Academic literature on the topic 'Root system strength and architecture'
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Journal articles on the topic "Root system strength and architecture"
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Ramos-Rivera, Johnatan, Harianto Rahardjo, Daryl Lee Tsen-Tieng, Nong Xuefeng, and Fong Yok King. "Mechanical response of the real tree root architecture under lateral load." Canadian Journal of Forest Research 50, no. 7 (July 2020): 595–607. http://dx.doi.org/10.1139/cjfr-2019-0332.
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The impact of climate change on tree stability is often associated with a higher risk of windthrow due to higher frequency and greater magnitude of extreme climatic conditions. Higher lateral loads due to an increase in maximum wind and rainfall reduce tree anchorage because of a decrease in soil matric suction and consequently the overall strength in the system of trunk, root, and soil. This study compared the mechanical response of trees with different root architectures using static loading tests conducted in the field and numerical analysis of laser-scanned root systems. For this case, mature trees of Khaya senegalensis (Desr.) A. Juss., Samanea saman (Jacq.) Merr., and Syzygium grande (Wight) Wight ex Walp. were tested and analyzed. The root system models consisted of root system architectures obtained using 3-D laser scanning. A parametric analysis was conducted by varying the modulus of elasticity of the soil (Es) from 2.5 to 25 MPa, and the results were compared with those of the static loading tests to obtain the overall mechanical responses of the root–soil systems. The results showed important dependencies of the mechanical responses of the root–soil system on the root architecture in withstanding the lateral load. The numerical models also allowed estimation of the effective leeward and windward anchorage zones with different soil elastic moduli and rooting architectures to define the extent of the tree root protection zones.
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Ola, A., I. C. Dodd, and J. N. Quinton. "Can we manipulate root system architecture to control soil erosion?" SOIL Discussions 2, no. 1 (March 26, 2015): 265–89. http://dx.doi.org/10.5194/soild-2-265-2015.
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Abstract. Soil erosion is a major threat to soil functioning. The use of vegetation to control erosion has long been a topic for research. Much of this research has focused on the above ground properties of plants, demonstrating the important role that canopy structure and cover plays in the reduction of water erosion processes. Less attention has been paid to plant roots. Plant roots are a crucial yet under-researched factor for reducing water erosion through their ability to alter soil properties, such as aggregate stability, hydraulic function and shear strength. However, there have been few attempts to manipulate plant root system properties to reduce soil erosion. Therefore, this review aims to explore the effects that plant roots have on soil erosion and hydrological processes, and how plant root architecture might be manipulated to enhance its erosion control properties. We clearly demonstrate the importance of root system architecture for the control of soil erosion. We also demonstrate that some plant species respond to nutrient enriched patches by increasing lateral root proliferation. The soil response to root proliferation will depend upon its location: at the soil surface dense mats of roots may block soil pores thereby limiting infiltration, enhancing runoff and thus erosion; whereas at depth local increases in shear strength may reinforce soils against structural failure at the shear plane. Additionally, in nutrient deprived regions, root hair development may be stimulated and larger amounts of root exudates released, thereby improving aggregate stability and decreasing erodibility. Utilising nutrient placement at depth may represent a potentially new, easily implemented, management strategy on nutrient poor agricultural land or constructed slopes to control erosion, and further research in this area is needed.
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Zhang, Dong, Jinhua Cheng, Ying Liu, Hongjiang Zhang, Lan Ma, Xuemei Mei, and Yihui Sun. "Spatio-Temporal Dynamic Architecture of Living Brush Mattress: Root System and Soil Shear Strength in Riverbanks." Forests 9, no. 8 (August 13, 2018): 493. http://dx.doi.org/10.3390/f9080493.
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As a basal measure of soil bioengineering, the living brush mattress has been widely applied in riparian ecological protection forest construction. The living brush mattress shows favorable protective effects on riverbanks. However, there are few reports on the root structure and the soil strengthening benefit of the living brush mattress. The present work reports a series of experiments on root morphology and soil shear strength enhancement at the temporal and spatial scales. The object of the study is 24 living brush mattress trees constructed with Salix alba L. ‘Tristis’ (LBS hereafter). Traditional root morphology and mechanical measurement methods were used to collect the parameters. The results showed that the root systems of LBS had the characteristics of symmetry and upslope growth. The roots were mainly distributed in a cylindrical region of the soil (radius × thickness: 0.4 m × 0.5 m) and their biomass increased with different growth rates for the periods from 1 to 5 and from 5 to 7 years. Both age and slope position were factors that influence root growth. The root diameter falls within 0–5 mm, has a significant effect on the soil shear strength and provides a conical-shape potentiation zone to ensure the efficient protection of a riverbank. The results of this study demonstrate that LBS is an efficient and feasible engineering measure in the field of riverbank protection.
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Ola, A., I. C. Dodd, and J. N. Quinton. "Can we manipulate root system architecture to control soil erosion?" SOIL 1, no. 2 (September 8, 2015): 603–12. http://dx.doi.org/10.5194/soil-1-603-2015.
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Abstract. Soil erosion is a major threat to soil functioning. The use of vegetation to control erosion has long been a topic for research. Much of this research has focused on the above-ground properties of plants, demonstrating the important role that canopy structure and cover plays in the reduction of water erosion processes. Less attention has been paid to plant roots. Plant roots are a crucial yet under-researched factor for reducing water erosion through their ability to alter soil properties, such as aggregate stability, hydraulic function and shear strength. However, there have been few attempts to specifically manipulate plant root system properties to reduce soil erosion. Therefore, this review aims to explore the effects that plant roots have on soil erosion and hydrological processes, and how plant root architecture might be manipulated to enhance its erosion control properties. We demonstrate the importance of root system architecture for the control of soil erosion. We also show that some plant species respond to nutrient-enriched patches by increasing lateral root proliferation. The erosional response to root proliferation will depend upon its location: at the soil surface dense mats of roots may reduce soil erodibility but block soil pores thereby limiting infiltration, enhancing runoff. Additionally, in nutrient-deprived regions, root hair development may be stimulated and larger amounts of root exudates released, thereby improving aggregate stability and decreasing erodibility. Utilizing nutrient placement at specific depths may represent a potentially new, easily implemented, management strategy on nutrient-poor agricultural land or constructed slopes to control erosion, and further research in this area is needed.
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Meijer, Gerrit J., David Muir Wood, Jonathan A. Knappett, A. Glyn Bengough, and Teng Liang. "Root branching affects the mobilisation of root-reinforcement in direct shear." E3S Web of Conferences 92 (2019): 12010. http://dx.doi.org/10.1051/e3sconf/20199212010.
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The contribution of roots to the mechanical behaviour of soil has typically only been studied for the ultimate limit state. In these approaches, roots are typically modelled as straight and unbranched structures. This approach overlooks the fact that roots may have to deform significantly to mobilise their strength, a process that will be influenced by root architecture effects such as branching, amongst others. Sequential mobilisation of roots affects the peak root-reinforcement, thus differences in mobilisation are important to consider when quantifying root-reinforcement. In this paper, the effect of root branching was modelled using a large-deformation Euler-Bernoulli beam-spring model. The effect of soil was incorporated using non-linear springs, similar to p-y and t-z theory used for foundation piles. By connecting multiple beams together (i.e. applying appropriate linked boundary conditions at root connection points) the effect of branching could be analysed. A soil displacement profile corresponding with direct shear loading was then imposed and the response of the root analysed. It was shown that adding branches led to a quicker mobilisation of root-reinforcement. Branches increased the axial resistance to root displacement and changed the shape of the deformed roots. The presence of branching counteracted root slippage, and thus increased reinforcement. Larger branching densities increased this effect. This analysis demonstrated that the architecture of the root system has a strong effect on the mobilisation of root strength, which directly affects the maximum amount of reinforcement the roots will provide. Future modelling of root-reinforcement, both at the ultimate and serviceable limit state, should account for this effect.
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Mehra, Promil, Pankaj Kumar, Nanthi Bolan, Jack Desbiolles, Susan Orgill, and Matthew D. Denton. "Changes in soil-pores and wheat root geometry due to strategic tillage in a no-tillage cropping system." Soil Research 59, no. 1 (2021): 83. http://dx.doi.org/10.1071/sr20010.
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Tillage management can influence soil physical properties such as soil strength, moisture content, temperature, nutrient and oxygen availability, which in turn can affect crop growth during the early establishment phase. However, a short-term ‘strategic’ conventional tillage (CT) shift in tillage practice in a continuous no-tillage (NT) cropping system may change the soil-pore and root geometry. This study identifies the impact of a tillage regime shift on the belowground soil-pore and root geometry. Micro X-ray computed tomography (µXCT) was used to quantify, measure and compare the soil-pore and root architecture associated with the impact of tillage shift across different plant growth stages. Soil porosity was 12.2% higher under CT in the top 0–100 mm and 7.4% in the bottom 100–200 mm of the soil core compared with NT. Soil-pore distribution, i.e. macroporosity (>75 μm), was 13.4% higher under CT, but mesoporosity (30–75 μm) was 9.6% higher under NT. The vertical distributions of root biomass and root architecture measurements (i.e. root length density) in undisturbed soil cores were 9.6% higher under the NT and 8.7% higher under the CT system respectively. These results suggest that low soil disturbance under the continuous NT system may have encouraged accumulation of more root biomass in the top 100 mm depth, thus developing better soil structure. Overall, µXCT image analyses of soil cores indicated that this tillage shift affected the soil total carbon, due to the significantly higher soil-pore (i.e. pore surface area, porosity and average pore size area) and root architecture (i.e. root length density, root surface density and root biomass) measurements under the CT system.
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Lee, Jung-Tai, Shun-Ming Tsai, Yu-Jie Wu, Yu-Syuan Lin, Ming-Yang Chu, and Ming-Jen Lee. "Root Characteristics and Water Erosion-Reducing Ability of Alpine Silver Grass and Yushan Cane for Alpine Grassland Soil Conservation." Sustainability 13, no. 14 (July 8, 2021): 7633. http://dx.doi.org/10.3390/su13147633.
