Differences in transpiration and leaf water potential (LWP) in relation to cassava yield were investigated along inland valley toposequence in a 4×4 Latin square design. The landrace with the highest transpirat...Differences in transpiration and leaf water potential (LWP) in relation to cassava yield were investigated along inland valley toposequence in a 4×4 Latin square design. The landrace with the highest transpiration rate and lowest LWP yielded the lowest, while TMS 91/02324 and TMS 91/02327 with intermediate rate and highest LWP yielded the highest, indicating that high transpiration rate associated with low LWP reduced yield. Transpiration was lower in the fringe with deeper water table than valley bottom at deep water table site, while at shallow water table, it was higher in the fringe than valley bottom, suggesting that drought and excess moisture reduced transpiration. LWP and water table depth correlated negatively indicating that shallow water table reduced transpiration by reducing LWP. Transpiration increased and LWP decreased as radiation, leaf temperature and vapour pressure deficit increased and differences in these microclimatic conditions caused differences in the two processes between sites, years and time of day. Under mild water stress, transpiration and LWP were higher in the afternoon than the morning, but the reverse occurred under severe stress. TMS 91/02324 and TMS 91/02327 had the highest LWP under severe stress, indicating their higher drought tolerance than the other cultivars.展开更多
The water deficit in arid and semi-arid regions is the primary limiting factor for the development of urban greenery and forestation. In addition, planting the species that consume low levels of water is useful in ari...The water deficit in arid and semi-arid regions is the primary limiting factor for the development of urban greenery and forestation. In addition, planting the species that consume low levels of water is useful in arid and semi-arid regions that have poor water management measures. Leaf water potential(Ψ) is a physiological parameter that can be used to identify drought resistance in various species. Indeed, Ψ is one of the most important properties of a plant that can be measured using a pressure chamber. Drought avoiding or drought resistant species have a lower Ψ than plants that use normal or high levels of water. To determine drought resistance of species that are suitable for afforestation in arid urban regions, we evaluated twenty woody species in the Isfahan City, central Iran. The experimental design was random split-split plots with five replications. The species were planted outdoor in plastic pots and then subjected to treatments that consisted of two soil types and five drip irrigation regimes. To evaluate the resistance of each species to drought, we used the Ψ and the number of survived plants to obtain the drought resistance index(DRI). Then, cluster analysis, dendrogram, and similarity index were used to group the species using DRI. Result indicates that the evaluated species were classified into five groups:(1) high water consuming species(DRI>–60 MPa);(2) above normal water consuming species(–60 MPa≥DRI>–90 MPa);(3) normal water consuming species(–90 MPa≥DRI>–120 MPa);(4) semi-drought resistant species(–120 MPa≥DRI>–150 MPa);and(5) drought resistant species(DRI≤–150 MPa). According to the DRI, Salix babylonica L., Populus alba L., and P. nigra L. are high water consuming species, Platanus orientalis L. and Albizia julibrissin Benth are normal water consuming species, and Quercus infectoria Oliv. and Olea europaea L. can be considered as drought resistant species.展开更多
A greenhouse experlment was performed In order to Investigate the effects of dlfferent levels of water stress on leaf water potentlal (ψw), stomatal resistance (rs), protein content and chlorophyll (Chl) conten...A greenhouse experlment was performed In order to Investigate the effects of dlfferent levels of water stress on leaf water potentlal (ψw), stomatal resistance (rs), protein content and chlorophyll (Chl) content of tomato plants (Lycoperslcon esculentum Mill. cv. Nlkita). Water stress was Induced by addlng polyethylene glycol (PEG 6 000) to the nutrlent solution to reduce the osmotlc potential (ψs). We Investlgated the behavlor of antl-oxldant enzymes, such as catalase (CAT) and superoxide dlsmutase (SOD), durlng the development of water stress. Moderate and severe water stress (i.e. ψs= -0.51 and -1.22 MPa, respectlvely) caused a decrease In ψw for all treated (water-stressed) plants compared with control plants, wlth the reductlon belng more pronounced for severely stressed plants. In addltion, rs was slgnlflcantly affected by the Induced water stress and a decrease in leaf soluble protelns and Chl content was observed. Whereas CAT actlvlty remained constant, SOD actlvlty was increased in water-stressed plants compared wlth unstressed plants. These results Indicate the possible role of SOD as an anti-oxidant protector system for plants under water stress condltlons. Moreover, It suggests the possibllity of using this enzyme as an addltional screening crlterlon for detecting water stress in plants.展开更多
