology

Hui Zhao

Fudan University

Jinhui Gao

Chengdu University of Information Technology

Xiuyong Zhao

China Energy Science and Technology Research Institute Co., Ltd. (China)

Rongjun Wu

Nanjing University of Information Science and Technology

Zhong-Fang Chu

Nanjing University of Information Science and Technology

Sheng Wang

Wuhan University

Xi Zhang

University of California, Santa Cruz

Cooperative Institutions

Nanjing University of Information Science and Technology

China Meteorological Administration

Chinese Academy of Sciences

Nanjing University

China Energy Science and Technology Research Institute Co., Ltd. (China)

Jinan University

Wuhan University

Zhejiang University

Tongji University

Ministry of Agriculture and Rural Affairs

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Effects of Reduced Solar Irradiance on Photosynthesis Characteristics and Membrane Lipid Peroxidation of Winter Wheat in Grain Filling Stage

The Research of Environmental Sciences (2011)

Jingxin Xu

The impacts of reduced solar irradiance on photosynthesis and the physiological characteristics,protective enzyme system and the membrane lipid peroxidation of winter wheat(Cultivars: Yangmai 13) in the grain filling stage were investigated by field experiments.Natural radiation(CK) as well as 60%,40%,20% and 15% of natural radiation were set as the five different treatments.The results showed that: 1) The reduced solar irradiance caused a reduced net photosynthetic rate(Pn),remarkably reduced stomatal conductance limitation(Ls) and transpiration rate(Tr),and slightly increased intercellular CO2 concentration(Ci).This signified that reduced solar irradiance significantly affects the photosynthetic physiological characteristics of winter wheat leaves.2) The activities of catalase(CAT),superoxide dismutase(SOD) and peroxidase(POD) in winter wheat leaves all increased significantly along with the decreased solar irradiance,presenting higher resistance.In contrast,malondialdehyde(MDA) contents and relative electrical conductivity decreased,indicating that the membrane system was not injured by the reduced radiation.3) Reduced solar radiation caused higher levels of photosynthetic pigment in winter wheat,but the ratio values of Chlorophyll a and Chlorophyll b decreased,indicating enhancement of the radiation absorption ability of biasing part short-wave band of solar irradiance.In conclusion,winter wheat in the grain filling stage can avoid membrane lipid peroxidation damage of the cell membrane system through improving protective enzyme system activity,and enhance the capacity of using light energy by increasing the content of Cholophyll b under reduced solar irradiance conditions.Nonetheless,solar irradiance deficiency still made the crops' net photosynthetic rate continuously decline,mainly resulting from non-stomatal factors.

Malondialdehyde

Photoinhibition

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Impacts of relative humidity on fine aerosol properties via environmental wind tunnel experiments

Atmospheric Environment (2019)

Jingxin Xu Fahua Zhu Sheng Wang Xiuyong Zhao Ming Zhang

Mass concentration (chemistry)

Inorganic ions

Particle (ecology)

10.1016/j.atmosenv.2019.03.002

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Citations (13)

[Simulated Ozone Damage on Gross Primary Productivity (GPP) in a Winter Wheat Field].

PubMed (2019)

Jingxin Xu Youfei Zheng Sheng Wang Liwen Wang Xiuyong Zhao

An eddy-covariance system combined with a semi-mechanistic model was used to analyze variations in gross primary productivity (GPP) and to simulate the impact of ozone (O3) on GPP under different levels O3 concentrations over a winter wheat field in Nanjing. The results showed that GPP was higher during the middle of the growth period and low during the early and late growth periods, reaching a maximum of 40 μmol·(m2·s)-1. Using high and low ozone sensitivity settings,O3-damage in 150, 100, 50 nL·L-1 and control treatment (CK) reduced GPP by -72%, -36%, -6%, and -10%, and by -13%, -6%, -1%, and -2%, respectively. These results provide a scientific basis for formulating defense strategies for O3 damage to crops.

Winter wheat

Primary productivity

10.13227/j.hjkx.201903038

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[Effects of reduced solar radiation on winter wheat flag leaf net photosynthetic rate].

PubMed (2011)

Youfei Zheng Yanli Ni B. Mai Rongjun Wu Feng Yan

Taking winter wheat Triticum aestivum L. (cv. Yangmai 13) as test material, a field experiment was conducted in Nanjing City to study the effects of simulated reduced solar radiation on the diurnal variation of winter wheat flag leaf photosynthetic rate and the main affecting factors. Five treatments were installed, i. e., 15% (T15), 20% (T20) , 40% (T40), 60% (T60), and 100% (CK) of total incident solar radiation. Reduced solar irradiance increased the chlorophyll and lutein contents significantly, but decreased the net photosynthetic rate (Pn). Under different solar irradiance, the diurnal variation of Pn had greater difference, and the daily maximum Pn was in the order of CK > T60 > T40 > T 20 > T15. In CK, the Pn exhibited a double peak diurnal curve; while in the other four treatments, the Pn showed a single peak curve, and the peak was lagged behind that of CK. Correlation analysis showed that reduced solar irradiance was the main factor affecting the diurnal variation of Pn, but the physiological parameters also played important roles in determining the diurnal variation of Pn. In treatments T60 and T40, the photosynthesis active radiation (PAR), leaf temperature (T1) , stomatal conductance (Gs) , and transpiration rate (Tr) were significantly positively correlated with Pn, suggesting their positive effects on Pn. The intercellular CO2 concentration (Ci) and stomatal limitation (Ls) had significant negative correlations with Pn in treatments T60 and T40 but significant positive correlations with Pn in treatments T20 and T15, implying that the Ci and Ls had negative (or positive) effects on Pn when the solar irradiance was higher (or lower) than 40% of incident solar irradiance.