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In Taiwan, intensive forest fires frequently cause serious forest degradation, soil erosion and impacts on alpine vegetation. Post-fire succession often induces the substitution of forest by alpine grassland. Alpine silver grass (Miscanthus transmorrisonensis Hay.) and Yushan cane (Yushania niitakayamensis (Hay.) Keng f.) are two main endemic species emerging on post-fire alpine grassland. These species play a major role in the recovery of alpine vegetation and soil conservation of alpine grassland. However, their root traits, root mechanical properties and water erosion-reducing ability have still not been well studied. In the present study, root characteristics were examined using a complete excavation method. Root mechanical characteristics were estimated by utilizing the uprooting test and root tensile test, and hydraulic flume experiments were performed to investigate the water erosion-reducing ability using 8-month-old plants. The results show that the root architecture system of Alpine silver grass belongs to fibrous root system, while the Yushan cane has sympodial-tufted rhizomes with a fibrous root system. Root characteristics reveal that relative to Alpine silver grass, Yushan cane has remarkably larger root collar diameter, higher root biomass, larger root volume, higher root density, and a higher root tissue density. Furthermore, uprooting resistance of Yushan cane is notably higher than that of Alpine silver grass. However, the root tensile strength of Alpine silver grass is significantly higher than that of Yushan cane. Additionally, hydraulic flume experiments reveal that Yushan cane has significantly lower soil detachment rates than that of Alpine silver grass. Collectively, these findings clearly show that Yushan cane has superior root characteristics and water erosion-reducing ability than Alpine silver grass and is thus more suitable for the conservation of alpine grassland.
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Fallahpour, A. R., and A. R. Moghassem. "Yarn Strength Modelling Using Adaptive Neuro-Fuzzy Inference System (ANFIS) and Gene Expression Programming (GEP)." Journal of Engineered Fibers and Fabrics 8, no. 4 (December 2013): 155892501300800. http://dx.doi.org/10.1177/155892501300800409.
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This study compares capabilities of two different modelling methodologies for predicting breaking strength of rotor spun yarns. Forty eight yarn samples were produced considering variations in three drawing frame parameters namely break draft, delivery speed, and distance between back and middle rolls. Several topologies with different architectures were trained to get the best adaptive neuro-fuzzy inference system (ANFIS) and gene expression programming (GEP) models. Prediction performance of the GEP model was compared with that of ANFIS using root mean square error (RMSE) and correlation coefficient (R2-Value) parameters on the test data. Results show that, the GEP model has a significant priority over the ANFIS model in term of prediction accuracy. The correlation coefficient (R2-value) and root mean square error for the GEP model were 0.87 and 0.35 respectively, while these parameters were 0.48 and 0.53 for the ANFIS model. Also, a mathematical formula was developed with high degree of accuracy using GEP algorithm to predict the breaking strength of the yarns. This advantage is not accessible in the ANFIS model.
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Chen, Yining, Charlotte Thompson, and Michael Collins. "Controls on creek margin stability by the root systems of saltmarsh vegetation, Beaulieu Estuary, Southern England." Anthropocene Coasts 2, no. 1 (January 1, 2019): 21–38. http://dx.doi.org/10.1139/anc-2018-0005.
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The retreat of cliffs (lateral expansion) within tidal creeks results in a net loss of saltmarshes, but this retreat process can be retarded by root systems. To understand the interaction between root presence and bank sediment, quantitative measurements of two saltmarsh species root systems (Atriplex portulacoides and Juncus maritima) were carried out in a saltmarsh in Southern England, and their relationships with bank stability were examined. Computed Tomography (CT) Scanning techniques were used to investigate three-dimensional root architecture. The data obtained (e.g., root volume, diameter, and distribution patterns of roots) were examined alongside more traditional root density measurements. The volumetric percentage, ratio between horizontal (lateral) and vertical roots (H/V ratio), and root diameter distribution are discussed in relation to their influence on bank sediment erosion threshold and shear strength. The results suggest that Atriplex portulacoides is more effective than Juncus maritimus in stabilising banks. This is because root systems that provide a high resistance to flow-induced erosion are better than those that provide a high resistance to gravity-induced erosion in stabilising cliff banks. This conclusion is relevant to future saltmarsh protection and re-establishment.
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Bahar, Mohammad Arsyad, Harida Samudro, and Ahmad Yulianto. "The modular structural system as an innovation for temporary public healthcare project of 4th-year architecture students at UIN Maulana Malik Ibrahim Malang." Proceedings of the International Conference on Green Technology 11, no. 1 (November 3, 2021): 12. http://dx.doi.org/10.18860/icgt.v11i1.1395.
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Abstract- The module structure system implements development by utilizing fabricated materials or components made outside the project site or on-site. Consumable shipping containers are often used to make architectural space rated more quickly and efficiently. The advantages of containers are customized, strength, durability, modular, labor, movable, availability, expense, and eco-friendly. The rapid spread of Covid-19 in various regions demands fast, proper, and adequate public health facilities. Containers can be an innovative solution for providing temporary, flexible, efficient, functional, and sustainable public health room facilities. This study describes the uses and advantages of modular container systems for architectural spaces. The result is a schematic design from the design studio of the 4th year architecture student of UIN Maulana Malik Ibrahim Malang, who is trying to improve the function of the use of consumable containers to get more benefits as a temporary architectural space for sustainability and public awareness of health and handling Covid-19.
Dissertations / Theses on the topic "Root system strength and architecture"
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Docker, Benjamin Brougham. "Biotechnical engineering on alluvial riverbanks of southeastern Australia: A quantified model of the earth-reinforcing properties of some native riparian trees." University of Sydney, 2004. http://hdl.handle.net/2123/1688.
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Doctor of Philosophy(PhD)It is generally accepted that tree roots can reinforce soil and improve the stability of vegetated slopes. Tree root reinforcement is also recognised in riverbanks although the contribution that the roots make to bank stability has rarely been assessed due to the reluctance of geomorphologists to examine riverbank stability by geomechanical methods that allow for the inclusion of quantified biotechnical parameters. This study investigates the interaction between alluvial soil and the roots of four southeastern Australian riparian trees. It quantifies the amount and distribution of root reinforcement present beneath typically vegetated riverbanks of the upper Nepean River, New South Wales, and examines the effect of the reinforcement on the stability of these banks. The ability of a tree to reinforce the soil is limited by the spatial distribution of its root system and the strength that the roots impart to the soil during shear. These two parameters were determined for the following four species of native riparian tree: Casuarina glauca, Eucalyptus amplifolia, Eucalyptus elata, and Acacia floribunda. The four species all exhibit a progressive reduction in the quantity of root material both with increasing depth and with increasing lateral distance from the tree stem. In the vertical direction there are two distinct zones that can be described. The first occurs from between 0 and approximately 15 % of the maximum vertical depth and consists of approximately 80 % of the total root material quantity. In this zone the root system consists of both vertical and lateral roots, the size and density of which varies between species. The second zone occurs below approximately 15 % of the maximum vertical depth and consists primarily of vertical roots. The quantity of root material in this zone decreases exponentially with depth due to the taper of individual roots. The earth reinforcement potential in terms of both geometric extent and the quantity of root material expressed as the Root Area Ratio (RAR) varies significantly from species to species. E. elata exhibited the highest values of RAR in soil zones beneath it while E. amplifolia reinforced a greater volume of soil than any of the other species examined. The increased shear resistance (Sr) of alluvial soil containing roots was measured by direct in-situ shear tests on soil blocks beneath a plantation. For three of the species (C. glauca, E. amplifolia, E. elata) Sr increased with increasing RAR measured at the shear plane, in a similar linear relationship. The shear resistance provided by A. floribunda roots also increased with increasing RAR at the shear plane but at a much greater rate than for the other three species. This is attributable to A. floribunda’s greater root tensile strength and therefore pull-out resistance, as well as its smaller root diameters at comparative RARs which resulted in a greater proportion of roots reaching full tensile strength within the confines of the test. Tree roots fail progressively in this system. Therefore determining the increased shear strength from the sum of the pull-out or tensile strengths of all individual roots and Waldron’s (1977) and Wu et al’s (1979) simple root model, would result in substantial over estimates of the overall strength of the soil-root system. The average difference between Sr calculated in this manner and that measured from direct in-situ shear tests is 10.9 kPa for C. glauca, 19.0 kPa for E. amplifolia, 19.3 kPa for E. elata, and 8.8 kPa for A. floribunda. A riverbank stability analysis incorporating the root reinforcement effect was conducted using a predictive model of the spatial distribution of root reinforcement beneath riparian trees within the study area. The model is based on measurements of juveniles and observations of the rooting habits of mature trees. It indicates that while the presence of vegetation on riverbank profiles has the potential to increase stability by up to 105 %, the relative increase depends heavily on the actual vegetation type, density, and location on the bank profile. Of the species examined in this study the greatest potential for improved riverbank stability is provided by E. amplifolia, followed by E. elata, A. floribunda, and C. glauca. The presence of trees on banks of the Nepean River has the potential to raise the critical factor of safety (FoS) from a value that is very unstable (0.85) to significantly above 1.00 even when the banks are completely saturated and subject to rapid draw-down. It is likely then that the period of intense bank instability observed within this environment between 1947 and 1992 would not have taken place had the riparian vegetation not been cleared prior to the onset of wetter climatic conditions. Typical ‘present-day’ profiles are critically to marginally stable. The introduction of vegetation could improve stability by raising the FoS up to 1.68 however the selection of revegetation species is crucial. With the placement of a large growing Eucalypt at a suitable spacing (around 3-5 m) the choice of smaller understorey trees and shrubs is less important. The effect of riparian vegetation on bank stability has important implications for channel morphological change. This study quantifies the mechanical earth reinforcing effect of some native riparian trees, thus allowing for improved deterministic assessment of historical channel change and an improved basis for future riverine management.
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Kellermeier, Fabian. "Environmental genetics of root system architecture." Thesis, University of Glasgow, 2013. http://theses.gla.ac.uk/4663/.