Hydraulic resistance components and water relations were studied on Haloxyolon ammoden-dron,a small xeric tree,growing at sites significantly differed in soil texture.Soil water content,leaf water potential(ψl),xylem...Hydraulic resistance components and water relations were studied on Haloxyolon ammoden-dron,a small xeric tree,growing at sites significantly differed in soil texture.Soil water content,leaf water potential(ψl),xylem water potential(ψx),root water potential(ψroot),leaf transpiration rate(TR) and stomatal conductance(gs) were measured at the two sites during the growing season of 2005 and 2006.Leaf spe-cific hydraulic resistance(Rplant) during the whole growing season,hydraulic resistance of plants(Rp),shoots(Rshoot) and roots(Rroot) in the August of both years were calculated and expressed on leaf area basis.The results showed the proportion of the hydraulic resistance of the aerial part(Rshoot) to the Rp was the same to the proportion of the hydraulic resistance of the soil part(Rroot) to the Rp,indicating that both parts were equivalent important to plant water hydraulic system from soil to leaf.Positive significant corre-lations were found between Rp and Rroot,suggesting that root hydraulics resistance was a major determinant of plant hydraulic resistance(Rp) and transpiration rate.The integrated effect of stomatal control,hy-draulic regulation and morphology adjustment enabled plants at heavy soil site surviving the extreme water deficit period.展开更多
[Objective] The aim was to explore the effects of water stress on leaf water and chlorophyll fluorescence parameters of sugarcane seedling,as well as to provide basis for the study on sugarcane production and evaluati...[Objective] The aim was to explore the effects of water stress on leaf water and chlorophyll fluorescence parameters of sugarcane seedling,as well as to provide basis for the study on sugarcane production and evaluation. [Method] Seven different sugarcane varieties were studied at the seedling stage under drought stress,and the changes of leaf water and chlorophyll fluorescence parameters under stress conditions were detected. [Result] leaf water potential,leaf relative water content and soil relative water content showed a certain amount of internal relationship,the sugarcane varieties that had more tolerant to drought had higher utilization rate of soil water; the correlation analysis and factor analysis suggested that the survival rate at seedling stage under drought stress,Fv/Fm,leaf water potential and relative water content could be used as drought resistance evaluation indicators. [Conclusion] As a relatively independent influencing factor,water potential had dominating effect on drought resistance,and the reliability of Fv/Fm as drought resistance evaluation indicator had been verified.展开更多
This paper focused on the water relations of two halophytes differing in photosynthetic pathway, phe- notype, and life cycle: Karelinia caspica (Pall.) Less. (C3, deep-rooted perennial Asteraceae grass) and Atrip...This paper focused on the water relations of two halophytes differing in photosynthetic pathway, phe- notype, and life cycle: Karelinia caspica (Pall.) Less. (C3, deep-rooted perennial Asteraceae grass) and Atriplex tatarica L. (C4, shallow-rooted annual Chenopodiaceae grass). Gas exchange, leaf water potential, and growth characteristics were investigated in two growing seasons in an arid area of Xinjiang to explore the physiological adaptability of the two halophytes. Both K. caspica and A. tatarica showed midday depression of transpiration, in- dicating that they were strong xerophytes and weak midday depression types. The roots of A. tatarica were con- centrated mainly in the 0-60 cm soil layer, and the leaf water potential (~L) increased sharply in the 0-20 cm layer due to high soil water content, suggesting that the upper soil was the main water source. On the other hand, K. caspica had a rooting depth of about 1.5 m and a larger root/shoot ratio, which confirmed that this species uptakes water mainly from deeper soil layer. Although A. tatarica had lower transpiration water consumption, higher water use efficiency (WUE), and less water demand at the same leaf water potential, it showed larger water stress impact than K. caspica, indicating that the growth of A. tatarica was restricted more than that of K. caspica when there was no rainfall recharge. As a shallow-rooted C4 species, A. tatarica displayed lower stomatal conductance, which could to some extent reduce transpiration water loss and maintain leaf water potential steadily. In contrast, the deep-rooted C3 species K. caspica had a larger root/shoot ratio that was in favor of exploiting groundwater. We concluded that C3 species (K. caspica) tapes water and C4 species (A. tatarica) reduces water loss to survive in the arid and saline conditions. The results provided a case for the phenotype theory of Schwinning and Ehleringer on halophytic plants.展开更多
