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Studies On Hydraulic Architecture And Characteristics Of Water Eco-physiology In Northern Urban Greening Tree Species

Posted on:2006-04-08Degree:MasterType:Thesis
Country:ChinaCandidate:J Q WangFull Text:PDF
GTID:2133360152488450Subject:Forest cultivation
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In order to study the characteristics of water eco-physiology in the urban greening tree species, establish the theories foundation of how to choose greening tree species in urban afforestation,8 tree species which were in common use were chosen as the research objects . the "flushing method" and pressure room were used in this paper. The diurnal courses of water potential and parameters of hydraulic architecture were studied at first, and 3 of these tree species were chosen to be use for the experiment of water stress followed. When the diurnal courses of water potential and parameters of hydraulic architecture of the 3 tree species were measured, Li-6400 was used to measure the diurnal courses of net photosynthetic rate and water use efficiency at the same time.Experiment 1 shew, the diurnal courses of water potential of 8 tree species appeared to be "single-peak" trend in different months, daily change ranges of hydraulic conductivity and special conductivity which reflected the vulnerability of xylem embolism showed Sophora japonica, Ligustrum lucidum, Salix matsudana, Cotinus coggria>Pinus tabulaefornis,Platycladus orientalis, Sabina vulgaris> Buxus microphylla; and, broadleaved tree species>conifer, ring-porous species> diffuse-porous species>none-porous species. The change ranges of leaf special conductivity of Sophora japonica and Cotinus coggria were not smaller obviously when their leaves fallen after October, and the strategy of plants was likely to be important to the water condition of the reserved leaves. The seasonal change rules of embolism in the 8 tree species were not obvious, and it had no negative relate with the diurnal courses of water condition.Experiment 2 shew, the ability of endure low water potential for the 3 tree species was Buxus microphylla> Ligustrum lucidum> Sophora japonica. the ability of endure low water potential for seedlings was elevated after drought exercise. After drought exercise, the change of parameters of hydraulic architecture shew: the ability of endure drought for Ligustrum lucidum and Sophora japonica was elevated. The water use efficiency waselevated also under normal water condition and light water stress, water use efficiency of Ligustrum lucidum and Sophora japonica was fall under severe water stress. Before deal with drought, the net photosynthetic rates of Buxus microphylla > Ligustrum lucidum and Sophora japonica were fall which was arouse by stoma when they were in light water stress, and the drop of net photosynthetic rates was due to none-stoma factors under severe water stress. After deal with drought, the drop of net photosynthetic rates for Ligustrum lucidum was due to the drop of leaf conductance and photosynthesis ability of mesophyllic cell when it fall across light water stress again. Sophora japonica and Ligustrum lucidum appeared photoinhibition at noon when they fall across severe water stress.
Keywords/Search Tags:hydraulic architecture, embolism, net photosynthetic rate, water use efficiency
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