Radial Water Exchange Between Roots and Soil

根系与土壤之间的径向水交换

• 批准号: 9419841
• 负责人: Park Nobel
• 金额: $ 26.37万
• 依托单位: University of California-Los Angeles
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1995
• 资助国家: 美国
• 起止时间: 1995-01-15 至 1998-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9419841&HistoricalAwards=false
• 关键词: Radial; Water; Exchange; Between; Roots

9419841 Nobel The primary goals of the proposed research are to investigate water movement across the root-soil interface and from the root surface to the root xylem. The focus will be on how the constraints on radial flow in each component of the pathway change in concert with changes in soil moisture availability. Structural modifications in the root and at the root-soil interface during drought and subsequent rewetting will be analyzed with respect to their consequences for water uptake or loss by roots of the monocotyledon Agave deserti and the dicotyledon Opuntia ficus-indica. The pathway across the root is composed of several tissues, each with its own hydraulic conductivity that can change in response to moisture availability and as a consequence of root development. The limitations on radial water flow imposed by individual root tissues will be investigated by measuring hydraulic conductivity for intact and dissected root segments; the contribution of the apoplast to the radial pathway will also be assessed by fluorescent tracers. Anatomical changes that occur in roots during short-term drought (less than one month) will be assessed along with possible changes in tissue osmotic pressure; the importance of such changes in limiting water flow will be anlyzed with respect to two driving forces, hydrostatic versus osmotic pressures. The responses of roots to prolonged drought (four to six months) will also be examined, with the focus on anatomical and morphological changes that restrict water loss yet allow rapid water uptake upon rewetting. Roots of these and many other species shrink during drought, as perhaps does the soil, leading to the development of air gaps between roots and soil. Physical verification and measurement of air gaps around roots will be obtained from soil thin-sections surrounding roots, accompaied by experimental assesment of the effects of air gaps on water movement across the root- soil interface. In summary, the proposed research will investigate how the limitations on the movement of water in the root-soil system change with soil moisture availability, with particular emphasis on the capability of roots to function in drying soil.

9419841诺贝尔这项研究的主要目标是研究水分在根-土界面和根表面到根木质部的运动。 重点将是如何在路径的每个组成部分的径向流的约束变化与土壤水分供应的变化。 在干旱和随后的复湿过程中，在根和根-土界面的结构修改将分析其后果的单子叶植物龙舌兰沙漠和双子叶植物仙人掌的根的水分吸收或损失。 穿过根系的通道由几个组织组成，每个组织都有自己的导水率，导水率可以根据水分供应情况和根系发育的结果而变化。 将通过测量完整和解剖的根段的水力传导率来研究单个根组织对径向水流的限制;还将通过荧光示踪剂来评估质外体对径向途径的贡献。 在短期干旱（不到一个月）发生在根的解剖变化将进行评估沿着随着组织渗透压的可能变化，这种变化在限制水流的重要性将分析相对于两个驱动力，静水压力与渗透压。 还将研究根系对长期干旱（4至6个月）的反应，重点是限制水分流失但允许在复湿后快速吸水的解剖学和形态学变化。 这些和许多其他物种的根在干旱期间收缩，土壤可能也是如此，导致根和土壤之间的空气间隙的发展。 将从根系周围的土壤薄片中获得根系周围气隙的物理验证和测量，同时进行气隙对根系-土壤界面水分运动影响的实验评估。 总之，拟议的研究将调查如何限制在根-土系统中的水运动的变化与土壤水分的可用性，特别强调的能力，根在干燥的土壤中发挥作用。