Bi, Yufen

Ma, X. L.

Sun, T.

English

University of Kentucky

University of Kentucky UKnowledge International Grassland Congress Proceedings 21st International Grassland Congress / 8th International Rangeland Congress Analysis of Photosynthetic Characteristics of Heteropogon contortusin Arid‐Hot Valley Areas of Jinsha River Yufen Bi Yunnan Agricultural University, China X. L. Ma Yunnan Agricultural University, China T. Sun Yunnan Agricultural University, China Follow this and additional works at: https://uknowledge.uky.edu/igc  Part of the Plant Sciences Commons, and the Soil Science Commons This document is available at https://uknowledge.uky.edu/igc/21/1-4/20 The 21st International Grassland Congress / 8th International Rangeland Congress took place in Hohhot, China from June 29 through July 5, 2008. Proceedings edited by Organizing Committee of 2008 IGC/IRC Conference Published by Guangdong People's Publishing House This Event is brought to you for free and open access by the Plant and Soil Sciences at UKnowledge. It has been accepted for inclusion in International Grassland Congress Proceedings by an authorized administrator of UKnowledge. For more information, please contact UKnowledge@lsv.uky.edu. 　 Multifunctional Grasslands in a Changing World 　 Volume Ⅰ 　 瞯 ]169　 瞯Grasslands/Rangelands Resources and Ecology ——— Ecology of Grasslands/RangelandsAnalysis of photosynthetic characteristics of Heteropogon contortus in Arid‐hot Valley Areas ofJinsha RiverY .F .Bi , X .L .Ma , T . SunCollege o f A nimal Science , Y unnan A gricultural University , K unming 650201 , China . E‐mail : biyu f enynnd＠ sina .comKey words : Heteropogon contortus , photosynthetic characteristics , midday‐depress of photosynthesisIntroduction Heteropogon contortus , as a dominant species in Arid‐hot Valley Areas of Jinsha River , plays an important role forboth maintaining ecological environment of grassland and realizing the ecological function . The aim of studying thephotosynthetic characteristics in Heteropogon contortus摧 leaves under different circumstances is to figure out the difference ofphotosynthetic mechanism of Heteropogon contortus during various periods , and provide theoretic reference and technologicalreserve for ecological system restoration of Arid‐hot Valley Areas of Jinsha River ( Liu Yuhua et al . , ２００６) .Materials and methods The trial field lies in the breeding sheep stud on Renhe Town , Yongsheng County in northwestward ofYunnan Province , which is a kind of the typical Arid‐hot Valley Areas . The altitude is １５００m , and the annual averagetemperature is １８‐２２ ℃ . The extremes of high and low temperature are respectively ３８ .２ ℃ and １ .５ ℃ . The annual precipitationis about ９００mm . The exchange of dry and rainy season is obvious in Arid‐hot Valley Areas . The vegetation are mainlyHeteropogon contortus and Fimbristy lis dichotoma( linn .) Vahl ,Enum , mixed with Salix my rtillacea Anderss . Heteropogoncontortus was used in this study ,whose photosynthesis was tested by CI‐３１０ photosynthesis system in an open system .Netphotosynthetic rate ( Pn ) , transpiration rate ( T r ) , stomatal conductance ( Gs ) , intercellular CO２ concentration ( Ci ) , leaftemperature ( Tl) , WUE(Water use efficiency) and LUE( Light use efficiency) were tested in different methods ( Tao Hanzhi etal) .The medium size , normal and fully expanded leaves were selected for the experiments . The leaves were sampled withtriplicate , and the measurements were made ３‐５ times . Data were analyzed by using EXCEL and SAS ６ .１２ tools .Results In this study , the diurnal changes of Pn , T r and Gs exhibited two‐peaked curves with an obvious midday‐depress ofphotosynthesis . The changes of Pn and Gs were synchronous ( Figure １ ) . The determinations of those in rainy season werehigher than those in dry one , however , the difference were not significant ( p ＞ ０ .０５) . The diurnal changes of Ci were similar intwo seasons ( Figure １ ) . Figure ２ showed that the diurnal changes of WUE and LUE were expressed as two‐peaked and �U"curves , respectively .Figure 1 Diurnal changes o f Pn , T r , Gs , Ci o f Heteropogoncontortus .　 　 　Figure 2 Diurnal changes o f WUE and LUEof Heteropogon contortus .Conclusions In specific circumstances of the Arid‐hot Valley Areas , Heteropogon contortus can avoid water losing and alleviatethe damage to photosynthetic organs from high light intensity and drought stress by midday‐depress of photosynthesis ,maintaining the lower T r and enhancing WUE . Moreover , the higher values of LUE in the rainy season indicated the rainyseason was the important period for Heteropogon contortus摧s grow th and yield摧s accumulation .ReferencesLiu Yuhua et al . , (２００６ ) . Daily dynamics of photosynthesis in alfalfa varieties under dry farming conditions . A cta EcologicaSinica ２６ (５) :１４６８‐１４７５ .Tao Hanzhi et al . , (２０００ ) . Studies on distribution of leaf area ,transpiration rate and water use efficiency in oppositifoliousmaize . A cta A gromomica Sinica ２６(１) : ６５‐７０ .3-2.5-i= 1.5 1 -0.5-8:00 10:0012:00 14:00 16:00 18:00 Time '1)~', 8:00 10:00 12:00 14:00 16:00 18:00 Time C 12 10-8 -CL 6 -8:00 10:00 12:00 14:00 16:00 18:00 Time 400 -300 -0 0 200-0 100 ~ I I --+- DRY .......,._RAIN 8:00 10:00 12:00 14:00 16:00 18:00 Time 201 --DRY ;:~-~ w 8:00 10:00 12:00 14:00 16:00 18:00 Time 0.025 0.02 :::::::~::N :J 0.015 0.01 0.005 0 +---+---+~~--+---+----< 8:00 10:00 12:00 14:00 16:00 18:00 Time 

Analysis of Photosynthetic Characteristics of \u3cem\u3eHeteropogon contortusin\u3c/em\u3e Arid‐Hot Valley Areas of Jinsha River

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Analysis of Photosynthetic Characteristics of \u3cem\u3eHeteropogon contortusin\u3c/em\u3e Arid‐Hot Valley Areas of Jinsha River

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