Photosynthetic capacity for heritage (Taewa) and modern potato cultivars were compared at different water and nitrogenregimes in the glasshouse and field. The glasshouse was 2*2*4 factorial design with two irrigation:...Photosynthetic capacity for heritage (Taewa) and modern potato cultivars were compared at different water and nitrogenregimes in the glasshouse and field. The glasshouse was 2*2*4 factorial design with two irrigation: 100% ET and 60% ET;two applied N: 50 kg N ha-1 and 200 kg N ha-1, two Taewa (Moe Moe, Tutaekuri) and two modern potatoes (Moonlight, Agria). The 2009/2010 field experiment was a split-plot, with irrigation and rain-fed regimes as the main treatments: four potatoes above were sub-treatments. The 2010/2011 field experiment was a split-split-plot, with three water regimes as the main treatments: three cultivars (Moe Moe, Tutaekuri, and Agria) were subplots;two N rates were sub-sub-treatments. Gaseous exchange was measured by CIRAS-2 at different days from emergence. Leaf water potential was measured using pressure chamber method. Taewa achieved high photosynthetic WUE in glasshouse and 2010/2011 experiment by maintaining high An, low gs and low Ci compared to modern cultivars (p The An, gs and T increased with irrigation and N increase while decreasing Ci (p < 0.01). Water stress significantly increased VPD resulting in low An and photosynthetic WUE in Moonlight in the glasshouse. The leaf water potential for Taewa was very tolerant while modern potatoes were weakened by water stress. The study indicated that Taewa can be scheduled at partial irrigation without more detrimental effects on photosynthetic capacity while modern potatoes need full irrigation to avoid detrimental effects on photosynthetic capacity.展开更多
We performed corrosion case study and corrosion tests to assess the corrosion resistance of stainless steel type 304 pipes in tap water and hot water facilities. Circulating test equipment used for corrosion tests and...We performed corrosion case study and corrosion tests to assess the corrosion resistance of stainless steel type 304 pipes in tap water and hot water facilities. Circulating test equipment used for corrosion tests and two types of sample, plates and straight pipe specimens, were examined under different conditions of residual chlorine concentration in the test water. The results of case study analysis indicated that high degrees of pitting corrosion occurred on straight pipes with inner diameter < 50 mm. The results of corrosion tests showed that the residual chlorine concentration around the pitting corrosion of stainless steel type 304 was greater than 0.3 mg/L in the plate, regardless of the remaining chlorine concentration in the straight pipe specimens. These results suggest that straight pipes have higher corrosion susceptibility because of bending during production.展开更多
Structural failure of buried cast/ductile iron water mains and tanks due to corrosion attacks manifests in leaks and is common in most cities throughout Nigeria. The appropriate corrective action, which aims to restor...Structural failure of buried cast/ductile iron water mains and tanks due to corrosion attacks manifests in leaks and is common in most cities throughout Nigeria. The appropriate corrective action, which aims to restore pipe/tank integrity is usually based on proper understanding of the degree of corrosiveness of the soil. In an attempt to determine the potential corrosiveness of the soil to buried metallic structures in Bayelsa State, surface geoelectrical sounding was carried out. Twenty-five Schlumberger Vertical Electrical Soundings (VES) was carried out in the freshwater and meander belt geomorphic zone and the salt water mangrove swamp and estuary complex of the state using a maximum current electrode separation ranging from 200 - 400 m. The data obtained was interpreted by computer iterative modeling using a 1D inversion technique software (1X1D, Interpex, USA). The results show a high degree of heterogeneity, both laterally and vertically, which is typical of a complex depositional environment. Generally, the sub-soil