Root Space Research Articles

GOLVEN peptides regulate lateral root spacing as part of a negative feedback loop on the establishment of auxin maxima.

Lateral root initiation requires the accumulation of auxin in lateral root founder cells, yielding a local auxin maximum. The positioning of auxin maxima along the primary root determines the density and spacing of lateral roots. The GOLVEN6 (GLV6) and GLV10 signaling peptides and their receptors have been established as regulators of lateral root spacing via their inhibitory effect on lateral root initiation in Arabidopsis. However, it was unclear how these GLV peptides interfere with auxin signaling or homeostasis. Here, we show that GLV6/10 signaling regulates the expression of a subset of auxin response genes, downstream of the canonical auxin signaling pathway, while simultaneously inhibiting the establishment of auxin maxima within xylem-pole pericycle cells that neighbor lateral root initiation sites. We present genetic evidence that this inhibitory effect relies on the activity of the PIN3 and PIN7 auxin export proteins. Furthermore, GLV6/10 peptide signaling was found to enhance PIN7 abundance in the plasma membranes of xylem-pole pericycle cells, which likely stimulates auxin efflux from these cells. Based on these findings, we propose a model in which the GLV6/10 signaling pathway serves as a negative feedback mechanism that contributes to the robust patterning of auxin maxima along the primary root.

Impact of Ten Years Conservation Tillage in Organic Farming on Soil Physical Properties in a Loess Soil—Northern Hesse, Germany

In conservation agriculture, conservation tillage potentially influences the physical, chemical, and biological quality of the soil. Although the effects of conservation agriculture on the soil’s physical properties have been studied in conventional management systems, studies on organic farming systems, especially concerning long-term changes, are scarce. This study summarizes the results of physical and mechanical soil parameters obtained over the initial 10 years of different conservation management treatments (plowing versus reduced tillage with and without compost application) in an organic field trial conducted in central Germany. Moreover, as a research objective, the effects of soil conservation measures on soil’s physical quality were evaluated. Differences in the soil’s physical quality during treatments were mainly detected in the topsoil. At a depth of 0.10–0.24 m, the total porosity and air capacity were lower, and the bulk density was higher in the reduced-tillage systems, compared to those of the plowed treatments. Additionally, the soil’s mechanical stability (precompression stress) was higher at a depth of 0.10 m for reduced-tillage systems combined with compost application. In addition, the soil’s aggregate stability was enhanced in the reduced-tillage systems (higher mean weight diameter, as determined via wet sieving). Overall, the reduced-tillage treatments did not exceed the critical physical values of the soil, nor affect the functionality of the soil (saturated hydraulic conductivity), thereby demonstrating its feasibility as a sustainable technique for organic farming. Future studies should include measures to ameliorate compaction zones in reduced-tillage treatments, e.g., by applying subsoiling techniques in combination with deep-rooting crops to prevent limited rooting space resulting from the high mechanical impedance, especially under dry soil conditions.

Determinantal Ideals and the Canonical Commutation Relations: Classically or Quantized

We construct homomorphic images of $$su(n,n)^{{\mathbb {C}}}$$ in Weyl Algebras $${{\mathcal {H}}}_{2nr}$$ . More precisely, and using the Bernstein filtration of $${{\mathcal {H}}}_{2nr}$$ , $$su(n,n)^{{\mathbb {C}}}$$ is mapped into degree 2 elements with the negative non-compact root spaces being mapped into second order creation operators. Using the Fock representation of $${{\mathcal {H}}}_{2nr}$$ , these homomorphisms give all unitary highest weight representations of $$su(n,n)^{{\mathbb {C}}}$$ thus reconstructing the Kashiwara–Vergne List for the Segal–Shale–Weil representation. Using an idea from the derivation of the their list, we construct a homomorphism of $$u(r)^{{\mathbb {C}}}$$ into $${{\mathcal {H}}}_{2nr}$$ whose image commutes with the image of $$su(n,n)^{{\mathbb {C}}}$$ , and vice versa. This gives the multiplicities. The construction also gives an easy proof that the ideal of $$(r+1)\times (r+1)$$ minors is prime. Here, of course, $$r\le n-1$$ and for a fixed such r, the space of any irreducible representation of $$su(n,n)^{{\mathbb {C}}}$$ is annihilated by this ideal. As a consequence, these representations can be realized in spaces of solutions to Maxwell type equations. We actually go one step further and determine exactly for which representations from our list there is a non-trivial homomorphism between generalized Verma modules, thereby revealing, by duality, exactly which covariant differential operators have unitary null spaces. We prove the analogous results for $${{\mathcal {U}}}_q(su(n,n)^{{\mathbb {C}}})$$ . The Weyl Algebras are replaced by the Hayashi–Weyl Algebras $${{\mathcal {H}}}{{\mathcal {W}}}_{2nr}$$ and the Fock space by a q-Fock space. Further, determinants are replaced by q-determinants, and a homomorphism of $${{\mathcal {U}}}_q(u(r)^{{\mathbb {C}}})$$ into $${{\mathcal {H}}}{{\mathcal {W}}}_{2nr}$$ is constructed with analogous properties. For this purpose a Drinfeld Double is used. We mention one difference: The quantized negative non-compact root spaces, while still of degree 2, are no longer given entirely by second order creation operators.

