Root Environment Research Articles

Ultra-Wideband Microwave Imaging System for Root Phenotyping.

The roots are a vital organ for plant growth and health. The opaque surrounding environment of the roots and the complicated growth process means that in situ and non-destructive root phenotyping face great challenges, which thus spur great research interests. The existing methods for root phenotyping are either unable to provide high-precision and high accuracy in situ detection, or they change the surrounding root environment and are destructive to root growth and health. Thus,we propose and develop an ultra-wideband microwave scanning method that uses time reversal to achieve in situ root phenotyping nondestructively. To verify the method’s feasibility, we studied an electromagnetic numerical model that simulates the transmission signal of two ultra-wideband microwave antennas. The simulated signal of roots with different shapes shows the proposed system’s capability to measure the root size in the soil. Experimental validations were conducted considering three sets of measurements with different sizes, numbers and locations, and the experimental results indicate that the developed imaging system was able to differentiate root sizes and numbers with high contrast. The reconstruction from both simulations and experimental measurements provided accurate size estimation of the carrots in the soil, which indicates the system’s potential for root imaging.

Transcriptional Landscape of Ectomycorrhizal Fungi and Their Host Provides Insight into N Uptake from Forest Soil.

ABSTRACTMineral nitrogen (N) is a major nutrient showing strong fluctuations in the environment due to anthropogenic activities. The acquisition and translocation of N to forest trees are achieved mainly by highly diverse ectomycorrhizal fungi (EMF) living in symbioses with their host roots. Here, we examined colonized root tips to characterize the entire root-associated fungal community by DNA metabarcoding-Illumina sequencing of the fungal internal transcribed spacer 2 (ITS2) molecular marker and used RNA sequencing to target metabolically active fungi and the plant transcriptome after N application. The study was conducted with beech (Fagus sylvatica L.), a dominant tree species in central Europe, grown in native forest soil. We demonstrate strong enrichment of 15N from nitrate or ammonium in the ectomycorrhizal roots by stable-isotope labeling. The relative abundance of the EMF members in the fungal community was correlated with their transcriptional abundances. The fungal metatranscriptome covered Kyoto Encyclopedia of Genes and Genomes (KEGG) and Eukaryotic Orthologous Groups (KOG) categories similar to those of model fungi and did not reveal significant changes related to N metabolization but revealed species-specific transcription patterns, supporting trait stability. In contrast to the resistance of the fungal metatranscriptome, the transcriptome of the host exhibited dedicated nitrate- or ammonium-responsive changes with the upregulation of transporters and enzymes required for nitrate reduction and a drastic enhancement of glutamine synthetase transcript levels, indicating the channeling of ammonium into the pathway for plant protein biosynthesis. Our results support that naturally assembled fungal communities living in association with the tree roots buffer nutritional signals in their own metabolism but do not shield plants from high environmental N levels.IMPORTANCE Although EMF are well known for their role in supporting tree N nutrition, the molecular mechanisms underlying N flux from the soil solution into the host through the ectomycorrhizal pathway remain widely unknown. Furthermore, ammonium and nitrate availability in the soil solution is subject to frequent oscillations that create a dynamic environment for the tree roots and associated microbes during N acquisition. Therefore, it is important to understand how root-associated mycobiomes and the tree roots handle these fluctuations. We studied the responses of the symbiotic partners by screening their transcriptomes after a sudden environmental flux of nitrate or ammonium. We show that the fungi and the host respond asynchronously, with the fungi displaying resistance to increased nitrate or ammonium and the host dynamically metabolizing the supplied N sources. This study provides insights into the molecular mechanisms of the symbiotic partners operating under N enrichment in a multidimensional symbiotic system.

Concentration cell based on electrogenic processes in the root environment

The experimental bioelectrochemical current source based on the concentration gradient of charge carriers in the root environment of plants has been created. A potential difference of about 70 mV is observed in the nutrient solution. It is gradually decreasing due to equalization of concentrations. The voltage increases to 200 mV when plant are placed in a cultivation system as the root system develops due to the intensification of diffusion processes. The potential-forming role of nitrate forms of nitrogen is shown on the example of lettuce grown according to the panoponics technology. The separation of electrical charges by the root system during the life of plants can become an alternative source of green energy. Keywords: rhizosphere, bioelectric potential, panoponics, green energy.

