Root Distribution Research Articles

A class of natural pinus koraiensis population system with time delay and diffusion term

In this paper, we consider the long-term sustainability of the northeast Korean pine. We propose a class of natural Korean pine population system with time delay and diffusion term. First, by analyzing the roots distribution of the characteristic equation, we study the stability of the model system with diffusion terms and prove the occurrence of Hopf bifurcation. Second, we introduce lactation time delay into a population model with a diffusion term, based on stability theory of ordinary differential equation, norm form methods and center manifold theorem, the stability of bifurcating periodic solutions and the relevant formula for the direction of Hopf bifurcation are given. Finally, some numerical simulations are given.

Design of the PID temperature controller for an alkaline electrolysis system with time delays

Electrolysis systems use proportional–integral–derivative (PID) temperature controllers to maintain stack temperatures around set points. However, because of heat transfer delays in electrolysis systems, the manual tuning of PID temperature controllers is time-consuming, and temperature oscillations often occur. This paper focuses on the design of the PID temperature controller for an alkaline electrolysis system to achieve fast and stable temperature control. A thermal dynamic model of an electrolysis system is established in the frequency domain for controller designs. Based on this model, the temperature stability is analysed by the root distribution, and the PID parameters are optimized considering the temperature overshoot and the settling time. The performance of the optimal PID controllers is experimentally verified. Furthermore, the simulation results show that the before-stack temperature should be used as the feedback variable for small lab-scale systems to suppress stack temperature fluctuations, and the after-stack temperature should be used for larger systems to improve the economy. This study helps ensure the temperature stability and control of electrolysis systems.

Global Stability of a MERS-CoV Infection Model with CTL Immune Response and Intracellular Delay

In this paper, we propose and study a Middle East respiratory syndrome coronavirus (MERS-CoV) infection model with cytotoxic T lymphocyte (CTL) immune response and intracellular delay. This model includes five compartments: uninfected cells, infected cells, viruses, dipeptidyl peptidase 4 (DPP4), and CTL immune cells. We obtained an immunity-inactivated reproduction number R0 and an immunity-activated reproduction number R1. By analyzing the distributions of roots of the corresponding characteristic equations, the local stability results of the infection-free equilibrium, the immunity-inactivated equilibrium, and the immunity-activated equilibrium were obtained. Moreover, by constructing suitable Lyapunov functionals and combining LaSalle’s invariance principle and Barbalat’s lemma, some sufficient conditions for the global stability of the three types of equilibria were obtained. It was found that the infection-free equilibrium is globally asymptotically stable if R0≤1 and unstable if R0>1; the immunity-inactivated equilibrium is locally asymptotically stable if R0>1>R1 and globally asymptotically stable if R0>1>R1 and condition (H1) holds, but unstable if R1>1; and the immunity-activated equilibrium is locally asymptotically stable if R1>1 and is globally asymptotically stable if R1>1 and condition (H1) holds.

Inferring Vertical Tree Growth Direction of Samanea saman and Delonix regia Trees with the Pattern of Lateral Root Distribution Using the Root Detector

The root system is important for supporting tree growth and stability. In this study, we analyzed the relationship between the main lateral root distribution pattern and vertical tree growth direction based on root detection and analysis of tree morphometry. Tree growth represented by morphometric data were measured directly, and the root distribution was identified using a sonic Root Detector. Sixteen targeted trees (eight Samanea saman and eight Delonix regia trees) in an urban area landscape were selected in this study. The Root Detector revealed that the average sonic velocity of lateral roots was 676.88 m∙s−1 for S. saman and 865.32 m∙s−1 for D. regia. For root distribution, Root Detector determined the average numbers of main lateral roots for S. saman and D. regia, which were 6 and 10, respectively. Based on correlation analysis, significant relationships were found between tree root sonic velocity and the degree of lean, height, and diameter of the tree; meanwhile the relationship between crown diameter and slenderness were not significant. Findings confirmed that, in relation to the root distribution and the growth direction of the trunk and crown, the lateral root is mainly distributed in the opposite direction of the tree lean rather than crown growth direction.