condition within the expected depth of installation of water mains and storage tanks (0 - 10 m) is slightly or moderately aggressive (effective aggressivity) in the freshwater and meander belt geomorphic zone but is very strongly aggressive in the salt water mangrove swamp and estuary complex. Corrosion cells which may lead to significant corrosion failures may occur in the vicinities of strongly aggressive stations. This poses a significant corrosion risk to metallic water pipes and storage tanks. Current day design should therefore either mandate the use of a non-metallic piping product (water mains) or cathodic protection system. Prediction of potential corrosiveness of a soil and thus the application of proper corrosion control measures will not only protect the environment from spillages but will also avert cost of repair, clean-up and replacement.展开更多
The water resources of rivers and reservoirs with a five-meter drop are used to discuss the technical theory and the cost and practical value of equipment cases.The high-quality development technology of water resourc...The water resources of rivers and reservoirs with a five-meter drop are used to discuss the technical theory and the cost and practical value of equipment cases.The high-quality development technology of water resources explored in this paper provides a feasible plan for achieving the goal of innovation to zero.展开更多
Carex planostachys Kunze (Cyperaceae, Cedar sedge) is an herbaceous species in a genus commonly inhabiting mesic or hydric habitats. Carex planostachys is found in arid and semi-arid Juniperus woodlands. Arid conditio...Carex planostachys Kunze (Cyperaceae, Cedar sedge) is an herbaceous species in a genus commonly inhabiting mesic or hydric habitats. Carex planostachys is found in arid and semi-arid Juniperus woodlands. Arid conditions impose survival challenges to plants in dry areas. Some plants have plasticity responses to soil water content and continued normal though reduced functions through droughts, but most herbaceous plants do not survive. Limited previous studies have suggested C. planostachys is tolerant of drought. Physiological responses of C. planostachys from Juniperus woodlands was examined is this study to determine how long plants could survive without water and if they are capable of recovery from very negative water potentials beyond what is considered the permanent wilting point for most herbaceous plants. Plants were placed in pots in partial shade in this experiment. Water loss from the soil with plants was an inverse 2nd order polynomial function with soil water decreasing from 32% to 8% by day 28 of the study. Leaf water potential was also an inverse 2nd order polynomial function but did not decline significantly until 14 days without watering. Leaf water potential was −10.0 MPa after 35 days without watering. Non-watered plants Anet, (photosynthetic rate) was significantly lower compared to the water treatment by day 21 as was stomatal conductance and transpiration. When non-watered plants were watered after 21, 28 or 35 days, full recovery of physiological responses occurred within 7 days. The length of time that C. planostachys was able to withstand drought was greater than the annual trends in lack of precipitation during springtime in this area. Carex planostachys can photosynthesize at water stress between −8 and −10 MPa. Carex planostachys drought and shade tolerance enables it to occupy an understory niche devoid of other herbaceous plants.展开更多
To know the annual water consumption of forest, it is necessary to acquire the annual transpiration value of stands. This paper is based on the data measured in the typical weather of the growth season, from 1998 to 2...To know the annual water consumption of forest, it is necessary to acquire the annual transpiration value of stands. This paper is based on the data measured in the typical weather of the growth season, from 1998 to 2000, with the LI 1600 Steady Porometer and the general weather information. The daily variation of transpiration in black locust forest ( Robinia pesudoacacia L.) is modeled by Penman Monteith equation. As a result of the model, a continuous daily transpiration in the growth season was calculated. The net radiation, intercepted by black locust forest canopy, was acquired from a semi empirical equation of measuring net radiation R n with the extinction coefficient k and leaf area index LAI . The canopy integral stomatic resistance is a mimesis with an empirical equation of measuring data. Compared with measuring data, the relative error of the modeled ones is less than 12% averagely. At last, the total transpiration of black locust forest during the period of 1998 and 2000 in the growth season of May to October, as an average transpiration of the different density stands, were 192 46, 187 07 and 195 59?mm respectively.展开更多
