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
The relation between soil water content and the growth of cotton root was studied for the scheme of field water and cotton yield under mulched drip irrigation. Based on the field experiments, three treatments of soil ...The relation between soil water content and the growth of cotton root was studied for the scheme of field water and cotton yield under mulched drip irrigation. Based on the field experiments, three treatments of soil water content were conducted with 90%, 75%θf, and 60%θf （θfis field water capacity）. Cotton roots and root-shoot ratio were studied with digging method, and the soil moisture was observed with TDR （time domain reflector）, and cotton yield was measured. The results indicated that the growth of cotton root accorded with Logistic growth curve in the three treatments, the cotton root grew quickly and its weight was very high under 75%θf because of the suitable soil water condition, while grew slowly and its weight was lower under 90%θf due to water moisture beyond the suitable condition, and the root weight was in between under 60%θf For the three water treatments, the cotton root weight decreased with soil depth, and decreased more significantly in deeper soil layer with the soil moisture increasing. And the ratio of cotton root weight in 0-30 cm soil layer to the total root weight was the highest under 75%θf. The cotton root system was distributed mainly in the soil of narrow row and wide row mulched with plastic film, and little in the soil outside plastic film. The weight of cotton root was the highest in the soil of narrow row or wide row mulched with plastic film under 75%θf. Root-shoot ratio decreased with the soil moisture increasing. The soil water content affected cotton yields, and cotton yield was the highest under 75%θf. The higher soil moisture level is unfavorable to the growth of cotton root system and yield of cotton under mulched drip irrigation.展开更多
A solution culture experiment was performed to investigate the effects of oxytetracycline （OTC） on wheat （Triticum aestivum L.） growth, chlorophyll contents, and photosynthesis at five levels of 0, 10, 20, 40, and...A solution culture experiment was performed to investigate the effects of oxytetracycline （OTC） on wheat （Triticum aestivum L.） growth, chlorophyll contents, and photosynthesis at five levels of 0, 10, 20, 40, and 80 mmol L-1 OTC. OTC is toxic to wheat. The wheat growth, especially wheat root was significantly decreased. Further OTC also significantly decreased root activity, chlorophyll contents, and photosynthetic parameters except for intercellular CO2 concentrations. The different responses of indicators such as root number, root activity and so on to OTC were also observed. The IC50 values for the tested indicators to OTC ranged from 7.1 to 113.4 mmol L-1 OTC. The order of indicator sensitivity to OTC was root number stomatal conductance chlorophyll a total chlorophyll photosynthetic rates total surface area transpiration rate chlorophyll b fresh weight of root dry weight of root total length dry weight of shoot = fresh weight of shoot total volume. The root number was more sensitive than other indicators with the IC50 value of 7.1 mmol L-1 OTC, and could be taken as the sensitive indicator to predict the hazards of OTC to wheat.展开更多
Some common staple roots and tubers (cassava, yam, sweet potato and yellow yam) were analyzed for selenium content level using hydride generation—atomic absorption spectrophotometry (HG-ASS) technique. Results for du...Some common staple roots and tubers (cassava, yam, sweet potato and yellow yam) were analyzed for selenium content level using hydride generation—atomic absorption spectrophotometry (HG-ASS) technique. Results for duplicate analysis revealed that sweet potato has the highest mean selenium content (19.2 ± 5.20 μg/kg), followed by yellow yam (18.3 ± 6.97 μg/kg), then yam (13.6 ± 7.12 μg/kg) and cassava the least (13.0 ± 5.84 μg/kg). In comparing our results with the literature values, most of the results obtained in this work such as <1.00, 1.09, 1.91, 2.35 and 11.0 μg/kg were lower while a few others like 52.6, 54.2, 72.3 and 81.8 μg/kg were higher than literature values. The variations could be due to the type of species/variety, geographical location, total selenium concentration in the soil and its bioavailability. In view of the importance of Se to human health and considering the levels found in the staples investigated, we recommend that sweet potato be popularized as a staple, much more than cassava as it is now the case in Central Nigeria.展开更多
