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Estimation of tree transpiration and response of tree conductance to meteorological variables in desert-oasis system of Northwest China

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Science China Earth Sciences 2004年第Z1期47卷 9-20页

作者： CHEN Rensheng KANG Ersi ZHANG Zhihui ZHAO Wenzhi SONG Kechao ZHANG Jishi LAN Yongchao Cold and Arid Regions Environmental and Engineering Research Institute Chinese Academy of Sciences Lanzhou 730000 China Cold and Arid Regions Environmental and Engineering Research Institute Chinese Academy of Sciences Lanzhou 730000 China Cold and Arid Regions Environmental and Engineering Research Institute Chinese Academy of Sciences Lanzhou 730000 China Cold and Arid Regions Environmental and Engineering Research Institute Chinese Academy of Sciences Lanzhou 730000 China Cold and Arid Regions Environmental and Engineering Research Institute Chinese Academy of Sciences Lanzhou 730000 China Cold and Arid Regions Environmental and Engineering Research Institute Chinese Academy of Sciences Lanzhou 730000 China Cold and Arid Regions Environmental and Engineering Research Institute Chinese Academy of Sciences Lanzhou 730000 China

Transpirations of three dominated tree species, namely Mongol Scotch Pine (Pinus sylvestris var. mongolica Litvin), White elm (Ulmus pumila) and Gansu Poplar (Populus gansuensis Wang et Yang) in oasis shelter forest (Linze site) and of two dominated tree species,namely Euphrates Poplar (Populus euphratica Oliv.) and Russia olive (Elaeagnus angustifolia Linn.) in lowland desert (Erjinaqi site) have been estimated using measured sapflow in summer,autumn and winter, 2002 and in spring, 2003. An ENVIS System was used for each site to measure microclimate variables, soil moisture and sapflow every half an hour, and the study time scale is one day. In the 104 days of observation during the growing season at the Linze site, the average daily sapflow of Gansu Poplar is 9.93L·d-1,and the average transpiration per unit leaf area is 1.99mm·*** White elm tree,the daily average sapflow is 4.08L·d-1,while the daily average transpiration per unit leaf area is 0.49mm·*** values for Mongol Scotch Pine are 3.91L·d-1 and 0.25mm·d-1,*** the total 73 days of observation during the growing season at the Erjinaqi site, the daily average sapflows of Russia olive and Euphrates Poplar are 12.1 and 20.97L·d-1,respectively,and the average transpirations per unit leaf area are 0.22 amd 0.31mm·d-1,*** the observation period of the growing season,tree conductances of Mongol Scotch Pine, White elm, Gansu Poplar or Russia olive show an exponential relationship with the daily average air temperature or vapour pressure deficit, but the relationship is not so obvious between tree conductance and global radiation. The transpiration process of each tree species is affected by all the observed four environmental variables. The response of tree conductance to different climatic factors changes with tree species. The effect of the same factor to the same tree species is also variable in different growing stages. The sapflow of every tree species is relatively large in later

关键词： sapflow, tree conductance, leaf area transpiration, soil water content, climatic variable.

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Simulation of CO_2 and latent heat fluxes in the North China Plain

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Science China Earth Sciences 2005年第Z1期48卷 172-181页

作者： ZHANG Yongqiang YU Qiang LIU Changming WANG Jing Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences Beijing 100101 China National Institute for Environmental Studies Onogawa 16-2 Tsukuba 305-8506 Japan Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences Beijing 100101 China Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences Beijing 100101 China Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences Beijing 100101 China

We constructed a coupled model for simulating plant photosynthesis and evapotranspiration (CPCEM). In the model, non-rectangular hyperbola is used to simulate leaf photosynthesis rate that is scaled up to estimate canopy gross photosynthesis rate by an integral method. Whole canopy in the model is separated into multi-layers, each of which is divided into sunlit leaves and shade leaves. Canopy net photosynthesis rate is expressed as a function of canopy conductance which is coupled with evapotranspiration. Included the coupled function,evapotranspiration is estimated with a two-layer submodel. The main features of CPCEM are: (1)easy suitability, (2) good physiological base, and (3) simple calculation procedure. Simulated results of CPCEM were compared with those by an eddy covariance system that was installed in a winter wheat farmland of the North China Plain. CPCEM gave a quite well diurnal and seasonal dynamics of net ecosystem exchange, compared with the measurements. The root mean square error between simulation and measurements was only about 2.94 μ mol m-2 s-1. Diurnal and seasonal patterns of latent heat flux with the CPCEM were similar to those of ***, simulated latent heat flux was evidently higher than the measured.