Water transfer is becoming a popular method for solving the problems of water quality deterioration and water level drawdown in lakes. However, the principle of choosing water sources for water transfer projects has m...Water transfer is becoming a popular method for solving the problems of water quality deterioration and water level drawdown in lakes. However, the principle of choosing water sources for water transfer projects has mainly been based on the effects on water quality, which neglects the influence in the variation of phytoplankton community and the risk of algal blooms. In this study, algal growth potential(AGP) test was applied to predict changes in the phytoplankton community caused by water transfer projects. The feasibility of proposed water transfer sources(Baqing River and Jinsha River) was assessed through the changes in both water quality and phytoplankton community in Chenghai Lake, Southwest China. The results showed that the concentration of total nitrogen(TN) and total phosphorus(TP) in Chenghai Lake could be decreased to 0.52 mg/L and 0.02 mg/L respectively with the simulated water transfer source of Jinsha River. The algal cell density could be reduced by 60%, and the phytoplankton community would become relatively stable with the Jinsha River water transfer project, and the dominant species of Anabaena cylindrica evolved into Anabaenopsis arnoldii due to the species competition. However, the risk of algal blooms would be increased after the Baqing River water transfer project even with the improved water quality. Algae gained faster proliferation with the same dominant species in water transfer source. Therefore, water transfer projects should be assessed from not only the variation of water quality but also the risk of algal blooms.展开更多
Dialysis water is directly related to the safety of hemodialysis patients, thus its quality is generally ensured by a stepwise water purification cascade. To study the effect of water treatment on the presence of anti...Dialysis water is directly related to the safety of hemodialysis patients, thus its quality is generally ensured by a stepwise water purification cascade. To study the effect of water treatment on the presence of antibiotic resistance genes (ARGs) in dialysis water, this study used propidium monoazide (PMA) in conjunction with high throughput quantitative PCR to analyze the diversity and abundance of ARGs found in viable bacteria from water having undergone various water treatment processes. The results indicated the presence of 35 ARGs in the eflfluents from the different water treatment steps. Twentynine ARGs were found in viable bacteria from the effluent following carbon filtration, the highest among all of the treatment processes, and at 6.96 Log (copies/L) the absolute abundance of the cphA gene was the highest. Two resistance genes, erm (36) and mtrD-02, which belong to the resistance categories macrolides-lincosamides-streptogramin B (MLSB) and other/efflux pump, respectively, were detected in the effluent following reverse osmosis treatment. Both of these genes have demonstrated the potential for horizontal gene transfer. These results indicated that the treated effluent from reverse osmosis, the final treatment step in dialysis-water production, was associated with potential health risks.展开更多
文摘Differences in transpiration and leaf water potential (LWP) in relation to cassava yield were investigated along inland valley toposequence in a 4×4 Latin square design. The landrace with the highest transpiration rate and lowest LWP yielded the lowest, while TMS 91/02324 and TMS 91/02327 with intermediate rate and highest LWP yielded the highest, indicating that high transpiration rate associated with low LWP reduced yield. Transpiration was lower in the fringe with deeper water table than valley bottom at deep water table site, while at shallow water table, it was higher in the fringe than valley bottom, suggesting that drought and excess moisture reduced transpiration. LWP and water table depth correlated negatively indicating that shallow water table reduced transpiration by reducing LWP. Transpiration increased and LWP decreased as radiation, leaf temperature and vapour pressure deficit increased and differences in these microclimatic conditions caused differences in the two processes between sites, years and time of day. Under mild water stress, transpiration and LWP were higher in the afternoon than the morning, but the reverse occurred under severe stress. TMS 91/02324 and TMS 91/02327 had the highest LWP under severe stress, indicating their higher drought tolerance than the other cultivars.