[Objectives] To optimize the extraction process of total flavonoids from Sanguisorbae Radix and carbonized Sanguisorba root,compare quality of different batches of Sanguisorbae Radix,study the effects of processing on...[Objectives] To optimize the extraction process of total flavonoids from Sanguisorbae Radix and carbonized Sanguisorba root,compare quality of different batches of Sanguisorbae Radix,study the effects of processing on the content of flavonoids,and provide scientific basis for reasonable utilization of Sanguisorbae Radix. [Methods] Test samples were prepared by heating,refluxing,and extraction,the extraction process was optimized by orthogonal experiment design,color was developed by NaNO_2-Al( NO_3)3-NaOH,and total flavonoids were measured by UV method at the wavelength of 510 nm. [Results] The linear relationship of rutin was excellent in the concentration range of 0. 1248 mg/mL-0. 5712 mg/mL,R^2= 0. 9997; the average recovery was 99. 67% and the RSD was 0. 70%. The optimum extraction conditions were as follows: the volume fraction of ethanol was 50%,the extraction temperature was 90℃,the extraction time was 90 min,and the solid-to-liquid ratio was 1∶ 20( g/mL). [Conclusions] After optimization of the extraction process,the extraction rate of total flavonoids in samples of Sanguisorbae Radix was significantly increased; there was certain difference in the content of total flavonoids between different batches of Sanguisorbae Radix and processed products; the total flavonoids significantly declines in carbonized sanguisorba root,and the influence of processing on its curative effect was to be further studied.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
Root distribution of three desert shrubs,Tamarix ramosissima Ledeb.,Haloxylon ammodendron(C.A.Mey.) Bunge and Reaumuria soongorica(Pall.) Maxim.was investigated under co-occurring conditions using a method for excavat...Root distribution of three desert shrubs,Tamarix ramosissima Ledeb.,Haloxylon ammodendron(C.A.Mey.) Bunge and Reaumuria soongorica(Pall.) Maxim.was investigated under co-occurring conditions using a method for excavating the whole root system.Assimilation shoot water potential and transpiration rates were monitored during the wet-dry cycle.Leaf-specific apparent hydraulic conductance and the index of water stress impact for the three species were calculated from shoot water potential and transpiration rate.The results showed that,along the soil profile,the root system of T.ramosissima mainly distributed at 50 to 310 cm interval,with an average total absorbing root-surface area of 30,249.2 cm2 per plant;the root system of H.ammodendraom distributed at 0 to 250 cm interval with an average total absorbing root-surface area of 12,847.3 cm2 per plant;the root system of R.soongorica distributed at 0-80 cm interval,with an average total absorbing root-surface area of 361.8 cm2.The root distribution shows the following:T.ramosissima uses groundwater as its main water source;H.ammodendraom uses both groundwater and rainwater;and R.soongorica uses rainwater only.During the wet-dry cycle,the hydraulic parameters of T.ramosissima showed no responses to precipitation.R.soongorica responded most significantly,and the responses of H.ammodendraom were intermediate.In conclusion,the plant response to rain events is closely related to their root distribution and plant water-use strategy.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