Концентрационный элемент на основе электрогенных процессов в корнеобитаемой среде

The experimental bioelectrochemical current source based on the concentration gradient of charge carriers in the root environment of plants has been created. A potential difference of about 70 mV is observed in the nutrient solution. It is gradually decreasing due to equalization of concentrations. The voltage increases to 200 mV when plant are placed in a cultivation system as the root system develops due to the intensification of diffusion processes. The potential-forming role of nitrate forms of nitrogen is shown on the example of lettuce grown according to the panoponics technology. The separation of electrical charges by the root system during the life of plants can become an alternative source of green energy.

Systemic resistance: Plant responses to interaction with fungal bio-control agents

Systemic resistance in plant against phytopathogens is mainly associated with systemic acquired resistance (SAR) and induced systemic resistance (ISR). SAR and ISR are mechanisms of induced defense that confers long-lasting protection against a broad spectrum of phytopathogens. SAR requires the signal molecule salicylic acid (SA) while ISR signal molecules are jasmonic acid (JA) and ethylene. These are associated with accumulation of pathogenesis-related proteins (PRP) which contribute resistance inside plant. Bio-control fungi (BCF) such as Trichoderma spp. and Pseudomonas spp. are agents that control plant diseases. They have the ability to control numerous soil-borne as well as many foliar and fruit pathogens. BCF also augments nutrient uptake and increase nitrogen use efficiency in crop plants. Some strains also have abilities to improve photosynthetic efficiency of plants. Furthermore, PcPCL1606 has displayed additional traits regarding its fitness in soil and plant root environments such as soil survival, efficient plant root colonization, promotion of plant growth. The present review highlights systemic resistance in plant concerns with SAR and ISR-mediated functional traits, such as enhancement of plant growth and bio-control of phytopathogens.

Inter-Kingdom Networks of Canola Microbiome Reveal Bradyrhizobium as Keystone Species and Underline the Importance of Bulk Soil in Microbial Studies to Enhance Canola Production.

The subterranean microbiota of plants is of great importance for plant growth and health, as root-associated microbes can perform crucial ecological functions. As the microbial environment of roots is extremely diverse, identifying keystone microorganisms in plant roots, rhizosphere, and bulk soil is a necessary step towards understanding the network of influence within the microbial community associated with roots and enhancing its beneficial elements. To target these hot spots of microbial interaction, we used inter-kingdom network analysis on the canola growth phase of a long-term cropping system diversification experiment conducted at four locations in the Canadian Prairies. Our aims were to verify whether bacterial and fungal communities of canola roots, rhizosphere, and bulk soil are related and influenced by diversification of the crop rotation system; to determine whether there are common or specific core fungi and bacteria in the roots, rhizosphere, and bulk soil under canola grown in different environments and with different levels of cropping system diversification; and to identify hub taxa at the inter-kingdom level that could play an important ecological role in the microbiota of canola. Our results showed that fungi were influenced by crop diversification, which was not the case on bacteria. We found no core microbiota in canola roots but identified three core fungi in the rhizosphere, one core mycobiota in the bulk soil, and one core bacterium shared by the rhizosphere and bulk soil. We identified two bacterial and one fungal hub taxa in the inter-kingdom networks of the canola rhizosphere, and one bacterial and two fungal hub taxa in the bulk soil. Among these inter-kingdom hub taxa, Bradyrhizobium sp. and Mortierella sp. are particularly influential on the microbial community and the plant. To our knowledge, this is the first inter-kingdom network analysis utilized to identify hot spots of interaction in canola microbial communities.