Wheat plant –Plant Growth Promoting Rhizobacteria (PGPR) interaction to alleviate the salt stress in vitro and in vivo

The current work studied the mechanistic basis of salt tolerant PGPR bacteria in alleviating salinity stress in wheat.Two experiments were conducted at the Agricultural Research Center (ARC), 2021-2022, to evaluate the interaction between wheat var. Misr1 and two salt tolerant PGPR bacterial strains, Azospirillum (A.) brasilense NO40 and Bacillus thuringiensis (Bt) under saline conditions. The staining technique used to detect the colonization effectiveness of applied bacteria. Images of 30-day wheat seedlings were captured and subjected to the following measurements: root area, leaf area, root length, shoot length, and dark green color index (DGCI). TEM was used to look for bacterial colonization in wheat seedling. Chlorophyll, proline, peroxidase activity, rhizosphere dehydrogenase activity and electrical conductivity (EC) were all quantified. Results revealed that the wheat seedling roots inoculated with the salt tolerant bacterial strains produced a highly intense red colour. The colonized bacteria appeared on the outer surface of the root and intercellular space of root tissue. The data showed a significant rise in all measured parameters in the inoculated wheat seedlings with the salt tolerant bacterial strains compared to the non-inoculated wheat seedlings. Additionally, the wheat seedlings inoculated with a mixture of NO40 and Bt showed the best results as compared to that inoculated with only NO40 or with only Bt. Finally, EC values before and after planting with the inoculated wheat seeds revealed a decrease in the salinity of the soil rhizosphere (9.27 mmhos/cm vs. 5.1 mmhos/cm). In conclusion: Salt stress in wheat saline soils was alleviated by bacterial strains studied. Optimum results were obtained from the mixture of A. brasilense and Bt. Results must later be verified in field trials.

The Role of Radiation in the Modelling of Crop Evapotranspiration from Open Field to Indoor Crops

The agricultural sector continues to be the largest consumer of useful water. Despite knowing the volume of water required by plants (evapotranspiration), methodologies must be adapted to current production systems. Based on the energy balance (radiation), it is feasible to establish models to estimate evapotranspiration depending on the production system: extensive crops, closed, and interior systems. The objective of this work was to present related research to measure and model the evapotranspiration of crops under current production techniques, based on the energy balance. The original FAO Penman–Monteith model is considered to be the model that best describes the evapotranspiration process, and with advances in instrumentation, there are sensors capable of measuring each of the variables it contains. From this model, procedures have been approximated for its use in extensive crops through remote sensing to calculate evapotranspiration, which jointly integrates the climatic variables and the type and age of the crop, with which real evapotranspiration is obtained. The same Penman–Monteith model has been adapted for use in greenhouse crops, where given the reduced root space and being in a closed environment, it is possible to know the variables specifically. Keeping the root container saturated, crop transpiration will basically depend on the physiology of the plant (LAI, stomatal resistance, etc.) and the characteristics of the air (radiation, VPD, wind speed, etc.). Models based on computational fluid dynamics (CFD) have been developed, which predict the real evapotranspiration of the crop by activating the discrete ordinate (DO) radiation sub-model. For indoor crops, in the absence of solar radiation, and replaced with artificial lights (LEDs)—although it is true that they are hydroponic crops and water can be estimated through a balance of levels—it would be possible to use CFD to estimate transpiration by transforming flux units (Mmol) into radiation (W m−2). The transpiration of indoor crops works as a cooling system and stabilizes the environment of the plant factory or vertical farm. In each crop production system (from open field to indoor crops) models have been developed to manage water and microclimate. The result is reports that more than 90% of the water is saved.

