EAGER: Real-time measurement of sap-flow dynamics in sunflower via nuclear magnetic resonance

水是我们这个星球的关键组成部分，特别是对于维持粮食生产和支持人类生存而言。要在宏观尺度（如盆地或流域）上明智地用水，就必须彻底了解影响较小尺度（如单个植物）需水量的因素。在植物尺度上，决定水分需求的主要驱动力是叶片的蒸腾作用。水分通过叶片流失的速度与树液流动直接相关，树液流动被定义为水分通过茎的速度。该项目的目标是开发一种基于核磁共振（NMR）的物理学原理的新技术，以准确确定植物茎中的液流及其在不同环境条件下的实时变化。与目前可用的设备不同，NMR工具是非侵入性和便携式的，这使得原位测量变得简单方便。核磁共振工具的结果将具有广泛的社会意义，填补了关于植物中水分和养分运输的重要知识空白。项目人员将参与校园活动和活动，以吸引K-12学生，增加他们对水管理的知识。项目pi将与代表性不足的科学团体合作，以提高妇女在科学和工程领域的地位（KAWSE），即女孩研究我们的世界（GROW）夏季讲习班，重点是水的使用和新的核磁共振技术。核磁共振工具具有商业化和应用于其他粮食作物和植物的潜力，以提高农业和生态系统的生产力。植物通过根和茎维管组织将水分和养分从土壤输送到叶片的唯一现象是高度动态的汁液流动。由于缺乏一种强大的、非侵入性的和便携式的系统，量化这种在时间和空间上变化的极其复杂的生理过程一直是作物科学的主要挑战。因此，本项目旨在(1)设计和制作一个方便的工具来准确测量向日葵汁液流动动态的时间变化；(2)测试和验证核磁共振（NMR）作为表征作物汁液流动的有用和实用工具。将设计一种便携式核磁共振工具，使用3D有限元模拟包和非主导排序遗传算法- ii的组合来优化磁体阵列和线圈。优化设计的核磁共振工具将在实验室进行原型设计，并通过实验验证其磁场均匀性和强度。此外，将使用窄管和两种流速（即1和100 (mg/s)）在稳定-稳定条件下微调核磁共振工具。向日葵植物将维持在最先进的步入式生长室中，蒸汽压力差为2、3和4千帕。植物失水将在高时间频率下使用称重传感器和质量平衡法进行测量。在不同的生长阶段，每天进行三次核磁共振测速，直到开花，以捕捉短时间间隔的速度分布。通过核磁共振估计的液流将与质量平衡法确定的液流进行比较。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Water is a key component to our planet, particularly to sustain food production and support human existence. To use water judiciously at macro scales e.g., basins or watersheds, a thorough understanding of factors affecting water requirement at smaller scales e.g., individual plants, is required. At the plant scale, the main driver determining water need is transpiration from the leaves. The rate of water loss through leaves is directly linked to sap flow, defined as the rate at which water moves through the stem. The goal of this project is to develop a new technology using principles from physics, based on nuclear magnetic resonance (NMR), to accurately determine sap flow and how it changes in real-time in a plant stem under different environmental conditions. Unlike currently available equipment, the NMR tool is non-invasive and portable, which allows making in-situ measurements easy and handy. Results from the NMR tool will have broad impacts that are of societal relevance by filling a significant knowledge gap about water and nutrient transport in plants. Project personnel will be involved in on-campus activities and events to engage K-12 students and increase their knowledge regarding water management. Project PIs will work with underrepresented groups in science for the Advancement of Women in Science and Engineering (KAWSE) i.e., Girls Researching Our World (GROW) summer workshops focusing on the water use and new NMR technology. The NMR tool has the potential for commercialization and application to other food crops and plants to advance agricultural and ecosystem productivity. The sole phenomenon transporting water and nutrients from soil to leaves through roots and stem vascular tissues in plants is the highly-dynamic sap flow. Quantifying this extremely complex physiological process varying temporally and spatially has been a major challenge in crop science, due to the lack of a robust, non-invasive and portable system. Therefore, this project aims to (1) design and prototype a handy tool to accurately measure temporal variations of sap-flow dynamics in sunflower, and (2) test and validate nuclear magnetic resonance (NMR) as a useful and practical tool for characterizing sap flow in crop plants. A portable NMR tool will be designed using a combination of 3D finite-element simulation package and a non-dominated sorting genetic algorithm-II to optimize the magnets' arrays and coils. The optimally-designed NMR tool will be prototyped in the lab, and its magnetic field homogeneity and intensity will be experimentally validated. Furthermore, a narrow tube and two flow rates i.e., 1 and 100 (mg/s) will be used to fine-tune the NMR tool under steady-steady conditions. Sunflower plants will be maintained in state-of-the-art, walk-in growth chambers at 2, 3 and 4 kPa vapor pressure deficit levels. Plant water loss will be measured at high temporal frequency using a load cell and the mass-balance method. NMR velocimetry will be performed thrice daily at different growth stages until flowering to capture velocity distribution at short time intervals. Sap flow estimated via NMR will be compared with that determined by the mass-balance method.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.