Dissertation Research: Does Hydraulic Redistribution Increase Microbial Activity in the Rhizosphere?

论文研究：水力重新分配是否会增加根际微生物活动？

• 批准号: 0408066
• 负责人: Zoe Cardon
• 金额: $ 1.2万
• 依托单位: University of Connecticut
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2004
• 资助国家: 美国
• 起止时间: 2004-07-15 至 2006-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0408066&HistoricalAwards=false
• 关键词: Dissertation; Research; Does; Hydraulic; Redistribution

Dissertation Research: Does Hydraulic Redistribution Increase Microbial Activity in the Rhizosphere?Z.G. Cardon and P.M. Herron The root systems of single plants can span a depth of soil exhibiting strong gradients of water availability. Often, in arid regions, dry soils are found at the surface and moister soils at depth. This gradient of water availability provides a driving force for the passive redistribution of water through the root systems from the deeper soils to the shallow, nutrient rich soils, usually at night. Such "hydraulic redistribution" is now recognized in almost 60 species worldwide, and has been shown to increase rates of transpiration, increase growth in neighboring plants, and alter the hydrology of entire regions. A number of hypotheses have emerged focusing on the potential importance of hydraulic redistribution of water into the shallow, nutrient-rich soil layers for maintenance of soil microbial activity, and thus potentially enhanced nutrient availability, around plant roots. This project explores whether hydraulic redistribution, and resulting patterns of water availability, affect rhizosphere microbial biomass, growth rates, and activity. We will test whether nutrient cycling around plant roots, and nutrient availability to plants, are enhanced by hydraulic redistribution in the greenhouse and in the field. The focal plant species is sagebrush (Artemisia tridentata), a deep-rooted shrub that is often a community dominant in semi-arid, western landscapes in the U.S. In field work, we will explore the relationship between the presence of hydraulic redistribution and the reproductive fitness of Artemisia; in the greenhouse, we will use soil bacteria that are genetically engineered to report soil water potentials to provide the first glimpse of soil water potentials at micro- and millimeter scales around roots. In both the greenhouse and the field, standard soil assays and soil psychrometers will be used to track microbial activity and bulk soil moisture. Results from this study will suggest mechanisms by which deep-rooted Artemisia tridentata can affect nutrient dynamics and water contents in shallow soils of semi-arid systems.

论文研究：水力再分配是否增加了根际微生物的活动？Z.G.Cardon和P.Herron单个植物的根系可以跨越土壤深处，表现出强烈的水分可利用性梯度。通常，在干旱地区，表层是干燥的土壤，深层是潮湿的土壤。这种水分可获得性的梯度提供了一种驱动力，促使水分通过根系被动地从深层土壤重新分配到营养丰富的浅层土壤，通常是在晚上。这种“水力再分配”现已在全世界近60个物种中得到认可，并已被证明可以增加蒸腾速率，促进邻近植物的生长，并改变整个地区的水文状况。已经出现了一些假设，着重于水力将水重新分配到浅层、营养丰富的土层对维持土壤微生物活动的潜在重要性，从而潜在地增强植物根部周围的养分可用性。该项目探索水力再分配和由此产生的水可获得性模式是否影响根际微生物生物量、生长速度和活性。我们将测试温室和田间的水力再分配是否提高了植物根部的养分循环以及对植物的养分利用率。重点植物物种是山艾(Artemisia Tridentata)，这是一种根深蒂固的灌木，通常是美国西部半干旱景观中的优势群落。在田间工作中，我们将探索水力再分配的存在与艾草繁殖适合性之间的关系；在温室中，我们将使用经过基因工程的土壤细菌来报告土壤水势，以第一次瞥见根部周围微米和毫米尺度的土壤水势。在温室和田间，将使用标准土壤分析和土壤湿度计来跟踪微生物活动和土壤水分。这项研究的结果将表明深植三齿艾会影响半干旱系统浅层土壤的养分动态和水分含量的机制。