【作者】 王圣杰；

【导师】 黄大庄；

【作者基本信息】 河北农业大学 ， 生态学， 2011， 硕士

【摘要】 当前,环境恶化严重威胁着人类的生存与发展,干旱成为世界上最为严重的灾害之一。本研究以藏川杨（Populus szechuanica var. tibetica）为材料,采用人为控水,模拟了4种梯度下的土壤水分胁迫,以研究不同土壤水分条件对藏川杨光合生理特性的影响,以期为华北干旱半干旱地区人工植被建设中树种选择和经营措施提供参考,以便更有效地利用、改良植物,对提高农林业生产力以及保护环境都具有重大意义。主要结果如下:藏川杨叶片的叶绿素a含量随着土壤水分胁迫程度的增加而逐渐降低,而叶绿素b含量变化不明显;叶绿素a/b在轻度及中度干旱胁迫下逐渐加大,而在重度干旱胁迫下,叶绿素a/b降低。随着土壤水分胁迫加剧,藏川杨的净光合速率（Pn）逐渐降低,气孔导度（Gs）也呈现出逐渐降低的趋势;胞间CO₂浓度（Ci）在轻度水分胁迫下降低,但随着水分胁迫的加剧,当水分条件处于中度及重度胁迫时,其胞间CO₂浓度又呈现出增加的趋势;藏川杨的气孔限制值（Ls）在轻度干旱胁迫下增大,在中度及重度干旱胁迫下减小。随着土壤水分胁迫的加剧,藏川杨叶片的蒸腾速率（Tr）日平均值减小,其中在中度及重度干旱胁迫条件下藏川杨的蒸腾速率与正常水分处理下的蒸腾速率差异显著。藏川杨叶片的水分利用效率在轻度干旱胁迫下高于正常水分处理,当土壤水分胁迫为中度及重度时,水分利用效率才明显低于正常水分处理,这表明一定的土壤水分胁迫条件可以提高藏川杨的水分利用效率。采用直角双曲线模型、非直角双曲线模型、直角双曲线修正模型和指数函数模型分别对藏川杨叶片光响应曲线进行了拟合与相互比较,拟合结果表明,采用直角双曲线修正模型拟合的藏川杨叶片光响应参数均比较准确。随土壤水分含量的降低,藏川杨的光量子效率（AQY）、最大净光合速率（Pmax）、光饱和点（LSP）、暗呼吸速率（Rd）均呈现下降的趋势,光补偿点（LCP）则呈现出升高的趋势。藏川杨对研究中设定的轻度干旱和中度干旱胁迫表现出一定的适应性,但对重度干旱胁迫适应性较差。干旱胁迫下,藏川杨对弱光和强光的适应性减弱,利用弱光和强光的能力降低,但仍保持在较高的水平上,基本能够适应华北干旱半干旱地区的自然光照条件。更多还原

【Abstract】 Environmental deterioration posed great threat on the survival and development of people,especially the drought which was one of the most serious disasters. Populus szechuanica var. tibetica was used as the experiment material in the study .Four kinds of the water stress was simulated with the method of water controlling. The effect of the water stress was studied on the photosynthetic characteristics of Populus szechuanica var. tibetica to provide the main theoretical basis for the selection and management of the trees. It also had the great significance for us to utilize the plant more effectively and enhance the productivity of the forest and protect the environment.The Chia of Populus szechuanica var. tibetica decreased gradually with the increasing of the water stress, but the Chib did not change obviously.The Chia/b increased gradually under the mild or moderate drought, but decreased under the serious drought.With the escalation of water stress in soil, net photosynthetic rate of Populus szechuanica var. gradually decreased, stomatal conductance also showed one kind of trend of gradual decrease. The intercellular carbon dioxide of Populus szechuanica var. decreased under the mild water stress. But with the escalation of water stress, when the water stress was moderate and severe, the concentration of intercellular carbon dioxide showed the trend of increase. The stomatal limitation of Populus szechuanica var. increased under the mild drought stress but decreased under moderate and severe drought stress. With the escalation of water stress in soil, daily average value of leaf transpiration rate of Populus szechuanica var. tibetica decreased. There were great differences of transpiration rate between Populus szechuanica var. under moderate and severe drought stress and Populus szechuanica var. under normal water treatment. The efficiency of water of Populus szechuanica var. under mild drought stress was higher than that under normal treatment. The efficiency of water utilization under moderate and severe water stress was obviously lower than that under normal treatment. It had been showed that appropriate intensity of water stress in soil could elevate the efficiency of water utilization of Populus szechuanica var.Four empirical models of light-response curve of leaf net photosynthesis, such as nonrectangular hyperbolic model, rectangular hyperbolic model, modified rectangular hyperbolic model and index function model, were tested to compare their fitness in this paper and the application of four empirical models in study on photosynthesis light response of Populus szechuanica var. tibetica was discussed. The results showed that the parameters of light-response curve simulated by modified rectangular hyperbolic model were more accurate than other models.The apparent quantum yield (AQY)、maximum net photosynthetic rate (Pmax)、light saturation point (LSP)、dark respiration rate (Rd) declined gradually with the decrease of the water in soil, but the light compensation point (LCP) increased. Certain adaptability of Populus szechuanica var. tibetica appeared to light drought and medium drought setted in the study, but it was out of condition to severe drought. Both of the adaptability to low light environment and high light environment and the ability to use low light and high light of Populus szechuanica var. tibetica reduced under drought stress, but both still remained at a high level, basically able to adapt to arid and semi-arid condition in North China.更多还原