Adaptability of indigenous vegetation on parking lots – A case study: Tree alleys in Novi Sad, Serbia

In this study five indigenous species on parking lots in Novi Sad, Serbia were examined (Acer platanoides ‘Globosum’, Celtis australis L., Tilia tomentosa Moench., Carpinus betulus ‘Fastigiata’, and Corylus colurna L.). The aim of this study is to represent their adaptability to urban stress and harsh environmental conditions which are present on parking lots by valuing their dimensions and vitality. Results showed that well-adapted species are Celtis australis L. and Carpinus betulus ‘Fastigiata’. Other species had low vitality values, asymmetrical canopy, and mechanical damages that were caused by insufficient root and canopy space and insufficient distance from buildings and traffic. Choosing well-adapted indigenous species for alleys can be very challenging. Adaptability assessment of indigenous trees on parking lots in Novi Sad can be used as guidance to urban planning in Novi Sad and other cities which have a high share of pavement to reduce the climate change effect.

Supercanonical coordinates for orthosymplectic evolution operators

A time-dependent self-adjoint even Hamiltonian is defined by a linear combination of generators of the semidirect sum osp(m′/n′)⊕sne(n′+1), of the orthosymplectic plus the even Heisenberg algebra by computing the supercommutator of odd binary forms Π, given as linear combinations of odd bilinear generators of the odd Heisenberg algebra no(m′+1) elements times ne(n′+1) elements, establishing a relationship between entangled boson systems and entangled fermion systems. This approach leads to the concept of intertwining, defined through the resulting quadratic Hamiltonians of bosons and, separately, of fermions with coefficients given in terms of the same coefficients of Π. Intertwining is invariant under transformations of Π, which leave certain binary forms of the coefficients of Π in the Hamiltonian unchanged. Alternatively, the coefficients can be interpreted as simultaneous time-dependent (super-) control parameters for both spin-statistics. Time-dependent inhomogeneous linear supercanonical transformations of wave vectors leave invariant the Heisenberg superalgebra n(m′/n′) and belong to the semidirect product Osp(m′/n′) ⋉ Ne(n′ + 1) of the orthosymplectic supergroup with the even Heisenberg group. The unitary time evolution operator is constructed using the adjoint map in canonical coordinates determined by the supercanonical transformation. The method is a generalization of an Inönu–Wigner contraction procedure and a Wei–Norman method for superalgebras with a selection of subalgebras associated with the root space decomposition of the Lie superalgebra. Analogously, this is a separation of variables method for quantum mechanical problems in systems with bosons and fermions. The standard Floquet theory leads to new results concerning stability for locally periodic coefficients. The lowest dimensional cases are explicitly computed. The intertwining of boson and fermions systems and the Hamiltonians considered here are of interest in quantum control theory for systems including fermions and bosons, in quantum optics, and quantum computation.

Trees in Planters—A Case Study of Time-Related Aspects

Urban spaces are often dominated by paved surfaces and ongoing processes of densification; consequently, intensifying the urban heat island effect. In order to strengthen the liveability of urban spaces, an adequate amount of green spaces is needed. Trees in planters are an alternative greening solution; however, the lack of root space due to underground infrastructure poses a challenge. Furthermore, temporal aspects such as tree growth, tree death, and growth responses to environmental factors are frequently overlooked in projects that use trees in planters. In multiple case studies that employ the method “Research through Drawing” we analyse five selected projects, which deal in sharply contrasting ways with the temporal aspects of trees in planters. Our results show that promising approaches exist, albeit they are not described explicitly in either written or graphical form. Consequently, temporal aspects are only vaguely considered in the projects’ design concept. This results in the neglect of the further use of trees in planters in temporary projects, or in the disregard for tree death in the design and responses to it in permanent projects. Therefore, the potential of trees in planters as an alternative and complementary greening solution remain unexploited. To overcome this, a coherent temporal approach that considers growth, death of plant parts or whole plants, and that is developed as an integral part of the design concept and communicated graphically, would ensure that the involved actors and their respective tasks are well coordinated throughout the lifetime of a project.

