Effects of soil moisture on cotton root length density (total root length per unit soil volume) and yield under drip irrigation with plastic mulch were studied through field experiments. The results indicate that spat...Effects of soil moisture on cotton root length density (total root length per unit soil volume) and yield under drip irrigation with plastic mulch were studied through field experiments. The results indicate that spatial distributions of root length density of cotton under various water treatments were basically similar. Horizontally, both root length densities of cotton in wide and narrow rows were similar, and higher than that between mulches. Vertically, root length density of cotton decreased with increasing soil depth. The distribution of root length density is different under different irrigation treatments. In conditions of over-irrigation, the root length density of cotton between mulches would increase. However, it would decrease in both the wide rows and narrow rows. The mean root length density of cotton increased with increasing irrigation water. Water stress caused the root length density to increase in lower soil layers. There is a significant correlation between root length density and yields of cotton at the flower-boll and wadding stages. The regression between irrigation amount and yield of cotton can be expressed as y = -0.0026x2+18.015x-24845 (R2 = 0.959). It showed that the irrigation volume of 3,464.4 m3/hm2 led to op-timal root length density. The yield of cotton was 6,360 .8 kg/hm2 under that amount of irrigation.展开更多
Furrow irrigation is a traditional widely-used irrigation method in the world. Understanding the dynamics of soil water distribution is essential to developing effective furrow irrigation strategies, especially in wat...Furrow irrigation is a traditional widely-used irrigation method in the world. Understanding the dynamics of soil water distribution is essential to developing effective furrow irrigation strategies, especially in water-limited regions. The objectives of this study are to analyze root length density distribution and to explore soil water dynamics by simulating soil water content using a HYDRUS-2D model with consideration of root water uptake for furrow irrigated tomato plants in a solar greenhouse in Northwest China. Soil water contents were also in-situ observed by the ECH_2O sensors from 4 June to 19 June and from 21 June to 4 July, 2012. Results showed that the root length density of tomato plants was concentrated in the 0–50 cm soil layers, and radiated 0–18 cm toward the furrow and 0–30 cm along the bed axis. Soil water content values simulated by the HYDRUS-2D model agreed well with those observed by the ECH_2O sensors, with regression coefficient of 0.988, coefficient of determination of 0.89, and index of agreement of 0.97. The HYDRUS-2D model with the calibrated parameters was then applied to explore the optimal irrigation scheduling. Infrequent irrigation with a large amount of water for each irrigation event could result in 10%–18% of the irrigation water losses. Thus we recommend high irrigation frequency with a low amount of water for each irrigation event in greenhouses for arid region. The maximum high irrigation amount and the suitable irrigation interval required to avoid plant water stress and drainage water were 34 mm and 6 days, respectively, for given daily average transpiration rate of 4.0 mm/d. To sum up, the HYDRUS-2D model with consideration of root water uptake can be used to improve irrigation scheduling for furrow irrigated tomato plants in greenhouses in arid regions.展开更多
A study to assess the effect of intercropping maize (Zea mays L.) and cowpea (Vigna unguiculata L.) within the same basin or outside the basin on root length density (RLD) was conducted at the International Crop Resea...A study to assess the effect of intercropping maize (Zea mays L.) and cowpea (Vigna unguiculata L.) within the same basin or outside the basin on root length density (RLD) was conducted at the International Crop Research Institute for Semi-Arid Tropics (ICRISAT) Matopos Research Station from December 2009 to April 2010. The experiment was laid out in a Randomised Complete Block Design (RCBD) with four treatments replicated four times namely;sole maize, sole cowpea, maize-cowpea intercrop with cowpea and maize planted within the same basin and maize-cowpea intercrop with cowpea planted 20 cm outside the maize basin. There was significant difference (P < 0.001) in RLD, grain yield and stover yield. Maize-cowpea intercropped within the same basin achieved higher RLD, grain yield and stover yield than cowpea that was intercropped outside the basin and the sole crops. The land equivalent ratio (LER) in both intercrop designs showed that intercropping had better grain yield performance when compared to sole cropping. It can be concluded that intercropping maize and cowpeas within the same basin can result in an environment around the crop achieving higher RLD which translates to better grain yield compared to the sole cropping and intercropping cowpeas outside the basin.展开更多
AIM:To compare the effects of different types of negative pressure suction on the macular and optic disc retinal vessel density(VD)in myopic patients with different axial lengths(ALs)undergoing femtosecond laser-assis...AIM:To compare the effects of different types of negative pressure suction on the macular and optic disc retinal vessel density(VD)in myopic patients with different axial lengths(ALs)undergoing femtosecond laser-assisted excimer laser in situ keratomileusis(FS-LASIK)by optical coherence tomography angiography(OCTA).METHODS:A prospective,nonrandomized,controlled study.Participants underwent FS-LASIK surgery were divided into the short AL group(SAL,22≤AL<26 mm)and the long AL group(LAL,26≤AL<28 mm)according to the different ALs.Further,the two groups were divided into subgroups according to the corneal flap using VisuMax or WaveLight FS200 femtosecond laser(FS)platform.All patients underwent OCTA before the surgery and 1-day/1-week/1-month after the surgery.ANOVA statistically analyzed data with two-factor repeated measurement in SPSS.RESULTS:Totally 108 participants(108 eyes,18–35y)were divided into SAL group[22 patients(4 males and 18 females)were treated with VisuMax,and 24(3 males and 21 females)were treated with WaveLight FS200]and LAL group[34 patients(4 males and 30 females)were treated with VisuMax,and 28 patients(6 males and 22 females)were treated with WaveLight FS200].In the LAL group,there was no significant difference in macular superficial capillary plexuses vessel density(SCP-VD)in the fovea and perifovea region,but compared with the VisuMax subgroup,SCP-VD in the parafoveal region(t=2.647,P=0.010)and the whole area(t=2.030,P=0.047)in WaveLight FS200 subgroup decreased at one day after the operation and increased to a preoperative level at 1-week and 1-month after operation.There was no significant difference between SCP-VD in the two SAL subgroups,neither of deep capillary plexuses vessel density(DCP-VD)and optic nerve head vessel density(ONH-VD)in the SAL and LAL groups.CONCLUSION:With the increase of AL and suction intensity,a transient decrease of SCP-VD in the macular region is observed at 1d postoperatively during FS-LASIK,and it increases to preoperative level at 1-week and 1-month postoperatively.However,the AL and suction intensity do not affect the macular DCP-VD and ONH-VD.展开更多
The effects ol different genotypes and planting densities on main agronomic traits, storage root traits and yield were studied with 6 high-quality sweetpotato varieties as study objects by 2-factor completely random d...The effects ol different genotypes and planting densities on main agronomic traits, storage root traits and yield were studied with 6 high-quality sweetpotato varieties as study objects by 2-factor completely random design. The results showed that there were significant differences in stem diameter, length of the longest vine and top/root （T/R） between different genotypes, T/R differed significantly under dif- ferent planting densities, and number of basal branches decreased with planting density increasing. Genotype and genotype x density showed significant or very sig- nificant effects on fresh root yield per plant, dry matter content and fresh root yield per hectare, fresh root yield per plant gradually decreased with planting density in- creasing, while fresh root yield per hectare increased with planting density increas- ing. Numbers of storage roots in different sizes of the 6 sweetpotato cultivars all exhibited an order of number of large-sized storage roots〈number of medium-sized storage roots〈small-sized storage root; and there were very significant differences in ratio of large-sized storage roots between different genotypes. The number of large- sized storage roots, ratio of large-sized storage roots and number of commercial storage roots deceased with planting density increasing, while there were no signifi- cant differences in number of medium-sized storage roots, number of small-sized storage roots, ratio of medium-sized storage roots and ratio of small-sized storage roots between different densities. Correlation analysis showed that there was signifi- cant positive correlation between number of basal branches and fresh root yield per plant; dry matter content in storage roots was in significant positive correlation with stem diameter, and in significant negative correlation with length of the longest vine; fresh root yield per hectare was in significant positive correlation with fresh root yield per plant, and in very significant negative correlation with dry matter content; and ratio of large-sized storage roots was in very significant positive correlation with number of large-sized storage root and fresh root yield per plant, and in very sig- nificant negative correlation with ratio of medium-sized storage roots and ratio of small-sized storage roots. This experiment showed that under the planting density of 7.5×104 plants/hm2, the 6 sweetpotato cultivars all reached the highest numbers of commercial storage roots and fresh root yields per hectare.展开更多
