基于地上—地下协同的石灰岩山地淡竹低磷适应机制研究

磷矿的日渐耗竭使大量施磷获得植物高产难以长久维系，解析植物低磷适应机制十分急迫。然而地上—地下协同机理不明制约了人们对适应机制的深入认知。石灰岩山地缺磷，但淡竹适应性强，在周期皆伐移失大量磷后仍生长良好。对此，本项目以最优分配理论为指导，通过双重对照、原位观测和控制试验，采用液相色谱、同位素标记和磷组分分析等方法对淡竹开展以下研究：1）量化根系分泌有机酸对土壤磷的活化效率，分析地上光合生产与地下根系有机酸分泌的耦合过程；2）测定根系磷吸收的功能性状与动力参数，明晰地上蒸腾引起的质流促进地下磷吸收作用机理；3）分析磷分配格局与叶片磷组分分配特征，阐明磷分配与光合生产的相互关系；4）构建SEM模型，梳理叶片光合、蒸腾促进根系磷活化与吸收，再以磷分配支持光合的反馈循环途径及定量关系。研究以整体视角阐释淡竹低磷地上—地下协同适应机制，为相关研究提供新思路，并为喀斯特农业生产和植被保育提供科学依据。

Phosphorus (P) is not a renewable resource, which was estimated to be half-depleted in the middle of this century. Thus, it is urgent to explore the efficient utilization mechanism of plants grown in P-impoverished soils. However, studies on the synergy of aboveground and belowground to cope with P-poor soils were weak, and its synergy mechanism is still unclear. Those weakness limited the understanding and application of the adaptation mechanism to P-poor soils. In this study, a dominant species (Phyllostachys glauca) grown in a limestone mountain in the Northwest of Jiangxi Province, was chosen as the research object. Based on the optimal allocation theory and adaptive strategies to P-infertile habitats, the experiment scheme was designed through double contrast, in situ survey and control experiments. Using high performance liquid chromatography (HPLC), isotope labeling, X rays, and phosphorus component analysis, the following contents will be developed : 1) to quantify the mobilizing efficiency of organic acids released by roots on soil phosphorus, and analyze the coupling process of photosynthetic production and underground root secretion of organic acids; 2) to measure the root functional characteristics and dynamic parameters of phosphorus absorption, and clarify the mechanism of mass flow promoting underground phosphorus absorption caused by the leaf transpiration; 3) to determine the distribution pattern of phosphorus and the distribution characteristics of phosphorus fraction in leaves, and explore the correlation between phosphorus distribution and photosynthetic production; 4) to construct a Structure Equation Model (SEM) by AMOS to analyze the feedback loop pathway and its quantitative relationships how leaf photosynthesis and transpiration promoted the organic acids releasing and then enhanced the P mobilization and absorption by roots, and how the P allocation to support the high photosynthetic production. This study aims to elucidate the adaptation mechanism of the bamboo species, Phyllostachys glauca, to P-poor limestone soil from a holistic perspective, and construct a new model based on synergy of aboveground and belowground to study the plants survived in P-infertile soil low phosphorus. And, it is expected to provide scientific basis for agricultural production and vegetation conservation in Karst areas.