L-phenylalanine in potato onion (Allium cepa var. aggregatum G. Don) root exudates mediates neighbor detection and trigger physio-morphological root responses of tomato.

Despite numerous recent insights into neighbor detection and belowground plant communication mediated by root exudates, less is known about the specificity and nature of substances within root exudates and the mechanism by which they may act belowground in root-root interactions. Here, we used a coculture experiment to study the root length density (RLD) of tomato (Solanum lycopersicum L.) grown with potato onion (Allium cepa var. aggregatum G. Don) cultivars with growth-promoting (S-potato onion) or no growth-promoting (N-potato onion) effects. Tomato plants grown with growth-promoting potato onion or its root exudates increased root distribution and length density oppositely and grew their roots away as compared to when grown with potato onion of no growth-promoting potential, its root exudates, and control (tomato monoculture/distilled water treatment). Root exudates profiling of two potato onion cultivars by UPLC-Q-TOF/MS showed that L-phenylalanine was only found in root exudates of S-potato onion. The role of L-phenylalanine was further confirmed in a box experiment in which it altered tomato root distribution and forced the roots grow away. In vitro trial revealed that tomato seedlings root exposed to L-phenylalanine changed the auxin distribution, decreased the concentration of amyloplasts in columella cells of roots, and changed the root deviation angle to grow away from the addition side. These results suggest that L-phenylalanine in S-potato onion root exudates may act as an "active compound" and trigger physio-morphological changes in neighboring tomato roots.

Role of reactive oxygen species in the modulation of auxin flux and root development in Arabidopsis thaliana.

Reactive oxygen species (ROS) play a dual role in plant biology, acting as important signal transduction molecules and as toxic byproducts of aerobic metabolism that accumulate in cells upon exposure to different stressors and lead to cell death. In plants, root architecture is regulated by the distribution and intercellular flow of the phytohormone auxin. In this study, we identified ROS as an important modulator of auxin distribution and response in the root. ROS production is necessary for root growth, proper tissue patterning, cell growth, and lateral root (LR) induction. Alterations in ROS balance led to altered auxin distribution and response in SOD and RHD2 loss-of-function mutants. Treatment of Arabidopsis seedlings with additional sources of ROS (hydrogen peroxide) or an ROS production inhibitor (diphenylene iodonium) induced phenocopies of the mutants studied. Simultaneous application of auxin and ROS increased LR primordia induction, and PIN-FORMED protein immunolocalization further demonstrated the existing link between auxin and ROS in orchestrating cell division and auxin flux during root development. In Arabidopsis roots, genetic alterations in ROS balance led to defective auxin distribution and growth-related responses in roots. Exogenous hydrogen peroxide alters the establishment of the endogenous auxin gradient in the root meristem through regulation of PIN-FORMED polarity, while the simultaneous application of hydrogen peroxide and auxin enhanced LR induction in a dose- and position-dependent manner through activation of cell division.

Apple–Soybean Mixed Stand Increased Fine Root Distribution and Soil Water Content with Reduced Soil Nitrate Nitrogen

In dryland agroecosystems, intercropping fruit trees with legumes is often an important option for maintaining and improving soil N quality and fertility. The relationships of fine root length density (FRLD), soil water content (SWC), and soil NO3−-N content (SNC) in agroforestry systems is essential for optimal orchard management. Our objective was to understand the temporal and spatial dynamics of FRLD, SWC, and SNC in an apple–soybean intercropping system and competition between species for ecological niches. We established an orchard with soybean and apple, including monoculture apple (MA), monoculture soybean (MS), and apple–soybean intercrop (AS) treatments. We collected data on the distribution of FRLD, SWC, SNC, and productivity under the MA, AS, and MS from 2020 to 2021. This study showed that AS had more FRLD compared to MA, and intercropping apple (IA) FRLD increased at 20–60 cm soil depth at 50 and 100 cm from the tree and decreased at 0–40 cm soil depth at 150 and 200 cm from the tree. Intercropping increased the SWC of the system and decreased the SNC, and the effect of intercropping was concentrated in the soybean cover area. The competition between apple and soybean reached its maximum at soybean seed filling stage, with competition occurring mainly at 100 cm from the tree and at 0–20 cm soil depth. Intercropping affected soybean growth and also reduced soybean yield with a land equivalent ratio = 1.45. By understanding the dynamics of subsoil resources in the apple–soybean intercropping system and interspecific competition, we can provide a theoretical basis for exploring the potential of sustainable intensification of agroforestry systems.

