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Root Morphology (root + morphology)
Selected AbstractsA multi-trait test of the leaf-height-seed plant strategy scheme with 133 species from a pine forest floraFUNCTIONAL ECOLOGY, Issue 3 2010Daniel C. Laughlin Summary 1.,Westoby's [Plant and Soil (1998), 199, 213] Leaf-Height-Seed (LHS) plant strategy scheme quantifies the strategy of a plant based on its location in a three-dimensional space defined by three functional traits: specific leaf area (SLA), height, and seed mass. This scheme is based on aboveground traits and may neglect strategies of belowground resource capture if root functioning is not mirrored in any of the axes. How then do fine roots fit into the LHS scheme? 2.,We measured 10 functional traits on 133 plant species in a ponderosa pine forest in northern Arizona, USA. This data set was used to evaluate how well the LHS scheme accounts for the variation in above and belowground traits. 3.,The three most important plant strategies were composed of multiple correlated traits, but SLA, seed mass, and height loaded on separate principle components. The first axis reflected the widely observed ,leaf economics spectrum'. Species at the high end of this spectrum had high SLA, high leaf and fine root nitrogen (N) concentration, and low leaf dry matter content. The second axis reflected variation in seed mass and fine root morphology. Plants at the positive end of this spectrum were plants with large seeds and low specific root length (SRL). The third axis reflected variation in height and phenology. Plants at the positive end of this spectrum were tall species that flower late in the growing season. 4.,Leaf N concentration was positively correlated with fine root N concentration. SRL was weakly positively correlated with SLA. SRL was not correlated with fine root N concentration. Leaf litter decomposition rate was positively correlated with the leaf economics spectrum and was negatively correlated with the height and phenology spectrum. 5.,Leaf traits, seed mass, and height appear to be integrating properties of species that reflect much of the variation in plant function, including root function. Fine root N concentration was positively mirrored by the leaf economics spectrum, and SRL was inversely mirrored by seed mass. The leaf and height axes play a role in controlling leaf litter decomposability, indicating that these strategy axes have important consequences for ecosystem functioning. [source] Effects of tractor wheeling on root morphology and yield of lucerne (Medicago sativa L.)GRASS & FORAGE SCIENCE, Issue 3 2008Summary The purpose of this study was to determine the effect of soil compaction on the herbage yield and root growth of lucerne (Medicago sativa L.). A field experiment was conducted on a silty loam Mollic Fluvisols soil in 2003,2006. Herbage yield and root morphology, in terms of root length density, mean root diameter, specific root length and distribution of dry matter (DM) in roots, were measured. Four compaction treatments were applied three times annually by tractor using the following number of passes: control without experimental traffic, two passes, four passes and six passes. The tractor traffic changed the physical properties of the soil by increasing bulk density and penetration resistance. Soil compaction also improved its water retention properties. These changes were associated with changes in root morphology and distribution of the DM in roots. Soil compaction resulted in higher proportions of the DM in roots, especially in the upper, 0,10 cm, soil horizon. Decreases in the root length density were observed in a root diameter range of 0·1,1·0 mm. It was also found that roots in a more compacted soil were significantly thicker. An effect of the root system of lucerne on soil compaction was observed. The root system of lucerne decreased the effects of soil compaction that had been recorded in the first and the second year of the experiment. An increase in the number of passes resulted in a decrease in the DM yield of herbage in the second and third harvests each year. [source] The effect of irrigation time, root morphology and dentine thickness on tooth surface strain when using 5% sodium hypochlorite and 17% EDTAINTERNATIONAL ENDODONTIC JOURNAL, Issue 3 2010O. E. Sobhani Sobhani OE, Gulabivala K, Knowles JC, Ng Y-L. The effect of irrigation time, root morphology and dentine thickness on tooth surface strain when using 5% sodium hypochlorite and 17% EDTA. International Endodontic Journal, 43, 190,199, 2010. Abstract Aim, To evaluate the effect of irrigation with 5% sodium hypochlorite (NaOCl) alone and in conjunction with 17% ethylenediaminetetraacetic acid (EDTA) on tooth surface strain (TSS) and to analyse the influence of irrigation time, root morphology and dentine thickness. Methodology, Thirty-six single-rooted pre-molars with single canals had their crown and enamel reduced and root canals prepared using a standardized protocol. Teeth were grouped according to anatomical criteria and randomly