The aim of this study was to analyze the specific influence of root canal anatomy on the accessibility of working length during root canal therapy. Four hundred seventy-six root canal therapy cases （amounting to a to...The aim of this study was to analyze the specific influence of root canal anatomy on the accessibility of working length during root canal therapy. Four hundred seventy-six root canal therapy cases （amounting to a total of 1 005 root canals） were examined. The anatomy risk factors assessed in each case included： tooth type （tooth location）, root canal curvature, and root canal calcification, as well as endodontic retreatment. The investigation examined the correlation between each of these anatomic factors and the working length, with statistical analysis consisting of Chi-square tests and multiple logistic regression analysis. In an independent factor analysis, tooth type （tooth iocation）, root canal curvature, canal calcification, and endodontic retreatment were determined to be the primary risk factors. In a multiple-factor regression model, root curvature and canal calcification were found to most significantly influence root canal working length accessibility （P〈0.05）. Root canal anatomy increases the difficulty of root canal preparation. Appropriate consideration of tooth anatomy will assist in accurate determination of preparation difficulty before instrumentation. This study alerts clinical therapists to anatomical factors influencing the working length accessibility, and allows for a direct estimate of success rate given in situ measurements of tooth factors during the root canal treatment procedure.展开更多
Anionic surfantant sodium dodecyl sulfate （SDS）, cationic surfactant cetyl trimethyl ammonium bromide （CTAB） and acrylic acid （AA） were introduced as molecular models to study the interaction between montmorillo...Anionic surfantant sodium dodecyl sulfate （SDS）, cationic surfactant cetyl trimethyl ammonium bromide （CTAB） and acrylic acid （AA） were introduced as molecular models to study the interaction between montmorillonite and organic molecules with different charge or chain length. The compounds were characterized by X-ray diffraction （XRD）, Fourier transform infrared spectroscopy （FT-IR） and 13C nuclear magnetic resonance （13C NMR）. The results show organic anion could interact strongly with montmorillonite, even the molecules could intercalate into the layers of MMT.展开更多
To address the relationships between the amount of nitrogen fertilizer application and the yield of double cropping rice systems,we investigated the effects of a cultivation pattern of strong seedlings with increased ...To address the relationships between the amount of nitrogen fertilizer application and the yield of double cropping rice systems,we investigated the effects of a cultivation pattern of strong seedlings with increased planting density and reduced nitrogen application(SDN)on the morphological and physiological characteristics of double cropping rice.Our results indicated that the effects of SDN on the morphological characteristics of the single plant roots of double cropping rice were not significant,but the morphological characteristics of the population roots were largely different.Specifically,SDN significantly increased the morphological indexes of the root population such as root fresh weight,root volume,root number,root length and root dry weight.The effects of SDN on the total root absorption areas and root active absorption areas of the single plants were non-significant,but it dramatically enhanced the total root absorption areas and root active absorption areas of the plant population during the tillering,heading and mature stages.In addition,SDN significantly increased the root bleeding intensity and elevated the soluble sugar and free amino acid contents of root bleeding sap.Compared to the traditional cultivation pattern(CK),SDN significantly increased root bleeding intensity at the heading stage by 4.37 and 8.90% for early and late rice,respectively.Meanwhile,SDN profoundly enhanced the soluble sugar contents of root bleeding sap by 12.85 and 10.41% for early and late rice,respectively.In addition,SDN also significantly enhanced free amino acid content of root bleeding sap by 43.25% for early rice and by 37.50% for late rice systems compared to CK.Furthermore,SDN increased the actual yield of double cropping rice mainly due to the higher effective panicle number and the larger seedsetting rate.The actual yields of early rice under SDN were higher than CK by 9.37 and 5.98% in 2016 and 2017,and the actual yields of late rice under SDN were higher than CK by 0.20 and 1.41% in 2016 and 2017,respectively.Correlation analysis indicated that the significant positive correlations were observed between the majority of the root indexes and the actual yield across the four different growth stages.展开更多
Background: There is paucity of literature on the determination of the root canal length of Bantu subjects in dental professional practicing in Africa and Democratic Republic of Congo in particular. Aims: The aim of t...Background: There is paucity of literature on the determination of the root canal length of Bantu subjects in dental professional practicing in Africa and Democratic Republic of Congo in particular. Aims: The aim of the present study was to determine the root canal length of teeth of Bantu patients extracts attending the Teaching Hospital of Kinshasa University. Methods and Material: Prospective cross-sectional study was carried out in the service of Conservative Dentistry. The patients suffering with pulpitis of permanent teeth which were selected for root canal treatment during the period of January 2014 to December 2016 were included. All patients whose main root canals were inaccessible, teeth carrying prosthesis, teeth with large coronal decay, teeth having periapical periodontitis, supernumerary teeth, wisdom and primary teeth were excluded. Results: The upper canines presented some significant longer canals compared to the lower canine (23.4 ± 2.3 mm and 21.6 ± 1.8 mm). Palatal canals of the first and second molar were respectively longer as compared to the superior teeth canals (21.5 ± 1 mm, 21.3 ± 2 mm). The distal canals of the first and second molar were the longest in the mandibular arch respectively measuring 20.7 ± 2.0 mm and 21.5 ± 1.7 mm. Conclusion: Data obtained from Bantu patients show slightly shorter roots compared to some European populations, but longer than some Asian populations.展开更多
Branch length and density have critical effects on membrane performances; however, it is regarded to be traditionally difficult to investigate the relationship due to the uncontrolled membrane modification methods. In...Branch length and density have critical effects on membrane performances; however, it is regarded to be traditionally difficult to investigate the relationship due to the uncontrolled membrane modification methods. In this study, zwitterionic polymer with controlled grafting branch chain length（degree of polymerization） and grafting density（grafting chains per membrane area） was tethered to the microporous polypropylene membrane surface based on the combination of reversible addition-fragmentation chain transfer（RAFT） polymerization technique with click reaction. The modified membranes were tested by filtrating protein dispersion to highlight the correlations of branch chain length and grafting density with the membrane permeation performances. The pure water flux, the flux recovery ratio are positively and significantly, and the irreversible fouling negatively and significantly correlated with grafting density. These results demonstrate that the larger the coverage of the membrane with poly{[2-（methacryloyloxy）ethyl]-dimethyl-（3-sulfopropyl） ammonium hydroxide}（PMEDSAH）, the higher the pure water flux and the higher the flux recover ratio, and the lower the irreversible fouling, which shows that high grafting density is favorable to fouling reducing.展开更多
