圆柏硅积累过程与水力结构的关系及其对干旱胁迫的响应

Silicon plays an important role in improving plant growth and enhancing plant resistance to biotic and abiotic stresses, and is environmentally friendly. However, the mechanism of plant silicon accumulation has no a definite conclusion. Most plants are passive absorption silicon, and the exploration of silicon absorption and transport from the view of hydraulic regulation helps to elucidate the regulation mechanism of silicon accumulation. The project team found that the silicon was significantly correlated with water use efficiency, but also significantly affected by environmental and climate factors. Based on the research progress of plant hydraulic structure and mineral metabolism response to environmental factors, we propose the hypothesis that plant silicon absorption driven by moisture is limited by plant hydraulic structure. In this study, Sabina chinensis (L.) Ant., which has heterotypic leaves and good ecological functions in urban landscapes and ecologically fragile areas, was used to study the relationship between hydraulic structure and silicon accumulation.Based on field investigation and control experiments, combined with stable silicon isotope detection. The individual and overall hydraulic structure in roots, stems and leaves is investigated in Sabina chinensis (L.) Ant. with heterotypic leaves according to the plant water transport continuity in plants, we studies the physiological basis of the silicon accumulation relied on water metabolism, and the study focuses on the regulation of hydraulic structure on silicon accumulation and its relationship with environmental moisture. This study is of great significance for elucidating the mechanism of plant stress-resistant and the silicon recycling and utilization , also serving the sustainable development of agroforestry .

硅具有改善植物生长、提高植物抵抗生物和非生物胁迫的作用，且对环境无污染。但植物硅积累的调控机制尚无明确的定论。大部分植物属于被动吸硅型，从水力调节的角度探索硅吸收和转运有助于阐明硅积累的调节机制。项目组前期研究发现，硅与水分利用率显著相关，且显著受到环境气候因子的影响。结合植物水力结构和矿物质代谢对环境响应的研究进展，我们推测水分驱动的植物硅积累受限于水力结构。本研究以在城市园林和生态脆弱地区均具有良好生态作用且具异型叶特征的圆柏为材料，根据植物水分运输连续性的特点，从根、茎和叶的个体和整体水力结构入手，通过野外调查和室内控制性试验，结合稳定硅同位素检测，研究硅积累依赖于水分代谢的生理学基础，重点探讨水力结构对硅积累的调控及其与水分的关系，对阐明植物硅积累及其对水分驱动的响应机制具有重要的意义，为植物抗旱机理、硅循环与利用的解析和农林业可持续发展服务。

木质部硅-水耦联蒸腾流是硅长距离运输、分配和积累的基础。为了揭示木质部水力结构与硅积累及其抗旱性状的关系，通过调查和采集了甘肃、陕西、山西和河南等地生长的圆柏和土壤样品；测定圆柏叶片中总矿物质和硅含量，分析硅积累与降雨和温度的关系；比较不同浓度硅酸根、K+和H+对水力导度的影响，结合木质部解剖结构分析，探索硅对水力导度和抗栓塞能力的影响，分析水力结构与抗旱性的关系；利用蒸腾抑制剂和代谢抑制剂对栽培圆柏进行水分代谢调节处理，研究硅积累对水分代谢的依赖和硅肥施加对水分运输的影响。结果证实，圆柏中硅和钾含量和年均降水量有显著相关性（p < 0.01），均与年均温度无显著相关性。K+、H+与SiO32-在水力传导过程中均存在离子效应，且SiO32-对K+、H+的离子效应存在拮抗的效果。加硅处理后，SiO32-有效的降低了茎木质部导水率，但提高了抗栓塞能力，这可能是硅提高植物抗旱性的一种策略。3种圆柏属植物阴阳面茎木质部水力功能不存在效率-安全权衡，木质部抗栓塞能力主要受管胞长度和管胞密度的影响；水分运输能力主要受叶片水势、管胞直径、木质部密度、恢复的相对导水率的影响。植物抗栓塞能力与其叶形及木质部结构特征有关，且鳞形叶龙柏水力结构方面表现出更强的耐旱性。