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The root system is the plant’s principal organ for water and mineral nutrient supply. Root growth follows an endogenous, developmental programme. Yet, this programme can be modulated by external cues which makes root system architecture (RSA), the spatial configuration of all root parts, a highly plastic trait. Presence or absence of nutrients such as nitrate (N), phosphate (P), potassium (K) and sulphate (S) serve as environmental signals to which a plant responds with targeted proliferation or restriction of main or lateral root growth. In turn, RSA serves as a quantitative reporter system of nutrient starvation responses and can therefore be used to study nutrient sensing and signalling mechanisms. In this study, I have analysed root architectural responses of various Arabidopsis thaliana genotypes (wildtype, mutants and natural accessions) to single and multiple nutrient deficiency treatments. A comprehensive analysis of combinatorial N, P, K an S supply allowed me to dissect the effect of individual nutrients on individual root parameters. It also highlighted the existence of interactive effects arising from simultaneous environmental stimuli. Quantification of appropriate RSA parameters allowed for targeted testing of known regulatory genes in specific nutritional settings. This revealed, for example, a novel role for CIPK23, AKT1 and NRT1.1 in integrating K and N effects on higher order lateral root branching and main root angle. A significant contribution to phenotypic variation also arose from P*K interactions. I could show that the iron (Fe) concentration in the external medium is an important driving force of RSA responses to low-P and low-K. In fact, P and K deprivation caused Fe accumulation in distinct parts of the root system, as demonstrated by Fe staining and synchrotron X-Ray fluorescence. Again, selected K, P and Fe transport and signalling mutants were tested for aberrant low-K and/or low-P phenotypes. Most notably, the two paralogous ER-localised multicopper oxidases LPR1 and LPR2 emerged as important signalling components of P and K deprivation, potentially integrating Fe homeostasis with meristematic activity under these conditions. In addition to the targeted characterisation of specific genotype-environment interactions, I investigated novel RSA responses to low-K via a non-targeted approach based on natural variation. A morphological gradient spanned the entire genotype set, linking two extreme strategies of low-K responses. Strategy I accessions responded to low-K with a moderate reduction of main root growth but a severe restriction of lateral root elongation. In contrast, strategy II genotypes ceded main root growth in favour of lateral root proliferation. The genetic basis of these low-K responses was then subsequently mapped onto the A. thaliana genome via quantitative trait loci (QTL) analysis using recombinant inbred lines derived from parental accessions that either adopt strategy I (Col-0) or II (Ct-1). In sum, this study addresses the question how plants incorporate environmental signals to modulate developmental programmes that underly RSA formation. I present evidence for novel phenotypic responses to nutrient deprivation and for novel genetic regulators involved in nutrient signalling and crosstalk.
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Johnson, James. "Quantitative analysis of plant root system architecture." Thesis, University of Nottingham, 2018. http://eprints.nottingham.ac.uk/55601/.
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The root system of a plant is responsible for supplying it with essential nutrients. The plant's ability to explore the surrounding soil is largely determined by its root system architecture (RSA), which varies with both genetic and environmental conditions. X-ray micro computed tomography (µCT) is a powerful tool allowing the non-invasive study of the root system architecture of plants grown in natural soil environments, providing both 3D descriptions of root architecture and the ability to make multiple measurements over a period of time. Once volumetric µCT data is acquired, the root system must first be segmented from the surrounding soil environment and then described. Automated and semi-automated software tools can be used to extract roots from µCT images, but current methods for the recovery of RSA traits from the resulting volumetric descriptions are somewhat limited. This thesis presents a novel tool (RooTh) which, given a segmented µCT image, skeletonises the root system and quantifies global and local root traits with minimal user interaction. The computationally inexpensive method used takes advantage of curve-fitting and active contours to find the optimal skeleton and thus evaluate root traits objectively. A small-scale experiment was conducted to validate and compare root traits extracted using the method presented here alongside other 2D imaging tools. The results show a good degree of correlation between the two methods.
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Linkohr, Birgit Isabel. "The control of root system architecture in 'Arabidopsis'." Thesis, University of York, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.428452.
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Ribrioux, Sebastien. "Phosphate control of root system architecture in Arabidopsis." Thesis, University of York, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.247735.
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Stokes, Alexia. "Responses of young trees to wind : effects on root architecture and anchorage strength." Thesis, University of York, 1994. http://etheses.whiterose.ac.uk/2438/.
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佑脩, 田和, and Yusuke Tawa. "Dynamics and architecture of fine root system in a Cryptomeria japonica plantation." Thesis, https://doors.doshisha.ac.jp/opac/opac_link/bibid/BB13106238/?lang=0, 2019. https://doors.doshisha.ac.jp/opac/opac_link/bibid/BB13106238/?lang=0.
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Tracy, Saoirse Rosanna. "The response of root system architecture to soil compaction." Thesis, University of Nottingham, 2013. http://eprints.nottingham.ac.uk/13037/.
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Soil compaction has been described as the most serious environmental problem caused by conventional agriculture, as it results in several stresses which may interact simultaneously, including increased soil strength, decreased aeration and reduced hydraulic conductivity. Root system architecture (RSA) is the arrangement of roots within the soil matrix and is important because the specific deployment of roots within the soil can determine soil exploration and resource uptake. As roots deliver water and nutrients to growing plants, whilst also providing anchorage, their importance cannot be overstated. Yet, our understanding of how roots interact with the surrounding soil, especially at the micro-scale level, remains limited because soil is an opaque medium, so preventing roots from being visualised without disturbing them. Destructive techniques are commonly employed for the analysis of RSA, however this can result in the loss of key information concerning root architecture, such as elongation rates and root angles and important soil characteristics such as soil structure and pore connectivity. However, X-ray Computed Tomography (CT) has been shown to be a promising technique for visualising RSA in an undisturbed manner. The species considered in this thesis were wheat (Triticum aestivum L.) and tomato (Solanum lycopersicum L.). Further information regarding the response of roots to soil compaction has been achieved through the use of X-ray CT, automatic root tracing software and novel image analysis procedures. Soil compaction significantly affected root length, volume, surface area, angle, diameter, elongation rates and root path tortuosity, however the influence of soil texture on root responses to soil compaction was significant. Moderate compaction benefits root growth in clay soil, possibly due to the greater nutrient and water holding capacity, but adversely affected root growth in loamy sand. The results suggest that there is an optimum level of soil compaction for the different soil types. Roots elongated rapidly between 2-3 days after germination (DAG), it is hypothesised that is related to the mobilization of seed storage substances to the growing roots. The use of transgenic mutants of tomato with altered levels of abscisic acid (ABA) has provided a greater insight into the role of ABA in mediating root responses to soil compaction. This work will enable better phenotyping of plant varieties with enhanced root system traits for resource foraging and uptake. Knowledge of the responses of root systems in heterogeneous soil is vital to validate root phenotypes and overcome future food security challenges.
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Adu, Michael Osei. "Variations in root system architecture and root growth dynamics of Brassica rapa genotypes using a new scanner-based phenotyping system." Thesis, University of Nottingham, 2014. http://eprints.nottingham.ac.uk/14259/.
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There is a need to breed for root systems architectures (RSAs) that optimise soil resource acquisition. This requires high resolution and high-throughput quantification of RSA in as natural an environment as possible. Current imaging techniques are limited by cost, reproducibility, throughput and complexity. This thesis describes (1) the construction of a low cost, high-resolution, root phenotyping platform that requires no sophisticated equipment which is adaptable to most laboratory and glasshouse environments and (2) its application to quantify environmental and temporal variation in RSA between genotypes of Brassica rapa L. The high resolution root phenotyping system (HRP) that was constructed employed 24 scanners and could screen up to 72 individual plants at any time, with the possibility of capturing thousands of root images daily depending on the operational number of scanners and scanning periodicity. Plants were supplied with a complete nutrient solution through the wick of a germination paper. Images of RSA were acquired automatically, over extended periods, using multiple scanners controlled by customised software. The RSA data was used to validate a mechanistic model and mixed effects models were used to describe the sources of variation in traits contributing to RSA. Plants were also grown in rhizoboxes and under varying concentrations of P ([P]ext). Broad-sense heritability (H2), was highest (≥ 0.70) for shoot biomass, length of primary roots (PRs), number of lateral roots (LRs). Coefficients of variation in RSA traits within a genotype were large and ranged between 5 and 103%. It was found that between 4 and 48 replicates were needed to detect a significant difference (95% CI, 50% difference between trait means). Significant differences were found between genotypes in root traits with strong positive correlations among RSA traits and between biomass and RSA traits. Principal component analyses identified 5 significant axes of variation, accounting for approximately 86 and 78% of the variation in the genotypes on paper and soil substrates, respectively. Cluster analysis of the genotypes produced 5 discrete groups. Genotypes with more or less shoot biomass or with bigger or smaller RSA could be distinguished. A density-based 2D model reproduced experimental results accurately by simulating PR length and total length of LRs. Mixed-effects statistical models demonstrated that root traits show temporal variations of various types with significant effects of genotype. All genotypes followed a similar growth pattern with time, but differed in their maximum total root length (TRL), primary root length (PRL) and LR growth. A 3-parameter logistic model satisfactorily described TRL and PRL when genotypes were grown on both paper and soil substrates. On paper substrate, TRL required only a single, random-effect parameter (asymptote), describing maximum TRL. On soil substrate, TRL required two random-effects parameters, asymptote and inflection, describing maximum TRL and time at which ½ of maximum TRL occurs, respectively. Primary root length on both paper and soil substrates required only a single, random-effect parameter, describing maximum PRL. The growth rate of LRs of all ages followed a quadratic function and required only a single, random-effect parameter, describing maximum growth rate. There was variation in specific RSA traits and plasticity in response to [P]ext among genotypes. Length of the apical un-branched zone of the PR increased with increasing [P]ext. Total root length, total LR length and number of LRs was positively correlated with total plant tissue P concentration at low [P]ext but not at high [P]ext. Paper substrate was more suitable for screening seedling root traits but root phenotypes must be validated in situ in the field or in soil media because some differences were evident between data observed on paper and soil substrates. Scanner-based phenotyping of RSA provides economical means of studying the mechanisms underlying the plant-soil interactions and can be used to quantify environmental and temporal variation in traits contributing to RSA. The HRP system can be extended to screen the large populations required for breeding for efficient resource acquisition. The necessity for high replication and time-consuming image analysis could however limit throughput in the phenotyping system.
