Horizontal Root Research Articles

Gibberellin signaling mediates lateral root inhibition in response to K+-deprivation.

The potassium ion (K+) is vital for plant growth and development, and K+-deprivation leads to reduced crop yields. Here we describe phenotypic, transcriptomic, and mutant analyses to investigate the signaling mechanisms mediating root architectural changes in Arabidopsis (Arabidopsis thaliana) Columbia. We showed effects on root architecture are mediated through a reduction in cell division in the lateral root (LR) meristems, the rate of LR initiation is reduced but LR density is unaffected, and primary root growth is reduced only slightly. This was primarily regulated through gibberellic acid (GA) signaling, which leads to the accumulation of growth-inhibitory DELLA proteins. The short LR phenotype was rescued by exogenous application of GA but not of auxin or by the inhibition of ethylene signaling. RNA-seq analysis showed upregulation by K+-deprivation of the transcription factors JUNGBRUNNEN1 (JUB1) and the C-repeat-binding factor (CBF)/dehydration-responsive element-binding factor 1 regulon, which are known to regulate GA signaling and levels that regulate DELLAs. Transgenic overexpression of JUB1 and CBF1 enhanced responses to K+ stress. Attenuation of the reduced LR growth response occurred in mutants of the CBF1 target gene SFR6, implicating a role for JUB1, CBF1, and SFR6 in the regulation of LR growth in response to K+-deprivation via DELLAs. We propose this represents a mechanism to limit horizontal root growth in conditions where K+ is available deeper in the soil.

Improving Water Use Efficiency by Optimizing the Root Distribution Patterns under Varying Drip Emitter Density and Drought Stress for Cherry Tomato

The spatial distribution of root systems in the soil has major impacts on soil water and nutrient uptake and ultimately crop yield. This research aimed to optimize the root distribution patterns, growth, and yield of cherry tomato by using a number of emitters per plant. A randomized complete block design technique was adopted by selecting eight treatments with two irrigation regimes and four levels of emitters under greenhouse conditions. The experiment results showed that the root distribution extended over the entire pot horizontally and shifted vertically upwards with increased emitter density. The deficit irrigation resulted in reduced horizontal root extension and shifted the root concentrations deeper. Notably, tomato plants with two emitters per plant and deficit irrigation treatment showed an optimal root distribution compared to the other treatments, showing wider and deeper dispersion measurements and higher root length density and root weight density through the soil with the highest benefit–cost ratio (1.3 and 1.1 cm cm−3, 89.8 and 77.7 µg cm−3, and 4.20 and 4.24 during spring–summer and fall-winter cropping seasons, respectively). The increases in yield and water use efficiency (due to increased yield) were 19% and 18.8%, respectively, for spring–summer cropping season and 11.5% and 11.8%, respectively, for fall–winter cropping season, with two emitters per plant over a single emitter. The decrease in yield was 5.3% and 4%, and increase in water use efficiency (due to deficit irrigation) was 26.2% and 27.9% for spring-summer and fall-winter cropping seasons, respectively, by deficit irrigation over full irrigation. Moreover, it was observed that two, three, and four emitters per plant had no significant effects on yield and water use efficiency. Thus, it was concluded that two emitters per plant with deficit irrigation is optimum under greenhouse conditions for the cultivation of potted cherry tomatoes, considering the root morphology, root distribution, dry matter production, yield, water use efficiency, and economic analysis.

Postępowanie terapeutyczne w poprzecznym złamaniu korzenia u 14-letniego pacjenta – opis przypadku klinicznego

Root fractures are lesions involving dentine, cementum and pulp. The highest incidence range of roots fractures is recorded in patients 16-20 years. Horizontal root fractures mainly affect the maxillary anterior region. Due to relatively rare occurrence of root fractures, they may be difficult to make appropriate diagnosis and treatment plan. The treatment success is determined by the location of fracture line. Additional the healing process depends on optimal fragments reposition an immobilization, regular clinical an radiological control, patients age, tooth mobility, degree of root formation, pulp condition, diastasis of fragments and time between trauma and treatment. The clinical study presents 18- month follow-up treatment of a 14 years old patient with horizontal root fracture located in 1/3 middle of root.

