Quantitative 3D Analysis of Plant Roots Growing in Soil Using Magnetic Resonance Imaging

Precise measurements of root system architecture traits are an important requirement for plant phenotyping. Most of the current methods for analyzing root growth require either artificial growing conditions (e.g. hydroponics), are severely restricted in the fraction of roots detectable (e.g. rhizotrons), or are destructive (e.g. soil coring). On the other hand, modalities such as magnetic resonance imaging (MRI) are noninvasive and allow high-quality three-dimensional imaging of roots in soil. Here, we present a plant root imaging and analysis pipeline using MRI together with an advanced image visualization and analysis software toolbox named NMRooting. Pots up to 117 mm in diameter and 800 mm in height can be measured with the 4.7 T MRI instrument used here. For 1.5 l pots (81 mm diameter, 300 mm high), a fully automated system was developed enabling measurement of up to 18 pots per day. The most important root traits that can be nondestructively monitored over time are root mass, length, diameter, tip number, and growth angles (in two-dimensional polar coordinates) and spatial distribution. Various validation measurements for these traits were performed, showing that roots down to a diameter range between 200 μm and 300 μm can be quantitatively measured. Root fresh weight correlates linearly with root mass determined by MRI. We demonstrate the capabilities of MRI and the dedicated imaging pipeline in experimental series performed on soil-grown maize (Zea mays) and barley (Hordeum vulgare) plants

Safe Brain Tumor Resection Does not Depend on Surgery Alone - Role of Hemodynamics

Aim of this study was to determine if perioperative hemodynamics have an impact on perioperative infarct volume and patients' prognosis. 201 cases with surgery for a newly diagnosed or recurrent glioblastoma were retrospectively analyzed. Clinical data and perioperative hemodynamic parameters, blood tests and time of surgery were recorded. Postoperative infarct volume was quantitatively assessed by semiautomatic segmentation. Mean diastolic blood pressure (dBP) during surgery (rho -0.239, 95% CI -0.11 - -0.367, p = 0.017), liquid balance (rho 0.236, 95% CI 0.1-0.373, p = 0.017) and mean arterial pressure (MAP) during surgery (rho -0.206, 95% CI -0.07 - -0.34, p = 0.041) showed significant correlation to infarct volume. A rank regression model including also age and recurrent surgery as possible confounders revealed mean intraoperative dBP, liquid balance and length of surgery as independent factors for infarct volume. Univariate survival analysis showed mean intraoperative dBP and MAP as significant prognostic factors, length of surgery also remained as significant prognostic factor in a multivariate model. Perioperative close anesthesiologic monitoring of blood pressure and liquid balance is of high significance during brain tumor surgery and should be performed to prevent or minimize perioperative infarctions and to prolong survival

Influence of the Ag to Cu ratio in Cu-Ag alloy foils on the product distribution for the electrochemical reduction of CO2 Research

This study dealt with the CO2RR product distributions of Cu-Ag alloys with different compositions at different current values. For this reason, the CO2RR activities of the utilized Cu-Ag alloys were previously assessed. The product distributions were obtained through the investigation of chromatography measurements, whereas the activity was investigated through electrochemical measurements. The increase of the product selectivity to CO and C2-C3-oxygenates compared to a pure Cu catalyst was especially of interest, while the product selectivity to H2, HCOO- and hydrocarbons was expected to decrease as a result

Design and construction of mobile, small scale devices for MRI and NMR of plants in the field

In this contribution we present the development of a mobile, fully integrated MR plant imager that can be used in greenhouse and field. To allow imaging of branches and stems an open C-shaped permanent magnet was constructed. In the design of the magnet, pole gap width and resilience against handling were prioritized over homogeneity and field strength. To overcome the adverse effects of short T2* that may result from these design choices multi-spin echo imaging strategies were employed, using short echo times and high spectral widths [1]. To still achieve microscopic resolution under these constraints requires fast switching field gradients, driven by strong and fast gradient amplifiers. While small-scale spectrometers and RF amplifiers are readily available, appropriate small-scale gradient amplifiers or designs thereof currently are not. We therefore constructed a small, 3-channel gradient amplifier on the basis of a conventional current-controlled AB amplifier design. Tailored to our small low-impedance gradient coils the amplifiers could remain small, suitable for battery driven operation and still meet our requirements regarding switching speed, power and duty cycle. The finished device weighs 5 kg and is capable of delivering 40 A gradient pulses of up to 6 ms in duration, sufficient for micro imaging and flow mapping. With all components built onto an aluminum hand trolley, the entire imaging setup weighs 45 kg and is small enough to fit into a car [2]. We demonstrate the mobility and utility of the device imaging quantitative water content and T2, first of an apple tree in an orchard; second, of a beech tree during spring leaf flushing in a greenhouse. Without imaging such systems can also be used as NMR relaxometer. Utilizing a reinterpretation of the solid fat content method, dry matter deposition into growing cereal spikes and bean pods can be monitored in a straightforward, sensor-like manner [3]. 1. Meixner, M., et al., A small-scale MRI scanner and complementary imaging method to visualize and quantify xylem embolism formation. New Phytologist, 2020. 226(5): p. 1517-1529.2. Meixner, M., et al., An integrated magnetic resonance plant imager for mobile use in greenhouse and field. Journal of Magnetic Resonance, 2021. 323: p. 106879.3. Windt, C.W., et al., A Mobile NMR sensor and relaxometric method to non-destructively monitor water and dry matter content in plants. Frontiers in Plant Science, 2021. 12(18)

