模拟根系对局部磷供应的响应

Root system architecture influences plant foraging and acquisition of water and nutrients from soil, and thus determines plant growth and crop productivity. Phosphorus (P) is the second nutrient element limiting plant growth in natural ecosystems, and its distribution in soil is often localized and heterogeneous involving P-enriched patches and P deficit in root surroundings. How roots responding timely and spatially to heterogeneous P status remains largely unknown. By integrating the use of novel noninvasive root observation and imaging techniques and 3-dimensional function-structural root models, this project aims to investigate root responsive strategies to localized and heterogeneous P supplies in 6 selected important crop species with contrasting root structure. Dynamic alterations in root system architecture and physiological changes will be monitored during plant growth and compared among the tested crops under varying P supplies. Complex root traits including topological properties, geometric properties and physiological properties will be measured to determine relationship among root traits and their correlation with P availability and distribution in soil. Two current 3-dimensional root models, SimRoot and ROOTMAP, will be parameterized using root trait data acquired from two early experiments and used to simulate root growth, root system architecture, root exudation and P acquisition in response to heterogeneous P environments. Simulated results will be compared with the experimental measurements. Modeling approaches affecting prediction of root growth and P update will be determined by comparing the two root models differed in algorithms for resource allocation. The outcomes of this research will enrich our understanding of the complexity of dynamic interactions between plant roots and soil P. This study will provide guidance for improved fertilization practices in agriculture, and for optimized root architectural traits and functions in the aid of crop breeding programs leading to more efficient and high-yielding crop cultivars.

根系构型影响植物对水分和营养吸收，对植物生长和产量起决定作用。在自然生态系统中，磷是制约植物生长的第二大养分因子,且在土壤中常呈异质性分布。根系对异质性磷局部供应在时间和空间上的动态反应尚缺乏系统研究。本项目采用试验观测与模型模拟相结合的研究方法，以作物根系对土壤局部磷供应的响应及调控机制为研究主线，以6种不同根系类型的作物为研究对象，综合采用半水培根系性状鉴定系统、根箱局部磷与异质性Patch控制体系和核磁共振图像技术，对不同类型根系的应答反应进行动态监测；通过三维根系模型SimRoot和ROOTMAP对根系构型、分泌物和磷吸收效应进行模拟和验证，揭示不同类型根系对局部磷供应的响应策略与调控机制，探明根系构型与生理变化间的协调关系。本研究将丰富对根系与局部磷供应复杂互作关系的认识，为优化根系构型与功能提高作物磷吸收效应和利用效率、培育高效高产作物新品种、探询合理施肥方式，提供科学依据。

土壤低磷和异质性磷供应影响作物的生长和产量。不同作物及不同基因型对低磷及局部磷供应的响应不同。本项目开展了五种作物及多种基因型根系对土壤低磷与局部磷环境的适应性研究。在控制环境下，采用半水培根系性状鉴定系统、根箱和PVC土柱等方法，探讨了根系构型不同的作物及品种在根系表型性状和根系生理性状方面对低磷胁迫的应答反应。并通过根系模型对根系构型和磷吸收效应进行模拟和验证。研究结果对助于提供我们对根系构型与生理性状对局部磷供应的复杂关系的认识，为优化根系构型与功能提高作物磷利用效率和培育高效高产作物新品种提供科学依据。