Asymptotic root distribution of Charlier polynomials with large negative parameter

We analyze the asymptotic distribution of roots of Charlier polynomials with negative parameter depending linearly on the index. The roots cluster on curves in the complex plane. We determine implicit equations for these curves and deduce the limiting density of the root distribution supported on these curves. The proof is based on a determination of the limiting Cauchy transform in a specific region and a careful application of the saddle point method. The obtained result represents a solvable example of a more general open problem.

Effects of different nutrient compensation treatments following forest fuel extraction on biomass of young Norway spruce (Picea abies (L.) Karst.)

Whole tree harvesting of forests may require compensation for losses of nutrients and alkalinity. The effects of three different practical ameliorative methods on spruce allometry, total biomass, and nutrient uptake were studied in an experiment in a 3-year-old Norway spruce ( Picea abies (L.) Karst.) stand in south-west Sweden. The treatments were one application of the fine fraction of logging residues, one application of granulated wood ash, two applications of an N-free vitality fertiliser, and untreated control. Analysis of covariance showed that spruce needle and stem allometry depended on treatment. Spruce fine root allometry was very variable, showing no discernible effect of treatment. Fine root distribution was shallower in treatments with higher graminoid biomass (vitality and wood ash). Vitality treatment increased average concentrations of Ca, Mg, and Zn in spruce total biomass. Ash treatment only increased the Zn concentration. The average N concentration was similar between treatments. Spruce total biomass per unit area was inversely correlated with graminoid biomass. Measurements of N uptake in spruce and graminoid biomass indicated that there was competition for N between spruce and graminoids. Thus, the effect of nutrient compensation on competition needs to be considered when predicting the effect on the growth of the target species.

Quantification of the three-dimensional root system architecture using an automated rotating imaging system

BackgroundCrop breeding based on root system architecture (RSA) optimization is an essential factor for improving crop production in developing countries. Identification, evaluation, and selection of root traits of soil-grown crops require innovations that enable high-throughput and accurate quantification of three-dimensional (3D) RSA of crops over developmental time.ResultsWe proposed an automated imaging system and 3D imaging data processing pipeline to quantify the 3D RSA of soil-grown individual plants across seedlings to the mature stage. A multi-view automated imaging system composed of a rotary table and an imaging arm with 12 cameras mounted with a combination of fan-shaped and vertical distribution was developed to obtain 3D image data of roots grown on a customized root support mesh. A 3D imaging data processing pipeline was developed to quantify the 3D RSA based on the point cloud generated from multi-view images. The global architecture of root systems can be quantified automatically. Detailed analysis of the reconstructed 3D root model also allowed us to investigate the Spatio-temporal distribution of roots. A method combining horizontal slicing and iterative erosion and dilation was developed to automatically segment different root types, and identify local root traits (e.g., length, diameter of the main root, and length, diameter, initial angle, and the number of nodal roots or lateral roots). One maize (Zea mays L.) cultivar and two rapeseed (Brassica napus L.) cultivars at different growth stages were selected to test the performance of the automated imaging system and 3D imaging data processing pipeline.ConclusionsThe results demonstrated the capabilities of the proposed imaging and analytical system for high-throughput phenotyping of root traits for both monocotyledons and dicotyledons across growth stages. The proposed system offers a potential tool to further explore the 3D RSA for improving root traits and agronomic qualities of crops.