Recent climate changes, including an increase in precipitation, have affected tree physiology in eastern Siberia. We investigated the response of larch to wet and dry soil water conditions in pot experiments using lar...Recent climate changes, including an increase in precipitation, have affected tree physiology in eastern Siberia. We investigated the response of larch to wet and dry soil water conditions in pot experiments using larch seedlings grown under near-natural conditions in eastern Siberia over two growing seasons. Three patterns of wet- and dry-treatment combinations were applied over 2 years: wet treatments in 2006 and 2007 (WW treatment), dry in 2006 and wet in 2007 (DW treatment), and dry in 2006 and 2007 (DD treatment). After 1 year of treatment, no significant difference between the dry and wet treatment was found in root distribution and needle water content, except for the content of abscisic acid in roots. After 2 years of treatment, the DW treatment induced different tendencies in the gas exchange activity and in the needle biomass and root distribution of seedlings in comparison with WW treatments, despite the same water condition in 2007. We suggest a possibility that seedlings that experience drought stress might store some memory of drought that influences their physiology in the next growing season.展开更多
Soil moisture availability to plant roots is very important for crop growth. When soil moisture is not available in the root zone, plants wilt and yield is reduced. Adequate knowledge of the distribution of soil moist...Soil moisture availability to plant roots is very important for crop growth. When soil moisture is not available in the root zone, plants wilt and yield is reduced. Adequate knowledge of the distribution of soil moisture within crop’s root zone and its linkage to the amount of water applied is very important as it assists in optimising the efficient use of water and reducing yield losses. The study aimed at evaluating the spatial redistribution of soil moisture within maize roots zone under different irrigation water application regimes. The study was conducted during two irrigatation seasons of 2012 at Nkango Irrigation Scheme, Malawi. The trials consisted of factorial arrangement in a Randomised Complete Block Design (RCBD). The factors were water and nitrogen and both were at four levels. The Triscan Sensor was used to measure volumetric soil moisture contents at different vertical and lateral points. The study inferred that the degree of soil moisture loss depends on the amount of water present in the soil. The rate of soil moisture loss in 100% of full water requirement regime (100% FWRR) treatment was higher than that in 40% FWRR treatment. This was particularly noticed when maize leaves were dry. In 100% FWRR treatment, the attraction between water and the surfaces of soil particles was not tight and as such “free” water was lost through evaporation and deep percolation, while in 40% FWRR, water was strongly attracted to and held on the soil particles surfaces and as such its potential of losing water was reduced.展开更多
Idaho locust （Robinia pseudoacacia ‘Idaho＇） is an exotic multi-purpose tree used in landscaping, soil and water conserva- tion, fodder sources and others. To improve its drought tolerance for reclaiming arid land,...Idaho locust （Robinia pseudoacacia ‘Idaho＇） is an exotic multi-purpose tree used in landscaping, soil and water conserva- tion, fodder sources and others. To improve its drought tolerance for reclaiming arid land, five lines of transformed mtl-D gene, as osmotic regulator in plant cells, have been selected and managed to determine their drought tolerance under experimental conditions. Qualitative and quantitative variables of transformed plants were studied. The critical value of drought tolerance was determined by detecting the 2,3,5-triphenyl tetrazolium chloride （TTC） reductants in roots and soil water content （SWC）. The critical value for drought tolerance was SWC 6% while for the control plants the critical SWC was 8%; a moderate level of SWC is 13% and the highest SWC for plant endurance was 18%. The method proved to be reliable and sensitive in the evaluation of drought tolerance for forest trees.展开更多
草地作为我国陆地生态系统重要的碳库,对我国气候调节和实现碳达峰碳中和具有重要意义。综合以往草地植被碳储量估算的相关文献,本文综述了草地植被碳储量代表性估算方法,并分析了不同估算结果的差异性来源。结果表明:自21世纪以来我国...草地作为我国陆地生态系统重要的碳库,对我国气候调节和实现碳达峰碳中和具有重要意义。综合以往草地植被碳储量估算的相关文献,本文综述了草地植被碳储量代表性估算方法,并分析了不同估算结果的差异性来源。结果表明:自21世纪以来我国草地植被碳储量的估算值之间差异较大,碳储量的估算结果介于0.56~4.66 Pg,均值为2.22 Pg,碳密度估算结果介于216~1148 g C·m^(-2),均值为654.23 g C·m^(-2);草地植被枯落物碳储量占比介于0.1%~8.6%,均值为5.6%,枯落物的忽略会导致碳储量估算总量偏低;采用全球单位碳密度估算方法同其他估算方法之间存在显著性差异(P<0.05);草地植被地上部、地下部和枯落物的含碳率分别为39.3%、36.6%和30.7%,植被地上部含碳率与枯落物含碳率之间呈显著性差异(P<0.05),采用较为普遍的碳转换系数45%会导致草地植被碳储量估算总量偏大;不同草地类型根茎比差异较大,介于0.76~41.80,均值为9.16。综上,草地植被碳储量的估算方法、数据源、重要参数的不同,导致了草地植被碳储量估算总量之间的差异。展开更多
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.