distributed to experimental irrigation groups: (A) saline (negative control); (B) 5% NaOCl (positive control); (C) 5% NaOCl alternated with 17% EDTA. TSS was measured using electrical strain gauges bonded to the cervico-proximal part of the tooth. Teeth, mounted in clear acrylic resin placed in a universal testing machine, were subjected to nine consecutive 10-min irrigation periods followed by non-destructive occlusal loading to record TSS. Statistical analysis was carried out using two-way hierarchical anova and post hoc multiple comparisons. Results, Two groups showed an increase in TSS from the baseline (initial 10-min irrigation with saline). Group A showed a negligible reduction of 1.2% (343,339 ,,), which was not statistically significant (P = 0.7). Group B showed a highly significant (P = 0.001) increase in TSS by 53.7% (178,253 ,,), and group C showed a significant (P = 0.02) increase in TSS by 17.4% (163,192 ,,). The rate of change in TSS was significantly different between test groups. The length of the tooth (P = 0.04) as well as the mesio-distal (P = 0.05) width had significant effects on TSS. Conclusions, Irrigation with 5% with or without 17% EDTA increased TSS. The increase was significantly greater with 5% NaOCl alone than with 5% NaOCl alternated with 17% EDTA in contrast to previous findings with longer duration of irrigant exposure. Tooth length and mesio-distal root width significantly contributed to the increase in TSS. [source] Anomalous mandibular premolars: a mandibular first premolar with three roots and a mandibular second premolar with a C-shaped canal systemINTERNATIONAL ENDODONTIC JOURNAL, Issue 11 2008B. M. Cleghorn Abstract Aim, To describe unusual variations in the root morphology and root canal systems of mandibular first and second premolar teeth extracted for orthodontic reasons. Summary, Normally mandibular first and second premolar teeth have single roots with single canals. A 15-year-old patient presented for orthodontic treatment and two mandibular premolar teeth were examined post-extraction. The mandibular first premolar exhibited three distinct, separate roots and the mandibular second premolar exhibited a C-shaped root canal system. The coronal morphology of each of the mandibular premolars revealed dimensions and anatomy within normal limits. The incidence of a three-rooted mandibular first premolar is approximately 0.2%. Key learning points ,,Thorough clinical and radiographic interpretation is important in recognizing anomalous root and root canal systems. ,,The most common forms of root and canal systems and its aberrations must be understood to realize variations from normal do occur. ,,Successful root canal treatment requires an accurate diagnosis of the root canal system using all available aids. ,,Value of microcomputed tomography in the study of anatomy ex vivo and cone-beam tomography in clinical endodontics of complex premolar cases is increasing. [source] Palatal radicular multigrooves associated with severe periodontal defects in maxillary central incisorsJOURNAL OF CLINICAL PERIODONTOLOGY, Issue 4 2001Koichi Nanba Abstract Background: This case report describes a rare condition of palatal radicular multigrooves on teeth 11 and 21 with severe periodontal defects and the findings at 3-year follow-up. Method: Radiculoplasty using hand curettes and rotary burs were used to remove the multigrooves on the root surfaces and change the wrinkled root form to the relatively flat and smooth normal root morphology. Minor tooth movement and frenotomy were performed for a diastema between teeth 11 and 21. Supportive periodontal therapy started immediately after completion of the active treatment. Results: Improved healthy periodontal tissues and adequate plaque control have been maintained. Zusammenfassung Dieser Fallbericht beschreibt das seltene Phänomen multipler palatinaler Wurzelfurchen an den Zähnen 11 und 21 bei einer 41-jährigen Japanerin in Assoziation mit schweren parodontalen Defekten und berichtet die Beobachtungen einer Verlaufskontrolle über 3 Jahre. Die Furchen wurden im Sinne einer Odontoplastik mit Handküretten und rotierenden Instrumenten entfernt und so die zerklüftete Wurzeloberfläche in eine glatte normale Wurzelmorphologie überführt. Geringfügige Zahnbewegungen und eine Frenektomie wurden zur Behandlung des Diastemas durchgeführt. Unmittelbar nach Abschluß der aktiven Therapie wurde die unterstützende Nachsorge begonnen. Ein verbesserter parodontaler Zustand und adäquate Plaquekontrolle haben seither aufrechterhalten werden können. Résumé Ce rapport de cas montre une rare présence de sillons radiculaires palatins multiples sur les dent 11 et 21 avec des lésions parodontales sévères et les résultats sur un suivi de 3 ans. Une radiculoplastie fut réalisée à l'aide de curettes à mains et de fraises rotatives pour éliminer les sillons radiculaires multiples et modifier la forme plissée de la racine en une morphologie radiculaire plate et lisse relativement normale. Des mouvements dentaires mineurs et une frénotomie ont été