Review on the Development of Drought Tolerant Maize Genotypes in Iraq

Stress is any physiological, physical or chemical change that leads to disturbance and imbalance in the plant. Water stress is one of the most important environmental stresses affecting plant growth and production. It is also known as the lack of available water in the soil to be absorbed by the plant at a stage of its growth, or the inability of the plant. On the absorption of water even if it is naturally present in the root environment due to the force affecting the holding of water molecules, as it was described as the state in which the amount of water absorbed by the roots is less than the water lost through transpiration from the vegetative system, meaning that it is the state in which the effort The water content of the plant and the fullness of its cells is low to a degree that affects the conduct of vital and physiological processes. During the occurrence of water stress, as the term “drought” is not accurate in the sense used, but it is sometimes expressed as the phenomenon of water shortage as a result of climatic elements of multiple weather conditions, As for the agricultural concept of drought (Agricultural Drought), it is according to the growth and formation of the crop, and it is assumed that it begins when the ready water is drained from the root zone, plant goes through three stages: First stage increases the water loss and the transpiration process until it reaches a point where the amount of water lost by transpiration exceeds the amount of water absorbed by the roots. On the water balance between these two processes in adaptation, and when the water stress intensifies, the plant moves to the third stage, after which the plants lose a large part of the water through transpiration, the stomata are closed and the photosynthesis process stops. Therefore water stress (drought) alone is one of the most influential environmental stresses in reducing maize productivity, Therefore, the role of the plant breeder came through the implementation of breeding programs for hybridization and selection until it obtains a plant adapted to drought through the occurrence of morphological changes that make plants phenotypically adaptable to conditions of lack of water and includes an increase in root size and reduction of leaf area.

The soil-borne ultimatum, microbial biotechnology and sustainable agriculture.

The soil-borne ultimatum, microbial biotechnology and sustainable agriculture.

High Persistence and Nonlinear Behavior in Financial Variables: A More Powerful Unit Root Testing in the ESTAR Framework

In this study, we consider the hybrid nonlinear features of the Exponential Smooth Transition Autoregressive-Fractional Fourier Function (ESTAR-FFF) form unit root test. As is well known, when developing a unit root test for the ESTAR model, linearization is performed by the Taylor approximation, and thereby the nuisance parameter problem is eliminated. Although this linearization process leads to a certain amount of information loss in the unit root testing equation, it also causes the resulting test to be more accessible and consistent. The method that we propose here contributes to the literature in three important ways. First, it reduces the information loss that arises due to the Taylor expansion. Second, the research to date has tended to misinterpret the Fourier function used with the Kapetanios, Shin and Snell (2003) (KSS) unit root test and considers it to capture multiple smooth transition structural breaks. The simulation studies that we carry out in this study clearly show that the Fourier function only restores the Taylor residuals of the ESTAR type function rather than accounting forthe smooth structural break. Third, the new nonlinear unit root test developed in this paper has very strong power in the highly persistent near unit root environment that the financial data exhibit. The application of the Kapetanios Shin Snell- Fractional Fourier (KSS-FF) test to ex-post real interest rates data of 11 OECD countries for country-specific sample periods shows that the new test catches nonlinear stationarity in many more countries than the KSS test itself.

Metabolic Profiling and Metabolite Correlation Network Analysis Reveal That Fusarium solani Induces Differential Metabolic Responses in Lotus japonicus and Lotus tenuis against Severe Phosphate Starvation.

Root fungal endophytes are essential mediators of plant nutrition under mild stress conditions. However, variations in the rhizosphere environment, such as nutrient depletion, could result in a stressful situation for both partners, shifting mutualistic to nonconvenient interactions. Mycorrhizal fungi and dark septate endophytes (DSEs) have demonstrated their ability to facilitate phosphate (Pi) acquisition. However, few studies have investigated other plant–fungal interactions that take place in the root environment with regard to phosphate nutrition. In the present research work, we aimed to analyze the effect of extreme Pi starvation and the fungal endophyte Fusarium solani on the model Lotus japonicus and the crop L. tenuis. We conducted metabolomics analysis based on gas chromatography-mass spectrometry (GC-MS) on plant tissues under optimal conditions, severe Pi starvation and F.solani presence. By combining statistical and correlation network analysis strategies, we demonstrated the differential outcomes of the two plant species against the combination of treatments. The combination of nutritional stress and Fusarium presence activated significant modifications in the metabolism of L. japonicus affecting the levels of sugars, polyols and some amino acids. Our results display potential markers for further inspection of the factors related to plant nutrition and plant–fungal interactions.