Protocolo de tratamento conservador em fraturas radiculares horizontais de terço cervical – Relato de caso

Os traumas dentais possuem uma significante ocorrência na odontologia. As fraturas radiculares podem ser consideradas como politraumatismos por envolverem diferentes tipos de tecido: dentina, cemento, polpa e periodonto. Objetivo: mostrar uma opção de protocolo terapêutico conservador no tratamento de fraturas radiculares horizontais a fim de preservar a estrutura dental levando em consideração a condição socioeconômica do paciente. Relato de caso: paciente do sexo masculino, 15 anos, procurou a clínica de Odontologia da Universidade Federal de Alagoas onde procurou atendimento após sofrer um trauma. Ao exame clínico, observou-se que o incisivo central superior (11) apresentava fratura radicular horizontal cervical e discreto deslocamento palatino. Optou-se pela instalação de contenção semirrígida como tratamento imediato. Posteriormente uma pulpectomia do segmento coronal até a linha de fratura foi realizada com medicação intracanal composta por hidróxido de cálcio e clorexidina gel a 2%. Após 2 semanas foi realizada obturação do canal com MTA. Conclusão: O tratamento endodôntico foi realizado com sucesso, seu prognóstico depende do tipo de reparo tecidual na linha de fratura e saúde dos tecidos periodontais.

Homeopatia na revascularização e consolidação de fratura radicular: relato de caso

Fraturas radiculares horizontais representam 7% dos traumas dentários. Fatores como a localização da fratura, o grau de deslocamento do fragmento e condição pulpar determinam a escolha de tratamentos e prognóstico do dente. O objetivo deste estudo é apresentar dois relatos de casos, bem-sucedidos com o auxílio dos medicamentos homeopáticos: Ferrum phosphoricum 6CH para a manutenção da vascularização e vitalidade pulpar no tratamento imediato e composto de Calcarea carbonica 6CH; Calcarea phosphorica 6CH e Calcarea fluorica 6CH na promoção de reparação tecidual destas fraturas. Ambos os pacientes com idade de 14 e 17 anos, respectivamente, apresentaram fraturas horizontais em terço cervical das raízes de incisivos superiores. Foram tratados com contenção radicular rígida por 20 dias, acompanhados com testes térmicos de vitalidade pulpar semanais durante 3 meses e exames de imagem por 06 anos. Os dentes mantiveram condições pulpares de normalidade, reparação tecidual das fraturas radiculares e funções mastigatórias ideais.

The mechanism of the plant roots' soil-reinforcement based on generalized equivalent confining pressure.

BackgroundTo quantitatively evaluate the contribution of plant roots to soil shear strength, the generalized equivalent confining pressure (GECP), which is the difference in confining pressure between the reinforced and un-reinforced soil specimens at the same shear strength, was proposed and considered in terms of the function of plant roots in soil reinforcement.MethodsIn this paper, silt loam soil was selected as the test soil, and the roots of Indigofera amblyantha were chosen as the reinforcing material. Different drainage conditions (consolidation drained (CD), consolidation undrained (CU), and unconsolidated undrained (UU)) were used to analyse the influences of different root distribution patterns (horizontal root (HR), vertical root (VR), and complex root (CR)) and root contents (0.25%, 0.50%, and 0.75%) on the shear strength of soil-root composites.ResultsThe cohesion (c) values of the soil-root composites varied under different drainage conditions and root contents, while the internal friction angle (φ ) values remain basically stable under different drainage conditions. Under the same root content and drainage conditions, the shear strength indexes ranked in order of lower to higher were HR, VR and CR. The GECP of the soil-root composites with a 0.75% root content was 1.5–2.0 times that with a 0.50% root content and more than 5 times that with a 0.25% root content under the CD and CU conditions. The GECP in reinforced soil followed the sequence of CD > CU > UU. The GECP of the plant roots increased as confining pressure increased under CD and CU conditions while showed a complex change to the confining pressure under the UU condition.ConclusionIt was concluded that the evaluation of plant root reinforcing soil based on GECP can be used to measure effectively the influences of roots on soil under different drainage conditions and root distribution patterns.