réalisés à cause d'un diastème entre 11 et 21. Le traitement parodontal de soutien a commencé immédiatement après l'achèvement du traitement actif. Des tissus parodontaux sains améliorés et un contrôle de plaque adéquat ont été maintenus. [source] Resource and non-resource root competition effects of grasses on early- versus late-successional treesJOURNAL OF ECOLOGY, Issue 3 2009Christian Messier Summary 1This study assessed the effects of resource (i.e. nutrients) and non-resource (i.e. interference for space) competition from fine roots of competing grasses on the growth, morphology and architecture of fine roots of four tree species of varying successional status: Populus deltoides ¥ P. balsamifera (a hybrid), Betula papyrifera, Acer saccharum and Fraxinus americana. We tested the general hypothesis that tree fine-roots are affected by both below-ground resource and non-resource competition from non-self plants, and the more specific hypothesis that this effect is stronger in early-successional tree species. 2The experiment was conducted in split-containers where half of the roots of tree seedlings experienced either below-ground resource competition or non-resource competition, or both, by grasses while the other half experienced no competition. 3The late-successional tree species A. saccharum and F. americana were mostly affected by resource competition, whereas the early-successional P. deltoides¥balsamifera and B. papyrifera were strongly affected by both resource and non-resource competition. Non-resource competition reduced fine-root growth, root branching over root length (a measure of root architecture) and specific root length (a measure of root morphology) of both early-successional species. 4Synthesis. This study suggests that early-successional tree species have been selected for root avoidance or segregation and late-successional tree species for root tolerance of competition as mechanisms to improve below-ground resource uptake in their particular environments. It also contradicts recent studies showing perennial and annual grasses tend to overproduce roots in the presence of non-self conspecific plants. Woody plants, required to grow and develop for long periods in the presence of other plants, may react differently to non-self root competition than perennial or annual grasses that have much shorter lives. [source] Lead Induced Changes in the Growth and Antioxidant Metabolism of the Lead Accumulating and Non-accumulating Ecotypes of Sedum alfrediiJOURNAL OF INTEGRATIVE PLANT BIOLOGY, Issue 2 2008Dan Liu Abstract The phytotoxicity and antioxidative adaptations of lead (Pb) accumulating ecotype (AE) and non-accumulating ecotype (NAE) of Sedum alfredii Hance were investigated under different Pb treatments involving 0, 0.02 mmol/L Pb, 0.1 mmol/L Pb and 0.1 mmol/L Pb/0.1 mmol/L ethylenediaminetetraacetic acid (EDTA) for 6 days. With the increasing Pb level, the Pb concentration in the shoots of AE plants enhanced accordingly, and EDTA supply helped 51% of Pb translocation to shoots of AE compared with those treated with 0.1 mmol/L Pb alone. Moreover, the presence of EDTA alleviated Pb phytotoxicity through changes in plant biomass, root morphology and chlorophyll contents. Lead toxicity induced hydrogen peroxide (H2O2) accumulation and lipid peroxidation in both ecotypes of S. alfredii. The activities of superoxide dismutase (SOD), guaiacol peroxidase (G-POD), ascorbate peroxidase, and dehydroascorbate reductase elevated in both leaves and roots of AE as well as in leaves of NAE with the increasing Pb levels, but SOD and G-POD declined in roots of NAE. Enhancement in glutathione reductase activity was only detected in roots of NAE while a depression in catalase activity was recorded in the leaves of NAE. A significant enhancement in glutathione and ascorbic acid (AsA)levels occurred in both ecotypes exposed to Pb and Pb/EDTA treatment compared with the control, however, the differences between these two treatments were insignificant. The dehydroascorbate (DHA) contents in roots of both ecotypes were 1.41 to 11.22-fold higher than those in leaves, whereas the ratios of AsA to DHA (1.38 to 6.84) in leaves altering more to the reduced AsA form were much higher than those in roots. These results suggested that antioxidative enzymes and antioxidants play an important role in counteracting Pb stress in S. alfredii. [source] Indirect facilitation and competition in tree species colonization of sub-Mediterranean grasslandsJOURNAL OF VEGETATION SCIENCE, Issue 3 2006Georges Kunstler Abstract: Questions: In the absence of herbivores, what is the importance of shrub facilitation for the colonization of grasslands by Fagus sylvatica and Quercus pubescens? Is there an indirect facilitative effect of shrubs on tree seedlings by limiting herb competition? Location: Causse du Larzac, southern Massif Central, France. Methods: We conducted field experiments on the facilitative role of shrubs in seedling emergence and survival, in relation to potential negative effects of shading and the presence of