Root distribution, soil water depletion, and water productivity of sweet corn under deficit irrigation and biochar application

Root modifications can play a vital role in crop adjustments to soil water deficit. It is important to understand root growth and soil water depletion patterns to develop effective cropping systems, especially in semi-arid regions like Texas High Plains (THP). This study evaluated root growth, soil water depletion, and water productivity (WP) of sweet corn under three deficit irrigation treatments [100 %, 70 % and 40 % crop evapotranspiration (ETc)] and biochar application (hardwood and softwood). The experimental units were replicated 4 times in a split-plot design. The results revealed no interaction between irrigation and biochar treatments for almost all measured parameters. The 70 % ETc treatment increased the root length density (RLD) over 100 % ETc during 2019, while no differences were observed among irrigation treatments in 2020. Both deficit irrigations (70 % and 40 % ETc) increased soil water depletion compared to 100 % ETc, the highest being in 40 % ETc. The 70 % ETc maintained a similar yield and increased WP by 21 % compared to 100 % ETc across two years. However, 40 % ETc resulted in significant decline in yield and WP in 2020. The hardwood biochar increased RLD over no biochar treatment without affecting the soil water status and WP. Long-term studies are needed to investigate biochar effects beyond two years of application. In case of limited water availability, 70 % ETc can be recommended as an alternative to 100 % ETc in the THP of the US.

Response of root growth and distribution of maize plants to foliar-sprayed antitranspirant and soil-amended hydrogel polymer

Root growth and development of maize (Zea mays L.) is an important process in determining grain yield. The effects of combined fulvic acid (FA, potassium humate as FA source) and super absorbent polymer (SAP) uses on maize root growth and yield were studied. A 2×3 factorial field experiment was applied by combining two SAP doses (0, 45 kg ha-1) and three FA rates (0, 1, and 2 g L-1) over 2 yr. Super absorbent polymer was applied to upper 20 cm soil layer at sowing, and FA solutions (1 or 2 g L-1, corresponding to FA1 and FA2) were sprayed onto the canopy three times during growing season. Root parameters, including root biomass, root length density (RLD), root surface-area density (RSD), and root diameter, were determined in the top 40 cm soil layer. Relative to control plants, both chemicals significantly increased root biomass, but these effects were not significantly different from their combined use. Compared to individual FA or SAP treatment, combined applications increased RLD and RSD in 0-20 cm depth. The combined SAP and FA2 improved RLD at 0-10 cm by 32% compared to FA2 treatment alone and by 82% compared to non-chemicals control plots over 2 yr. Averaged root diameters also significantly increased in the 40 cm soil layer in FA and SAP treatments alone compared to control, but they were not significantly different with the combined treatment. Similar patterns were found for maize yield each year. The combined application of SAP (45 kg ha-1) and FA2 (2 g L-1) greatly increased root length density and biomass than their individual application, and it could be suitable for high production of maize grown under low rainfall conditions.

Increasing Application Efficiency of Supplemental Irrigation by Adding the Water in the Root Distribution Zoon

Increasing Application Efficiency of Supplemental Irrigation by Adding the Water in the Root Distribution Zoon

Optimal strategies of the age-specific vaccination and antiviral treatment against influenza

Influenza, caused by any of several human influenza viruses, is a highly contagious respiratory disease and it produces millions of cases worldwide. Vaccination and antiviral treatment are two main biomedical interventions for curtailing influenza spread. In this paper, an age-structured SVIR influenza model is used to take account for the efficacy of vaccination and antiviral treatment. Next, the stability of the disease-free equilibrium is captured by analyzing the root distributions of the characteristic equation and the existence of the endemic equilibrium is established by employing a generalized fixed point theorem. Moreover, the consideration of the availability of medical resources is settled as an optimal control problem to investigate the cost-effective interventions for the guidelines of optimal policy selection. Numerical simulations show that the outcomes of optimal control are characterized by the cost of control strategies, age structured of hosts and the different measures of influenza intervention. As a result of consequences, we recommend projecting vaccination at the early period and the implement of therapy at the entire infectious course, to slow down or eradicate influenza transmission.