Conservative Management of the Horizontal Root Fracture in the Middle Third using Fiber Post as an Intraradicular Splint

BACKGROUND: Root fractures are uncommon injuries in permanent teeth and account for only 0.5–7% of dental trauma. It occurs more frequently in fully erupted permanent teeth, in which the completely formed root with closed apices is solidly supported in the bone and periodontium. This may lead to complex consequences due to the combined damage to the pulp, dentine, cementum, bone, and periodontium. They are transverse to oblique in direction and result from a horizontal impact. Their incidence is more in the middle third of the root than at the cervical and apical thirds.
 CASE REPORT: This paper describes a case of complicated horizontal root fracture at the middle third of the maxillary right central incisor. After receiving an endodontic treatment, the fractured root fragments of the maxillary right central incisors were united with the help of a glass fibre post. Eventually, the incisor was restored with a zirconia crown.
 CONCLUSION: Follow-up after a year revealed a well-stabilized assembly of the root fragments and the post.

Treatment of Multiple Horizontal Root Fractures of the Maxillary Anterior: A case report

Objectives: Management of a horizontal root fracture of an anterior teeth is challenging and often requires multiple approaches for improving the functional and esthetic outcomes. This case report describes the treatment and 2-yr follow up of 3 maxillary incisors with horizontal root fracture. Two maxillary central incisors were treated with Mineral Trioxide Aggregate (ProRoot MTA, Dentsply, Tulsa, OK, USA). Left maxillary lateral incisors were treated with endodontic treatment and submerged. During 2-yr of follow-up evaluation, the root-fractured teeth of the present patients were well retained in the arch, showing periodontal healing even after endodontic treatment.

Endodontic management of incisors with horizontal root fractures using H-file as endodontic implant – Two Case Reports.

Accidental injury to anterior region with fractured and mobile teeth can be an awful experience to young female patient. Treating such patient requires knowledge judgment and skill of the operator. In the present case report multiple horizontal root fracture in cervical third region with mobile undetached crown was successfully stabilized by a very simple procedure using hedstrome endodontic file as an endodontic implant. In a two year follow-up period the tooth was completely asymptomatic clinically as well as radiographically. Immobilization of fractured root by endodontic instrument with MTA considered to be a simple ,reliable and cost effective method to save a tooth that would have been difficult to restore with good long term prognosis. Key-words: Incisors, Horizontal Root Fractures, H File

Diagnosis of root fractures using cone-beam computed tomography: difference of vertical and horizontal root fracture.

The aim of this study was to investigate the occurrence of vertical and horizontal root fractures using cone-beam computed tomography (CBCT). We reviewed the CBCT images of 51 patients who were examined by CBCT for the diagnosis of root fracture. The occurrences of vertical and horizontal root fractures were investigated concerning the pulpal vitality and the kind of tooth, and analyzed by cross-tabulation. The fracture direction of vertical root fracture and the fracture angle were also investigated, and analyzed by cross-tabulation and Kruskal-Wallis test, respectively. The occurrence of vertical and horizontal root fractures was statistically significantly different between vital tooth and non-vital tooth (p = 0.044). The occurrence of vertical and horizontal root fractures was also different among anterior, premolar, and molar teeth (p = 0.004). The kind of tooth on traumatized tooth was only anterior teeth and the number was larger on horizontal root fracture. The occurrence of vertical and horizontal root fractures on non-traumatized tooth was different among the kind of tooth (p = 0.007), and the number of vertical root fracture was larger than that of horizontal root fracture on premolar teeth. Fracture direction was not different, but the fracture angle was different among the kind of tooth on vertical root fracture (p = 0.027). The results suggested that the number of vertical root fracture was larger on non-vital tooth and that of horizontal root fracture was larger on vital tooth. The number of vertical root fracture was larger on premolar teeth.