Reducing sodium accumulation in the root environment of tomato in a closed-loop cultivation system using a split root system

ISHS II International Symposium on Growing Media, Soilless Cultivation, and Compost Utilization in Horticulture Reducing sodium accumulation in the root environment of tomato in a closed-loop cultivation system using a split root system

Root morphology and kinetics of Zn absorption by roots of common bean influenced by Zn status of the root environment

Understanding the kinetics of Zn absorption by roots and its effect on morphology of this organ is relevant for improving crop management, but still poorly studied for common beans. Therefore, an experiment was conducted in a hydroponic system with five initial concentrations of Zn (CZnI): 0.0; 1.0; 4.0; 16.0 and 48.0 µmol L-1. The experiment was installed with plants at V3 stage of development and aliquots of the solution collected over 24 h. The maximum absorption rate (Vmax), Michaelis-Menten constant (Km) and the absorption power (α) increased as a function of CZnI. The minimum concentration of Zn estimated for its absorption (Cmin) was at 0.0028 mg L-1. The influx of Zn (Imax) was higher in higher CZnI, 16,0 µmol L-1. Root length, root volume, root Zn content and Zn absorption efficiency increased with the increase of CZnI. Therefore, the increase of CZnI positively influenced kinetic parameters of root Zn absorption and common bean root morphology, characteristics that favor Zn absorption by roots and improves overall plant nutrition, favoring agronomical biofortification practices for Zn and other nutrients.

Influence of Chloride- and Soda-Dominated Salinity on Physiological and Biochemical Aspects of Halophytes with Different Strategies of Salt Metabolism

The authors study the effect of NaCl and NaHCO3 at concentrations of 1 M on the physiological and biochemical state of Salicornia perennans and Artemisia santonica for 24 hours. In our experiment, we evaluated: the accumulation of Na in the aerial part of plants, the stress index is lipid peroxidation (LPO); the state of membranes – by the composition and content of lipids and proteins, the level of photosynthetic pigments. The euhalophyte S. perennans accumulated Na on average 30% more than the glycohalophyte A. santonica. The addition of NaCl and NaHCO3 to the root environment promoted an increase in LPO in S. perennans by 2.4 times as compared to the control. In the case of A. santonica, LPO concentration increased by 1.2 times, but only when NaHCO3 was added to the soil. In addition, NaCl and NaHCO3 negatively affected plant lipids and proteins. Thus, in S. perennans plants, NaCl contributed to a decrease in phosphlipids by 34%, and NaHCO3 in glycolipids by 22% in comparison with the control. The quantitative content of the sum of water-soluble and membrane-bound proteins in the studied plants decreased by 10–36%. Chloride and soda-dominated salinity caused a decrease in the proportion of chlorophyll a and carotenoids only in S. perennans. The authors concluded that the response of the photosynthetic system and membrane complexes to various types of salinity in euhalophyte and glycohalophyte was different.

Physiological and biochemical evaluation of <i>Dioscorea alata L.</i> tubes cultivated on a modified ion-exchange substrate

Relevance. Currently, there is an increased interest in medicinal plants and preparations from natural herbal raw materials. This is due to the fact that biologically active substances of plants are more easily included in vital processes and do not cause side effects in humans. They can be products of primary (vitamins, fats, carbohydrates, proteins) and secondary biosynthesis (alkaloids, glycosides, tannins). Plants always contain a complex of biologically active substances, but one or several have a therapeutic and prophylactic effect. They are classified as active ingredients and are used in the production of medicines. Some of the promising medicinal plants are species from the genus Dioscorea, for example, Dioscorea alata L., containing a complex of biologically active substances. The aim of this work is to study the effect of humidity and the level of mineral nutrition in the root environment on the accumulation of biologically active compounds in the tubers of the dioscorea winged plant, adapted to in vivo conditions on an ion-exchange substrate of various chemical composition and agrophysical properties.Results. It has been shown that Dioscorea alata L. plants are able to accumulate the greatest amount of starch, dry matter, ascorbic acid, and flavonoids in an ion-exchange substrate modified with 1 g/l of the coarse hydrogel fraction. The data obtained can be used for practical purposes.