To determine the effects of sika deer (Cervus nippon) browsing on the physical defences of the Japanese pricklyash “Zanthoxylum ailanthoides Sieb. et Zucc.” (Rutaceae), we compared the length and density of prickles...To determine the effects of sika deer (Cervus nippon) browsing on the physical defences of the Japanese pricklyash “Zanthoxylum ailanthoides Sieb. et Zucc.” (Rutaceae), we compared the length and density of prickles on Japanese islands which were under different browsing pressures. We measured the length and density of prickles on the midribs, leaf rachis, and stems. We found that the prickles of Z. ailanthoides on Kashima island were not significantly longer or at higher densities than those in the neighbouring areas;the longest pickles at the highest densities were found on Akune island. The density of sika deer on Akune (ca. 520-600/km2) was higher than that on Kashima (ca. 38.5/km2), and consequently, Akune was under greater browsing pressure. Our results suggest that the increased length and density of prickles on Akune is a response by Z. ailanthoides to the high density of sika deer found on the island.展开更多
Postoperative tunnel enlargement has been frequently reported after anterior cruciate ligament（ACL）reconstruction.Interference screw,as a surgical implant in ACL reconstruction,may influence natural loading transmis...Postoperative tunnel enlargement has been frequently reported after anterior cruciate ligament（ACL）reconstruction.Interference screw,as a surgical implant in ACL reconstruction,may influence natural loading transmission and contribute to tunnel enlargement.The aims of this study are（1）to quantify the alteration of strain energy density（SED）distribution after the anatomic single-bundle ACL reconstruction;and（2）to characterize the influence of screw length and diameter on the degree of the SED alteration.A validated finite element model of human knee joint was used.The screw length ranging from 20 to 30 mm with screw diameter ranging from 7 to 9 mm were investigated.In the post-operative knee,the SED increased steeply at the extra-articular tunnel aperture under compressive and complex loadings,whereas the SED decreased beneath the screw shaft and nearby the intra-articular tunnel aperture.Increasing the screw length could lower the SED deprivation in the proximal part of the bone tunnel;whereas increasing either screw length or diameter could aggravate the SED deprivation in the distal part of the bone tunnel.Decreasing the elastic modulus of the screw could lower the bone SED deprivation around the screw.In consideration of both graft stability and SED alteration,a biodegradable interference screw with a long length is recommended,which could provide a beneficial mechanical environment at the distal part of the tunnel,and meanwhile decrease the bone-graft motion and synovial fluid propagation at the proximal part of the tunnel.These findings together with the clinical and histological factors could help to improve surgical outcome,and serve as a preliminary knowledge for the following study of biodegradable interference screw.展开更多
The objective of this study was to compare the wood properties related to wood pulp quality of two widely planted Acacia species viz.Acacia mangium Willd.and Acacia auriculiformis A.Cunn.Ex Benth.and their hybrid.Acid...The objective of this study was to compare the wood properties related to wood pulp quality of two widely planted Acacia species viz.Acacia mangium Willd.and Acacia auriculiformis A.Cunn.Ex Benth.and their hybrid.Acid insoluble lignin content(Klason),mean stem density and fibre length differed considerably among the species and hybrids.A.mangium possessed a high percent of lignin content compared to A.auriculiformis and the Acacia hybrid.However,mean stem density of A.auriculiformis was higher than A.mangium and the hybrid.Fibre length of heartwood tissues was generally shorter than that of sapwood tissues.The hybrid had longer fibres than the parent species.Lignin was negatively correlated with mean stem density.Generally,the wood properties of the hybrid were superior to its parent species.The significant intraspecific variation observed for wood properties of Acacia species could be used in breeding superior hybrids combining desirable traits of the two species.Considering thedifficulty involved in accurately measuring the lignin content compared to mean stem density,selection for plants with low lignin content can be achieved by indirect selection of high mean stem density.展开更多
Background In the smoothed particle hydrodynamics(SPH)fluid simulation method,the smoothing length affects not only the process of neighbor search but also the calculation accuracy of the pressure solver.Therefore,it ...Background In the smoothed particle hydrodynamics(SPH)fluid simulation method,the smoothing length affects not only the process of neighbor search but also the calculation accuracy of the pressure solver.Therefore,it plays a crucial role in ensuring the accuracy and stability of SPH.Methods In this study,an adaptive SPH fluid simulation method with a variable smoothing length is designed.In this method,the smoothing length is adaptively adjusted according to the ratio of the particle density to the weighted average of the density of the neighboring particles.Additionally,a neighbor search scheme and kernel function scheme are designed to solve the asymmetry problems caused by the variable smoothing length.Results The simulation efficiency of the proposed algorithm is comparable to that of some classical methods,and the variance of the number of neighboring particles is reduced.Thus,the visual effect is more similar to the corresponding physical reality.Conclusions The precision of the interpolation calculation performed in the SPH algorithm is improved using the adaptive-smoothing length scheme;thus,the stability of the algorithm is enhanced,and a larger timestep is possible.展开更多
Exploring approaches to regulate meristem is of special importance and broad interest.In this study,we found that the flavonoid scutellarin,which has a 6-hydroxyl and a 7-glucoside,increased root length through the tr...Exploring approaches to regulate meristem is of special importance and broad interest.In this study,we found that the flavonoid scutellarin,which has a 6-hydroxyl and a 7-glucoside,increased root length through the transcription factor NUTCRACKER(NUC).This root lengthening disappeared in NUCknockout and reappeared in NUC-rescue plants.Scutellarin induced NUC expression and promoted the division of cortex/endodermal initials.In contrast,naringenin,which has same chemical backbone but without 6-hydroxyl and with 7-hydroxyl group,showed the opposite or no effects.Our results demonstrate that scutellarin promotes root length through NUC-mediated regulatory pathways and reveal that flavonoids with and without the 6-hydroxyl and 7-glucoside have positive and negative effects on meristem size,respectively。展开更多
Increasing evidence suggests that fine roots are particularly sensitive to environmental changes,making them essential in responding and adapting forest ecosystems to climate change.However,we still lack a fundamental...Increasing evidence suggests that fine roots are particularly sensitive to environmental changes,making them essential in responding and adapting forest ecosystems to climate change.However,we still lack a fundamental understanding of the underlying mechanisms that control fine root plasticity.The objective of this study was to determine the influence of soil moisture changes on fine root dynamics and morphology of European beech(Fagus sylvatica L.).We conducted a 30-month study of fine root traits,i.e.,fine root biomass(FRB),productivity,mortality,turnover,specific root length(SRL),specific root area(SRA),and root tip frequency(RTF),along a soil moisture gradient from dry,intermediate,and wet conditions in a near-natural mature beech forest.Sequential root coring with accompanying soil measurements was carried out at three study sites reflecting the gradient in soil water availability.For most fine root traits,we found significant differences between the upper 10 cm and lower soil depths.FRB showed significant differences between study sites,with the lowest FRB at the dry site.However,productivity,turnover,SRL,SRA,and RTF showed no significant differences between sites,but a high variability between seasons,suggesting an adaptation to short-term fluctuations but not to long-term gradients in soil water content(SWC).Linear mixed models revealed that decreasing SWC led to a significant increase in SRL,SRA,and RTF(standardized coefficients:-1.0±0.46,-1.1±0.46,and-1.1±0.43,respectively).Our observations indicate an adaptation strategy of beech to low availability of soil water and drought by forming thin absorptive roots and by maintaining a high seasonal plasticity to tolerate fluctuations in soil moisture.By highlighting the belowground morphological adaptations of mature forests to low soil water availability,our results provide novel insights into the structure and dynamics of forest ecosystem adaptations to climate change.展开更多