Algebraic Number Starscapes

We study the geometry of algebraic numbers in the complex plane, and their Diophantine approximation, aided by extensive computer visualization. Motivated by the resulting images, which we have called algebraic starscapes, we describe the geometry of the map from the coefficient space of polynomials to the root space, focusing on the quadratic and cubic cases. The geometry describes and explains the notable features of the illustrations, and motivates a geometric-minded recasting of fundamental results in the Diophantine approximation of the complex plane. Meanwhile, the images provide a case-study in the symbiosis of illustration and research, and an entry-point to geometry and number theory for a wider audience. In particular, the paper is written to provide an accessible introduction to the study of homogeneous geometry and Diophantine approximation. We investigate the homogeneous geometry of root and coefficient spaces under the natural action. Hyperbolic geometry and the discriminant play an important role in low degree. In particular, we rediscover the quadratic and cubic root formulas as isometries of and its unit tangent bundle, respectively. Utilizing this geometry, we determine when the map sending certain families of polynomials to their complex roots (our starscape images) are embeddings. We reconsider the fundamental questions of the Diophantine approximation of complex numbers by algebraic numbers of bounded degree, from the geometric perspective developed. In the quadratic case (approximation by quadratic irrationals), we consider approximation in terms of hyperbolic distance between roots in the complex plane and the discriminant as a measure of arithmetic height on a polynomial. In particular, we determine the supremum on the exponent k for which an algebraic target α has infinitely many approximations β whose hyperbolic distance from α does not exceed . It turns out to fall into two cases, depending on whether α lies on the image of a plane of rational slope in coefficient space (a rational geodesic). The result comes as an application of Schmidt’s subspace theorem. Our results recover the quadratic case of results of Bugeaud and Evertse, and give some geometric explanation for the dichotomy they discovered. Our statements go a little further in distinguishing approximability in terms of whether the target or approximations lie on rational geodesics. The paper comes with accompanying software, and finishes with a wide variety of open problems.

Flow distribution and mass removal in floating treatment wetlands arranged in series and spanning the channel width

Floating treatment wetlands (FTWs) use plants’ roots for water quality improvement. The plants are supported by a buoyant structure deployed at the water surface. The roots form a porous zone beneath the structure and remove pollutants carried in suspension through filtering, absorption and uptake. This paper used CFD simulation to model FTWs arranged in series and spanning the channel width and to study the effects of root length and spacing between FTWs on flow distribution and mass removal. The root zone was modelled as a porous media, and removal was computed using first-order decay, for which a range of removal constants was tested. Longer roots increased the reactive volume of the root zone, which increased the fraction of pollutant inflow entering the FTWs. Increasing the distance between FTWs allowed greater mixing between water that went through and beneath the upstream FTW. This increased the concentration entering each FTW, which enhanced mass removal per FTW. However, a larger distance between FTWs reduced the number of FTWs in the channel, reducing the reactive volume. In the tradeoff between mixing and reactive volume, the reactive volume was more important, such that total removal in the channel increased with longer roots and more units of FTW (shorter gap distance). However, removing the gap entirely was detrimental, as FTWs in series removed more mass than a continuous FTW of same volume. This study points to two design recommendations for FTWs in series. First, if resources for building FTWs are not limiting, but the channel length is, it is preferable to prioritize higher reactive volume (shorter gap distance) to achieve maximum removal per channel length. Second, if resources for FTWs are limiting, but channel length is not, it is better to place the FTWs with a longer gap distance, preferably along enough to allow mixing over the full depth between FTWs, as this will achieve maximum removal per FTW.

“One day visit”: a predictable clinical procedure.

