The ecophysiological traits of three karst rockey desert restoration species
HE Cheng-Xin1,HUANG Yu-Qing 1,2,LI Xian-Kun1,WANG Xiao-Ying1,WANG Qing 1,3(1.Guangxi Institute of Botany,Guangxi Zhuangzu Autonomous Region and the Chinese Academy of Sciences,Guilin 541006,China;2.South China Botanical Garden,The Chinese Academy of Sciences,Guangzhou 510650,China;3.College of Life Sciences,Guangxi Normal University,Guilin 541004,China)
The light curve and diurnal patterns of gas exchange were measured for 3 plant species(Zenia insignis,Lonicera japonica and Cratoxylum prunifolium)grown under dryland karst rocky desert conditions in Guangxi.Our objective was to characterize some of the physiological traits of these species to gain more insight into its ecophysiological characteristics,which may in turn contribute to the improvement of management practices in ecological restoration.Maximum photosynthetic rates,obtained by light curve in the morning,peaked at 15.88 μmol·m-2·s-1 of Z.insignis and 4.58 μmol·m-2·s-1 of C.prunifolium,suggesting that Z.insignis is better adaptation to rocky desert condition than C.prunifolium does.A marked decrease in photosynthesis was observed during midday together with a reduction in stomatal conductance and transpiration rate.It is significant correlated between Pn and gs of three species;the relationship between Ls and Ci showed that the decline in photosynthesis of Z.insignis and L.japonica were mainly the result of stomatal limitations before 14∶00 but nonstomatal limitation in the afternoon,while that of C.prunifolium was mainly the result of nonstomatal limitation.These limitations on photosynthetic activity are likely induced by intensive solar radiation and high temperature,and enhanced by the increasing vapor pressure deficit.Stomata of Z.insignis and L.japonica were open with a decreasing rate toward midday.However,the openness of stomata of C.prunifolium remained very small and slightly decrease toward 14∶20 and throughout the brief adverse conditions of midday.Z.insigni processed highest water use efficiency(WUE),followed by L.japonica and C.prunifolium.With the result,we suggest that in karst rocky desert area,drought and high temperature are two main stress factors to affect plant photosynthesis,transpiration and WUE.Plant with a deep and developed root system,e.g.Z.insignis and L.japonica,was probably to uptake water from deep karst volume to allow transpiration so as to protect the photosynthetic apparatus and meanwhile to maintain high photosynthesis during midday,thereby to enhance the WUE.But plant like young C.prunifolium with a shallow root distribution,is easily suffered by drought that unsufficient water for transpiration may increase the leaf temperature therefore damage the photosynthetic apparatus.The result suggests that a root trait of capacity of plunge into rock gap would be a key feature for plant to survive in rocky desert terrain while plants are introduced for vegetation restoration.
【Fund】： 广西科技攻关项目(桂科攻0322021);; 中科院西部之光人才培养项目(2005);; 广西自然科学基金(桂科回0575009)~~
【CateGory Index】： Q945.79
【CateGory Index】： Q945.79