herbs. The effects of shade and herbs on allocation and root morphology were analysed in a pot experiment. Results: According to these experiments, the establishment of both tree species was facilitated by shrubs, but the two species differed in the processes underlying this facilitation. Shade directly facilitates the emergence rate of both species. Shade also indirectly facilitates Fagus survival by limiting herb competition. No indirect facilitation of Quercus survival was detected. These differences reflect variation in the tolerance of herb competition by seedlings of the two species. The tolerance of herb competition by Quercus seedlings allows regeneration over a wide area under each shrub and some regeneration events in grasslands at low grazing intensity. In contrast, for Fagus, only a narrow area under each shrub is suitable; regeneration is zero in grassland. The high tolerance of herb competition by Quercus seedlings may result from the avoidance of root competition. Conclusions In grasslands with severe drought stress, and almost obligatory shrub facilitation for tree seedling regeneration, the tolerance of herb competition may alter the precise role of facilitation in the colonization process. [source] Earliest rooting system and root : shoot ratio from a new Zosterophyllum plantNEW PHYTOLOGIST, Issue 1 2010Shougang Hao Summary ,,The enhanced chemical weathering by rooted vascular plants during the Silurian,Devonian period played a crucial role in altering global biogeochemical cycles and atmospheric environments; however, the documentation of early root morphology and physiology is scarce because the existing fossils are mostly incomplete. ,,Here, we report an entire, uprooted specimen of a new Zosterophyllum Penhallow, named as Z. shengfengense, from the Early Devonian Xitun Formation (Lochkovian, c. 413 Myr old) of Yunnan, south China. This plant has the most ancient known record of a rooting system. ,,The plant consists of aerial axes of 98 mm in height, showing a tufted habit, and a rhizome bearing a fibrous-like rooting system, c. 20 mm in length. The rhizome shows masses of branchings, which produce upwardly directed aerial axes and downwardly directed root-like axes. ,,The completeness of Z. shengfengense made it possible to estimate the biomass allocation and root : shoot ratio. The root : shoot ratio of this early plant is estimated at a mean value of 0.028, and the root-like axes constitute only c. 3% of the total biomass. Zosterophyllum shengfengense was probably a semi-aquatic plant with efficient water use or a strong uptake capacity of the root-like axes. [source] Carboxylate composition of root exudates does not relate consistently to a crop species' ability to use phosphorus from aluminium, iron or calcium phosphate sourcesNEW PHYTOLOGIST, Issue 1 2007Stuart J. Pearse Summary ,,The relationship between carboxylate release from roots and the ability of the species to utilize phosphorus from sparingly soluble forms was studied by comparing Triticum aestivum, Brassica napus, Cicer arietinum, Pisum sativum, Lupinus albus, Lupinus angustifolius and Lupinus cosentinii. ,,Plants were grown in sand and supplied with 40 mg P kg,1 in the sparingly soluble forms AlPO4, FePO4 or Ca5OH(PO4)3, or as soluble KH2PO4; control plants received no P. ,,The ability to utilize sparingly soluble forms of P differed between forms of P supplied and species. Pisum sativum and C. arietinum did not access AlPO4 or FePO4 despite releasing carboxylates into the rhizosphere. ,,Species accessed different forms of sparingly soluble P, but no species was superior in accessing all forms. We conclude that a single trait cannot explain access to different forms of sparingly soluble P, and hypothesize that in addition to carboxylates, rhizosphere pH and root morphology are key factors. [source] Technical note: Morphometric maps of long bone shafts and dental roots for imaging topographic thickness variationAMERICAN JOURNAL OF PHYSICAL ANTHROPOLOGY, Issue 2 2010Luca Bondioli Abstract Qualitative and quantitative characterization through functional imaging of mineralized tissues is of potential value in the study of the odontoskeletal remains. This technique, widely developed in the medical field, allows the bi-dimensional, planar representation of some local morphometric properties, i.e., topographic thickness variation, of a three-dimensional object, such as a long bone shaft. Nonetheless, the use of morphometric maps is still limited in (paleo)anthropology, and their feasibility has not been adequately tested on fossil specimens. Using high-resolution microtomographic images, here we apply bi-dimensional virtual "unrolling" and synthetic thickness mapping techniques to compare cortical bone topographic variation across the shaft in a modern and a fossil human adult femur (the Magdalenian from Chancelade). We also test, for the first time, the possibility to virtually unroll and assess for dentine thickness variation in modern and fossil (the Neanderthal child from Roc de Marsal) human deciduous