Stomatal Conductance

Diurnal temperature variation

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Evaluations on numerical simulations of ozone dry deposition over the Yangtze River Delta

Zenodo (CERN European Organization for Nuclear Research) (2023)

Jingxin Xu Sheng Wang Mai Boru Youfei Zheng Shuang Qiu

Regional simulation of ozone dry deposition is an important tool for understanding ozone pollution threats and quantifying the ozone impact on terrestrial ecosystems. In this study, we evaluate ozone dry deposition in the Yangtze River Delta (YRD) region using two different dry deposition schemes. The WRF-Chem model, Wesely dry deposition scheme, and revised Surfatm dry deposition scheme were used to simulate the ozone dry deposition process in the YRD region, and results are compared with the observation over a winter wheat field. The results show that the simulated ozone concentrations (c_O3) of the two dry deposition schemes were good and lower than the measurements. The simulated ozone dry deposition velocity (V_d) in the Surfatm dry deposition scheme was more close to the measurements. The mean value of c_O3and V_d in the YRD region ranged from 30 to 50 nL·L⁻¹ and from 0.2 to 0.5 cm·s⁻¹in the daytime, respectively. To improve the simulation results of the ozone dry deposition process, the simulation errors due to different land use types, the meteorological factors on dry deposition resistance functions, and the influence of chemical reactions must all be considered.

Yangtze river

Deposition

10.5281/zenodo.7525285

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The analysis and validation of LAMBDA method in GPS kinematics positioning

Engineering of Surveying and Mapping (2009)

Jingxin Xu

The key technology of the GPS kinematic positioning is the Ambiguity Resolution on the Fly(AROF) using the carrier phase measurement.So the instance and reliability are the concentration and difficulty in the study of the AROF all the time.The LAMBDA theory and method is analyzed,and is certified with the experiment data.The result indicates that the LAMBDA is indeed an efficient,precise and reliable solution in kinematics with the better value of practicability.

Ambiguity Resolution

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Value of dynamic contrast-enhanced magnetic resonance imaging combined magnetic resonance spectroscopy in the early diagnosis of breast cancer

Hainan yixue (2013)

Jingxin Xu

Objective To discuss the value of dynamic contrast-enhanced magnetic resonance imaging (MRI) combined magnetic resonance spectroscopy (MRS) in the the early diagnosis of breast cancer. Methods Seventy-three female patients were successively performed with MR plain scan, dynamic contrast-enhanced MRI and 1 H-MRS imaging. The benign and malignancy lesions time, TIC curve types, and diagnosis sensitivity, specificity and accuracy of combined diagnosis were observed. Results The inflow type curve and outflow type curve were 56.76% and 10.81% in the benign group, significantly different from those in the malignant group (11.11%, 58.33%), P0.05. The sensitivity, specificity and accuracy of combined diagnosis were 89.04%, 97.26% and 94.53%, respectively, significantly higher than MR plain scan (47.95%, 58.91%, 49.32%), P0.05. Conclusion Combination of dynamic contrast-enhanced MRI and magnetic resonance spectroscopy has pretty good clinical application value in the early diagnosis of breast cancer.

Dynamic contrast

Dynamic Contrast-Enhanced MRI

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Combination effects of reduced radiation and enhanced O3 stress on chlorophyll fluorescence characteristics and yield of soybean.

Nanfang nongye xuebao (2013)

Youfei Zheng Gu KangLe Rongjun Wu Jingxin Xu Minghua Shi

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Evaluations on numerical simulations of ozone dry deposition over the Yangtze River Delta1

Atmospheric Environment (2023)

Jingxin Xu Sheng Wang Borui Mai Youfei Zheng Shuang Qiu

Deposition

10.1016/j.atmosenv.2023.119760

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Citations (1)

[Long Term Variations of Ozone Concentration of in a Winter Wheat Field and Its Loss Estimate Based on Dry Matter and Yield].

PubMed (2017)

Hui Zhao Youfei Zheng Shuo Li Jingxin Xu Jiachen Cao

Surface ozone pollution and its negative effects on crops and food safety have attracted the attention of many people. In this study, ozone concentration and meteorological parameters in a winter wheat field were measured from 2014 to 2016. We analyzed the variations in ozone concentration and AOT40 during the growing season for winter wheat. According to the revised stomatal model, the leaf stomatal conductance of winter wheat was simulated and verified by comparing with measured results. Based on the flux model, the leaf stomatal fluxes of winter wheat were calculated. In addition, we estimated the effects of ozone concentration on winter wheat dry matter and yield by using exposure-response relationships and flux-response relationships. The results suggested that the concentration of ozone gradually increased during the growing season for winter wheat and showed a distinct unimodal pattern of diurnal variation. The mean concentrations of ozone were 36.2, 37.7, and 33.6 nL·L-1, respectively, and the ozone AOT40 values were 17.08, 17.90, and 11.84 μL·(L·h)-1, respectively, during the growing seasons for winter wheat from 2014 to 2016. The Jarvis-type factorial model of stomatal conductance could be used to simulate the stomatal conductance of winter wheat in the region, and approximately 81% of the variation of measured stomatal conductance could be accounted for by the model. The leaf stomatal ozone fluxes of winter wheat were 9.36, 9.32, and 8.65 mmol·m-2, respectively, from 2014 to 2016. Winter wheat yield decreased about 18.03%, and its dry matter decreased about 19.31% under ozone stress during these three years.

Stomatal Conductance

Winter wheat

Growing season

10.13227/j.hjkx.201704117

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Citations (3)