关键词： photosynthesis, canopy conductance, evapotranspiration, coupled model.

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Stomatal movement in response to long distance-communicated signals initiated by heat shock in partial roots of Commelina communis L.

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Science China(Life Sciences) 2006年第1期49卷 18-25页

作者： YANG Songjie1, HUANG Conglin2, WU Zhongyi2, HU Jianfang3, LI Tianzhong3, LIU Shigui1 & JIA Wensuo3 1. School of Life Science, Sichuan University, Chengdu 610064, China 2. Beijing Agriculture and Forestry Academy, Beijing Agriculture and Biotechnology Center, Beijing 10089, China . 3. State Key Laboratory of Plant Physiology and Biochemistry, College of Agronomy and Biotechnology, China Agricultural University, Beijing 100094, China School of Life Science Sichuan University Chengdu 610064 China Beijing Agriculture and Forestry Academy Beijing Agriculture and Biotechnology Center Beijing 10089 China State Key Laboratory of Plant Physiology and Biochemistry College of Agronomy and Biotechnology China Agricultural University Beijing 100094 China

The systematic or long-distance signal transmission plays crucial roles in animal lives. Compared with animals, however, much less is known about the roles of long-distance signal com-munication in plant lives. Using the model plant Commelina communis L., we have probed the root to shoot communication mediated by heat-shock signals. The results showed that a heat shock of 5 min at 40℃ in partial roots, i.e. half or even 1/4 root system, could lead to a significant decrease in stomatal conductance. The regulation capability depends on both heat shock temperature and the amount of root system, i.e. with higher temperature and more roots stressed, the leaf conductance would decrease more significantly. Interestingly, the stomatal regulation by heat shock signal is in a manner of oscillation: when stomata conductance decreased to the lowest level within about 30 min, it would increase rapidly and sometimes even exceed the initial level, and after several cycles the sto-mata conductance would be finally stabilized at a lower level. Feeding xylem sap collected from heat-shocked plants could lead to a decrease in stomata conductance, suggesting that the heat shock-initiated signal is basically a positive signal. Further studies showed that heat shock was not able to affect ABA content in xylem sap, and also, not able to lead to a decrease in leaf water status, which suggested that the stomatal regulation was neither mediated by ABA nor by a hydraulic signal. Heat shock could lead to an increase in xylem sap H2O2 content, and moreover, the removal of H2O2 by catalase could partially recover the stomatal inhibition by xylem sap collected from heat-shocked plants, suggesting that H2O2 might be able to act as one of the root signals to control the stomatal movement. Due to the fact that heat-shock and drought are usually two concomitant stresses, the stomatal regulation by heat-shock signal should be of significance for plant response to stresses. The observation for the stoma

关键词： root signal, leaf conductance, heat shock, long-distance, signal transmission, abscisic acid.

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Photosynthesis-transpiration coupling model at canopy scale in terrestrial ecosystem

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Science China Earth Sciences 2005年第Z1期48卷 160-171页

作者： REN Chuanyou, YU Guirui, WANG Qiufeng & GUAN Dexin Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China Shenyang Agricultural University, Shenyang 110161, China Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016, China Graduate School of the Chinese Academy of Sciences, Beijing 100039, China Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences Beijing 100101 China Shenyang Agricultural University Shenyang 110161 China Graduate School of the Chinese Academy of Sciences Beijing 100039 China Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences Beijing 100101 China Institute of Geographic Sciences and Natural Resources Research Chinese Academy of Sciences Beijing 100101 China Graduate School of the Chinese Academy of Sciences Beijing 100039 China Institute of Applied Ecology Chinese Academy of Sciences Shenyang 110016 China