基金supported by the National Natural Science Foundation of China (50569004)
文摘The relation between soil water content and the growth of cotton root was studied for the scheme of field water and cotton yield under mulched drip irrigation. Based on the field experiments, three treatments of soil water content were conducted with 90%, 75%θf, and 60%θf （θfis field water capacity）. Cotton roots and root-shoot ratio were studied with digging method, and the soil moisture was observed with TDR （time domain reflector）, and cotton yield was measured. The results indicated that the growth of cotton root accorded with Logistic growth curve in the three treatments, the cotton root grew quickly and its weight was very high under 75%θf because of the suitable soil water condition, while grew slowly and its weight was lower under 90%θf due to water moisture beyond the suitable condition, and the root weight was in between under 60%θf For the three water treatments, the cotton root weight decreased with soil depth, and decreased more significantly in deeper soil layer with the soil moisture increasing. And the ratio of cotton root weight in 0-30 cm soil layer to the total root weight was the highest under 75%θf. The cotton root system was distributed mainly in the soil of narrow row and wide row mulched with plastic film, and little in the soil outside plastic film. The weight of cotton root was the highest in the soil of narrow row or wide row mulched with plastic film under 75%θf. Root-shoot ratio decreased with the soil moisture increasing. The soil water content affected cotton yields, and cotton yield was the highest under 75%θf. The higher soil moisture level is unfavorable to the growth of cotton root system and yield of cotton under mulched drip irrigation.
基金supported by the National Natural Science Foundation of China (40701163)the Natural Science Foundation of Beijing City, China (6092019)+1 种基金the International Foundation for Science, Stockholm, Sweden, the Organization for the Prohibition of Chemical Weapons, the Hague, and the Netherlands, through a grant to Li Zhaojun (C/4076)the National Basic Research Program of China (973 Program, 2007CB109305)
文摘A solution culture experiment was performed to investigate the effects of oxytetracycline （OTC） on wheat （Triticum aestivum L.） growth, chlorophyll contents, and photosynthesis at five levels of 0, 10, 20, 40, and 80 mmol L-1 OTC. OTC is toxic to wheat. The wheat growth, especially wheat root was significantly decreased. Further OTC also significantly decreased root activity, chlorophyll contents, and photosynthetic parameters except for intercellular CO2 concentrations. The different responses of indicators such as root number, root activity and so on to OTC were also observed. The IC50 values for the tested indicators to OTC ranged from 7.1 to 113.4 mmol L-1 OTC. The order of indicator sensitivity to OTC was root number stomatal conductance chlorophyll a total chlorophyll photosynthetic rates total surface area transpiration rate chlorophyll b fresh weight of root dry weight of root total length dry weight of shoot = fresh weight of shoot total volume. The root number was more sensitive than other indicators with the IC50 value of 7.1 mmol L-1 OTC, and could be taken as the sensitive indicator to predict the hazards of OTC to wheat.