Soil erosion and shallow landslides in the upper reaches of the Yellow River,China,are increasing due to extreme climate events and human disturbances.The biomechanical properties of vegetation roots play an important...Soil erosion and shallow landslides in the upper reaches of the Yellow River,China,are increasing due to extreme climate events and human disturbances.The biomechanical properties of vegetation roots play an important role in soil stabilization and fixation,as they resist soil erosion and shallow landslides in this area.However,the biomechanical properties of the roots of dominant herbs and their influencing factors in this area remain poorly understood.Therefore,we selected two dominant herbs in this area,Stipa aliena Keng and Poa crymophila Keng,and carried out a series of uniaxial tensile tests on the roots of the two herbs under different treatments.Meanwhile,the effects of root diameter,plant species,gauge length,root water content,and loading rate on the biomechanical properties of the two herbs'roots were analyzed.The results showed that root diameter was the most significant factor affecting the root biomechanical properties(P<0.010),and root tensile force displayed a positive power law relationship with root diameter,whereas root tensile strength and Young's modulus followed negative power law correlations with root diameter,and fracture strain increased linearly with root diameter.Root tensile force,tensile strength,and fracture strain of S.aliena were significantly greater than those of P.crymophila(P<0.001),which was mainly due to the higher lignin content and lignin:cellulose ratio of S.aliena roots.During uniaxial tensile process,hydrated roots exhibited elastic-plastic-brittle behavior,whereas dried roots exhibited elastic-brittle behavior.Root fracture strain of the two herbs was significantly lower under 100 mm gauge length than under 50 mm gauge length(P<0.001),and the Young's modulus was significantly greater(P<0.050).Tensile strength and fracture strain of hydrated roots of the two herbs were significantly greater than those of dried roots(P<0.050),whereas the Young's modulus was significantly lower(P<0.001).Root tensile force,tensile strength,and fracture strain of S.aliena were significantly greater under 20 mm/min loading rate than under 200 mm/min loading rate(P<0.050),whereas loading rate had no significant effect on the root biomechanical properties of P.crymophila(P>0.050).Fibrous roots of the two herbs were well developed,with relatively high tensile strengths and Young's moduli of 78.498 and 837.901 MPa for S.aliena,and 67.541 and 901.184 MPa for P.crymophila,respectively.The two herbs can stabilize soil and prevent soil erosion and can be used as pioneer species for ecological restoration in the upper reaches of the Yellow River.These results provide a theoretical basis for soil erosion and shallow landslide control in the giant landslide area of the upper reaches of the Yellow River.展开更多
Plant root systems serve as a natural reinforcing material,significantly improving soil stability.Furthermore,the tensile strength of soil is crucial in mitigating the formation of cracks.Consequently,this study aims ...Plant root systems serve as a natural reinforcing material,significantly improving soil stability.Furthermore,the tensile strength of soil is crucial in mitigating the formation of cracks.Consequently,this study aims to investigate the influence of plant roots on the tensile strength of soil.For this investigation,Amorpha fruticose was selected due to its large root diameter and the ease of root extraction.Indoor tensile tests were conducted on individual roots and root-soil complexes under three varying factors.The results indicate a power law relationship between root diameter and tensile strength.Increased root content and dry density notably enhance the tensile strength of the root-soil complex while roots mitigate damage associated with soil brittleness.When root content increases from 0 to 10,the maximum enhancement in tensile strength of the root-soil complex reaches 42.3 kPa.The tensile strength of the root-soil complex at a dry density of 1.7 g/cm^(3)is four to five times greater than that of the complex at a dry density of 1.4 g/cm^(3).Moreover,as moisture content increases,the tensile strength of the root-soil complex initially rises before declining,with an increase range of 7.7-35.8 kPa.These findings provide a scientific basis for understanding the role of vegetation roots in soil tensile strength and for guiding slope reinforcement strategies.展开更多
To study growth responses of the roots of Panicum miliaceum L. to heterogeneous supply of nutrients. The authors analyzed the effects of the nutrient levels in both original patches (O) and destination patches (D) on ...To study growth responses of the roots of Panicum miliaceum L. to heterogeneous supply of nutrients. The authors analyzed the effects of the nutrient levels in both original patches (O) and destination patches (D) on the root growth of P. miliaceum when its roots were allowed to extend from original patch into destination patch. When the nutrient levels in the original patches were low, coarse root biomass ratio (coarse root biomass in the D/total coarse root biomass), coarse root length ratio (coarse root length in the D/total coarse root length), coarse root surface area ratio (coarse root surface area in the D/total coarse root surface area) and fine root length ratio (fine root length in the D/total fine root length) were greater in the destination patches with lower nutrient levels than in the destination patches with higher nutrient levels, while fine root length, fine root length density, fine root surface index, and fine root surface area density were smaller in the former than in the latter. When the nutrient levels in the original patches were high, fine root length, fine root length density, fine root surface area index and fine root surface density were greater in the destination patches with lower nutrient levels than in the destination patches with higher nutrient levels, coarse roots did not respond to the nutrient levels in the destination patches significantly. When the roots extended from the original patches with the same nutrient level into the destination patches with contrasting nutrient levels, fine root biomass and its percentage allocation did not respond to the nutrient levels in the destination patches significantly, whereas both root length and root surface area did. This indicates that the fine roots of P. miliaceum responded to difference in nutrient supply by plasticity in their length and surface area, rather than in their root biomass.展开更多
基金supported by the National 973 project (2009CB421302)the National Project (2007BAC03A0604)the key National Natural Science Foundation (40830640)
文摘Effects of soil moisture on cotton root length density (total root length per unit soil volume) and yield under drip irrigation with plastic mulch were studied through field experiments. The results indicate that spatial distributions of root length density of cotton under various water treatments were basically similar. Horizontally, both root length densities of cotton in wide and narrow rows were similar, and higher than that between mulches. Vertically, root length density of cotton decreased with increasing soil depth. The distribution of root length density is different under different irrigation treatments. In conditions of over-irrigation, the root length density of cotton between mulches would increase. However, it would decrease in both the wide rows and narrow rows. The mean root length density of cotton increased with increasing irrigation water. Water stress caused the root length density to increase in lower soil layers. There is a significant correlation between root length density and yields of cotton at the flower-boll and wadding stages. The regression between irrigation amount and yield of cotton can be expressed as y = -0.0026x2+18.015x-24845 (R2 = 0.959). It showed that the irrigation volume of 3,464.4 m3/hm2 led to op-timal root length density. The yield of cotton was 6,360 .8 kg/hm2 under that amount of irrigation.
