荒漠植物梭梭对风沙流胁迫的响应及适应机理研究

Under the serious threatening of more frequent wind-blown sand for desert shrub, it is a popular phenomenon of degradation, decline and low survival rate of seedling. This has caused a main reason of influencing on natural renewed for desert vegetation. Haloxylon ammodendron is a kind of fine wind prevention and sand fixation plants which can endure drought, saline-alkaline, wind erosion. At present, the research on the influence of wind-blown sand threatening at home and abroad more focusing on the response of plants morphological characteristics, and.it rare report on research photosynthetic function and configuration adaptation. The project is to research desert shrub H. ammodendron PSII reactive center photosynthetic electron transport and photochemistry, non-photochemistry dissipation of energy dynamic state under the different wind-drift sand threatening condition by means of wind tunnel simulation test. The decline mechanism of plant configuration to wind-blown sand was explored and its protective effect on photosynthetic apparatus within plants osmotic adjustment substances were revealed. The response process of physiology and biochemistry to wind-blown sand threatening on H. ammodendron were analyzed, combining with the analysis of characteristic of overground and underground part component allocation model and spatial arrangement feature. The quantitative relation of seedling extent of damage and different wind-blown sand condition were confirmed and established, and the response mechanism of desert shrub seedling for wind-blown sand were revealed. This study is conductive to illustrate the damage and existing mechanism of desert shrub in sand environments and its configuration selection of shrub which can prevent wind and sand, and provide scientific guide on improving natural replacement rate.

荒漠灌木在日益频繁风沙流胁迫下，普遍存在着退化、衰败，幼苗存活率低的现象，已构成影响荒漠区植被自然更新的主要原因之一。梭梭是一种耐干旱、耐盐碱、耐风蚀的优良防风固沙植物。目前国内外有关风沙流胁迫对植物影响的研究多集中在植株形态特征的响应等方面，有关光合功能和构型适应的研究尚少有报道。本项目拟通过风洞模拟试验，研究不同风沙流胁迫条件下荒漠灌木幼苗梭梭PSII反应中心光合电子传递及光化学和非光化学能量耗散动态，探讨植株构型对风沙流胁迫的消减机制，揭示植物体内渗透调节物质等在光合机构有效运行中的保护作用；分析梭梭幼苗对风沙流胁迫的生理生化响应过程，以及地上及地下部分的构件分配模式和空间排列特征，确定并建立幼苗受损程度与不同风沙流条件之间的量化关系，揭示荒漠灌木幼苗对风沙流胁迫的响应机制。此研究有助于阐明风沙环境中荒漠灌木的受损和生存机制，以及防风固沙灌木的构型选择，为提高天然更新率提供科学依据。

荒漠灌木在日益频繁风沙流胁迫下，普遍存在着退化、衰败，幼苗存活率低的现象，已构成影响荒漠区植被自然更新的主要原因之一。梭梭是一种耐干旱、耐盐碱、耐风蚀的优良防风固沙植物。目前国内外有关风沙流胁迫对植物影响的研究多集中在植株形态特征的响应等方面，有关光合功能和构型适应的研究尚少有报道。.本项目以广泛分布在西部沙区的典型防风固沙植物-梭梭为研究对象，通过风沙环境风洞模拟试验，研究不同风沙流胁迫条件下荒漠灌木幼苗梭梭PSII反应中心光合电子传递及光化学和非光化学能量耗散动态及过程，分析梭梭幼苗对风沙流胁迫的生理生化响应过程，确定并建立梭梭幼苗受损程度与不同风沙流强度间的量化关系和构件排列特征，揭示荒漠灌木幼苗对风沙流胁迫的生态响应机制。研究结果表明：（1）风沙流胁迫加剧了梭梭同化枝非辐射能量耗散过程和PSⅡ非光化学猝灭系数的减小。随着风沙流胁迫时间增加，PSⅡ最大光化学量子效率Fv / Fm明显降低，梭梭幼苗的NPQ值也逐步下降；在光合作用中引起光抑制甚至光合器官损伤的可能性也逐渐增加。（2）风沙流胁迫会导致梭梭同化枝条水分含量不平衡，持续的风沙流胁迫严重影响光合作用器官的活性和活力，导致光抑制、光合色素含量下降，造成枝条脱水枯萎和不可逆转的损害。18m/s极重度风沙流胁迫20min已经达到梭梭致死伤害的风速，枝条永久死亡。（3）梭梭在不同的风沙流胁迫环境中冠形和构型特征表现不一，具有较强的形态可塑性与变异性。随着风沙流胁迫强度的增加，梭梭枝条长度、数量和枝条直径均呈现先增加后减小的二项式曲线变化过程。新生枝对风沙流胁迫较为敏感，新生枝长度累加量随风沙流强度的增加呈直线方程快速减少。此研究结果有助于解释梭梭新生幼苗难以持续更新的深层原因，阐明了风沙环境中梭梭的受损机理和生存机制，以及防风固沙灌木的构型特征，为提高梭梭天然更新率提供了重要的科学依据和理论基础。