文摘Some common staple roots and tubers (cassava, yam, sweet potato and yellow yam) were analyzed for selenium content level using hydride generation—atomic absorption spectrophotometry (HG-ASS) technique. Results for duplicate analysis revealed that sweet potato has the highest mean selenium content (19.2 ± 5.20 μg/kg), followed by yellow yam (18.3 ± 6.97 μg/kg), then yam (13.6 ± 7.12 μg/kg) and cassava the least (13.0 ± 5.84 μg/kg). In comparing our results with the literature values, most of the results obtained in this work such as <1.00, 1.09, 1.91, 2.35 and 11.0 μg/kg were lower while a few others like 52.6, 54.2, 72.3 and 81.8 μg/kg were higher than literature values. The variations could be due to the type of species/variety, geographical location, total selenium concentration in the soil and its bioavailability. In view of the importance of Se to human health and considering the levels found in the staples investigated, we recommend that sweet potato be popularized as a staple, much more than cassava as it is now the case in Central Nigeria.
基金Supported by National Science and Technology Project of the Ministry of Science and Technology in the 13th Five-Year Plan Period(2015BAC05B02)Key Technology R&D Program of Sichuan Province,China(2015SZ0034)Innovating Research Program of Postgraduates of Southwest Minzu University in2016(CX2016SZ038)
文摘[Objectives] To optimize the extraction process of total flavonoids from Sanguisorbae Radix and carbonized Sanguisorba root,compare quality of different batches of Sanguisorbae Radix,study the effects of processing on the content of flavonoids,and provide scientific basis for reasonable utilization of Sanguisorbae Radix. [Methods] Test samples were prepared by heating,refluxing,and extraction,the extraction process was optimized by orthogonal experiment design,color was developed by NaNO_2-Al( NO_3)3-NaOH,and total flavonoids were measured by UV method at the wavelength of 510 nm. [Results] The linear relationship of rutin was excellent in the concentration range of 0. 1248 mg/mL-0. 5712 mg/mL,R^2= 0. 9997; the average recovery was 99. 67% and the RSD was 0. 70%. The optimum extraction conditions were as follows: the volume fraction of ethanol was 50%,the extraction temperature was 90℃,the extraction time was 90 min,and the solid-to-liquid ratio was 1∶ 20( g/mL). [Conclusions] After optimization of the extraction process,the extraction rate of total flavonoids in samples of Sanguisorbae Radix was significantly increased; there was certain difference in the content of total flavonoids between different batches of Sanguisorbae Radix and processed products; the total flavonoids significantly declines in carbonized sanguisorba root,and the influence of processing on its curative effect was to be further studied.
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supported by National Natural Science Foundation of China (Grant No. 40725002)
文摘Root distribution of three desert shrubs,Tamarix ramosissima Ledeb.,Haloxylon ammodendron(C.A.Mey.) Bunge and Reaumuria soongorica(Pall.) Maxim.was investigated under co-occurring conditions using a method for excavating the whole root system.Assimilation shoot water potential and transpiration rates were monitored during the wet-dry cycle.Leaf-specific apparent hydraulic conductance and the index of water stress impact for the three species were calculated from shoot water potential and transpiration rate.The results showed that,along the soil profile,the root system of T.ramosissima mainly distributed at 50 to 310 cm interval,with an average total absorbing root-surface area of 30,249.2 cm2 per plant;the root system of H.ammodendraom distributed at 0 to 250 cm interval with an average total absorbing root-surface area of 12,847.3 cm2 per plant;the root system of R.soongorica distributed at 0-80 cm interval,with an average total absorbing root-surface area of 361.8 cm2.The root distribution shows the following:T.ramosissima uses groundwater as its main water source;H.ammodendraom uses both groundwater and rainwater;and R.soongorica uses rainwater only.During the wet-dry cycle,the hydraulic parameters of T.ramosissima showed no responses to precipitation.R.soongorica responded most significantly,and the responses of H.ammodendraom were intermediate.In conclusion,the plant response to rain events is closely related to their root distribution and plant water-use strategy.