Fratura radicular horizontal: manejo conservador

A manutenção do dente em função e com uma estética favorável na cavidade bucal consiste em um dos principais objetivos da odontologia. Os traumatismos alvéolo-dentário por vezes se apresenta como um desafio na clínica odontológica, principalmente no caso de fratura radicular. O objetivo deste artigo é exibir um caso clínico onde o paciente que sofreu um traumatismo levando a uma fratura horizontal, e foi adotada uma conduta conservadora.

Ageing of TotalFill BC Sealer and MTA Fillapex in Simulated Body Fluid.

Objective:The bioactivities of TotalFill BC and the MTA Fillapex sealers were evaluated.Methods:Sixty horizontal root sections were enlarged to size 5 Gates Glidden and randomly divided into six groups (n=10 in each group). In Groups 1–3, sections were filled with TFBCS, while sections in groups 4–6 were filled with MTAFS. Specimens from groups 1 and 4 were soaked in simulated body fluid (SBF) for one day, those from groups 2 and 5 for one week, and those from groups 3 and 6 for two months. All specimens were processed for scanning electron microscope (SEM) examination. Apatite precipitation on sealer and sealer–dentine interfaces was quantified using image analysis software (ImageJ). Energy dispersive X-ray (EDX) was used to analyse calcium (Ca) and phosphate (P) contents of surface precipitation on which calculation of the calcium phosphate (Ca/P) ratio was based.Results:TFBCS samples, regardless of the duration of SBF soaking, yielded a significantly higher surface area of precipitation compared to MTAFS (P<0.05); such precipitation increased over time, and the differences among the three time-points were also statistically significant. Following one day of SBF soaking, MTAFS samples showed only limited precipitation that started to appear after one week. EDX showed that Ca content and the Ca/P ratio of surface deposits on TFBCS samples increased over time with no difference between one week and two months of SBF soaking. The Ca content and Ca/P ratio of surface deposits on MTAFS were significantly lower than that of TFBCS samples regardless of the SBF soaking time.Conclusion:Ageing TotalFill BC sealer in SPF can induce considerable apatite formation. In addition, the TotalFill BC sealer surface showed high Ca2+ ion release as reflected by the formation of apatite with a high Ca/P ratio. These bioactivity features increased over time. In comparison, the MTAFS appears to have lower and delayed bioactivity.

Accuracy of digital image enhancement in detection of vertical and horizontal root fracture

Two-dimensional intraoral radiography is the most common tool for recognizing root fractures. Improving the quality of images by means of enhancement tools can increase the recognition power of them. The aim of this study is to evaluate the effect of digital image enhancement on vertical and horizontal root fractures (HRFs) diagnostic accuracy. In this in vitro study, 100 human extracted teeth, involving 50 mandibular premolars and 50 maxillary incisors, were investigated. In total, 25 premolar teeth were vertically fractured and other 25 sound teeth served as testing group. According to the verified methods, 25 incisor teeth were fractured and other 25 teeth of this group served as testing ones. Following, by using the charge-coupled device sensor, preapical digital images were recorded. The original images were altered using reverse-contrast and colorization enhancement tools. Two different observers independently investigated all of the images. Receiver operating characteristic analysis was used to calculate the area under the curve (AUC) and sensitivity and specificity of all images. Data analyzde using receiver operating characteristic (ROC) analysis. Two-ways variance analysis was used to assess differences in the values (P = 0.05 ). AUC and sensitivity and specificity related to the original, reverse-contrast, and colorized images were calculated (0.84, 0.64, 0.99), (0.84, 0.64, 0.96), and (0.82, 0.64, 0.92) respectively, for vertically root fractured images. AUC and sensitivity and specificity related to the original, reverse-contrast, and colorized images were calculated (0.49, 0.44, 0.56), (0.50, 0.44, 0.60), and (0.48, 0.48, 0.48), respectively, for horizontally root-fractured images. The results of the present study revealed that reverse-contrast and colorized enhancement filters cannot be used as critical methods in detecting in vitro vertical and HRF.