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Mairhofer, Stefan. "Extracting root system architecture from X-ray micro computed tomography images using visual tracking." Thesis, University of Nottingham, 2014. http://eprints.nottingham.ac.uk/27739/.
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X-ray micro computed tomography (µCT) is increasingly applied in plant biology as an imaging system that is valuable for the study of root development in soil, since it allows the three-dimensional and non-destructive visualisation of plant root systems. Variations in the X-ray attenuation values of root material and the overlap in measured intensity values between roots and soil caused by water and organic matter represent major challenges to the extraction of root system architecture. We propose a novel technique to recover root system information from X-ray CT data, using a strategy based on a visual tracking framework embedding a modiffed level set method that is evolved using the Jensen-Shannon divergence. The model-guided search arising from the visual tracking approach makes the method less sensitive to the natural ambiguity of X-ray attenuation values in the image data and thus allows a better extraction of the root system. The method is extended by mechanisms that account for plagiatropic response in roots as well as collision between root objects originating from different plants that are grown and interact within the same soil environment. Experimental results on monocot and dicot plants, grown in different soil textural types, show the ability of successfully extracting root system information. Various global root system traits are measured from the extracted data and compared to results obtained with alternative methods.
Books on the topic "Root system strength and architecture"
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Nicola, Silvana. Lettuce (Lactuca sativa L.) root morpholgy, architecture, growth and development in an autotrophic culture system. 1997.
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Zydroń, Tymoteusz. Wpływ systemów korzeniowych wybranych gatunków drzew na przyrost wytrzymałości gruntu na ścinanie. Publishing House of the University of Agriculture in Krakow, 2019. http://dx.doi.org/10.15576/978-83-66602-46-5.
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The aim of the paper was to determine the influence of root systems of chosen tree species found in the Polish Flysch Carpathians on the increase of soil shear strength (root cohesion) in terms of slope stability. The paper's goal was achieved through comprehensive tests on root systems of eight relatively common in the Polish Flysch Carpathians tree species. The tests that were carried out included field work, laboratory work and analytical calculations. As part of the field work, the root area ratio (A IA) of the roots was determined using the method of profiling the walls of the trench at a distance of about 1.0 m from the tree trunk. The width of the. trenches was about 1.0 m, and their depth depended on the ground conditions and ranged from 0.6 to 1.0 m below the ground level. After preparing the walls of the trench, the profile was divided into vertical layers with a height of 0.1 m, within which root diameters were measured. Roots with diameters from 1 to 10 mm were taken into consideration in root area ratio calculations in accordance with the generally accepted methodology for this type of tests. These measurements were made in Biegnik (silver fir), Ropica Polska (silver birch, black locust) and Szymbark (silver birch, European beech, European hornbeam, silver fir, sycamore maple, Scots pine, European spruce) located near Gorlice (The Low Beskids) in areas with unplanned forest management. In case of each tested tree species the samples of roots were taken, transported to the laboratory and then saturated with water for at least one day. Before testing the samples were obtained from the water and stretched in a. tensile testing machine in order to determine their tensile strength and flexibility. In general, over 2200 root samples were tested. The results of tests on root area ratio of root systems and their tensile strength were used to determine the value of increase in shear strength of the soils, called root cohesion. To this purpose a classic Wu-Waldron calculation model was used as well as two types of bundle models, the so called static model (Fiber Bundle Model — FIRM, FBM2, FBM3) and the deformation model (Root Bundle Model— RBM1, RBM2, mRBM1) that differ in terms of the assumptions concerning the way the tensile force is distributed to the roots as well as the range of parameters taken into account during calculations. The stability analysis of 8 landslides in forest areas of Cicikowicleie and Wignickie Foothills was a form of verification of relevance of the obtained calculation results. The results of tests on root area ratio in the profile showed that, as expected, the number of roots in the soil profile and their ApIA values are very variable. It was shown that the values of the root area ratio of the tested tree species with a diameter 1-10 ram are a maximum of 0.8% close to the surface of the ground and they decrease along with the depth reaching the values at least one order of magnitude lower than close to the surface at the depth 0.5-1.0 m below the ground level. Average values of the root area ratio within the soil profile were from 0.05 to 0.13% adequately for Scots pine and European beech. The measured values of the root area ratio are relatively low in relation to the values of this parameter given in literature, which is probably connected with great cohesiveness of the soils and the fact that there were a lot of rock fragments in the soil, where the tests were carried out. Calculation results of the Gale-Grigal function indicate that a distribution of roots in the soil profile is similar for the tested species, apart from the silver fir from Bie§nik and European hornbeam. Considering the number of roots, their distribution in the soil profile and the root area ratio it appears that — considering slope stability — the root systems of European beech and black locust are the most optimal, which coincides with tests results given in literature. The results of tensile strength tests showed that the roots of the tested tree species have different tensile strength. The roots of European beech and European hornbeam had high tensile strength, whereas the roots of conifers and silver birch in deciduous trees — low. The analysis of test results also showed that the roots of the studied tree species are characterized by high variability of mechanical properties. The values Of shear strength increase are mainly related to the number and size (diameter) of the roots in the soil profile as well as their tensile strength and pullout resistance, although they can also result from the used calculation method (calculation model). The tests showed that the distribution of roots in the soil and their tensile strength are characterized by large variability, which allows the conclusion that using typical geotechnical calculations, which take into consideration the role of root systems is exposed to a high risk of overestimating their influence on the soil reinforcement. hence, while determining or assuming the increase in shear strength of soil reinforced with roots (root cohesion) for design calculations, a conservative (careful) approach that includes the most unfavourable values of this parameter should be used. Tests showed that the values of shear strength increase of the soil reinforced with roots calculated using Wu-Waldron model in extreme cases are three times higher than the values calculated using bundle models. In general, the most conservative calculation results of the shear strength increase were obtained using deformation bundle models: RBM2 (RBMw) or mRBM1. RBM2 model considers the variability of strength characteristics of soils described by Weibull survival function and in most cases gives the lowest values of the shear strength increase, which usually constitute 50% of the values of shear strength increase determined using classic Wu-Waldron model. Whereas the second model (mRBM1.) considers averaged values of roots strength parameters as well as the possibility that two main mechanism of destruction of a root bundle - rupture and pulling out - can occur at the same. time. The values of shear strength increase calculated using this model were the lowest in case of beech and hornbeam roots, which had high tensile strength. It indicates that in the surface part of the profile (down to 0.2 m below the ground level), primarily in case of deciduous trees, the main mechanism of failure of the root bundle will be pulling out. However, this model requires the knowledge of a much greater number of geometrical parameters of roots and geotechnical parameters of soil, and additionally it is very sensitive to input data. Therefore, it seems practical to use the RBM2 model to assess the influence of roots on the soil shear strength increase, and in order to obtain safe results of calculations in the surface part of the profile, the Weibull shape coefficient equal to 1.0 can be assumed. On the other hand, the Wu-Waldron model can be used for the initial assessment of the shear strength increase of soil reinforced with roots in the situation, where the deformation properties of the root system and its interaction with the soil are not considered, although the values of the shear strength increase calculated using this model should be corrected and reduced by half. Test results indicate that in terms of slope stability the root systems of beech and hornbeam have the most favourable properties - their maximum effect of soil reinforcement in the profile to the depth of 0.5 m does not usually exceed 30 kPa, and to the depth of 1 m - 20 kPa. The root systems of conifers have the least impact on the slope reinforcement, usually increasing the soil shear strength by less than 5 kPa. These values coincide to a large extent with the range of shear strength increase obtained from the direct shear test as well as results of stability analysis given in literature and carried out as part of this work. The analysis of the literature indicates that the methods of measuring tree's root systems as well as their interpretation are very different, which often limits the possibilities of comparing test results. This indicates the need to systematize this type of tests and for this purpose a root distribution model (RDM) can be used, which can be integrated with any deformation bundle model (RBM). A combination of these two calculation models allows the range of soil reinforcement around trees to be determined and this information might be used in practice, while planning bioengineering procedures in areas exposed to surface mass movements. The functionality of this solution can be increased by considering the dynamics of plant develop¬ment in the calculations. This, however, requires conducting this type of research in order to obtain more data.
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Commercial Vehicles 2021. VDI Verlag, 2021. http://dx.doi.org/10.51202/9783181023808.
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Contents Ways to achieve Zero Emission ZF E-Mobility products and software for commercial vehicles ..... 1 Thermoelectric generators for heavy-duty vehicles as an economical waste heat recovery system ..... 17 Hybridization of heavy duty trucks – Market analysis and technology for high voltage as well as low voltage solutions ..... 33 Development processes and methods Lightweight construction and cost reduction – a lean, agile MSCDPS® product development process ..... 43 eDrive & Fuel Cell powertrain systems engineering for commercial vehicles ..... 55 Fatigue development of a 10x10 commercial vehicle frame using dynamic and/or strength simulation, virtual iteration and component testing together with measurement data acquisition ..... 73 Data-driven selection of vehicle variants for the E/E integration test – Increasing variants and complex technology versus test coverage ..... 81 Hydrogen propulsion High performance and efficiency hydrogen engine using westport fuel systems’ Commercially available HPDI fuel system ..... 97 E/E architecture and operating strategy for fuel-cell trucks – Challenges...
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Skiba, Grzegorz. Fizjologiczne, żywieniowe i genetyczne uwarunkowania właściwości kości rosnących świń. The Kielanowski Institute of Animal Physiology and Nutrition, Polish Academy of Sciences, 2020. http://dx.doi.org/10.22358/mono_gs_2020.