基金supported by the National Key Research and Development Program of China (2016YFC0400207)the National Natural Science Foundation of China (51222905, 51621061, 51509130)+2 种基金the Natural Science Foundation of Jiangsu Province, China (BK20150908)the Discipline Innovative Engineering Plan (111 Program, B14002)the Jiangsu Key Laboratory of Agricultural Meteorology Foundation (JKLAM1601)
文摘Furrow irrigation is a traditional widely-used irrigation method in the world. Understanding the dynamics of soil water distribution is essential to developing effective furrow irrigation strategies, especially in water-limited regions. The objectives of this study are to analyze root length density distribution and to explore soil water dynamics by simulating soil water content using a HYDRUS-2D model with consideration of root water uptake for furrow irrigated tomato plants in a solar greenhouse in Northwest China. Soil water contents were also in-situ observed by the ECH_2O sensors from 4 June to 19 June and from 21 June to 4 July, 2012. Results showed that the root length density of tomato plants was concentrated in the 0–50 cm soil layers, and radiated 0–18 cm toward the furrow and 0–30 cm along the bed axis. Soil water content values simulated by the HYDRUS-2D model agreed well with those observed by the ECH_2O sensors, with regression coefficient of 0.988, coefficient of determination of 0.89, and index of agreement of 0.97. The HYDRUS-2D model with the calibrated parameters was then applied to explore the optimal irrigation scheduling. Infrequent irrigation with a large amount of water for each irrigation event could result in 10%–18% of the irrigation water losses. Thus we recommend high irrigation frequency with a low amount of water for each irrigation event in greenhouses for arid region. The maximum high irrigation amount and the suitable irrigation interval required to avoid plant water stress and drainage water were 34 mm and 6 days, respectively, for given daily average transpiration rate of 4.0 mm/d. To sum up, the HYDRUS-2D model with consideration of root water uptake can be used to improve irrigation scheduling for furrow irrigated tomato plants in greenhouses in arid regions.
文摘A study to assess the effect of intercropping maize (Zea mays L.) and cowpea (Vigna unguiculata L.) within the same basin or outside the basin on root length density (RLD) was conducted at the International Crop Research Institute for Semi-Arid Tropics (ICRISAT) Matopos Research Station from December 2009 to April 2010. The experiment was laid out in a Randomised Complete Block Design (RCBD) with four treatments replicated four times namely;sole maize, sole cowpea, maize-cowpea intercrop with cowpea and maize planted within the same basin and maize-cowpea intercrop with cowpea planted 20 cm outside the maize basin. There was significant difference (P < 0.001) in RLD, grain yield and stover yield. Maize-cowpea intercropped within the same basin achieved higher RLD, grain yield and stover yield than cowpea that was intercropped outside the basin and the sole crops. The land equivalent ratio (LER) in both intercrop designs showed that intercropping had better grain yield performance when compared to sole cropping. It can be concluded that intercropping maize and cowpeas within the same basin can result in an environment around the crop achieving higher RLD which translates to better grain yield compared to the sole cropping and intercropping cowpeas outside the basin.
基金Supported by Wu Jieping Medical Foundation(No.320.6750.2021-4-15).
文摘AIM:To compare the effects of different types of negative pressure suction on the macular and optic disc retinal vessel density(VD)in myopic patients with different axial lengths(ALs)undergoing femtosecond laser-assisted excimer laser in situ keratomileusis(FS-LASIK)by optical coherence tomography angiography(OCTA).METHODS:A prospective,nonrandomized,controlled study.Participants underwent FS-LASIK surgery were divided into the short AL group(SAL,22≤AL<26 mm)and the long AL group(LAL,26≤AL<28 mm)according to the different ALs.Further,the two groups were divided into subgroups according to the corneal flap using VisuMax or WaveLight FS200 femtosecond laser(FS)platform.All patients underwent OCTA before the surgery and 1-day/1-week/1-month after the surgery.ANOVA statistically analyzed data with two-factor repeated measurement in SPSS.RESULTS:Totally 108 participants(108 eyes,18–35y)were divided into SAL group[22 patients(4 males and 18 females)were treated with VisuMax,and 24(3 males and 21 females)were treated with WaveLight FS200]and LAL group[34 patients(4 males and 30 females)were treated with VisuMax,and 28 patients(6 males and 22 females)were treated with WaveLight FS200].In the LAL group,there was no significant difference in macular superficial capillary plexuses vessel density(SCP-VD)in the fovea and perifovea region,but compared with the VisuMax subgroup,SCP-VD in the parafoveal region(t=2.647,P=0.010)and the whole area(t=2.030,P=0.047)in WaveLight FS200 subgroup decreased at one day after the operation and increased to a preoperative level at 1-week and 1-month after operation.There was no significant difference between SCP-VD in the two SAL subgroups,neither of deep capillary plexuses vessel density(DCP-VD)and optic nerve head vessel density(ONH-VD)in the SAL and LAL groups.CONCLUSION:With the increase of AL and suction intensity,a transient decrease of SCP-VD in the macular region is observed at 1d postoperatively during FS-LASIK,and it increases to preoperative level at 1-week and 1-month postoperatively.However,the AL and suction intensity do not affect the macular DCP-VD and ONH-VD.