The present clinical case aims to introduce a cluster of techniques based on a digital and biological basis, to be used at intrasurgical time, in order to achieve a predictable clinical outcome. In fact, the possibility of merging data could allow a single-step procedure, introducing concepts like ‘one day visit’ with Socket shield (SS), implant and provisional crown, same-day delivery. This procedure is well accepted by the patient as reducing surgery sessions and prosthetic time. A CBCT and a digital impression were used for initial diagnosis, obtaining data about tooth anatomy, bone quality, and bundle bone extension. Surgical planning and relative stent, allowed a careful position of implant inter-radicularly to achieve best primary stability, required for an immediate load on the mandibular molar area. It was first performed an SS on molar #46, with a seagull wing configuration (i.e., maintaining a small septum area between vestibular roots laminae. The implant was positioned in the inter-radicular area using a safe surgical stent: IT, IT curve and the implant stability quotient (ISQ (>70) were measured establishing criteria for immediate loading. An intra surgical impression scan was taken using a T-Base system allowing the planning of an immediate digital provisional crown in 40 minutes. Meanwhile, the SS shoulder was reduced, root spaces were filled with bone chips mixed with Fibrin glue and covered with platelet-rich-fibrin (PRF) A large healing cap was inserted on waiting time. The provisional crown fit was excellent requiring minor adjustment, and was immediately positioned. Seven months later a digital crown copy on disilicate was inserted. SS proved to maintain marginal gingiva and bundle bone. A novel intrasurgical action allows the implant stability measurement and immediate digital impression, picking high-quality prosthetic data.(time 0 concept. Follow-up shows crown stability and maintenance of both soft and hard tissue volume over 3 years. This is a proof of principle clinical case. Hardware & Software technologies were used to improve the predictability of outcome and stability over time of soft and hard tissue. Several activities were done at intra-surgical time and allowed to achieve unique data for prosthetic planning. The SS typically used on an anterior maxillary area was here used on posterior region and it is a fundamental step on ‘single day visit’ approach. The technique is operator sensitive and may not be applicable in any single case. More studies and clinical confirmation are therefore required.

Influence of shrub root combinations and spacing on slope stability: study case at the Yongding River flooding regime, Langfang, China.

Research on the mechanism of plant root-soil consolidation is a current focus in research into the ecological restoration of banks. The stability of ecological banks is central to this research, and bank stability is closely related to plant combinations and spacing. Recent research on reinforced anchorage of plant roots has mainly focused on root length and angle, and on other parts of the root system, and only a few studies have examined the combination of different types of roots. In this study, a coupled slope stability assessment system is created, composed of root morphological parameters and involving calculations using the finite element model ABACUS. This paper selects the two banks of the lower reaches of the Tiantang River in the flood zone of Yongding River as the research area, and examines slope surface plants. And then the reinforcement effect of different shrub roots combinations and plant spacing are evaluated for determining the optimal shrub layout, with the aim of solving the instability problem of collapsible silty clay bank slopes and associated risks. The results indicated that when the shrub plant spacing is 0.65m, the optimal shrub combination is Tamarix chinensis + Philadelphus incanus, and when the shrub plant spacing is 0.75m, the optimal shrub combination is Tamarix chinensis + Euonymus alatus. The study found that the root system morphology and the fibrous roots amount at the foot of the slope can have different degrees of influence on the shallow soil stability of the silty clay slope under different shrubs plant spacing conditions.

Two phylogenetically unrelated peptide-receptor modules jointly regulate lateral root initiation via a partially shared signaling pathway in Arabidopsis thaliana.

Summary Peptide‐receptor signaling is an important system for intercellular communication, regulating many developmental processes. A single process can be controlled by several distinct signaling peptides. However, since peptide‐receptor modules are usually studied separately, their mechanistic interactions remain largely unexplored.Two phylogenetically unrelated peptide‐receptor modules, GLV6/GLV10‐RGI and TOLS2/PIP2‐RLK7, independently described as inhibitors of lateral root initiation, show striking similarities between their expression patterns and gain‐ and loss‐of‐function phenotypes, suggesting a common function during lateral root spacing and initiation.The GLV6/GLV10‐RGI and TOLS2/PIP2‐RLK7 modules trigger similar transcriptional changes, likely in part via WRKY transcription factors. Their overlapping set of response genes includes PUCHI and PLT5, both required for the effect of GLV6/10, as well as TOLS2, on lateral root initiation. Furthermore, both modules require the activity of MPK6 and can independently trigger MPK3/MPK6 phosphorylation.The GLV6/10 and TOLS2/PIP2 signaling pathways seem to converge in the activation of MPK3/MPK6, leading to the induction of a similar transcriptional response in the same target cells, thereby regulating lateral root initiation through a (partially) common mechanism. Convergence of signaling pathways downstream of phylogenetically unrelated peptide‐receptor modules adds an additional, and hitherto unrecognized, level of complexity to intercellular communication networks in plants.

The Economics Spectrum Drives Root Trait Strategies in Mediterranean Vegetation.