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Bones are multifunctional passive organs of movement that supports soft tissue and directly attached muscles. They also protect internal organs and are a reserve of calcium, phosphorus and magnesium. Each bone is covered with periosteum, and the adjacent bone surfaces are covered by articular cartilage. Histologically, the bone is an organ composed of many different tissues. The main component is bone tissue (cortical and spongy) composed of a set of bone cells and intercellular substance (mineral and organic), it also contains fat, hematopoietic (bone marrow) and cartilaginous tissue. Bones are a tissue that even in adult life retains the ability to change shape and structure depending on changes in their mechanical and hormonal environment, as well as self-renewal and repair capabilities. This process is called bone turnover. The basic processes of bone turnover are: • bone modeling (incessantly changes in bone shape during individual growth) following resorption and tissue formation at various locations (e.g. bone marrow formation) to increase mass and skeletal morphology. This process occurs in the bones of growing individuals and stops after reaching puberty • bone remodeling (processes involve in maintaining bone tissue by resorbing and replacing old bone tissue with new tissue in the same place, e.g. repairing micro fractures). It is a process involving the removal and internal remodeling of existing bone and is responsible for maintaining tissue mass and architecture of mature bones. Bone turnover is regulated by two types of transformation: • osteoclastogenesis, i.e. formation of cells responsible for bone resorption • osteoblastogenesis, i.e. formation of cells responsible for bone formation (bone matrix synthesis and mineralization) Bone maturity can be defined as the completion of basic structural development and mineralization leading to maximum mass and optimal mechanical strength. The highest rate of increase in pig bone mass is observed in the first twelve weeks after birth. This period of growth is considered crucial for optimizing the growth of the skeleton of pigs, because the degree of bone mineralization in later life stages (adulthood) depends largely on the amount of bone minerals accumulated in the early stages of their growth. The development of the technique allows to determine the condition of the skeletal system (or individual bones) in living animals by methods used in human medicine, or after their slaughter. For in vivo determination of bone properties, Abstract 10 double energy X-ray absorptiometry or computed tomography scanning techniques are used. Both methods allow the quantification of mineral content and bone mineral density. The most important property from a practical point of view is the bone’s bending strength, which is directly determined by the maximum bending force. The most important factors affecting bone strength are: • age (growth period), • gender and the associated hormonal balance, • genotype and modification of genes responsible for bone growth • chemical composition of the body (protein and fat content, and the proportion between these components), • physical activity and related bone load, • nutritional factors: – protein intake influencing synthesis of organic matrix of bone, – content of minerals in the feed (CA, P, Zn, Ca/P, Mg, Mn, Na, Cl, K, Cu ratio) influencing synthesis of the inorganic matrix of bone, – mineral/protein ratio in the diet (Ca/protein, P/protein, Zn/protein) – feed energy concentration, – energy source (content of saturated fatty acids - SFA, content of polyun saturated fatty acids - PUFA, in particular ALA, EPA, DPA, DHA), – feed additives, in particular: enzymes (e.g. phytase releasing of minerals bounded in phytin complexes), probiotics and prebiotics (e.g. inulin improving the function of the digestive tract by increasing absorption of nutrients), – vitamin content that regulate metabolism and biochemical changes occurring in bone tissue (e.g. vitamin D3, B6, C and K). This study was based on the results of research experiments from available literature, and studies on growing pigs carried out at the Kielanowski Institute of Animal Physiology and Nutrition, Polish Academy of Sciences. The tests were performed in total on 300 pigs of Duroc, Pietrain, Puławska breeds, line 990 and hybrids (Great White × Duroc, Great White × Landrace), PIC pigs, slaughtered at different body weight during the growth period from 15 to 130 kg. Bones for biomechanical tests were collected after slaughter from each pig. Their length, mass and volume were determined. Based on these measurements, the specific weight (density, g/cm3) was calculated. Then each bone was cut in the middle of the shaft and the outer and inner diameters were measured both horizontally and vertically. Based on these measurements, the following indicators were calculated: • cortical thickness, • cortical surface, • cortical index. Abstract 11 Bone strength was tested by a three-point bending test. The obtained data enabled the determination of: • bending force (the magnitude of the maximum force at which disintegration and disruption of bone structure occurs), • strength (the amount of maximum force needed to break/crack of bone), • stiffness (quotient of the force acting on the bone and the amount of displacement occurring under the influence of this force). Investigation of changes in physical and biomechanical features of bones during growth was performed on pigs of the synthetic 990 line growing from 15 to 130 kg body weight. The animals were slaughtered successively at a body weight of 15, 30, 40, 50, 70, 90, 110 and 130 kg. After slaughter, the following bones were separated from the right half-carcass: humerus, 3rd and 4th metatarsal bone, femur, tibia and fibula as well as 3rd and 4th metatarsal bone. The features of bones were determined using methods described in the methodology. Describing bone growth with the Gompertz equation, it was found that the earliest slowdown of bone growth curve was observed for metacarpal and metatarsal bones. This means that these bones matured the most quickly. The established data also indicate that the rib is the slowest maturing bone. The femur, humerus, tibia and fibula were between the values of these features for the metatarsal, metacarpal and rib bones. The rate of increase in bone mass and length differed significantly between the examined bones, but in all cases it was lower (coefficient b <1) than the growth rate of the whole body of the animal. The fastest growth rate was estimated for the rib mass (coefficient b = 0.93). Among the long bones, the humerus (coefficient b = 0.81) was characterized by the fastest rate of weight gain, however femur the smallest (coefficient b = 0.71). The lowest rate of bone mass increase was observed in the foot bones, with the metacarpal bones having a slightly higher value of coefficient b than the metatarsal bones (0.67 vs 0.62). The third bone had a lower growth rate than the fourth bone, regardless of whether they were metatarsal or metacarpal. The value of the bending force increased as the animals grew. Regardless of the growth point tested, the highest values were observed for the humerus, tibia and femur, smaller for the metatarsal and metacarpal bone, and the lowest for the fibula and rib. The rate of change in the value of this indicator increased at a similar rate as the body weight changes of the animals in the case of the fibula and the fourth metacarpal bone (b value = 0.98), and more slowly in the case of the metatarsal bone, the third metacarpal bone, and the tibia bone (values of the b ratio 0.81–0.85), and the slowest femur, humerus and rib (value of b = 0.60–0.66). Bone stiffness increased as animals grew. Regardless of the growth point tested, the highest values were observed for the humerus, tibia and femur, smaller for the metatarsal and metacarpal bone, and the lowest for the fibula and rib. Abstract 12 The rate of change in the value of this indicator changed at a faster rate than the increase in weight of pigs in the case of metacarpal and metatarsal bones (coefficient b = 1.01–1.22), slightly slower in the case of fibula (coefficient b = 0.92), definitely slower in the case of the tibia (b = 0.73), ribs (b = 0.66), femur (b = 0.59) and humerus (b = 0.50). Bone strength increased as animals grew. Regardless of the growth point tested, bone strength was as follows femur > tibia > humerus > 4 metacarpal> 3 metacarpal> 3 metatarsal > 4 metatarsal > rib> fibula. The rate of increase in strength of all examined bones was greater than the rate of weight gain of pigs (value of the coefficient b = 2.04–3.26). As the animals grew, the bone density increased. However, the growth rate of this indicator for the majority of bones was slower than the rate of weight gain (the value of the coefficient b ranged from 0.37 – humerus to 0.84 – fibula). The exception was the rib, whose density increased at a similar pace increasing the body weight of animals (value of the coefficient b = 0.97). The study on the influence of the breed and the feeding intensity on bone characteristics (physical and biomechanical) was performed on pigs of the breeds Duroc, Pietrain, and synthetic 990 during a growth period of 15 to 70 kg body weight. Animals were fed ad libitum or dosed system. After slaughter at a body weight of 70 kg, three bones were taken from the right half-carcass: femur, three metatarsal, and three metacarpal and subjected to the determinations described in the methodology. The weight of bones of animals fed aa libitum was significantly lower than in pigs fed restrictively All bones of Duroc breed were significantly heavier and longer than Pietrain and 990 pig bones. The average values of bending force for the examined bones took the following order: III metatarsal bone (63.5 kg) <III metacarpal bone (77.9 kg) <femur (271.5 kg). The feeding system and breed of pigs had no significant effect on the value of this indicator. The average values of the bones strength took the following order: III metatarsal bone (92.6 kg) <III metacarpal (107.2 kg) <femur (353.1 kg). Feeding intensity and breed of animals had no significant effect on the value of this feature of the bones tested. The average bone density took the following order: femur (1.23 g/cm3) <III metatarsal bone (1.26 g/cm3) <III metacarpal bone (1.34 g / cm3). The density of bones of animals fed aa libitum was higher (P<0.01) than in animals fed with a dosing system. The density of examined bones within the breeds took the following order: Pietrain race> line 990> Duroc race. The differences between the “extreme” breeds were: 7.2% (III metatarsal bone), 8.3% (III metacarpal bone), 8.4% (femur). Abstract 13 The average bone stiffness took the following order: III metatarsal bone (35.1 kg/mm) <III metacarpus (41.5 kg/mm) <femur (60.5 kg/mm). This indicator did not differ between the groups of pigs fed at different intensity, except for the metacarpal bone, which was more stiffer in pigs fed aa libitum (P<0.05). The femur of animals fed ad libitum showed a tendency (P<0.09) to be more stiffer and a force of 4.5 kg required for its displacement by 1 mm. Breed differences in stiffness were found for the femur (P <0.05) and III metacarpal bone (P <0.05). For femur, the highest value of this indicator was found in Pietrain pigs (64.5 kg/mm), lower in pigs of 990 line (61.6 kg/mm) and the lowest in Duroc pigs (55.3 kg/mm). In turn, the 3rd metacarpal bone of Duroc and Pietrain pigs had similar stiffness (39.0 and 40.0 kg/mm respectively) and was smaller than that of line 990 pigs (45.4 kg/mm). The thickness of the cortical bone layer took the following order: III metatarsal bone (2.25 mm) <III metacarpal bone (2.41 mm) <femur (5.12 mm). The feeding system did not affect this indicator. Breed differences (P <0.05) for this trait were found only for the femur bone: Duroc (5.42 mm)> line 990 (5.13 mm)> Pietrain (4.81 mm). The cross sectional area of the examined bones was arranged in the following order: III metatarsal bone (84 mm2) <III metacarpal bone (90 mm2) <femur (286 mm2). The feeding system had no effect on the value of this bone trait, with the exception of the femur, which in animals fed the dosing system was 4.7% higher (P<0.05) than in pigs fed ad libitum. Breed differences (P<0.01) in the coross sectional area were found only in femur and III metatarsal bone. The value of this indicator was the highest in Duroc pigs, lower in 990 animals and the lowest in Pietrain pigs. The cortical index of individual bones was in the following order: III metatarsal bone (31.86) <III metacarpal bone (33.86) <femur (44.75). However, its value did not significantly depend on the intensity of feeding or the breed of pigs.
