Recipient Organization
Aerodyne Research, Inc.
45 Manning Road
Billerica,MA 01821
Performing Department
(N/A)
Non Technical Summary
Understanding the transport and utilization of nutrients in crops is critical for sustaining the global food supply, ensuring crop climate resilience, and managing the environmental impacts of agriculture. Nitrogen inputs, particularly from fertilizers, are a central component of modern agricultural practices but excess application can lead to greenhouse gas emissions, contiamination of ground and surface waters, and reduced food quality. Tools that provide insights into how nutrients are transported in plants would i) guide fertilization strategies to improve productivity and sustainability by synchronizing nitrogen addition with crop demands, and ii) inform farming practices that adapt to the effects of short and long term climate variability. The overall objective of this project is to develop and commercialize a field-deployable sampling and measurement system for high temporal and spatial resolution monitoring of nitrogen transport and transformations in living plants. We propose to couple needle-sized probes installed along the nutrient transport paths in plants to a sensitive and selective monitor. A tool for ease of installation of probes into the stem, roots, and leaf veins of plants will be developed. The system will yield nondestructive observation of the transport of important nitrogen species over a plant's growth cycle.The proposed research and development will result in a monitoring system for real-time, in situ mapping of nutrients. It will be marketed to the plant science community which needs new tools to advance the understanding of nitrogen cycling and usage. The market is large due to the continued need for increased crop productivity, food quality, and climate resilience.
Animal Health Component
20%
Research Effort Categories
Basic
20%
Applied
20%
Developmental
60%
Goals / Objectives
The overall goal of thisresearch and development project is to design, build and deploy a measurement system to observe nutrient transport and transformations in plant roots and shoots with high spatial and temporal resolution. The goal isto couple microdialysis probes installed along nutrient transport paths to a novel detection system utilizing high resolution infrared spectroscopy, to non-destructively observe the real-time transport of inorganic nitrogen over the growth cycle of a plant.Our novel system will integrate microdialysis probes; a method to inject liquid samples into our gas phase monitor; and a sensitive, selective real-time monitor.The technical objectives are todesigna nondestructive sampling system for the quantitative collection of nitrate, nitrate, and ammonium in solutes from plant; design system for the conversion of these species to their gas phase equivalents (i.e., HNO3, HONO, and NH3, respectively); and then quantitative detection of these species.We have identified four important tasks designed to answer the above technical questions and challenges. These tasks and the objectives they address are as follows:Task 1: TILDAS Monitoring of Ammonium-- the objective is to configure and integrate a dual laser instrument with microdialysis (MD) probes for monitoring ammonium, nitrate, and nitrite in vaporized liquid samples.Task 2: Design Microdialysis probe installation approach--- the goal of task 2 is to develop a means to insert microdialysis probes reproducibly and reliably into plant matter. The objective is to design and test a process to insert probes in four main plant components: roots, stems, leaves (veins), and fruit.Task 3: Laboratory Testing with Plants-- the goal of this task is to test the MD probes' ability to determine concentrations and fluxes qualitatively and quantitatively in a real-world plant system. We plan to perform these tests on a tomato plant, which are easy to grow, have larger xylem diameters and flow rates, high nitrate concentrations, and produce fruit that is easy to inject an MD probe into.Task 4: Phase II Preliminary Design--the goal of Task 4 is to outline the preliminary design of the Phase II sampling and analysis system to investigate nitrogen transport and transformations in plants. The objective is a design that integrates (1) array of MD probes; (2) TILDAS with heated inlet and low volume heated cell; (3) valving and sampling line; (4) solftware and interface for autonomous operation.