Low-volume and thin-layer panoponics in intensive artificial-light culture of cucumber: basics and results of application

Relevance. The year-round provision of the population of our country with fresh vegetable products remainsis relevant. The creation and widespread implementation of high-tech automated phytotechnological complexes based on innovative technologies for growing plants in intensive light culture, including the development of new-generation root-dwelling environments, low-volume and thin-layer analogs of soil and systems for providing plants with water and mineral nutrition elements, is one of the promising ways to solve this problem.The purpose. Assessment of the influence of root environment conditions on the production process of cucumber plants in intensive light culture is the aim of our work.Methods. The research was carried out under controlled conditions of intensive artificial-light culture, when growing a hybrid of cucumber Tristan F1 by using of low-volume and thin-layer analogs of soil with the supply of a nutrient solution to the plant roots through a slit capillary and by drip irrigation with the use of plant growing light equipment developed at Agrophysical Institute.Results. Evaluation of the influence of the conditions of the root environment - alow-volume analogue of the soil based on high-moor peat – agrophyte and a thin-layer analog of the soil based on a clay suspension with a feed of nutrient solution through a slit capillary, on the production process of cucumber plants showed that in comparison with the control – a low-volume analog of the soil-agrophyte with a feed of nutrient solution by drip irrigation, there is growth acceleration of the cucumber hybrid Tristan F1 in the form of a positive trend and reliable values; as well as a significant increase in the number of fruits by 38-43%, the weight of fruits by 52-53% from the plant; an increase in the accumulation of raw by 38-40% and dry weight by 27-32% by cucumber leaves; an increase in the leaf surface area by 38-40%, leaf water content by 7.3- 9.6%; a significant or positive trend increase in the content of calcium in cucumber fruits by 18-29%, magnesium by 20-29%, iron by 5-16%, vitamin C by 17-23%, while the content of heavy metals and nitrates does not exceed exceeded the MPC in all variants. Methods of growing plants on low-volume and thin - layer analogs of soil with the supply of a nutrient solution to the roots through a slit capillary can be recommended for any cultivation facilities in conditions of intensive light culture.

Theoretical Development of Plant Root Diameter Estimation Based on GprMax Data and Neural Network Modelling

The in situ non-destructive quantitative observation of plant roots is difficult. Traditional detection methods are not only time-consuming and labor-intensive, but also destroy the root environment. Ground penetrating radar (GPR), as a non-destructive detection method, has great potential in the estimation of root parameters. In this paper, we use GprMax software to perform forward modeling of plant roots under different soil dielectric constants, and analyze the situation of plant roots with different dielectric constants and different root diameters under 1.5 GHz frequency antenna detection. Firstly, root systems with increasing diameter under different values of root and soil dielectric constant were scanned. Secondly, from the scanning results, two time points T1 and T2 of radar wave entering and penetrating the root system were defined, and the correlation between root diameter D and time interval ΔT between T1 and T2 was analyzed. Finally, the least square regression model and back propagation (BP) neural network model for root diameter parameter estimation were established, and the estimation effects of the two models were compared and evaluated. The research results show that the root diameter (12–48 mm) is highly correlated with the time interval. Given the dielectric constants of the root and soil, the prediction results of the two models are accurate, but the prediction result of the neural network model is more stable, and the residual between the predicted value and the actual value is mainly concentrated in the [−1.5 mm, 1.5 mm] range, as well as the average of prediction error percentage being 3.62%. When the dielectric constants of the root and soil are unknown, the accuracy of the prediction results of the two models is decreased, but the stability of the neural network model is still superior to the least squares model, and the residual error is mainly concentrated in the range of [−5.3 mm, 5.0 mm], the average of prediction error percentage is 10.19%. This study uses GprMax to simulate root system detection and reveals the theoretical potential of GPR technology for non-destructive estimation of root diameter parameters. It is also pointed out that in the field exploration process, if the dielectric constants of the root and soil in the experimental site are sampled and measured first, the prediction accuracy of the model for root diameter would be effectively improved. This research is based on simulation experiments, so further simulation followed by laboratory and field testing is warranted using non-uniform roots and soil.