At the hypothesis of big leaf, an ecosystem photosynthesis-transpiration coupling cycle model was established by the scaled SMPT-SB model from single leaf to canopy, and model parameterization methods were discussed. Through simulating the canopy light distribution, canopy internal conductance to CO2 can be scaled from single leaf to canopy by integrating to canopy using the relationship between single internal conductance and photosynthetic photon flux density. Using the data observed by eddy covariance method from the Changbai Mountains site of ChinaFLUX, the application of the model at the canopy scale was examined. Under no water stress, the simulated net ecosystem photosynthesis rate fitted with the observed data very well, the slope and R2 of the line regression equation of the observed and simulated values were 0.7977 and 0.8892, respectively (n = 752), and average absolute error was 3.78 μmol CO2 m-2s-1; the slope, R2 and average absolute error of transpiration rate were 0.7314, 0.4355 and 1.60mmol H2O m-2 s-1, respectively (n = 752). The relationship between canopy photosynthesis,transpiration and external environmental conditions was discussed by treating the canopy as a whole and neglecting the comprehensive feedback mechanism within canopy, and it was noted that the precipitation course affected the transpiration rate simulation badly. Compared to the models based on eco-physiological processes, the SMPT-SB model was simple and easy to be used. And it can be used as a basic carbon and water coupling model of soil-plant-atmosphere continuum.

关键词： photosynthesis rate, transpiration rate, SMPT-SB model, internal conductance, canopy scale.

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Physiological characteristics of the primitive CO_(2) concentrating mechanism in PEPC transgenic rice

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Science China(Life Sciences) 2003年第4期46卷 438-446页

作者：焦德茂匡廷云李霞戈巧英黄雪清郝乃斌白克智 Institute of Agrobiological Geneticsand Physiology Jiangsu Academyof Agriculturalsciences Institute of Botany Chinese Academy of Sciences

The relationship between carbon assimilation and high-level expression of the maize PEPC in PEPC transgenic rice was studied by comparison to that in the untransformed rice, japonica kitaake. Stomatal conductance and photosynthetic rates in PEPC transgenic rice were higher than those of untransformed rice, but the increase of stomatal conductance had no statistical correlation with that of photosynthetic rate. Under high levels of light intensity, the protein contents of PEPC and CA were increased significantly. Therefore the photosynthetic capacity was increased greatly (50%) with atmospheric CO2 supply. While CO2 release in leaf was reduced and the compensation point was lowered correspondingly under CO2 free conditions. Treatment of the rice with the PEPC-specific inhibitor DCDP showed that overexpression of PEPC and enhancement of carbon assimilation were related to the stability of Fv/Fm. Labeling with 14CO2 for 20 s showed more 14C was distributed to C4 primary photosynthate asperate in PEPC transgenic rice, suggesting that there exists a limiting C4 photosynthetic mechanism in leaves. These results suggest that the primitive CO2 concentrating mechanism found in rice could be reproduced through metabolic engineering, and shed light on the physiological basis for transgenic breeding with high photosynthetic efficiency.

关键词： PEPC transgenic rice, phosphoenopyruvate carboxylase (PEPC), carbonic anhydrase (CA), stomatal conductance, CO2 concentrating mechanism.

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Electrical Resistance as A Measure of Soft Tissue Injuryfrom Delayed Onset Muscle Soreness

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Journal of Health Science 2014年第8期2卷 353-362页

作者： Timothy Hui Jerrold Petrofsky Iman Akef Khowailed Research Department of Physical Therapy Loma Linda University Loma Linda California 92350 United States

Assessment of muscle damage relies commonly on subjective sensation of pain. The purpose of this research was to test thevalidity of microcurrent conductance on skin over injured tissue to quantify soft tissue injury and recovery following heavy exercisecompared to other indexes of muscle soreness. A randomized, controlled, single-blinded, 1-week trial on 60 ***-University Interventions： Subjects did 3 sets of squats for 5 min each. There were 3 groups of 20 subjects. One did nothing andone had heat applied for 8 h post exercise. The final group had heat 24 h after exercise. Tissue resistance and muscle strength force tomove the knee, analog visual pain scale. In the control group, microcurrent continually decreased, eventually decreasing 32% by thethird day post exercise. When heat was given immediately following exercise, microcurrent was 26% greater （P 〈 0.001）. The painscale rose to 3.1/10 as opposed to 5.4/10 for controls. Strength and muscle elasticity stayed mostly constant after heat as opposed to a28% decrease in strength and increase in stiffness in the control subjects. For 24 h delayed heat, microcurrent was 14% greater（P 〈 0.02）, and was unchanged for the first 24 h when no therapy was given. Pain scale rose to 4.8/10. Stiffness was unchanged whilemuscle strength decreased the same as controls. Microcurrent shows agreement with loss of strength, and stiffness from DOMS but notthe subjective pain measure. It appears that microcurrent is a good measure of muscle damage.

关键词： Microcurrent conductance, soft tissue injury, recovery.

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