Cations make a difference: Soil nutrient patches and fine‐scale root abundance of individual species in a mountain grassland

Abstract Root densities in the field vary at the centimetre scale, but we have no information on whether this variation is linked to the variation in nutrient concentrations and availability. Roots of many species are able to proliferate in nutrient‐rich patches in controlled conditions in culture, but because data on nutrient concentrations and, in particular, on their temporal stability in the field are scarce, we do not know to what extent root distribution in the soil bears traces of such a response. Here, we linked centimetre‐scale measurements of soil nutrient concentrations over 6 weeks with estimation of root biomass and its species composition at the same points to determine whether there is any association between the two. In addition to phosphorus, nitrate and ammonium, we determined the concentrations of metal cations (magnesium, calcium and potassium). We used qPCR to determine the quantities of individual species in the root biomass samples. We found that calcium and magnesium (and to a lesser degree phosphorus and potassium) showed fine‐scale patchiness that was stable throughout the study (6 weeks) and was consistent over all these elements. Nutrient patches were associated with high root biomass and the occurrence of roots of several species. Such patches are formed primarily by elements with known low mobility in soil (cations, phosphorus). In contrast, nitrogen ions showed overwhelmingly high temporal variation with no relationship between root density and nitrogen concentration. Soil nutrient concentrations, thus, constitute a multidimensional signal. Some elements strongly vary in time, while some are much more stable and, thus, form stable patches that permit root response over periods of weeks or months. Among them, calcium and magnesium play an important role in forming soil heterogeneity at a scale comparable with the scale at which fine root densities also vary. As these cations affect a number of plant functions, their association with higher root densities confirms their role in the growth dynamics of terrestrial ecosystems. Read the free Plain Language Summary for this article on the Journal blog.

Soil Compaction and Maize Root Distribution under Subsoiling Tillage in a Wheat–Maize Double Cropping System

Huang-Huai-Hai Plain is the most important region for grain production in China. In this area, long-term rotary tillage in winter wheat and no tillage in summer maize have significantly increased soil bulk density, which impede maize root growth and reduce the grain yield. Subsoiling tillage is an effective practice to improve soil properties and crop growth. The objective of this study was to investigate the integrated effects of subsoiling tillage in both winter wheat and summer maize seasons on soil bulk density, maize root growth and spatial distribution. A two-year field experiment was conducted in winter wheat–summer maize rotation system. Tillage treatments included rotary tillage (RT) and subsoiling tillage (ST) in wheat season, and no tillage (NT), inter–row subsoiling tillage (STIR), and on–row subsoiling tillage (STOR) in maize season. It was found that in the second year, i.e., in 2018, ST decreased soil bulk density by 3.87% and increased porosity by 5.86% at 30–40 cm soil depth at maize maturity. Meanwhile, maize root length density at 40–50 cm depth increased by 30.00% and grain yield increased by 4.70% under ST. In maize season tillage treatments, STOR decreased soil bulk density by 4.52% and increased soil porosity by 6.96% at 20–30 cm soil depth. Compared with NT, the STOR significantly increased maize root length density at 20–30 cm soil depth by 78.45%, and increased root length density in a horizontal area 0–10 cm for both years, with a significant increase of 58.89% in 2018. Therefore, this study demonstrated that in the Huang-Huai-Hai Plain, which has a tidal soil type, subsoiling tillage in winter wheat season and on–row subsoiling tillage in maize season can loosen the soil and improve vertical extension of maize root system in the soil.

Maize straw mulching with no-tillage increases fertile spike and grain yield of dryland wheat by regulating root-soil interaction and nitrogen nutrition

Straw mulching increases soil water availability, but the influence of tillage practices with straw mulching on soil water, soil nitrogen, root distribution, and the physiological response of wheat plants is poorly understood. Field experiments (2013–2017) were conducted to determine the combined effects of straw mulching (0 and 8,000 kg ha−1) and tillage methods (no-tillage, rotary tillage, and plow tillage) on soil water, N, root distribution, plant N nutrition, tiller capability, and grain yield of dryland wheat. Straw mulching with no-tillage showed higher soil moisture, mineral N, and Olsen-P content than no-mulch with rotary tillage or plow tillage. These changes increased the total root length and surface area in the 0–20 cm soil layer but not in the 20–40 cm soil layer. Topsoil foraging strategies of root increased total N uptake, wheat return N from straw, and N balance while reducing N surplus, indicating that maize straw harvesting by mulching with no-tillage leads to a more efficient N recycling in the winter wheat–summer maize rotation system. Straw mulching with no-tillage showed greater aboveground plant dry mass and shoot N%, leading to increased plant N nutrition, tillering capability, and grain yield. Our results indicated that maize straw mulch with no-tillage increased fertile spike and grain yield by increasing soil water and N availability and maximizing root-soil interactions among the different combinations studied. Maize straw mulching with no-tillage could hence be recommended to dryland farming communities to transition from rotary tillage to a no-tillage conservation system and to increase soil and crop productivity in the maize-wheat rotation system.

