梣属不同性系统植物繁育系统特征及其对资源分配的影响

The theory of plant life history is largely concerned with optimal resource allocation between male and female functions. It is assumed that there is a resource trade-off between reproductive and vegetative distribution, which means that if more resources are allocated to female functions, less resources will be allocated to male functions. The structure and function of the breeding system are the core of plant reproductive success and sexual system evolution. The breeding system characteristics in sexual dimorphic plants are complex and changeable, which usually leads to complex resource allocation patterns. However, the relationship between them is still unclear. In this study, two sexual dimorphic Fraxinus species (androdioecious Fraxinus americana and dioecious Fraxinus velutina Torr ) are used as research samples. We will conduct not only field investigations and laboratory analysis tests, but also an artificial pollination control experiments on androdioecious plants. Therefore, both the breeding system characteristics and the reproductive resource allocation patterns will be measured, especially the mating system type and gender distribution. We will analyze the effects of breeding system characteristics on the gender-related resource allocation patterns in different sexual systems. The innovation of this project is that we try to use the resource allocation model of Evolutionarily Stable Strategy (ESS) to explore the effects of breeding system characteristics (gender distribution) on the resource allocation process of reproductive and vegetative growth in the two sexual systems. Both F. americana and F. velutina are common afforestation tree species and street tree greening species in northern China, but the researches about the breeding system and resource costs between genders are limited. This study is able to contribute to our understanding of the reproductive strategies, as well as the related key technologies of tree species selection and management of these species.

植物生活史理论认为，植物体能够在环境中获得的资源是有限的，各个功能之间存在着权衡关系，分配给生殖功能的资源较多，则分配给营养功能的资源较少。繁育系统的结构与功能是植物生殖成功及性系统进化的核心，性二态植物的繁育系统特征复杂多变，导致资源分配格局也十分复杂，两者之间究竟有何关联尚不明确。本项目以梣属雄全异株美国白蜡和雌雄异株绒毛白蜡为对象，通过野外观测和控制试验，研究两种性系统植物的繁育系统特征，尤其是交配系统类型和性别分配，结合生殖生长和营养生长资源分配格局调查，分析梣属不同性系统植物的繁育系统特征对资源分配格局的影响。本项目将繁育系统与生殖营养资源分配格局相联系，探讨两种性系统植物繁育系统特征（性别分配）对资源分配过程的影响。梣属植物是我国北方常见造林树种及行道树绿化树种，项目成果有助于认识梣属植物的生殖策略和形成相关的树种选择与管护关键技术。

造林绿化树种的营养生长状况直接影响个体在生态系统服务功能中的贡献，对于性二态植物而言，不同的资源分配策略可直接影响到不同性别植物的个体生长、抵御能力，甚至种群的死亡率。绒毛白蜡作为北方主要绿化树种，其繁殖投资成本对营养生长的影响机制模式尚不完全明确，生理生长特性与繁殖投资的关系研究也罕见报道。本项目基于此背景下，重点开展了绒毛白蜡不同构件水平的生殖资源分配格局、光合特征及光合氮分配策略、叶功能性状对繁殖强度的响应以及同化物分配策略等方面的研究，研究结果发现：性别对绒毛白蜡资源分配策略存在显著影响，雄树具有更高的营养投资而雌树的繁殖投资更高，尤其是枝条和全株水平上；雄树在坐果期和果实成熟期均表现出更强的净光合速率（Pn）和叶绿素含量（Chl），而雌树在果实膨大期表现出更强Pn和Chl；不同发育阶段，雄树和雌树的生长策略不同，坐果期与果实成熟期，雌树的Pn、气孔导度（gs）、胞间CO2浓度（Ci）、蒸腾速率（Tr）、瞬时水分利用效率（WUEi）、最大羧化速率（Vcmax）和最大电子传递速率（Jmax）显著高于雌树，但在果实膨大期，绒毛白蜡雌树的Pn、gs、Ci、Tr、WUEi、Vcmax、Jmax显著高于雄树；性别对结构性碳水化合物的影响显著。本项目针对性二态植物的“繁殖投资-营养生长”资源分配机理，揭示了雌雄异株绒毛白蜡的生殖资源分配策略及碳氮耦合关系，研究结果对全面认识梣属性二态植物的生活史策略、科学推进相关树种绿化工作奠定理论基础和数据支撑。