基金Supported by Earmarked Fund for China Agriculture Research System(CARS-11,sweetpotato)Jiangsu Science and Technology Support Program(BE2014315)+1 种基金Jiangsu Agricultural Science and Technology Independent Innovation Fund(CX(13)2032)Jiangsu Key Research and Development Program(modern agriculture)(BE2015313)~~
文摘The effects ol different genotypes and planting densities on main agronomic traits, storage root traits and yield were studied with 6 high-quality sweetpotato varieties as study objects by 2-factor completely random design. The results showed that there were significant differences in stem diameter, length of the longest vine and top/root （T/R） between different genotypes, T/R differed significantly under dif- ferent planting densities, and number of basal branches decreased with planting density increasing. Genotype and genotype x density showed significant or very sig- nificant effects on fresh root yield per plant, dry matter content and fresh root yield per hectare, fresh root yield per plant gradually decreased with planting density in- creasing, while fresh root yield per hectare increased with planting density increas- ing. Numbers of storage roots in different sizes of the 6 sweetpotato cultivars all exhibited an order of number of large-sized storage roots〈number of medium-sized storage roots〈small-sized storage root; and there were very significant differences in ratio of large-sized storage roots between different genotypes. The number of large- sized storage roots, ratio of large-sized storage roots and number of commercial storage roots deceased with planting density increasing, while there were no signifi- cant differences in number of medium-sized storage roots, number of small-sized storage roots, ratio of medium-sized storage roots and ratio of small-sized storage roots between different densities. Correlation analysis showed that there was signifi- cant positive correlation between number of basal branches and fresh root yield per plant; dry matter content in storage roots was in significant positive correlation with stem diameter, and in significant negative correlation with length of the longest vine; fresh root yield per hectare was in significant positive correlation with fresh root yield per plant, and in very significant negative correlation with dry matter content; and ratio of large-sized storage roots was in very significant positive correlation with number of large-sized storage root and fresh root yield per plant, and in very sig- nificant negative correlation with ratio of medium-sized storage roots and ratio of small-sized storage roots. This experiment showed that under the planting density of 7.5×104 plants/hm2, the 6 sweetpotato cultivars all reached the highest numbers of commercial storage roots and fresh root yields per hectare.
基金supported by State Key Laboratory of Oral Diseases and Department of Endodontics and Operative Dentistry, West China School of Stomatology, Sichuan Universitysupported by the Key Clinical Program of the Ministry of Health of China (2010)National Key Clinical Program of China (2010)
文摘The aim of this study was to analyze the specific influence of root canal anatomy on the accessibility of working length during root canal therapy. Four hundred seventy-six root canal therapy cases （amounting to a total of 1 005 root canals） were examined. The anatomy risk factors assessed in each case included： tooth type （tooth location）, root canal curvature, and root canal calcification, as well as endodontic retreatment. The investigation examined the correlation between each of these anatomic factors and the working length, with statistical analysis consisting of Chi-square tests and multiple logistic regression analysis. In an independent factor analysis, tooth type （tooth iocation）, root canal curvature, canal calcification, and endodontic retreatment were determined to be the primary risk factors. In a multiple-factor regression model, root curvature and canal calcification were found to most significantly influence root canal working length accessibility （P〈0.05）. Root canal anatomy increases the difficulty of root canal preparation. Appropriate consideration of tooth anatomy will assist in accurate determination of preparation difficulty before instrumentation. This study alerts clinical therapists to anatomical factors influencing the working length accessibility, and allows for a direct estimate of success rate given in situ measurements of tooth factors during the root canal treatment procedure.
文摘Anionic surfantant sodium dodecyl sulfate （SDS）, cationic surfactant cetyl trimethyl ammonium bromide （CTAB） and acrylic acid （AA） were introduced as molecular models to study the interaction between montmorillonite and organic molecules with different charge or chain length. The compounds were characterized by X-ray diffraction （XRD）, Fourier transform infrared spectroscopy （FT-IR） and 13C nuclear magnetic resonance （13C NMR）. The results show organic anion could interact strongly with montmorillonite, even the molecules could intercalate into the layers of MMT.
基金financially supported by the National Key Research and Development Program of China(2017YFD0300106,2018YFD0301103,and 2016YFD0300108)the National Key Technologies R&D Program of China during the 12th Five-Year Plan period(2013BAD07B12)the National Natural Science Foundation of China(31601263)。
文摘To address the relationships between the amount of nitrogen fertilizer application and the yield of double cropping rice systems,we investigated the effects of a cultivation pattern of strong seedlings with increased planting density and reduced nitrogen application(SDN)on the morphological and physiological characteristics of double cropping rice.Our results indicated that the effects of SDN on the morphological characteristics of the single plant roots of double cropping rice were not significant,but the morphological characteristics of the population roots were largely different.Specifically,SDN significantly increased the morphological indexes of the root population such as root fresh weight,root volume,root number,root length and root dry weight.The effects of SDN on the total root absorption areas and root active absorption areas of the single plants were non-significant,but it dramatically enhanced the total root absorption areas and root active absorption areas of the plant population during the tillering,heading and mature stages.In addition,SDN significantly increased the root bleeding intensity and elevated the soluble sugar and free amino acid contents of root bleeding sap.Compared to the traditional cultivation pattern(CK),SDN significantly increased root bleeding intensity at the heading stage by 4.37 and 8.90% for early and late rice,respectively.Meanwhile,SDN profoundly enhanced the soluble sugar contents of root bleeding sap by 12.85 and 10.41% for early and late rice,respectively.In addition,SDN also significantly enhanced free amino acid content of root bleeding sap by 43.25% for early rice and by 37.50% for late rice systems compared to CK.Furthermore,SDN increased the actual yield of double cropping rice mainly due to the higher effective panicle number and the larger seedsetting rate.The actual yields of early rice under SDN were higher than CK by 9.37 and 5.98% in 2016 and 2017,and the actual yields of late rice under SDN were higher than CK by 0.20 and 1.41% in 2016 and 2017,respectively.Correlation analysis indicated that the significant positive correlations were observed between the majority of the root indexes and the actual yield across the four different growth stages.
文摘Background: There is paucity of literature on the determination of the root canal length of Bantu subjects in dental professional practicing in Africa and Democratic Republic of Congo in particular. Aims: The aim of the present study was to determine the root canal length of teeth of Bantu patients extracts attending the Teaching Hospital of Kinshasa University. Methods and Material: Prospective cross-sectional study was carried out in the service of Conservative Dentistry. The patients suffering with pulpitis of permanent teeth which were selected for root canal treatment during the period of January 2014 to December 2016 were included. All patients whose main root canals were inaccessible, teeth carrying prosthesis, teeth with large coronal decay, teeth having periapical periodontitis, supernumerary teeth, wisdom and primary teeth were excluded. Results: The upper canines presented some significant longer canals compared to the lower canine (23.4 ± 2.3 mm and 21.6 ± 1.8 mm). Palatal canals of the first and second molar were respectively longer as compared to the superior teeth canals (21.5 ± 1 mm, 21.3 ± 2 mm). The distal canals of the first and second molar were the longest in the mandibular arch respectively measuring 20.7 ± 2.0 mm and 21.5 ± 1.7 mm. Conclusion: Data obtained from Bantu patients show slightly shorter roots compared to some European populations, but longer than some Asian populations.