Biological Nitrogen Fixation of Cowpea in a No-Till Intercrop under Contrasting Rainfed Agro-Ecological Environments

Nitrogen (N) availability under no-till intercropping systems has not been widely investigated in diverse agro-ecological regions in Limpopo Province. Two seasons of rainfed experiments were conducted during 2018/19 and 2020/21 in a 2 × 4 × 2 factorial design to measure the biological nitrogen fixation (BNF) ability of cowpea in an intercropping system with four grain sorghum cultivars at two test locations, Ofcolaco and Syferkuil, of Limpopo Province using the natural abundance technique. The cowpea nitrogen isotope composition (δ 15N‰) ranged from 0.2 ‰ to 4‰ at Ofcolaco, whereas at Syferkuil, the range was 2 ‰ to 7 ‰. The N derived from air (Ndfa) was from 35% to 92% at Ofcolaco and 4% to 70% at Syferkuil during the two cropping seasons. The amount of N2 fixed across locations and seasons ranged from 1 kg ha−1 to 71 kg ha−1. In the intercropping system, cowpea fixed more N at higher densities compared with lower densities at the two experimental sites. Biomass was significantly correlated with N accumulated by cowpea (r2 > 0.9) at all locations and across seasons. N accumulated in sole cultures was 30% more at Ofcolaco and 36% more at Syferkuil compared with binary cultures. Furthermore, the treatment combination, cowpea density, as well as cropping system, significantly affected N fixation and accumulation. For high productivity, cowpea intercrop with grain sorghum cultivar Enforcer is recommended, as both crops complemented each other when intercropped. The research should investigate further the root distribution and biomass production of sorghum and cowpea, as well as their impact on N intake.

Root Location and Root Diameter Estimation of Trees Based on Deep Learning and Ground-Penetrating Radar

A full understanding of the growth and distribution of tree roots is conducive to guiding precision irrigation, fertilization, and other agricultural work during agricultural production. Detecting tree roots with a ground-penetrating radar is a repeatable detection method that does no harm to the earth surface and tree roots. In this research, a rapid and accurate automatic detection was conducted on hyperbolic waveforms formed by root targets in B-scan images based on YOLOv5s. Following this, the regions of interest containing target hyperbolas were generated. Three or more coordinate points on the hyperbola were selected according to the three-point fixed circle (TPFC) method to locate the root system and estimate the root diameter. The results show that the accuracy of hyperbola detection using YOLOv5s was 96.7%, the recall rate was 86.6%, and the detection time of a single image was only 13 ms. In the simulation image, the TPFC method was used to locate the root system and estimate the root diameter through three different frequency antennas (500 MHz, 750 MHz, and 1000 MHz). A more accurate result was obtained when the antenna frequency was 1000 MHz, with the average distance error of root system positioning being 3.17 cm, and the slope and R2 of the linear fitting result between the estimated root diameter and the actual one being 1.029 and 0.987, respectively. Verified by the pre-buried root test and wilderness field test, both root localization and root diameter estimation in our research were proved to gain good results and conform to the rules found in simulation experiments. Therefore, we believe that this method can quickly and accurately detect the root system, locate and estimate the root diameter, and provide a new perspective for the non-destructive detection of the root system and the three-dimensional reconstruction of the root system.

Ant invasion is associated with lower root density and different root distribution of a foundational savanna tree species

Ant invasion is associated with lower root density and different root distribution of a foundational savanna tree species