Project Methods
The methods of this project will leverage our recent advances using microdialysis probes coupled to trace gas optical sensors to quantify dissolved solutes in soil water and extend this technology to measure solutes in plant roots, stems, leaves, and fruits. Below we will describe each aspect of this approach.Microdialysis ExtractionMicrodialysis (MD) probes are non-destructive, minimally disruptive tools used to interrogate the composition of fluids in a range of medical and environmental applications. Each MD probe consist of a cylindrical membrane (typically ~500 µm in diameter and 1-3 cm length) that allows for transport of solutes across the membrane from regions of high concentration to regions of low concentration. Deionized water is injected into a concentric smaller tube, which then flows along the outer region of the tube to contact the surrounding fluid and exchange solutes, producing dialysate for chemical testing. Typical flow rates through the probe are 0.1-10 µL/min and can be controlled with either a syringe pump or a positive displacement pump.Although initially developed for sampling interstitial fluid for medical applications, microdialysis probes have been used extensively in diverse environmental science measurements. The nature of microdialysis measurements, namely water flowing against a semipermeable membrane of fixed area, allows for two measurement modes: retrieving solute concentrations or quantifying solute fluxes. Both measurement modes are valuable in different applications; fluxes can provide information about rates of nutrient availability, while concentration measurements afford mm-scale mapping of solutes throughout plant tissues. The proposed system will be capable of measuring either solute concentrations or fluxes.A central focus of Phase I will be to determine best probe installation practices for plants, optimal flow rates for representative fluxes or concentrations, and best methods to move and manage the dialysate. This includesdeveloping a means to insert microdialysis probes reproducibly and reliably into plant matter.Coupling to a Laser SpectrometerThe Aerodyne Tunable Infrared Laser Direct Absorption Spectrometer (TILDAS) is a flexible, sensitive, and selective trace gas detection platform well-suited for this application. In atmospheric sampling applications, a flow of gas (e.g., ~1 liter per minute) is directed through a low-pressure (~10-50 Torr) multipass absorption cell that is coupled to a high-resolution infrared laser. The laser wavelength is software-controlled to scan over the rovibrational absorption of the analyte, providing fast, precise, and accurate gas concentrations 17. However, because the cell operates at low pressure and can be heated to >150 °C, it is also amenable to injections of small liquid samples, generally 1-25 µL. In the proposed application 10 µL of dialysate can be directly injected into a hot, evacuated cell to produce a ~20 Torr trapped sample for analysis. NO3-, NO2-, and NH4+ are detected in their neutralized forms, nitric acid (HNO3), nitrous acid (HONO) and ammonia (NH3). The vapor pressure of these species can be further enhanced by slightly altering the pH of the sample before evaporation. Acidification shifts the acid dissociation equilibrium of NO3- and NO2-, toward HNO3 and HONO, respectively, while alkalinization of NH4+ drives the equilibrium toward NH3. As the droplets of sample in the cell rapidly evaporate, the concentration of the solutes will exponentially rise, driving them to their neutralized forms and increasing their partial pressure (by Henry's law). We note that this approach is also amenable to detection of other species, including carbonates, acetates, and organic acids.We have previously demonstrated the ability to quantify NO3- and NO2- solutions with high sensitivity by injecting small liquid samples into a hot, evacuated TILDAS cell. During Phase I we will i) install the appropriate pair of lasers for detection of NO3-, NO2- and NH4+ in an existing TILDAS; and ii) further refine the dialysate injection technique with specific focus on quantitative detection of NH4+.Flow systemWhile bringing a liquid sample from the probe to the TILDAS is straightforward, the proposed system will incorporate alternating addition of either an acid or base to the dialysate, and utilizes a probe array, enabling nutrient mapping of solutes in various plant components. Aerodyne has extensive experience with similar challenges in soil gas sampling, and more recently with MD probes in soils, all of which utilize selector and trapping valves (VICI Valco). These allow for up to 16 probes to be attached to one analyzer, and controlled by the TILDAS software, TDLWintel. During Phase I we will build upon our extensive knowledge of these valves to optimize and automate them for liquid handling in this application.Testing with real plantsWe willtest the MD probes' ability to determine concentrations and fluxes qualitatively and quantitatively in a real-world plant system. We plan to perform these tests on a tomato plant, which are easy to grow, have larger xylem diameters and flow rates, high nitrate concentrations, and produce fruit that is easy to inject an MD probe into. A sequence of tests will include plant stems in which we quantify ability to recover concetrations and fluxes; dye tests as an analyte instead of nitrate or ammonium; nitrate/ammonium recovery demonstrations; and finally full plants tests. These tests will evaluate success of the methods..