A Rare Complication in an Untreated Horizontal Root Fracture Case

Intra-alveolar root fractures in permanent teeth are rare following dental traumatic injuries. The diagnosis of root fractures depends on careful clinical and radiographic examination. The successful treatment of a root-fractured tooth involves repositioning and fixation. Although the outcome of a root fracture is generally favourable, complications such as pulpal necrosis, radicular resorption and pulpal canal obliteration can arise. A radicular cyst is an inflammatory cyst that develops as a result of untreated dental caries, with pulp necrosis and periapical infection following chemical, physical or bacterial injury. In this case report, the diagnosis and treatment of a rare case of a radicular cyst, which occurred as a result of pulp necrosis following horizontal root fracture, and an apical root fragment, which was displaced by the cystic lesion to the base of the nasal cavity, are presented.

In Vitro Comparison of Three Dimensional Cone Beamed Dental Tomography with Intraoral Radiography in Detection of Dental Tomography with Intraoral Radiography in Detection of Dental Root Factures Root Factures

The precise diagnosis of dental root fractures in clinical practice is quite difficult. The aim of this study is to compare the results of three dimensional cone beam computed tomography (CBCT) and conventional intraoral radiography images in the diagnosis of dental root fractures. 50 maxillar central teeth with healthy roots were shot in a single blow in laboratory environment for cracks were studied for 10 teeth and horizontal root fractures created for 40 teeth. Parts of root fractures were sticked together by forming root fractures in five groups as crack, fracture without gap and fracture with 0,2 mm, 0,4 mm and 0,6 mm gaps. Images of all teeth were taken with CBCT and conventional intraoral radiography. Accurate diagnosis averages and positive predictive value test calculated through the data taken from the evaluation results of 30 dentists. Generally the results showed that images taken by the CBCT are better than images taken by the periapical radiography which obtained with traditional methods for the diagnosis of root fractures and cracks. The results also showed that the quality of the images increased as the voxel of the CBCT images decreased. It is shown that images taken by the CBCT provides better and clearer than the images taken by the traditional intraoral radiography in order to diagnose root fractures and cracks.

Construction of swept source optical coherence tomography imaging system for root canal endoscopy and application in diagnosis of root fractures

To construct swept source optical coherence tomography (SS-OCT) imaging system for root canal endoscopy, and to evaluate the accuracy of diagnosing artificial root fractures. An ultra-high-speed (40 kHz) swept laser source was developed based on the piezoelectric tuning filter and the Fourier domain mode locking (FDML) swept laser technology (patent number: 200620135940.2). Ultra-miniature gradient index lens technology (patent number: 201320241218.7) was used to create a thin endoscopic probe with a diameter of 0.86 mm for real-time image transmission. The SS-OCT light source had a wavelength of 1 310 nm and a bandwidth of 100 nm. The axial and transverse image resolutions were 15 μm and 25 μm, respectively. Artificial fractures were created on human mandibular premolars with single root and the premolar roots were prepared to 41 horizontal sections (1 mm thick). 27 root sections with fractures (width: 52-284 μm) and 14 the sections without fractures were observed under an optical stereomicroscope with a cold light source as the gold standard. The horizontal root sections were scanned by self-developed SS-OCT imaging system for root canal endoscopy with a central wavelength of 1 310 nm and bandwidth of 100 nm. The data were reconstructed with 30 μm thick slices at an interval of 30 μm. Two observers, a radiologist and an endodontist, were trained and independently evaluated all the reconstructed images blindly. The diagnostic performance of SS-OCT imaging system was calculated, and statistical analysis was performed. SS-OCT root canal endoscopic imaging system composed of high-speed swept laser source, fiber coupler, endoscopic probe, reference arm and differential detector. Root sections could be scanned by SS-OCT and imaged in realtime at a depth of 1 to 2 mm. The kappa value for interobserver agreement was 0.792, and the intraobserver agreement was 1.000 and 0.709 for two observers respectively. All of 27 fractured root sections and 12 of 14 root sections without fractures were accurately diagnosed while 2 unfractured root sections were misdiagnosed. The sensitivity was 1.000 and the specificity was 0.857 for diagnosis of artificial root fractures by SS-OCT. The positive predictive value (PPV), negative predictive value (NPV) and the overall accuracy rate were 0.931, 1.000 and 0.951 respectively. The swept source optical coherence tomography imaging system for root canal endoscopy is a promising imaging method for observing root fractures．.

