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题名	塔里木河下游干旱环境下胡杨的生理适应性机理研究
作者	陈亚鹏
学位类别	博士
答辩日期	2007
授予单位	中国科学院．新疆生态与地理研究所
导师	陈亚宁，中科院新疆生态与地理研究所
关键词	塔里木河下游
其他题名	The study on physiological adaptability mechanics of populus euphratica to drought in the lower reaches of Tarim River
中文摘要	塔里木河下游随着河道断流，地下水位大幅度下降，以胡杨林为主体的荒漠植被全面衰败，所以保护和恢复胡杨为主的天然植被已成为一项刻不容缓的任务。本文结合塔里木河下游实施的生态输水工程，以塔里木河下游地下水埋深变化及胡杨生理响应为核心，采取地下水埋深变化监测、植物抗旱生理指标、光合作用参数的测试和植被样地调查对对比相结合的方法，运用植物生理生态学理论和数理统计方法，对塔里木河下游地下水变化对胡杨生理代谢及光合作用的响应进行了初步研究，分析了不同地下水埋深下胡杨生理和光合作用的响应特点及原因，阐述了胡杨的干旱适应性机理，并揭示了不同地下水埋深条件下胡杨遭受干旱胁迫的程度结果如下：（1）地下水埋深与胡杨脯氨酸、ABA、MDA、POD、SOD、可溶性糖和叶绿素等生理生化指标间存在密切相关关系，地下水埋深的变化直接导致胡杨生理上的明显变化，可确定地下水是影响胡杨生长的主导环境因子。（2）从胡杨各生理指标随着地下水埋深的增加、干旱程度的加剧而变化的原因来看，胡杨丙二醛和叶绿素的增加和减少是胡杨遭受环境胁迫所受伤害的表现，这两个指标可作为胡杨是否遭受干旱胁迫和受伤害程度多少的直接指示因子；而胡杨脯氨酸、脱落酸、可溶性糖和SOD随地下水埋深的增加而增加则是对干旱环境变化做出的主动适应的措施，可将其作为胡杨抗旱性的指标。（3）随着地下水埋深的变化，胡杨的光合速率、气孔导度、水分利用效率发生明显变化：当地下水埋深大于4m时，胡杨的光合速率便开始明显的下降，但是随着地下水埋深的增加到在4.2-6.8m这一范围内时，胡杨光合速率对地下水埋深变化不敏感，并且胡杨在地下水埋深较深的环境下（胡杨遭受中度干旱胁迫时），有很强的气孔调节作用以避免过多的水分损失；胡杨的水分利用效率在不同的地下水埋深范围内其变化特征也有所不同，起初随着地下水埋深的增加，胡杨的水分利用效率不断减小，但是当地下水埋深继续增加到6.8m时，胡杨叶片的内在水分利用效率会因此而增加。（4）在不同的地下水埋深下，胡杨遭受干旱胁迫的状态不同，使得限制胡杨光合作用的主要因素也不同。在轻度和中度干旱胁迫下，限制胡杨光合作用的主要因子分别是气孔关闭和非气孔因素。并且当干旱胁迫从轻度过渡到中度胁迫状态时，胡杨可以维持其光合速率，而渗透调节作用很可能是胡杨遭受中度干旱胁迫时维持其光合速率的一种重要方式。（5）在不同地下水埋深环境下，高温不仅抑制了胡杨的光合速率，还加大了气孔关闭的程度，并且随着地下水埋深的增加，高温使得胡杨光合速率和气孔导度的下降幅度增加，表明高温加强了干旱胁迫对胡杨光合作用的负面效应。胡杨叶片的光合速率、气孔导度和瞬间水分利用效率对CO2浓度增加的响应与胡杨生长所处地下水埋深条件存在密切关系。地下水埋深最终控制着干旱荒漠区胡杨气体交换对CO2浓度升高的响应。（6）地下水埋深的增加会降低植物利用地下水的有效性，进而增加胡杨遭受干旱胁迫的可能性或是加剧胡杨遭受干旱胁迫的程度。所以地下水埋深对胡杨光合作用的影响，本质上是地下水埋深变化引起胡杨遭受干旱胁迫程度发生变化，进而影响胡杨的光合作用过程。（7）胡杨生理生化代谢和光合作用对地下水埋深的响应共同反映了塔里木河下游不同地下水埋深范围内胡杨生长时所处的干旱胁迫状态：在地下水埋深小于4m时，胡杨未遭受到干旱胁迫，所以胡杨的合理的地下水埋深是4m；而在4-5.8m，胡杨遭受着轻度干旱胁迫；而5.8-8m，胡杨遭受着中度干旱胁迫，8-9m，胡杨遭受重度干旱胁迫，当地下水埋深大于9m时，胡杨将面临着死亡的威胁，所以胡杨死亡的临界地下水埋深为9m。With the watercourse cut-off in the lower reaches of Tarim River, groundwater depth descends greatly and desert vegetation with Populus euphratica as main-body ruins, which shows that it is an imperative task to protect and restore natural vegetation. Combined with ecological water-transportation project carried out in the lower reaches of Tarim River, based on the groundwater depth change and physiological and photosynthetic response of P. euphratica, adopting the means of monitoring the groundwater depth change, testing physiological index and photosynthetic parameters of P. euphratica, and investigating plant sample plots, using the theory of plant physioecology and the method of mathematical statistics, this paper studies the effect of groundwater change on the physiological and photosynthetic response primarily, analyzes the features and reasons of P. euphratica’s physiological and photosynthetic response under different groundwater depth, expounds adaptability mechanism of P. euphratica to drought, and discloses the degree of drought stress from which P. euphratica suffers under different groundwater level. The results are as follows: (1) Groundwater has a close relationship with physiological index （Proline，ABA，MDA, POD, SOD, Soluble Sugar, chlorophyll）of P. euphratica. The change of groundwater directly causes an obvious change of P. euphratica’s physiology, which can confirm that groundwater is the dominant environmental factor affecting P. euphratica’s growth. (2) Seeing from the reasons why P. euphratica’s physiological index change with the groundwater descending and drought degree increasing, MDA’s increasing and chlorophyl’s decreasing are manifestation of damage from which P. euphratica suffer. These two indexes can be seen as direct indicative factors whether P. euphratica suffer from drought-stress and what the degree