Book chapters on the topic "Root system strength and architecture"
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Orman-Ligeza, Beata, René Civava, Sophie de Dorlodot, and Xavier Draye. "Root System Architecture." In Soil Biology, 39–56. Berlin, Heidelberg: Springer Berlin Heidelberg, 2014. http://dx.doi.org/10.1007/978-3-642-54276-3_3.
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Pagès, L., S. Asseng, S. Pellerin, and A. Diggle. "Modelling Root System Growth and Architecture." In Root Methods, 113–46. Berlin, Heidelberg: Springer Berlin Heidelberg, 2000. http://dx.doi.org/10.1007/978-3-662-04188-8_4.
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Pagès, Loïc. "Why model root system architecture?" In The Supporting Roots of Trees and Woody Plants: Form, Function and Physiology, 187–94. Dordrecht: Springer Netherlands, 2000. http://dx.doi.org/10.1007/978-94-017-3469-1_18.
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Pagès, Loïc. "Root System Architecture: Analysis from Root Systems to Individual Roots." In Encyclopedia of Agrophysics, 712–17. Dordrecht: Springer Netherlands, 2011. http://dx.doi.org/10.1007/978-90-481-3585-1_209.
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Kerk, Nancy. "The root meristem and its relationship to root system architecture." In Root Demographics and Their Efficiencies in Sustainable Agriculture, Grasslands and Forest Ecosystems, 509–21. Dordrecht: Springer Netherlands, 1998. http://dx.doi.org/10.1007/978-94-011-5270-9_42.
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Stanisz, J., Ł. Kaczmarek, T. Zydroń, A. Gruchot, T. Wejrzanowski, and P. Popielski. "Impact of Root System on Soil Strength in Shallow Landslide." In Springer Series in Geomechanics and Geoengineering, 1530–34. Cham: Springer International Publishing, 2018. http://dx.doi.org/10.1007/978-3-319-97115-5_139.
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Tepfer, David, Jean-Pierre Damon, Gozal Ben-Hayyim, Alessandro Pellegrineschi, Daniel Burtin, and Josette Martin-Tanguy. "Control of Root System Architecture through Chemical and Genetic Alterations of Polyamine Metabolism." In Biology of Adventitious Root Formation, 181–89. Boston, MA: Springer US, 1994. http://dx.doi.org/10.1007/978-1-4757-9492-2_14.
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Sinha, Nishant K., M. Mohanty, Somasundaram Jayaraman, Jitendra Kumar, Dhiraj Kumar, and Alka Rani. "Implication of Different Tillage System on Root System Architecture and Their Environment." In Conservation Agriculture: A Sustainable Approach for Soil Health and Food Security, 451–75. Singapore: Springer Singapore, 2021. http://dx.doi.org/10.1007/978-981-16-0827-8_23.
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Kitomi, Yuka, Jun-Ichi Itoh, and Yusaku Uga. "Genetic Mechanisms Involved in the Formation of Root System Architecture." In Rice Genomics, Genetics and Breeding, 241–74. Singapore: Springer Singapore, 2018. http://dx.doi.org/10.1007/978-981-10-7461-5_14.
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Hooker, J. E., G. Berta, G. Lingua, A. Fusconi, and S. Sgorbati. "Quantification of AMF-Induced Modifications to Root System Architecture and Longevity." In Mycorrhiza Manual, 515–31. Berlin, Heidelberg: Springer Berlin Heidelberg, 1998. http://dx.doi.org/10.1007/978-3-642-60268-9_34.
Full textConference papers on the topic "Root system strength and architecture"
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Pages, Loic, Delphine Moreau, Vaia Sarlikioti, Hassan Boukcim, and Christophe Nguyen. "ArchiSimple: A parsimonious model of the root system architecture." In 2012 IEEE 4th International Symposium on Plant Growth Modeling, Simulation, Visualization and Applications (PMA). IEEE, 2012. http://dx.doi.org/10.1109/pma.2012.6524849.
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Green, Scott A., Mark Billinghurst, XiaoQi Chen, and J. Geoffrey Chase. "Human Robot Collaboration: An Augmented Reality Approach—A Literature Review and Analysis." In ASME 2007 International Design Engineering Technical Conferences and Computers and Information in Engineering Conference. ASMEDC, 2007. http://dx.doi.org/10.1115/detc2007-34227.
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Future space exploration will demand the cultivation of human-robotic systems, however, little attention has been paid to the development of human-robot teams. Current methods for autonomous plan creation are often complex and difficult to use. So a system is needed that enables humans and robotic systems to naturally and effectively collaborate. Effective collaboration takes place when the participants are able to communicate in a natural and effective manner. Grounding, the common understanding between conversational participants, shared spatial referencing and situational awareness, are crucial components of communication and collaboration. This paper briefly reviews the fields of human-robot interaction and Augmented Reality (AR), the overlaying of computer graphics onto the real worldview. The strengths of AR are discussed and how they might be used for more effective human-robot collaboration is described. Then a description of an architecture that we have developed is given that uses AR as a means for real time understanding of the shared spatial scene. This architecture enables grounding and enhances situational awareness, thus laying the necessary groundwork for natural and effective human-robot collaboration.
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Liu, Yufeng, Degang Xu, Haiming Cai, and Chunhua Yang. "System architecture design of PCIe root complex based on SOPC." In 2017 36th Chinese Control Conference (CCC). IEEE, 2017. http://dx.doi.org/10.23919/chicc.2017.8028228.
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Teng, Xuefeng, Duoqi Shi, and Xiaoguang Yang. "Experimental and Modeling Study on Tension Characteristics of a 2.5D Woven Composites." In ASME Turbo Expo 2019: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2019. http://dx.doi.org/10.1115/gt2019-90838.
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Abstract 2.5D woven composites have recently attracted much attention in the fields of aerospace and automobile industry due to their excellent properties such as low density, high thermal shock resistance, high specific strength and enhanced mechanical properties. Before the 2.5D woven composites are applied as load-bearing structure, it is necessary to have an in-depth understanding of their mechanical behavior and load transfer mechanism under external loads. In this paper, in-plane tensile tests including longitude direction and transverse direction were conducted for a 2.5D woven SiO2f/SiO2 composites at room temperature. With the full-field displacements and strains retrieved by digital image correlation (DIC) method, the mechanical properties and deformation features of the 2.5D woven composites were obtained and observed. The results show that the composite has a lower elastic modulus and fracture strength in the weft direction, and the warp yarn has weaker mechanical properties than weft yarn in the loading direction due to its crimp feature. Remarkable deformation features of the full-field displacement and strain distributions were observed, indicating that the woven structure has a great influence on the deformation evolution and load-bearing mechanism of the composite. Also, based on the actual geometrical architecture of the composite, a mesoscale finite element (FE) model was established and the deformation characteristics of the material were analyzed. The crimp of the warp yarns causes the local fiber axis to rotate with respect to the global coordinate system, which causes the effective modulus in the global direction to vary. Local coordinate systems were assigned to each node such that the local 1 direction is always parallel to the local fiber axis along the length of the warp yarns, which improves the accuracy of the simulation results. Deformation features of the 2.5D woven SiO2f/SiO2 composites were obtained in FEM simulation and discussed comparing with experimental results.
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"3D reconstruction, modelling and analysis of in situ root system architecture." In 20th International Congress on Modelling and Simulation (MODSIM2013). Modelling and Simulation Society of Australia and New Zealand (MSSANZ), Inc., 2013. http://dx.doi.org/10.36334/modsim.2013.b1.kumar.
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Rasooli, Mr Eng Amanullah, and Dr Eng Hideki Idota. "Assesment of Steel Structural System Maximum Strength Properties." In Annual International Conference on Architecture and Civil Engineering. Global Science & Technology Forum (GSTF), 2013. http://dx.doi.org/10.5176/2301-394x_ace13.160.
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Hui, Fang, Yan Guo, Baoguo Li, Chunli Lv, and Yuntao Ma. "Quantification of differences in root system architecture under maize/soybean interspecific interactions." In 2018 6th International Symposium on Plant Growth Modeling, Simulation, Visualization and Applications (PMA). IEEE, 2018. http://dx.doi.org/10.1109/pma.2018.8611603.
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Colombo, Vittorio, Diletta Forgione, Matteo Gherardi, Romolo Laurita, Emanuele Simoncelli, Augusto Stancampiano, and Riccardo Tonini. "Plasma treatment of tooth root canal for enhancement of bond strength of dental adhesive system." In 2016 IEEE International Conference on Plasma Science (ICOPS). IEEE, 2016. http://dx.doi.org/10.1109/plasma.2016.7534073.
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Jain, A., A. Morgenthal, M. Aman, M. Horton, and S. Khan. "Creating an Auto-Encoder Based Predictive Maintenance Tool for Offshore Annulus Wells." In SPE Annual Technical Conference and Exhibition. SPE, 2022. http://dx.doi.org/10.2118/210220-ms.