Alocasia: a promising food crop for next generation

In India, three types of alocasia are present, especially in Bengal, Assam and South India in abundance. Alocasia cuculata (Lour.) thrives well under Bengal conditions as a tall herb and it is famous for its edible rhizomes. The second species, A. indica Schott; Eng., is a gaint taro having large leave caladium and belonging to family Araceae. It is generally grown in Bengal, Assam, Maharastra and South India. Stem and rootstocks are edible, leaf juice is astringent and rhizome is used as mild laxative and diuretic. The third type of Alocasia present in India and Sri Lanka is Alocasia microrhiza (L.) Schott; Eng. (giant taro, Araceae), a large herb with edible corm; after treating with 2% w/v sodium bicarbonate 20 min after boiling it is used as vegetable with minimum raphaites (71 mg 100 g(-1) edible part). In ICAR-RCER, Research Center for Makhana, 10 edible alocasia accessions from Bengal, Jharkhand and Bihar were collected. ‘Ranchi-3’ alocasia is a dwarf whose horizontal root along with stem are edible. An upright alocasia (‘RKM-1’) was collected from Kolkata. It can be planted in a minimum distance. A small alocasia was collected from West Bengal (‘WB-1’) which is a favorite for making postharvest products like Bari. The alocasia collection WB-2 is spreading and suitable for twin use like vegetables and medicinal treatment in arthritis. A. microrhiza is lucrative for its voluminous and quick growth and it is an easy growing food plant for the future generation. Typical of leaf vegetables, alocasia leaves are a good source of thiamin, riboflavin, iron, phosphorus, and zinc, and a very good source of vitamin B6, vitamin C, niacin, potassium, copper, and manganese. So in India immediate nationwide attention is required to conserve these valuable plants without any delay and pave the way for them for cultivation in fertile land. As the world population is growing alocasia may be a promising food for the future. It may be grown as a sole crop or a companion crop of a mix cropping system with sweet flag and makhana.

Long Term Effects of Concussion on Eye Tracking Patterns

PURPOSE: The purpose of this study is to investigate long-term changes in eye-tracking patterns in previously concussed individuals (>1-year post-injury) compared to non-concussed controls. METHODS: This case control study will include 40 total participants, but currently includes 12 participants with (n=5 concussed, 3.00±1.79 concussions, 4.92±2.43 years post-injury, 22.80+2.23 years, 170.18+6.62 cm, 71.49+9.19 kg) and without (n=7; 27.00+4.96 years, 177.8+9.40 cm, 77.69+12.83 kg) a concussion history were evaluated. Participants were excluded if they only had a previously undiagnosed concussion, were currently playing contact sports, did not have normal or corrected to normal vision without glasses. Participants completed two eye-tracking tasks: an anti-saccade task consisting of 5 test blocks, 40 trials each and a circle tracking task consisting of 3 trials. The anti-saccade task measured saccadic and anti-saccadic movements, while the circle tracking task measured smooth pursuit eye movements. In both groups, results were analyzed using independent T-tests. RESULTS: The mean reaction and processing times in the saccade task in formerly concussed subjects was significantly different from controls (p=0.02 and p<0.01). The control group had a 7.41% slower reaction time and 12.64% slower processing time than the concussed group. Other anti-saccade task variables (i.e. movement time, number of correct saccades, number of trials where saccade ended outside of the target zone, percent of accurate saccades, distance from target block, distance from target block for correct trials) and circle tracking (i.e. horizontal root mean squared error (RMSE), vertical RMSE, horizontal delay, mean vertical delay) were not significant (p’s>0.05). CONCLUSIONS: Counter to work on the acute effects of concussion, the preliminary findings of this study indicate that concussion may not have a long-term effect on eye-tracking reaction and processing time. Additional work in this area with larger samples is warranted.

