Dissertation > Biological Sciences > Botany > Plant Physiology

Study on Photosynthetic, Water Consumption Characteristics and Drought Resistance of Sevarel Shrubs in Kubuqi Desert

Author WangXiaoJiang
Tutor HeKangNing
School Beijing Forestry University
Course Eco - environmental engineering
Keywords Drought tolerance Tree transpiration Net photosynthetic rate Water use efficiency Water potential SPAC system Desert shrubs
CLC Q945
Type PhD thesis
Year 2008
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In order to provide reliable proof for the selections of plants in the course of vegetation recovering,a series of studies on Water Consumption Characteristics,water potential and Photosynthetic Characteristics of Atriplex canescens,Caragana microphylla,Hedysarum laeve, Tamarix chinensis,Buddleja alternifolia and Caryopteris mongolica were done in Kubuqi desert.The focused aspects are as following:1.Analysis of the climate character of the research area2.Study on the diurnal courses and mechanism of net photosynthetic and transpiration rate of six plants in different soil water content.3.Study on the responses of Photosynthesis and Transpiration of six plants in different soil moisture to light.4.Study on the influence of environmental factors on the diurnal courses of leaf water potential of six plants;5.The changes of water potential grades in the system of Soil-Plant-Atmosphere Continuum6.Responses of free proline and soluble sugar of six plants to the water pressure7.Responses of superoxide dismutase and catalase of six plants to the water pressure8.Responses of malondialdehyde of six plants to the water pressure9.Study on drought resistance mechanism of the potted plants,10.A comprehensive evaluation of drought resistance of the potted plants.Major conclusions are as following:1.The order of water Consumption of six shrubs in annual growing stage is 113.831mm、134.48mm、129.75mm、108.7mm、103.54mm and 141.88mm;2.Through the study on the relationship between growing and photosynthesis characteristics under different soil water content and light intensity,the light saturation point is differently:1611.00, 1479.33,1476.67,1430.00,1391.00,1287.33μmol·s-1-m-2,and the light compensate point differently is:4.3%,4.4%,4.54%,4.46%,4.55%,3.89%.3.According to the change of leaf water potential in early morning,water recovery of Hedysarum mongolicum Turcz is the best.And it shows that some water wane in Acriplex canescens(Purgh.)Butt and Caragana microphylla.There has relationship between the degree of water wane and water recover. 4.The change of leaf water potential is the result of the rate of transpiration and water supply of roots,and some meteorologic factors can effect leaf water potential through effect transpiration.5.Main energy is consumed in the link of leaf and atmosphere in the system of SPAC,and secondly in the link of soil and root.Energy is consumed in the link of stem and leaf similarly.The difference of water potential takes a trend of falling follow increasing.The highest difference of leaf water potential and atmosphere water potential is in June and the lowest is in August.The highest difference of soil water potential and root water potential is in July and the lowest is in September.6.The result of daily course of transpiration in July shows that Atriplex canescensButt has normal transpiration,which indicates that it has better water condition,and that water supply is not ample in Caragana microphylla and Hedysarum laeve,so the water supply of Hedysarum laeve is worse.7.Tt has little difference in the daily change of Transpriation and Photosynthesis of potted plants under different soil water content.Tr takes a trend of falling follow increasing with the development of drough.At the same time,Pn of Atriplex canescens increase continually,whereas Hedysarum laeve falls continually,and Caragana microphylla and Tamarix ramosissma take a trend of falling follow increasing.The light responses of potted plants lower continually with the development of water drough.8 The Soil water content is 0.578%of Atriplex canescens,0.711%of Caragana microphylla, 0.687%of Hedysarum laeve,2.11%of Caryopteris mongolicaoT,1.09%of Tamarix ramosissma Ledeb,1.22%of Caryopteris mongolica Bunge differently when potted plants withered.The efficiency of water using of potted plants are all above 90%.The capability of plants resisting drough is sized up according soil water depleted index as following:Acriplex canescens(Purgh.)Butt>Caragana microphylla > Hedysarum laeve > Caryopteris mongolica > Caryopteris mongolicaor > Tamarix ramosissma.9.The resisting drough Mechanism of potted plants based on the relatationship between leaf water potential and soil water content is summed up as Caragana microphylla,Hedysarum laeve and Caryopteris mongolica belong to the plant that have high water potential to delaying dehydration; Atriplex canescens and Caryopteris mongolica belong to the plant that have sub-high water potential to delaying dehydration;Tamarix ramosissma belongs to the plant that has sub-low water potential to resisting dehydration.10.12 indexes of six trees were contrasted and compared by the way of subordination function of vague mathematics.The transpiration rate.,the drought-resistant abilities of the six trees species were listed in descending order as following:Hedysarum laeve >Atripldex canescens >Tamarix chinensis>Caryopteris mongolica >Caragana microphylla >Buddleja alternifolia.

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