MOBILE NMR FOR THE PLANT SCIENCES: ENGINEERING FOR SENSOR-LIKE, OUTDOOR USE

Some of the most important indicators of plant performance and yield are water content, dry matter content and sap flow velocity. None of these parameters are easy to measure without harvesting or destroying the plant, yet have shown to be fairly straightforward to measure by means of NMR relaxometry, MR imaging and MR velocimetry. It would therefore be attractive to make such NMR methods available for agronomic outdoor use. However, despite the exciting developments that have been made in the realm of mobile NMR in the last decade, the application of NMR methods on plants has mostly remained restricted to the laboratory. The most important limitations for more widespread use are cost, complexity and poor suitability for outdoor and glasshouse use.The largest challenges in bringing NMR to the field are in the hardware. The magnet needs to be light and small enough to be mobile, yet for integrative (non-unilateral) measurements should have a homogeneous region that is large enough to contain the object of interest, and should offer access to the samples of interest - stems, branches or fruit. The RF coil, the gradient set (if applicable) and the shielding should be open or openable as well. It further should be possible to mount the system in an arbitrary position in, under or around the plant part of interest. Finally, the setup should be robust and be able to cope with the presence of moisture. Possibly the most challenging factor when working under field conditions is temperature. Not only the magnet should be temperature controlled or temperature stable, so should the spectrometer. The temperature of the sample, on the other hand, should (if possible) be allowed to change with the environment, but should be measured and recorded in order to compensate for temperature induced changes in the Boltzmann equilibrium. In this contribution we present a number of ways to address these challenges and bring mobile NMR to the field. We tested a number of magnet designs and explored their suitability for use in a number of simple NMR devices. For sensor-like applications we explored the use of simplified relaxometric methods to estimate water- and solid content. Such measurements could be done in a highly automated fashion, either leaving the spectrometer to run autonomously for days or controlling it remotely, and were found to produce data of surprisingly high information content on subjects ranging from growing seeds to droughted trees. We further demonstrate the application of a mobile low-end NMR device as a fully battery-driven imager

Root water uptake in relation to plant transpiration

Typically, root water uptake (RWU or Utot) is said to be driven by transpiration (Tr). It is however more accurate to state that transpiration causes a reduction in leaf water content that reduces the leaf water potential such that a water potential gradient builds up between leafs and soil water, such that water can be extracted from the soil. For herbaceous plants, the amount of water that is hereby lost is typically assumed to be negligible so the plant can be treated as a resistive system. In how far this is true is open to discussion as quantifying shoot water changes is not easily feasible, especially when the soil-root system is drying out. A balance cannot observe water moving between the soil and the shoot and shoots have empty spaces such that 3D cameras provide an incomplete picture. Shoot weight determination requires that the amount of soil water is independently assessed to discriminate between the two pools of water. This can be achieved when a balance is combined with a Soil Water Profiler (SWaP) on the same soil-plant system. The precision of the SWaP is comparable to that of an expensive balance (3 most of the transpired water stems from the shoot, not from root water uptake, indicating that Tr is a poor proxy for RWU for pot experiments where soil is drying at a rate of ~5% per day at well watered conditions. This is very important for calculations of root conductance during drying scenarios. We found significant differences between sunflower sensitivity to soil drying as compared to faba beans that are somewhat more sensitive. We also present data that shows that the delay between Tr and local water uptake is rather dependent on depth and not so much dependent on local pF, which is typically lower for shallow sections of the pot. This may potentially be explained by loss of root water when Tr increases with light, analogous to shoot water losses, as the soil dries