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Recent climate changes, including an increase in precipitation, have affected tree physiology in eastern Siberia. We investigated the response of larch to wet and dry soil water conditions in pot experiments using larch seedlings grown under near-natural conditions in eastern Siberia over two growing seasons. Three patterns of wet- and dry-treatment combinations were applied over 2 years: wet treatments in 2006 and 2007 (WW treatment), dry in 2006 and wet in 2007 (DW treatment), and dry in 2006 and 2007 (DD treatment). After 1 year of treatment, no significant difference between the dry and wet treatment was found in root distribution and needle water content, except for the content of abscisic acid in roots. After 2 years of treatment, the DW treatment induced different tendencies in the gas exchange activity and in the needle biomass and root distribution of seedlings in comparison with WW treatments, despite the same water condition in 2007. We suggest a possibility that seedlings that experience drought stress might store some memory of drought that influences their physiology in the next growing season.
文摘Soil moisture availability to plant roots is very important for crop growth. When soil moisture is not available in the root zone, plants wilt and yield is reduced. Adequate knowledge of the distribution of soil moisture within crop’s root zone and its linkage to the amount of water applied is very important as it assists in optimising the efficient use of water and reducing yield losses. The study aimed at evaluating the spatial redistribution of soil moisture within maize roots zone under different irrigation water application regimes. The study was conducted during two irrigatation seasons of 2012 at Nkango Irrigation Scheme, Malawi. The trials consisted of factorial arrangement in a Randomised Complete Block Design (RCBD). The factors were water and nitrogen and both were at four levels. The Triscan Sensor was used to measure volumetric soil moisture contents at different vertical and lateral points. The study inferred that the degree of soil moisture loss depends on the amount of water present in the soil. The rate of soil moisture loss in 100% of full water requirement regime (100% FWRR) treatment was higher than that in 40% FWRR treatment. This was particularly noticed when maize leaves were dry. In 100% FWRR treatment, the attraction between water and the surfaces of soil particles was not tight and as such “free” water was lost through evaporation and deep percolation, while in 40% FWRR, water was strongly attracted to and held on the soil particles surfaces and as such its potential of losing water was reduced.
文摘Idaho locust （Robinia pseudoacacia ‘Idaho＇） is an exotic multi-purpose tree used in landscaping, soil and water conserva- tion, fodder sources and others. To improve its drought tolerance for reclaiming arid land, five lines of transformed mtl-D gene, as osmotic regulator in plant cells, have been selected and managed to determine their drought tolerance under experimental conditions. Qualitative and quantitative variables of transformed plants were studied. The critical value of drought tolerance was determined by detecting the 2,3,5-triphenyl tetrazolium chloride （TTC） reductants in roots and soil water content （SWC）. The critical value for drought tolerance was SWC 6% while for the control plants the critical SWC was 8%; a moderate level of SWC is 13% and the highest SWC for plant endurance was 18%. The method proved to be reliable and sensitive in the evaluation of drought tolerance for forest trees.
文摘草地作为我国陆地生态系统重要的碳库,对我国气候调节和实现碳达峰碳中和具有重要意义。综合以往草地植被碳储量估算的相关文献,本文综述了草地植被碳储量代表性估算方法,并分析了不同估算结果的差异性来源。结果表明:自21世纪以来我国草地植被碳储量的估算值之间差异较大,碳储量的估算结果介于0.56~4.66 Pg,均值为2.22 Pg,碳密度估算结果介于216~1148 g C·m^(-2),均值为654.23 g C·m^(-2);草地植被枯落物碳储量占比介于0.1%~8.6%,均值为5.6%,枯落物的忽略会导致碳储量估算总量偏低;采用全球单位碳密度估算方法同其他估算方法之间存在显著性差异(P<0.05);草地植被地上部、地下部和枯落物的含碳率分别为39.3%、36.6%和30.7%,植被地上部含碳率与枯落物含碳率之间呈显著性差异(P<0.05),采用较为普遍的碳转换系数45%会导致草地植被碳储量估算总量偏大;不同草地类型根茎比差异较大,介于0.76~41.80,均值为9.16。综上,草地植被碳储量的估算方法、数据源、重要参数的不同,导致了草地植被碳储量估算总量之间的差异。