Extensive research efforts are devoted to understand fine root trait variation and to confirm the existence of a belowground root economics spectrum (RES) from acquisitive to conservative root strategies that is analogous to the leaf economics spectrum (LES). The economics spectrum implies a trade-off between maximizing resource acquisition and productivity or maximizing resource conservation and longevity; however, this theoretical framework still remains controversial for roots. We compiled a database of 320 Mediterranean woody and herbaceous species to critically assess if the classic economics spectrum theory can be broadly extended to roots. Fine roots displayed a wide diversity of forms and properties in Mediterranean vegetation, resulting in a multidimensional trait space. The main trend of variation in this multidimensional root space is analogous to the main axis of LES, while the second trend of variation is partially determined by an anatomical trade-off between tissue density and diameter. Specific root area (SRA) is the main trait explaining species distribution along the RES, regardless of the selected traits. We advocate for the need to unify and standardize the criteria and approaches used within the economics framework between leaves and roots, for the sake of theoretical consistency.

Mechanized method of laying drop tape when growing potatoes in the Moscow region

The use of a drip irrigation system allows the most efficient use of irrigation water, since it is delivered directly to the root space. In recent years, the production of drip tape at domestic enterprises has significantly increased by introducing additional capacities at existing plants and commissioning new production facilities, which will halve the import of drip tape and related equipment and fittings. However, the share of lands occupied by drip irrigation among the territories using irrigation measures has practically not increased and amounts to 2-4 %. The design of drip irrigation systems, taking into account the peculiarities of the growing season of a particular agricultural crop, its dynamics of water consumption throughout the life cycle, and the planting scheme, will help to change the situation and expand the use of drip irrigation. One of the limiting factors is the low degree of mechanization when laying the drip tape. The use of handicraft devices for these purposes leads to an uneven tension of the tape and, as a consequence, its breakage and twisting during the laying process. To eliminate this drawback, the working equipment for laying the drip tape into the potato comb was developed and installed on the Grimme GF-75/4 comb shaper. Traction resistance increased by 6-8 %, without affecting the performance of the machine. During the tests, a brake system was installed that maintains the belt tension within acceptable limits and prevents the coil from spinning when the machine stops suddenly. The use of a drip tape stacker based on the Grimme GF-75/4 ridge former has increased the productivity of work by 32–36 %.

Preliminary ecophysiological observations of the fern Asplenium platyneuron growing in two microenvironments varying in light intensity at an urban location in New York City1

Asplenium platyneuron growing at two locations (outer sunlit location and inner shaded location) in a low brick and masonry wall in upper Manhattan (New York City) was studied to assess the effects of the two different microenvironments on the ecophysiology of the two fern populations. The intensity of illumination at the inner location was ca. 40% of the intensity at the outer location, where the photosynthetic active radiation (PAR) at mid-day was ca. 1,484 µmol m–2 s–1. Generally, root space temperatures tracked air temperature, varying from 26 to 31 °C for the outer location, and 25 to 28.7 °C for the inner location. Based on prior published literature with other fern species, we hypothesized that samples of A. platyneuron growing on the outer surface exposed to maximum illumination would exhibit higher maximum photosynthesis rates, higher respiration in the light, and smaller leaves compared to the less illuminated samples growing on the inner surface. The results supported our hypothesized relationships. Mean leaf length (cm) was longer for leaves of plants at the shaded inner location (30 ± 1.1) compared to those of plants at the more illuminated outer location (9 ± 1.2). The maximum photosynthetic rate (Amax) for the outside sample of ferns (6.3 ± 0.25) was statistically significantly different from the Amax for the inside sample (4.3 ± 0.72) as hypothesized. The mean respiration in the light was significantly larger for the ferns growing outside (-0.52 ± 0.03) compared to those inside (-0.36 ± 0.04). Additionally, light response (A–Q) curves and relevant other physiological evidence are presented for ferns at the two sampling sites.

Influence of Various Gauge Lengths, Root Spacing and Root Numbers on Root Tensile Properties of Herbaceous Plants

The mechanical properties of root system play an important role in soil reinforcement by plants. Root tensile properties are affected by many factors. It is necessary to explore the mechanical properties of root system and the influencing factors. In this study, tensile tests were conducted on roots of Kochia scoparia (L.) Schrad and Artemisia sacrorum Ledeb to study root tensile properties, including maximum tensile force, tensile strength and elastic modulus under the three factors, gauge length (50, 100, 150, and 200 mm), root spacing (0, 1, and 2 cm) and root number (single root, double roots, and triple roots). The results showed that the maximum tensile force, tensile strength, and elastic modulus of the roots decreased with increasing gauge length in power functions. Under 100 mm gauge length, the maximum tensile force, tensile strength and elastic modulus decreased with increasing root spacing, but the effect of root spacing considered in this study on the maximum tensile force and tensile strength was not significant. Besides, with increasing root number, the maximum tensile force increased, tensile strength, and elastic modulus decreased. These findings stretched our understanding of the relationship between gauge length, root spacing and root number on root tensile characteristics, and provided the necessary data basis for root tensile properties and soil reinforcement by plants.