COMPARISON OF UAV IMAGERY-DERIVED POINT CLOUD TO TERRESTRIAL LASER SCANNER POINT CLOUD

Abstract. A small unmanned aerial vehicle (UAV) with survey-grade GNSS positioning is used to produce a point cloud for topographic mapping and 3D reconstruction. The objective of this study is to assess the accuracy of a UAV imagery-derived point cloud by comparing a point cloud generated by terrestrial laser scanning (TLS). Imagery was collected over a 320 m by 320 m area with undulating terrain, containing 80 ground control points. A SenseFly eBee Plus fixed-wing platform with PPK positioning with a 10.6 mm focal length and a 20 MP digital camera was used to fly the area. Pix4Dmapper, a computer vision based commercial software, was used to process a photogrammetric block, constrained by 5 GCPs while obtaining cm-level RMSE based on the remaining 75 checkpoints. Based on results of automatic aerial triangulation, a point cloud and digital surface model (DSM) (2.5 cm/pixel) are generated and their accuracy assessed. A bias less than 1 pixel was observed in elevations from the UAV DSM at the checkpoints. 31 registered TLS scans made up a point cloud of the same area with an observed horizontal root mean square error (RMSE) of 0.006m, and negligible vertical RMSE. Comparisons were made between fitted planes of extracted roof features of 2 buildings and centreline profile comparison of a road in both UAV and TLS point clouds. Comparisons showed an average +8 cm bias with UAV point cloud computing too high in two features. No bias was observed in the roof features of the southernmost building.

Soil Moisture Determines Horizontal and Vertical Root Extension in the Perennial Grass Lolium perenne L. Growing in Karst Soil.

Karst regions are characterized by heterogeneous soil habitats, with shallow wide soil (SW) on hilly slopes and deep narrow soil (DN) in rocky trenches. To make full use of limited water and nutrients, plants have therefore developed a number of root extension strategies. This study investigated the effect of soil moisture on horizontal root extension in SW and vertical root extension in DN by assessing root growth responses, biomass allocation, and root distribution. A full two-way factorial blocked design of soil dimensions by water availability was followed. The perennial grass Lolium perenne L. was grown in SW and DN under high (W100%), moderate (W50%), and low (W30%) water availability, respectively. The main results were as follows: (1) The total biomass of L. perenne was not influenced either by soil habitat or by water application. Root length, root surface area, root biomass and root to shoot ratio all decreased with decreasing water application in SW, but not in DN soil. (2) With decreasing water application, the cumulative percentage of root length, root surface area and root biomass in 4 rings from the center out to 12 cm of SW soil showed a trend of W50% > W30% > W100% in SW, however, the cumulative percentage of root biomass in 4 layers from the surface to a depth of 36 cm was not significantly different between different water treatments in DN. (3) Under all three water treatments, specific root length showed an increase but root length density showed a decreasing trend from the center outward in SW soil or from the surface to bottom in DN soil. Overall, these results suggest that in SW habitat, soil moisture determines horizontal expansion of the roots in L. perenne, although the overall expansion ability was limited in severe drought. However, due to the relatively strong water retention ability, soil moisture changes were less obvious in DN, resulting in no significant vertical extension of the root system. The root response of L. perenne helps our understanding of how herbaceous plants can adjust their belowground morphology to support their growth in harsh karst soil environments.