Root traits of contrasting crop genotypes and their influence on soil biogeochemical cycles

我的研究计划的长期目标是调查植物根和土壤生物地球化学循环之间的联系。根直接与土壤相互作用，改变物理和生化环境，支持植物生长。然而，我们对根系如何间接影响土壤过程的了解相对有限，这些过程对作物生产以外的农业生态系统功能至关重要，包括养分循环、土壤有机质形成和结构稳定性。解决我们在根与土壤过程相互作用方面的知识差距在农业系统中尤为重要，因为由于全球市场和气候条件的变化，加拿大各地的农民正在放弃单一栽培，转而进行越来越多样化的轮作。预测在我们的农业系统中种植不同的不同作物基因型对生态系统功能的影响，需要更好地描述它们的根特征以及这些特征如何影响土壤生物地球化学循环。 我的计划将采用基于植物特性的方法来了解对植物生产力至关重要的营养循环的根部影响，以及影响土壤质量和全球气候的碳动态。本研究的具体目标是调查根化学和结构特征及其相互作用对：(1)根分解速率和土壤磷、氮的生物有效性；(2)根源碳在土壤团聚体和土壤微生物群落中的去向；(3)根际化学和微生物群落结构的空间分布。我将使用先验已知的作物物种，它们的根系结构和品种在遗传上被选择来改变植物组织化学，在一系列研究中，这些研究在五年计划的过程中以越来越复杂的方式检查根-土壤界面。植物的稳定同位素标记将被用来研究来自根的输入在土壤中的去向，分子生物学技术将表征根驱动的土壤微生物群落的结构，而胞外酶活性成像的新技术将被用来阐明根对潜在的养分生物有效性的影响。了解不同结构和化学成分的根输入的微生物过程将改善我们对植物养分供应和土壤中碳在不断变化的农艺和气候条件下的去向的预测。通过采用基于特征的方法来了解根系对土壤生物地球化学过程的影响，这项工作可以为利用理想的根系特征来提高作物生产力和生态系统功能的种植制度的设计提供信息。

The long-term objective of my research program is to investigate the link between plant roots and soil biogeochemical cycles. Roots directly interact with the soil to alter the physical and biochemical environment to support plant growth. However, our knowledge on how roots indirectly affect soil processes vital to agroecosystem functioning beyond crop production, including nutrient cycling, soil organic matter formation, and structural stability, is relatively limited. Addressing the gap in our knowledge on root interactions with soil processes is especially important in agricultural systems as farmers across Canada are abandoning monocultures for increasingly diverse crop rotations due to changing global market and climate conditions. Predicting the effects of growing a diversity of different crop genotypes in our agricultural systems on ecosystem function requires better characterization of their root traits and how those traits affect soil biogeochemical cycles. My program will take a plant traits based approach to understand root influences on nutrient cycles important to plant productivity as well as on carbon dynamics that affect soil quality and global climate. The specific objectives of my research program are to investigate the influence of root chemical and structural traits and their interactions on: (1) root decomposition rates and soil phosphorus and nitrogen bioavailability; (2) the fate of root-derived carbon in soil aggregates and the soil microbial community; and (3) the spatial profile of rhizosphere chemistry and microbial community structure. I will use crop species known a priori to differ markedly in the structure of their root systems and cultivars that have been genetically selected to vary in plant tissue chemistry throughout a series of studies that examine the root-soil interface with increasing complexity over the course of the five-year program. Stable isotope labeling of plants will be used to investigate the fate of root-derived inputs in soil, molecular biological techniques will characterize root-driven structuring of soil microbial communities, and novel techniques in imaging extracellular enzyme activities will be used to elucidate the influence of roots on potential nutrient bioavailability. Understanding the microbial processing of structurally and chemically diverse root inputs will improve our predictions of plant nutrient supply and the fate of carbon in the soil under changing agronomic and climate conditions. By taking a trait-based approach to understanding root influences on soil biogeochemical processes, this work can inform the design of cropping systems that exploit desirable root traits to enhance crop productivity and ecosystem function.