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Abstract Objectives/Scope A key component of well integrity is annular integrity. Much of the focus on this has been on establishing maximum and minimum pressure limits and designing envelopes under various well conditions encountered during well construction and subsequent production and injection operations. Many operators have established systems for operating wells within this design envelope to monitor for pressure excursions. However, abnormal annulus pressure behavior within the design envelope could be overlooked using a system that relies on limit monitoring and excursions. Methods, Procedures, Process We propose a modeling workflow that combines novel deep learning techniques with statistical analysis to create online models which predict potential asset failures and alert on abnormal behavior such as abrupt pressure build up in producer and water injection wells’ A-Annulus. The model uses autoencoder architecture to learn the behavior of the wells during normal operating periods and generates alerts when it encounters new or abnormal behavior. The autoencoder architecture outputs a risk score aggregated over the residuals from all input features. Sequential Probability Ratio Test (SPRT) is performed on the risk score to determine abnormal regime during operation to raise alerts. These alerts can be used for root cause analysis based on the top contributors to the risk score. In our approach, we use feature thresholds as filters to determine normal operating periods for training the model. To simulate live conditions during model training, the historical time series data is divided into training and prediction windows. The model is trained on each training window and risk scores are created for the prediction window using a sliding window technique. To find the optimum model, a grid search is performed over a wide distribution of autoencoder and SPRT hyper-parameters. The models are scored based on recall, precision and lead time provided before a failure. Results, Observations, Conclusions We demonstrate this workflow using annulus pressure, downhole pressure, upstream choke pressure and upstream choke temperature as input to the model. The model does not require the physical properties of a well but uses historic well data lending itself to be applicable to already existing well stock. Next, we demonstrate using engineered features and synthesized data to efficiently train and score the models. During our experiments, we have explored several engineered features across multiple platforms and found that the correct set of engineered features can deliver a model that accurately alerts on asset abnormalities and potential failures. Novel/Additive Information Our approach combines the strengths of deep learning techniques, statistical analytics and subject matter expertise to provide a framework that has demonstrated efficient scaling across multiple assets and sites and has potential application on a variety of oil and gas equipment.
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Shi, Xiaomeng, Daeun Choi, Paul Heinz Heinemann, Molly Hanlon, and Jonathan Lynch. "<i>RootRobot: A Field-based Platform for Maize Root System Architecture Phenotyping</i>." In 2019 Boston, Massachusetts July 7- July 10, 2019. St. Joseph, MI: American Society of Agricultural and Biological Engineers, 2019. http://dx.doi.org/10.13031/aim.201900806.
Full textReports on the topic "Root system strength and architecture"
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Falk, Kevin, and Asheesh Singh. Studies of Soybean Root System Architecture. Ames: Iowa State University, Digital Repository, 2018. http://dx.doi.org/10.31274/farmprogressreports-180814-1950.
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Savaldi-Goldstein, Sigal, and Siobhan M. Brady. Mechanisms underlying root system architecture adaptation to low phosphate environment. United States Department of Agriculture, January 2015. http://dx.doi.org/10.32747/2015.7600024.bard.
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In order to advance our understanding towards potential biotechnology improvement of plant performance, we studied root responses to limited P in two different plants, Arabidopsis and tomato. Arabidopsis is among the most studied model plants that allows rapid application of molecular and developmental experiments while tomato is an important crop, with application in agriculture. Using Arabidopsis we found that steroid hormones modulate the extent of root elongation in response to limited P, by controlling the accumulation of iron in the root. We also found that the availability of P and iron control the activity of the steroid hormone in the root. Finally, we revealed the genes involved in this nutrient-hormone interaction. Hence, the ferroxidase LPR1 that promotes iron accumulation in response to low P is repressed by the transcription factor BES1/BZR1. Low P inhibits the steroid hormone pathway by enhancing the accumulation of BKI1. High levels of BKI1 inhibit the activity of the steroid hormone receptor at the cell surface and iron accumulation increases inside the root, resulting in a slow growth. Together, the extent of root elongation depends on interactions between an internal cue (steroid hormone) and cues derived from the availability of P and iron in the environment. Using tomato, we found that the response of two cultivated tomato varieties (M82 and New Yorker) to limited P is distinct from that of the wild species, Solanumpennellii. This is implicated at both the levels of root development and whole plant physiology. Specifically, while the root system architecture of cultivated tomato is modulated by limited P availability, that of the wild type species remained unaffected. The wild species appears to be always behaving as if it is always in phosphate deprived conditions, despite sufficient levels of phosphate. Hyper-accumulation of metals appears to mediate this response. Together, this knowledge will be used to isolate new genes controlling plant adaptation to limited P environment.
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Eshel, Amram, Jonathan P. Lynch, and Kathleen M. Brown. Physiological Regulation of Root System Architecture: The Role of Ethylene and Phosphorus. United States Department of Agriculture, December 2001. http://dx.doi.org/10.32747/2001.7585195.bard.
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Specific Objectives and Related Results: 1) Determine the effect of phosphorus availability on ethylene production by roots. Test the hypothesis that phosphorus availability regulates ethylene production Clear differences were found between the two plants that were studied. In beans ethylene production is affected by P nutrition, tissue type, and stage of development. There are genotypic differences in the rate of ethylene production by various root types and in the differential in ethylene production when P treatments are compared. The acceleration in ethylene production with P deficiency increases with time. These findings support the hypothesis that ethylene production may be enhanced by phosphorus deficiency, and that the degree of enhancement varies with genotype. In tomatoes the low-P level did not enhance significantly ethylene production by the roots. Wildtype cultivars and ethylene insensitive mutants behaved similarly in that respect. 2) Characterize the effects of phosphorus availability and ethylene on the architecture of whole root systems. Test the hypothesis that both ethylene and low phosphorus availability modify root architecture. In common bean, the basal roots give rise to a major fraction of the whole root system. Unlike other laterals these roots respond to gravitropic stimulation. Their growth angle determines the proportion of the root length in the shallow layers of the soil. A correlation between ethylene production and basal root angle was found in shallow rooted but not deep-rooted genotypes, indicating that acceleration of ethylene synthesis may account for the change in basal root angle in genotypes demonstrating a plastic response to P availability. Short-time gravitropic response of the tap roots of young bean seedlings was not affected by P level in the nutrient solution. Low phosphorus specifically increases root hair length and root hair density in Arabidopsis. We tested 7 different mutants in ethylene perception and response and in each case, the response to low P was lower than that of the wild-type. The extent of reduction in P response varied among the mutants, but every mutant retained some responsiveness to changes in P concentration. The increase in root hair density was due to the increase in the number of trichoblast cell files under low P and was not mediated by ethylene. Low P did not increase the number of root hairs forming from atrichoblasts. This is in contrast to ethylene treatment, which increased the number of root hairs partly by causing root hairs to form on atrichoblasts. 3) Assess the adaptive value of root architectural plasticity in response to phosphorus availability. A simulation study indicated that genetic variation for root architecture in common bean may be related to adaptation to diverse competitive environments. The fractal dimension of tomato root system was directly correlated with P level.
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Waisel, Yoav, Bobbie McMichael, and Amram Eshel. Decision Making within Plant Root Systems. United States Department of Agriculture, March 1996. http://dx.doi.org/10.32747/1996.7613030.bard.
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Architecture of a root system is the expression of the potential of various root types to branch, to grow and to coordinate with other plant organs, under the specific limitations of the environmental conditions. The present investigation has proven the following points. 1) Genotypes with different types of root systems were identified. The growth patterns of their roots and the distribution of laterals along their main axes were recorded. 2) The patterns of development of the root systems of four cotton genotypes, throughout the entire life cycle of the plants, were described, even at such a late stage of development when the total length of the roots exceeded two kilometers. To the best of our knowledge, this is the first time that an analysis of this type is accomplished. 3) The development of root systems under restrictive soil conditions were compared with those that have developed under the non-restrictive conditions of aeroponics. Results indicate that in the absence of the mechanical impedance of the soil, cotton plants develop single roots that reach the length of 6 m, and have a total root length of 2000 m. Thus, root growth is strongly inhibited by the soil, with some root types being inhibited more than others. 4) One of the important decisions, in constructing an operational root system architecture of mature plants, is the shift of the balance between various root fractions in favor of the very fine roots. 5) Root system architecture is determined, in part, by the sites of initiation of the lateral roots. This is determined genetically by the number of xylem archs and by the totuosity of the stele. Selection for such traits should be sought.
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LaBonte, Don, Etan Pressman, Nurit Firon, and Arthur Villordon. Molecular and Anatomical Characterization of Sweetpotato Storage Root Formation. United States Department of Agriculture, December 2011. http://dx.doi.org/10.32747/2011.7592648.bard.
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Original objectives: Anatomical study of storage root initiation and formation. Induction of storage root formation. Isolation and characterization of genes involved in storage root formation. During the normal course of storage root development. Following stress-induced storage root formation. Background:Sweetpotato is a high value vegetable crop in Israel and the U.S. and acreage is expanding in both countries and the research herein represents an important backstop to improving quality, consistency, and yield. This research has two broad objectives, both relating to sweetpotato storage root formation. The first objective is to understand storage root inductive conditions and describe the anatomical and physiological stages of storage root development. Sweetpotato is propagated through vine cuttings. These vine cuttings form adventitious roots, from pre-formed primordiae, at each node underground and it is these small adventitious roots which serve as initials for storage and fibrous (non-storage) “feeder” roots. What perplexes producers is the tremendous variability in storage roots produced from plant to plant. The marketable root number may vary from none to five per plant. What has intrigued us is the dearth of research on sweetpotato during the early growth period which we hypothesize has a tremendous impact on ultimate consistency and yield. The second objective is to identify genes that change the root physiology towards either a fleshy storage root or a fibrous “feeder” root. Understanding which genes affect the ultimate outcome is central to our research. Major conclusions: For objective one, we have determined that the majority of adventitious roots that are initiated within 5-7 days after transplanting possess the anatomical features associated with storage root initiation and account for 86 % of storage root count at 65 days after transplanting. These data underscore the importance of optimizing the growing environment during the critical storage root initiation period. Water deprivation during this phenological stage led to substantial reduction in storage root number and yield as determined through growth chamber, greenhouse, and field experiments. Morphological characterization of adventitious roots showed adjustments in root system architecture, expressed as lateral root count and density, in response to water deprivation. For objective two, we generated a transcriptome of storage and lignified (non-storage) adventitious roots. This transcriptome database consists of 55,296 contigs and contains data as regards to differential expression between initiating and lignified adventitious roots. The molecular data provide evidence that a key regulatory mechanism in storage root initiation involves the switch between lignin biosynthesis and cell division and starch accumulation. We extended this research to identify genes upregulated in adventitious roots under drought stress. A subset of these genes was expressed in salt stressed plants.