of damage is. While the continuing increase of Proline, ABA, soluble sugar and SOD with the decreasing of groundwater depth is adaptive measures that P. euphratica takes under drought environment. These four indexes can be regarded as drought-resistant indexes for P. euphratica. (3) With the change of groundwater depth, the photosynthesis rate, stomatal conductance, water use efficiency also changes significantly. When the groundwater depth is more than 4m, the photosynthesis rate begins to decrease markedly, but when the groundwater depth increases to 4.2-6.8m, the photosynthesis rate is not sensitive to its change. P. euphratica grown at deeper groundwater depth, suffered from moderate drought stress, can avoid overfull water losses by stomatal adjustment. The change characteristics of water use efficiency in P. euphratica grown at different groundwater depths are different. The water use efficiency of P. eupratica firstly decreases with the increasing groundwater depth, but it increases when the groundwater depth kept increasing to 6.8m. (4) With different groundwater depths, the P. euphratica suffered from different drought stress, which makes the main limiting factors for photosynthesis in P. euphratica different. Under the mild and moderate drought stress, the main limiting factors for photosynthesis of P. euphratica are stomatal closure and non-stomatal factors, respectively. Furthermore, P. euphratica could maintain photosynthesis rate as drought stress increased from mild to moderate level, and P. euphratica under moderate drought stress maintains photosynthetic rate by osmotic adjustment. (5) Under the condition of different groundwater depths, high temperature not only restrains the photosynthetic rate but also increases the degree of stomatal closure of P. euphratica. Furthermore, the decreasing magnitude of photosynthetic rate and stomatal conductance increase under the high temperature with the increasing groundwater depth, indicating that high temperatures exacerbate the negative effect of drought stress on photosynthesis of P. eupratica. Groundwater depth has a close relation to the response of photosynthesis rate, stomatal conductance and transient water use efficiency of P. euphratica to CO2 enrichment. The groundwater depth determines the response of gas exchange to CO2 enrichment for p. euphratica in arid desert area. (6) The increasing groundwater depth would reduce the validity of plants using groundwater, subsequently increase the possibility or degree of p. euphratica’s suffering from drought stress. Essentially, the effect of groundwater depth on photosynthesis is that the changing groundwater depth arose the change of drought stress degree then affects the photosynthesis of p. euphratica. (7) Both the physiological and photosynthetic responses to groundwater depth indicated that P. euphratica grown at different groundwater depth suffers from different drought stress. When the groundwater depth is less than 4m, P. euphratica does not under the drought stress; therefore the reasonable ecological groundwater depth for P. euphratica is 4m. When it ranges in 4-5.8m, 5.8-8m and 8-9m, P. euphratica suffers from mild, moderate and severe drought stress, respectively. When it is more than 9m, P. euphratica will face the menace of death, so the critical groundwater depth for P. euphratica is 9m.
语种	中文
学科主题	植物生理学
公开日期	2010-11-12
页码	共134页
内容类型	学位论文
源URL	[http://ir.xjlas.org/handle/365004/7882]
专题	新疆生态与地理研究所_中国科学院新疆生态与地理研究所(2010年以前数据)
推荐引用方式 GB/T 7714	陈亚鹏. 塔里木河下游干旱环境下胡杨的生理适应性机理研究[D]. 中国科学院．新疆生态与地理研究所. 2007.

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