基金financially supported by the National Natural Science Foundation of China (No. 21371008)
文摘Branch length and density have critical effects on membrane performances; however, it is regarded to be traditionally difficult to investigate the relationship due to the uncontrolled membrane modification methods. In this study, zwitterionic polymer with controlled grafting branch chain length（degree of polymerization） and grafting density（grafting chains per membrane area） was tethered to the microporous polypropylene membrane surface based on the combination of reversible addition-fragmentation chain transfer（RAFT） polymerization technique with click reaction. The modified membranes were tested by filtrating protein dispersion to highlight the correlations of branch chain length and grafting density with the membrane permeation performances. The pure water flux, the flux recovery ratio are positively and significantly, and the irreversible fouling negatively and significantly correlated with grafting density. These results demonstrate that the larger the coverage of the membrane with poly{[2-（methacryloyloxy）ethyl]-dimethyl-（3-sulfopropyl） ammonium hydroxide}（PMEDSAH）, the higher the pure water flux and the higher the flux recover ratio, and the lower the irreversible fouling, which shows that high grafting density is favorable to fouling reducing.
文摘To determine the effects of sika deer (Cervus nippon) browsing on the physical defences of the Japanese pricklyash “Zanthoxylum ailanthoides Sieb. et Zucc.” (Rutaceae), we compared the length and density of prickles on Japanese islands which were under different browsing pressures. We measured the length and density of prickles on the midribs, leaf rachis, and stems. We found that the prickles of Z. ailanthoides on Kashima island were not significantly longer or at higher densities than those in the neighbouring areas;the longest pickles at the highest densities were found on Akune island. The density of sika deer on Akune (ca. 520-600/km2) was higher than that on Kashima (ca. 38.5/km2), and consequently, Akune was under greater browsing pressure. Our results suggest that the increased length and density of prickles on Akune is a response by Z. ailanthoides to the high density of sika deer found on the island.
基金supported by the National Science & Technology Pillar Program of China(2012BAI18B07 and 2012BAI22B02)the National Natural Science Foundation of China(10925208 and 11120101001)the National Key Lab of Virtual Reality Technology
文摘Postoperative tunnel enlargement has been frequently reported after anterior cruciate ligament（ACL）reconstruction.Interference screw,as a surgical implant in ACL reconstruction,may influence natural loading transmission and contribute to tunnel enlargement.The aims of this study are（1）to quantify the alteration of strain energy density（SED）distribution after the anatomic single-bundle ACL reconstruction;and（2）to characterize the influence of screw length and diameter on the degree of the SED alteration.A validated finite element model of human knee joint was used.The screw length ranging from 20 to 30 mm with screw diameter ranging from 7 to 9 mm were investigated.In the post-operative knee,the SED increased steeply at the extra-articular tunnel aperture under compressive and complex loadings,whereas the SED decreased beneath the screw shaft and nearby the intra-articular tunnel aperture.Increasing the screw length could lower the SED deprivation in the proximal part of the bone tunnel;whereas increasing either screw length or diameter could aggravate the SED deprivation in the distal part of the bone tunnel.Decreasing the elastic modulus of the screw could lower the bone SED deprivation around the screw.In consideration of both graft stability and SED alteration,a biodegradable interference screw with a long length is recommended,which could provide a beneficial mechanical environment at the distal part of the tunnel,and meanwhile decrease the bone-graft motion and synovial fluid propagation at the proximal part of the tunnel.These findings together with the clinical and histological factors could help to improve surgical outcome,and serve as a preliminary knowledge for the following study of biodegradable interference screw.
基金funded by e-Science 02-01-02-SF0403 from the Ministry of Science,Technology and Innovation,Malaysia
文摘The objective of this study was to compare the wood properties related to wood pulp quality of two widely planted Acacia species viz.Acacia mangium Willd.and Acacia auriculiformis A.Cunn.Ex Benth.and their hybrid.Acid insoluble lignin content(Klason),mean stem density and fibre length differed considerably among the species and hybrids.A.mangium possessed a high percent of lignin content compared to A.auriculiformis and the Acacia hybrid.However,mean stem density of A.auriculiformis was higher than A.mangium and the hybrid.Fibre length of heartwood tissues was generally shorter than that of sapwood tissues.The hybrid had longer fibres than the parent species.Lignin was negatively correlated with mean stem density.Generally,the wood properties of the hybrid were superior to its parent species.The significant intraspecific variation observed for wood properties of Acacia species could be used in breeding superior hybrids combining desirable traits of the two species.Considering thedifficulty involved in accurately measuring the lignin content compared to mean stem density,selection for plants with low lignin content can be achieved by indirect selection of high mean stem density.
基金National Natural Science Foundation of China(61976052,61876043)National Key R&D Program of China(2017YFB1002701,2017YFB1201203).
文摘Background In the smoothed particle hydrodynamics(SPH)fluid simulation method,the smoothing length affects not only the process of neighbor search but also the calculation accuracy of the pressure solver.Therefore,it plays a crucial role in ensuring the accuracy and stability of SPH.Methods In this study,an adaptive SPH fluid simulation method with a variable smoothing length is designed.In this method,the smoothing length is adaptively adjusted according to the ratio of the particle density to the weighted average of the density of the neighboring particles.Additionally,a neighbor search scheme and kernel function scheme are designed to solve the asymmetry problems caused by the variable smoothing length.Results The simulation efficiency of the proposed algorithm is comparable to that of some classical methods,and the variance of the number of neighboring particles is reduced.Thus,the visual effect is more similar to the corresponding physical reality.Conclusions The precision of the interpolation calculation performed in the SPH algorithm is improved using the adaptive-smoothing length scheme;thus,the stability of the algorithm is enhanced,and a larger timestep is possible.
基金This research was funded by Yunnan Applied Basic Research Project(2017FB057 and 2017AB001)as well as National Natural Science Foundation of China(31700235 and 31770375).