tooth roots. The analyses demonstrate the feasibility of using two-dimensional morphometric maps for the synthetic functional imaging and comparative biomechanical interpretation of cortical bone thickness variation in extant and fossil specimens and show the interest of using this technique also for the subtle characterization of root architecture and dentine topography. More specifically, our preliminary results support the use of virtual cartography as a tool for assessing to what extent internal root morphology is capable of responding to loading and directional stresses and strains in a predictable way. Am J Phys Anthropol, 2010. © 2010 Wiley-Liss, Inc. [source] Root/Shoot Allocation and Root Architecture in Seedlings: Variation among Forest Sites, Microhabitats, and Ecological Groups1BIOTROPICA, Issue 3 2003Horacio Paz ABSTRACT I analyzed patterns of variation in root mass allocation and root morphology among seedlings of woody species in relation to environmental factors in four Neotropical forests. Among forests, I explored the response of root traits to sites varying in water or nutrient availability. Within each forest, I explored the plastic response of species to different microhabitats: gaps and understory. Additionally, I explored evidence for life history correlation of root and shoot traits by comparing species differing in their successional group (light-demanding [22 spp.] or shade tolerant [27 spp.]) and germination type (species with photosynthetic cotyledons or species with reserve cotyledons). At each forest site, young seedlings from 10 to 20 species were excavated. A total of 55 species was collected in understory conditions and 31 of them were also collected in gaps. From each seedling, six morphological ratios were determined. Allocation to roots was higher in forest sites with the lowest soil resources. Roots were finer and longer in the most infertile site, while roots were deeper in the site with the longest dry season. Seedling traits did not differ between germination types. Shade tolerant species allocated more to roots and developed thicker roots than light-demanding species. Light-demanding species showed stronger plastic responses to habitat than shade tolerant species, and species with photo-synthetic cotyledons showed lower plasticity than species with reserve cotyledons. Overall, these results suggest that among Neotropical species, root allocation and root morphology of seedlings reflect plant adjustments to water or nutrient availability at geographic and microhabitat scales. In addition, life history specialization to light environments is suggested by differences among groups of species in their allocation to roots and in their root morphology. RESUMEN Analicé los patrones de variación en la asignación de biomasa y en la morfología de raíces de plántulas de especies leñosas en relación a factores ambientales en cuatro bosques Neotropicales. Entre los bosques, exploré la respuesta promedia de características de las plántulas en sitios que varían en disponibilidad de agua o nutrientes en el suelo. Dentro de cada bosque, exploré la respuesta fenotípica de las especies entre claros y sotobosque. Además, explore correlaciones de la historia de vida de las especies con características de raíces y parte aérea, comparando especies con diferente hábito sucesional (demandante de luz [22 spp.] o tolerante a la sombra [27 spp.]) y tipo de germinación (especies con cotiledones fotosintéticos o cotiledones de reserva). En cada bosque, se excavaron plántulas de 10 a 20 especies manteniendo la integridad de sus raíces. Se colectaron 55 especies en el sotobosque y 31 de ellas fueron colectadas también en claros. De cada plántula obtuve seis parámetros morfológicos de raíces y parte aérea. La asignación de biomasa a raíces fue mayor en los bosques con menos recursos. Las plántulas desarrollaron raíces más finas, y con mayor longitud por unidad de superficie fotosintética, en el sitio menos fértil. En cambio, las raíces tendieron a ser más profundas en relación al área fotosintética en el sitio más estacional. Las especies tolerantes a la sombra asignaron más biomasa a raíces y desarrollaron raíces más gruesas que las especies demandantes de luz. Las características morfológicas de las plántulas no difirieron entre tipos de germinación. Las especies demandantes de luz mostraron mayor plasticidad al hábitat en la asignación de biomasa a raíces, que las especies tolerantes a la sombra. Las especies con cotiledones fotosintéticos mostraron menor plasticidad al hábitat en la asignación de biomasa a raíces que las especies con cotiledones de reserva. En conjunto, mis resultados sugieren que para especies Neotropicales la asignación de biomasa y la morfología de raíces en plántulas reflejan ajustes de las plantas a la disponibilidad de agua o nutrientes a escala geográfica y de micro-hábitat. Además, se sugiere que la asignación de biomasa y la morfología de raíces son componentes del síndrome de especialización a ambientes lumínicos en el bosque. [source] | ||||||||||||||||