Aeroponics Root Chamber Temperature Conditioning Design for Smart Mini-Tuber Potato Seed Cultivation

The aeroponic plant root environment has a significant role in producing high-quality seed tuber potatoes. However, in lowland and tropical regions, the aeroponic system cannot yield high-quality potato seed because the average environment temperature year-round is high. In a high-temperature environment, the potato plant roots cannot optimally absorb the nutrient solution for healthy plant growth. This paper presents the method used to maintain the aeroponics root chamber temperature conditions. An air conditioning system was adopted to supply air with the optimal temperature range for mini-tuber potato seed cultivation. The vapor compression refrigeration type was applied in the air conditioning system. The root chamber temperature is controlled and monitored using an Arduino Uno board system. The mini-tuber potato seed cultivation field experiment results show the proposed method can maintain the aeroponic root chamber temperature. The root chamber temperature treatment operated in the 10 °C–20 °C range. This temperature range improved the potato seed tuber yield. The potato seed tuber yield potential is observed from the stolon number produced by the mini-tuber potato plants cultivated in the root chamber with the conditioned temperature. The field experiment reveals that the stolon number produced by potato seeds cultivated in the root chamber with conditioned temperature was up to 77% greater than the number of potato seeds cultivated in the root chamber with the unconditioned temperature.

Conservation tillage and nutrient management practices in summer rice (Oryza sativa L.) favoured root growth and phenotypic plasticity of succeeding winter pea (Pisum sativumL.) under eastern Himalayas, India

Low soil moisture during dry season, poor soil properties and lack of adequate crop varieties are the major constraints for sustainable intensification of eastern Himalayas in changing climate. Suitable varieties, tillage alteration and integrated nutrient management with emphasis on locally available crop residues/plant biomass may help addressing these issues. The role of minimum tillage (MT) and no-till (NT), and organic matter substitution on conferring of favourable root environment, improvement in morpho-physiology and subsequent productivity of the crops are not objectively studied in Himalayan ecosystems. Thus, a six year field study was conducted for examining the residual effect of tillage and nutrient management (NM) practices applied to summer (rainy) rice (Oryza sativa L) on root growth-attributes and impact on morpho-physiology of succeeding winter pea (Pisums ativum L.) grown uniformly under NT. Higher root surface area, total root length, root volume, root length ratio (RLR) and root tissue densityin pea crop were observed under residual effect of conventional tillage (CT) relative to NT and MT. In addition, significantly higher values of functional root traits viz., root length ratio (RLR), root mass ratio and root finenessin pea were observed under CT and application of 50% NPK and 100% NPK relative to other tillage and NM practices. However, increased root exudation was observed under NT and MTalong with organic residue addition. Noticeable changes in stress responsive morpho-physiological traits like enhanced chlorophyll pigmentation and favourable leaf characteristics were observed in pea crop grown under NT with 50% NPK+weed biomass (WB)/green leaf manure (GLM) applications. Higher leaf area expansion and thickness were recorded with optimum turgidity under NT and MT than that under CT. Comparative increase in green pod and stover yield of pea with enhanced partition efficiency and harvest index were recorded under MT/NT along with 50% NPK+WB/GLM application than that under CT and other NM practices. Thus, adoption of MT/NT along with 50% NPK+WB/GLM in summer rice is recommended for inducing favourable root environment and optimised pea production in succeeding winter season in study region of the Eastern Himalayas, India and other similar agro-ecosystems.

Application of Plant Growth Promoting Microorganism and Plant Growth Regulators in Agricultural Production and Research

Plant growth-promoting microorganisms (PGPM) are rhizosphere microorganisms that colonize the root environment [...]

Simple tests for stock return predictability with good size and power properties

We develop easy-to-implement tests for return predictability which, relative to extant tests in the literature, display attractive finite sample size control and power across a wide range of persistence and endogeneity levels for the predictor. Our approach is based on the standard regression t-ratio and a variant where the predictor is quasi-GLS (rather than OLS) demeaned. In the strongly persistent near-unit root environment, the limiting null distributions of these statistics depend on the endogeneity and local-to-unity parameters characterising the predictor. Analysis of the asymptotic local power functions of feasible implementations of these two tests, based on asymptotically conservative critical values, motivates a switching procedure between the two, employing the quasi-GLS demeaned variant unless the magnitude of the estimated endogeneity correlation parameter is small. Additionally, if the data suggests the predictor is weakly persistent, our approach switches to the standard t-ratio test with reference to standard normal critical values.