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Chefetz, Benny, Baoshan Xing, Leor Eshed-Williams, Tamara Polubesova, and Jason Unrine. DOM affected behavior of manufactured nanoparticles in soil-plant system. United States Department of Agriculture, January 2016. http://dx.doi.org/10.32747/2016.7604286.bard.
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The overall goal of this project was to elucidate the role of dissolved organic matter (DOM) in soil retention, bioavailability and plant uptake of silver and cerium oxide NPs. The environmental risks of manufactured nanoparticles (NPs) are attracting increasing attention from both industrial and scientific communities. These NPs have shown to be taken-up, translocated and bio- accumulated in plant edible parts. However, very little is known about the behavior of NPs in soil-plant system as affected by dissolved organic matter (DOM). Thus DOM effect on NPs behavior is critical to assessing the environmental fate and risks related to NP exposure. Carbon-based nanomaterials embedded with metal NPs demonstrate a great potential to serve as catalyst and disinfectors. Hence, synthesis of novel carbon-based nanocomposites and testing them in the environmentally relevant conditions (particularly in the DOM presence) is important for their implementation in water purification. Sorption of DOM on Ag-Ag₂S NPs, CeO₂ NPs and synthesized Ag-Fe₃O₄-carbon nanotubebifunctional composite has been studied. High DOM concentration (50mg/L) decreased the adsorptive and catalytic efficiencies of all synthesized NPs. Recyclable Ag-Fe₃O₄-carbon nanotube composite exhibited excellent catalytic and anti-bacterial action, providing complete reduction of common pollutants and inactivating gram-negative and gram-positive bacteria at environmentally relevant DOM concentrations (5-10 mg/L). Our composite material may be suitable for water purification ranging from natural to the industrial waste effluents. We also examined the role of maize (Zeamays L.)-derived root exudates (a form of DOM) and their components on the aggregation and dissolution of CuONPs in the rhizosphere. Root exudates (RE) significantly inhibited the aggregation of CuONPs regardless of ionic strength and electrolyte type. With RE, the critical coagulation concentration of CuONPs in NaCl shifted from 30 to 125 mM and the value in CaCl₂ shifted from 4 to 20 mM. This inhibition was correlated with molecular weight (MW) of RE fractions. Higher MW fraction (> 10 kDa) reduced the aggregation most. RE also significantly promoted the dissolution of CuONPs and lower MW fraction (< 3 kDa) RE mainly contributed to this process. Also, Cu accumulation in plant root tissues was significantly enhanced by RE. This study provides useful insights into the interactions between RE and CuONPs, which is of significance for the safe use of CuONPs-based antimicrobial products in agricultural production. Wheat root exudates (RE) had high reducing ability to convert Ag+ to nAg under light exposure. Photo-induced reduction of Ag+ to nAg in pristine RE was mainly attributed to the 0-3 kDa fraction. Quantification of the silver species change over time suggested that Cl⁻ played an important role in photoconversion of Ag+ to nAg through the formation and redox cycling of photoreactiveAgCl. Potential electron donors for the photoreduction of Ag+ were identified to be reducing sugars and organic acids of low MW. Meanwhile, the stabilization of the formed particles was controlled by both low (0-3 kDa) and high (>3 kDa) MW molecules. This work provides new information for the formation mechanism of metal nanoparticles mediated by RE, which may further our understanding of the biogeochemical cycling and toxicity of heavy metal ions in agricultural and environmental systems. Copper sulfide nanoparticles (CuSNPs) at 1:1 and 1:4 ratios of Cu and S were synthesized, and their respective antifungal efficacy was evaluated against the pathogenic activity of Gibberellafujikuroi(Bakanae disease) in rice (Oryza sativa). In a 2-d in vitro study, CuS decreased G. fujikuroiColony- Forming Units (CFU) compared to controls. In a greenhouse study, treating with CuSNPs at 50 mg/L at the seed stage significantly decreased disease incidence on rice while the commercial Cu-based pesticide Kocide 3000 had no impact on disease. Foliar-applied CuONPs and CuS (1:1) NPs decreased disease incidence by 30.0 and 32.5%, respectively, which outperformed CuS (1:4) NPs (15%) and Kocide 3000 (12.5%). CuS (1:4) NPs also modulated the shoot salicylic acid (SA) and Jasmonic acid (JA) production to enhance the plant defense mechanisms against G. fujikuroiinfection. These results are useful for improving the delivery efficiency of agrichemicals via nano-enabled strategies while minimizing their environmental impact, and advance our understanding of the defense mechanisms triggered by the NPs presence in plants.
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Kapulnik, Yoram, Maria J. Harrison, Hinanit Koltai, and Joseph Hershenhorn. Targeting of Strigolacatones Associated Pathways for Conferring Orobanche Resistant Traits in Tomato and Medicago. United States Department of Agriculture, July 2011. http://dx.doi.org/10.32747/2011.7593399.bard.
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This proposal is focused on examination of two plant interactions: parasitic with Orobanche, and symbiosis with arbuscular mycorrhiza fungi (AMF), and the involvement of a newly define plant hormones, strigolactones (SLs), in these plant interactions. In addition to strigolactones role in regulation of above-ground plant architecture, they are also known to be secreted from roots, and to be a signal for seed germination of the parasitic plants Orobanche. Moreover, secreted strigolactones were recognized as inducers of AMFhyphae branching. The present work was aimed at Generation of RNAi mutants of both tomato and Medicago, targeting multiple genes that may be involved in strigolactone production, carotenoid biosynthesis pathway, Pi signaling or other metabolic pathways, and hence affect AMF colonization and/or Orobanche resistance. Following the newly formed and existing RNAi mutants were examined for AMF colonization and Orobanche resistance. At the first phase of this project Orobanche seed germination assays and AMF colonization were examined in intact plants. These assays were shown to be effective and resulted with enhancement of Orobanche seed germination and AMF colonization in WT tomato plants, whereas roots of strigolactones impaired lines did not result with Orobanche seed germination and mycorrhiza colonization. Unexpectedly, root organ cultures (ROC) that were produced from the same wild type (WT) and mutant lines did not induce the Orobanche seed germination and AMFhyphal branching. This implies that under in vitro conditions ROC cultures are missing an important component for induction of Orobanche seed germination and AMFhyphal branching. In another line of experiments we have tested transgenic lines of Medicagotruncatula for AMFhuyphal branching and Orobanche seed germination assays. These lines included lines silenced for a GRAS transcription factor (RNAi 1845), an NBS-LRR type resistance gene (RNAi 1847), a kinase (RNAi 2403) and a protein of unknown function (RNAi 2417). In all cases, five independent transgenic root lines showed altered AMFphenotypes with reduced or aberrant colonization patterns. Following, we transformed tomato plants with the M. truncatulaTC 127050 PhosphoinositidekinaseRNAi construct. Transgenic lines that contained GUS constructs were used as control. All transgenic lines showed reduced level of Orobanche seed germination, masking any strigoalctones-specific effect. The research demonstrated that SLs production may not be examined in ROC –based bioassays. It was shown by the 3 independent assays employed in this project that none of the recognized characters of SLs may be reflected in these bioassays. However, when the whole plant root exudates were examined, SLs activity in root exudates was demonstrated. Hence, it can be concluded that the presence of an intact shoot, and possibly, shoot factors, may be necessary for production of SLs in roots. Another point of interest that rises from these results is that the presence of SLs is not necessary for AMF completion of life cycle. Hence, it may be concluded that SLs are important for AMFhyphal branching, before symbiosis, but not essential for AMF colonization and life cycle completion under ROC system conditions.
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Eshed-Williams, Leor, and Daniel Zilberman. Genetic and cellular networks regulating cell fate at the shoot apical meristem. United States Department of Agriculture, January 2014. http://dx.doi.org/10.32747/2014.7699862.bard.
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The shoot apical meristem establishes plant architecture by continuously producing new lateral organs such as leaves, axillary meristems and flowers throughout the plant life cycle. This unique capacity is achieved by a group of self-renewing pluripotent stem cells that give rise to founder cells, which can differentiate into multiple cell and tissue types in response to environmental and developmental cues. Cell fate specification at the shoot apical meristem is programmed primarily by transcription factors acting in a complex gene regulatory network. In this project we proposed to provide significant understanding of meristem maintenance and cell fate specification by studying four transcription factors acting at the meristem. Our original aim was to identify the direct target genes of WUS, STM, KNAT6 and CNA transcription factor in a genome wide scale and the manner by which they regulate their targets. Our goal was to integrate this data into a regulatory model of cell fate specification in the SAM and to identify key genes within the model for further study. We have generated transgenic plants carrying the four TF with two different tags and preformed chromatin Immunoprecipitation (ChIP) assay to identify the TF direct target genes. Due to unforeseen obstacles we have been delayed in achieving this aim but hope to accomplish it soon. Using the GR inducible system, genetic approach and transcriptome analysis [mRNA-seq] we provided a new look at meristem activity and its regulation of morphogenesis and phyllotaxy and propose a coherent framework for the role of many factors acting in meristem development and maintenance. We provided evidence for 3 different mechanisms for the regulation of WUS expression, DNA methylation, a second receptor pathway - the ERECTA receptor and the CNA TF that negatively regulates WUS expression in its own domain, the Organizing Center. We found that once the WUS expression level surpasses a certain threshold it alters cell identity at the periphery of the inflorescence meristem from floral meristem to carpel fate [FM]. When WUS expression highly elevated in the FM, the meristem turn into indeterminate. We showed that WUS activate cytokinine, inhibit auxin response and represses the genes required for root identity fate and that gradual increase in WUCHEL activity leads to gradual meristem enlargement that affect phyllotaxis. We also propose a model in which the direction of WUS domain expansion laterally or upward affects meristem structure differently. We preformed mRNA-seq on meristems with different size and structure followed by k-means clustering and identified groups of genes that are expressed in specific domains at the meristem. We will integrate this data with the ChIP-seq of the 4 TF to add another layer to the genetic network regulating meristem activity.