Soil Macropores Affect the Plant Biomass of Alpine Grassland on the Northeastern Tibetan Plateau

Macropores are an important part of soil structure. However, in alpine regions, the effects of soil macropores on soil properties and vegetation growth are not clear. We used the X-ray computed tomography (CT) method to obtain 3D images and visualize the distribution and morphology of soil macropores. By combining principal component analysis (PCA) and stepwise regression methods, we studied the relationships between soil macropores and both soil properties and vegetation growth in three types of grassland [alpine degraded steppe (ADS), alpine typical steppe (ATS), and alpine meadow steppe (AMS)] on the Tibetan Plateau. More tubular and continuous macropores occurred in the soil profiles of the AMS and ATS than in that of the ADS. In addition, the AMS soil had the highest macropore number (925 ± 189), while the ADS soil had the lowest macropore number (537 ± 137). PCA and correlation analysis suggested that macroporosity (MP) has significant positive correlations with the contents of soil organic matter, total nitrogen (TN), available phosphorus (AP) and total phosphorus (TP) (p < 0.05). The two parameters with the greatest influence on aboveground and belowground biomass were the shape factor (p < 0.05) and MP (p < 0.05), respectively. However, there was no significant correlation between plant diversity and soil macropores. We conclude that the irregularity of soil macropores restricts the growth space of roots and causes plants to sacrifice the accumulation of aboveground biomass for that of roots to find suitable sites for nutrient and water absorption.

Estimating Air Pollution Removal and Monetary Value for Urban Green Infrastructure Strategies Using Web-Based Applications

More communities around the world are recognizing the benefits of green infrastructure (GI) and are planting millions of trees to improve air quality and overall well-being in cities. However, there is a need for accurate tools that can measure and value these benefits whilst also informing the community and city managers. In recent years, several online tools have been developed to assess ecosystem services. However, the reliability of such tools depends on the incorporation of local or regional data and site-specific inputs. In this communication, we have reviewed two of the freely available tools (i.e., i-Tree Canopy and the United Kingdom Office for National Statistics) using Bristol City Centre as an example. We have also discussed strengths and weaknesses for their use and, as tree planting strategy tools, explored further developments of such tools in a European context. Results show that both tools can easily calculate ecosystem services such as air pollutant removal and monetary values and at the same time be used to support GI strategies in compact cities. These tools, however, can only be partially utilized for tree planting design as they do not consider soil and root space, nor do they include drawing and painting futures. Our evaluation also highlights major gaps in the current tools, suggesting areas where more research is needed.

Arabidopsis Restricts Sugar Loss to a Colonizing Trichoderma harzianum Strain by Downregulating SWEET11 and -12 and Upregulation of SUC1 and SWEET2 in the Roots.

Phosphate (Pi) availability has a strong influence on the symbiotic interaction between Arabidopsis and a recently described root-colonizing beneficial Trichoderma harzianum strain. When transferred to media with insoluble Ca3(PO4)2 as a sole Pi source, Arabidopsis seedlings died after 10 days. Trichoderma grew on the medium containing Ca3(PO4)2 and the fungus did colonize in roots, stems, and shoots of the host. The efficiency of the photosynthetic electron transport of the colonized seedlings grown on Ca3(PO4)2 medium was reduced and the seedlings died earlier, indicating that the fungus exerts an additional stress to the plant. Interestingly, the fungus initially alleviated the Pi starvation response and did not activate defense responses against the hyphal propagation. However, in colonized roots, the sucrose transporter genes SWEET11 and -12 were strongly down-regulated, restricting the unloading of sucrose from the phloem parenchyma cells to the apoplast. Simultaneously, up-regulation of SUC1 promoted sucrose uptake from the apoplast into the parenchyma cells and of SWEET2 sequestration of sucrose in the vacuole of the root cells. We propose that the fungus tries to escape from the Ca3(PO4)2 medium and colonizes the entire host. To prevent excessive sugar consumption by the propagating hyphae, the host restricts sugar availability in its apoplastic root space by downregulating sugar transporter genes for phloem unloading, and by upregulating transporter genes which maintain the sugar in the root cells.