文摘Exploring approaches to regulate meristem is of special importance and broad interest.In this study,we found that the flavonoid scutellarin,which has a 6-hydroxyl and a 7-glucoside,increased root length through the transcription factor NUTCRACKER(NUC).This root lengthening disappeared in NUCknockout and reappeared in NUC-rescue plants.Scutellarin induced NUC expression and promoted the division of cortex/endodermal initials.In contrast,naringenin,which has same chemical backbone but without 6-hydroxyl and with 7-hydroxyl group,showed the opposite or no effects.Our results demonstrate that scutellarin promotes root length through NUC-mediated regulatory pathways and reveal that flavonoids with and without the 6-hydroxyl and 7-glucoside have positive and negative effects on meristem size,respectively。
基金supported by the Federal Ministry of Food and Agriculture (BMEL)the Federal Ministry for the Environment,Nature Conservation,Nuclear Safety and Consumer Protection (BMUV) through the Fachagentur Nachwachsende Rohstoffe e. V.(FNR)(grant no. 2218 WK53X4)
文摘Increasing evidence suggests that fine roots are particularly sensitive to environmental changes,making them essential in responding and adapting forest ecosystems to climate change.However,we still lack a fundamental understanding of the underlying mechanisms that control fine root plasticity.The objective of this study was to determine the influence of soil moisture changes on fine root dynamics and morphology of European beech(Fagus sylvatica L.).We conducted a 30-month study of fine root traits,i.e.,fine root biomass(FRB),productivity,mortality,turnover,specific root length(SRL),specific root area(SRA),and root tip frequency(RTF),along a soil moisture gradient from dry,intermediate,and wet conditions in a near-natural mature beech forest.Sequential root coring with accompanying soil measurements was carried out at three study sites reflecting the gradient in soil water availability.For most fine root traits,we found significant differences between the upper 10 cm and lower soil depths.FRB showed significant differences between study sites,with the lowest FRB at the dry site.However,productivity,turnover,SRL,SRA,and RTF showed no significant differences between sites,but a high variability between seasons,suggesting an adaptation to short-term fluctuations but not to long-term gradients in soil water content(SWC).Linear mixed models revealed that decreasing SWC led to a significant increase in SRL,SRA,and RTF(standardized coefficients:-1.0±0.46,-1.1±0.46,and-1.1±0.43,respectively).Our observations indicate an adaptation strategy of beech to low availability of soil water and drought by forming thin absorptive roots and by maintaining a high seasonal plasticity to tolerate fluctuations in soil moisture.By highlighting the belowground morphological adaptations of mature forests to low soil water availability,our results provide novel insights into the structure and dynamics of forest ecosystem adaptations to climate change.
基金funded by the National Natural Science Foundation of China(42267024,42041006)the Youth Research Fund Project of Qinghai University,China(2023-QGY-10).
文摘Soil erosion and shallow landslides in the upper reaches of the Yellow River,China,are increasing due to extreme climate events and human disturbances.The biomechanical properties of vegetation roots play an important role in soil stabilization and fixation,as they resist soil erosion and shallow landslides in this area.However,the biomechanical properties of the roots of dominant herbs and their influencing factors in this area remain poorly understood.Therefore,we selected two dominant herbs in this area,Stipa aliena Keng and Poa crymophila Keng,and carried out a series of uniaxial tensile tests on the roots of the two herbs under different treatments.Meanwhile,the effects of root diameter,plant species,gauge length,root water content,and loading rate on the biomechanical properties of the two herbs'roots were analyzed.The results showed that root diameter was the most significant factor affecting the root biomechanical properties(P<0.010),and root tensile force displayed a positive power law relationship with root diameter,whereas root tensile strength and Young's modulus followed negative power law correlations with root diameter,and fracture strain increased linearly with root diameter.Root tensile force,tensile strength,and fracture strain of S.aliena were significantly greater than those of P.crymophila(P<0.001),which was mainly due to the higher lignin content and lignin:cellulose ratio of S.aliena roots.During uniaxial tensile process,hydrated roots exhibited elastic-plastic-brittle behavior,whereas dried roots exhibited elastic-brittle behavior.Root fracture strain of the two herbs was significantly lower under 100 mm gauge length than under 50 mm gauge length(P<0.001),and the Young's modulus was significantly greater(P<0.050).Tensile strength and fracture strain of hydrated roots of the two herbs were significantly greater than those of dried roots(P<0.050),whereas the Young's modulus was significantly lower(P<0.001).Root tensile force,tensile strength,and fracture strain of S.aliena were significantly greater under 20 mm/min loading rate than under 200 mm/min loading rate(P<0.050),whereas loading rate had no significant effect on the root biomechanical properties of P.crymophila(P>0.050).Fibrous roots of the two herbs were well developed,with relatively high tensile strengths and Young's moduli of 78.498 and 837.901 MPa for S.aliena,and 67.541 and 901.184 MPa for P.crymophila,respectively.The two herbs can stabilize soil and prevent soil erosion and can be used as pioneer species for ecological restoration in the upper reaches of the Yellow River.These results provide a theoretical basis for soil erosion and shallow landslide control in the giant landslide area of the upper reaches of the Yellow River.
基金The authors would like to acknowledge financial support from the Joint Funds of the National Nature Science Foundation of China(No.U22A20232)Supported by Open Project Funding of Key Laboratory of Intelligent Health Perception and Ecological Restoration of Rivers and Lakes,Ministry of Education(HGKFZ07)+2 种基金the National Natural Science Foundation of China(No.51978249)Innovation Research Team Project of the Hubei Provincial Department of Science and Technology(JCZRQT202500027)the International Collaborative Research Fund for Young Scholars in the Innovation Demonstration Base of Ecological Environment Geotechnical and Ecological Restoration of Rivers and Lakes.
文摘Plant root systems serve as a natural reinforcing material,significantly improving soil stability.Furthermore,the tensile strength of soil is crucial in mitigating the formation of cracks.Consequently,this study aims to investigate the influence of plant roots on the tensile strength of soil.For this investigation,Amorpha fruticose was selected due to its large root diameter and the ease of root extraction.Indoor tensile tests were conducted on individual roots and root-soil complexes under three varying factors.The results indicate a power law relationship between root diameter and tensile strength.Increased root content and dry density notably enhance the tensile strength of the root-soil complex while roots mitigate damage associated with soil brittleness.When root content increases from 0 to 10,the maximum enhancement in tensile strength of the root-soil complex reaches 42.3 kPa.The tensile strength of the root-soil complex at a dry density of 1.7 g/cm^(3)is four to five times greater than that of the complex at a dry density of 1.4 g/cm^(3).Moreover,as moisture content increases,the tensile strength of the root-soil complex initially rises before declining,with an increase range of 7.7-35.8 kPa.These findings provide a scientific basis for understanding the role of vegetation roots in soil tensile strength and for guiding slope reinforcement strategies.
文摘To study growth responses of the roots of Panicum miliaceum L. to heterogeneous supply of nutrients. The authors analyzed the effects of the nutrient levels in both original patches (O) and destination patches (D) on the root growth of P. miliaceum when its roots were allowed to extend from original patch into destination patch. When the nutrient levels in the original patches were low, coarse root biomass ratio (coarse root biomass in the D/total coarse root biomass), coarse root length ratio (coarse root length in the D/total coarse root length), coarse root surface area ratio (coarse root surface area in the D/total coarse root surface area) and fine root length ratio (fine root length in the D/total fine root length) were greater in the destination patches with lower nutrient levels than in the destination patches with higher nutrient levels, while fine root length, fine root length density, fine root surface index, and fine root surface area density were smaller in the former than in the latter. When the nutrient levels in the original patches were high, fine root length, fine root length density, fine root surface area index and fine root surface density were greater in the destination patches with lower nutrient levels than in the destination patches with higher nutrient levels, coarse roots did not respond to the nutrient levels in the destination patches significantly. When the roots extended from the original patches with the same nutrient level into the destination patches with contrasting nutrient levels, fine root biomass and its percentage allocation did not respond to the nutrient levels in the destination patches significantly, whereas both root length and root surface area did. This indicates that the fine roots of P. miliaceum responded to difference in nutrient supply by plasticity in their length and surface area, rather than in their root biomass.