文摘The water deficit in arid and semi-arid regions is the primary limiting factor for the development of urban greenery and forestation. In addition, planting the species that consume low levels of water is useful in arid and semi-arid regions that have poor water management measures. Leaf water potential(Ψ) is a physiological parameter that can be used to identify drought resistance in various species. Indeed, Ψ is one of the most important properties of a plant that can be measured using a pressure chamber. Drought avoiding or drought resistant species have a lower Ψ than plants that use normal or high levels of water. To determine drought resistance of species that are suitable for afforestation in arid urban regions, we evaluated twenty woody species in the Isfahan City, central Iran. The experimental design was random split-split plots with five replications. The species were planted outdoor in plastic pots and then subjected to treatments that consisted of two soil types and five drip irrigation regimes. To evaluate the resistance of each species to drought, we used the Ψ and the number of survived plants to obtain the drought resistance index(DRI). Then, cluster analysis, dendrogram, and similarity index were used to group the species using DRI. Result indicates that the evaluated species were classified into five groups:(1) high water consuming species(DRI>–60 MPa);(2) above normal water consuming species(–60 MPa≥DRI>–90 MPa);(3) normal water consuming species(–90 MPa≥DRI>–120 MPa);(4) semi-drought resistant species(–120 MPa≥DRI>–150 MPa);and(5) drought resistant species(DRI≤–150 MPa). According to the DRI, Salix babylonica L., Populus alba L., and P. nigra L. are high water consuming species, Platanus orientalis L. and Albizia julibrissin Benth are normal water consuming species, and Quercus infectoria Oliv. and Olea europaea L. can be considered as drought resistant species.
基金supported by the National Natural Science Foundation of China(30424813)Science Publication Foundation of the Chinese Academy of Sciences
文摘A greenhouse experlment was performed In order to Investigate the effects of dlfferent levels of water stress on leaf water potentlal (ψw), stomatal resistance (rs), protein content and chlorophyll (Chl) content of tomato plants (Lycoperslcon esculentum Mill. cv. Nlkita). Water stress was Induced by addlng polyethylene glycol (PEG 6 000) to the nutrlent solution to reduce the osmotlc potential (ψs). We Investlgated the behavlor of antl-oxldant enzymes, such as catalase (CAT) and superoxide dlsmutase (SOD), durlng the development of water stress. Moderate and severe water stress (i.e. ψs= -0.51 and -1.22 MPa, respectlvely) caused a decrease In ψw for all treated (water-stressed) plants compared with control plants, wlth the reductlon belng more pronounced for severely stressed plants. In addltion, rs was slgnlflcantly affected by the Induced water stress and a decrease in leaf soluble protelns and Chl content was observed. Whereas CAT actlvlty remained constant, SOD actlvlty was increased in water-stressed plants compared wlth unstressed plants. These results Indicate the possible role of SOD as an anti-oxidant protector system for plants under water stress condltlons. Moreover, It suggests the possibllity of using this enzyme as an addltional screening crlterlon for detecting water stress in plants.
基金supported by the National Natural Science Foundation of China (40971042)the Western Light project of the Chinese Academy of Sciences (XBBS 200808)
文摘Hydraulic resistance components and water relations were studied on Haloxyolon ammoden-dron,a small xeric tree,growing at sites significantly differed in soil texture.Soil water content,leaf water potential(ψl),xylem water potential(ψx),root water potential(ψroot),leaf transpiration rate(TR) and stomatal conductance(gs) were measured at the two sites during the growing season of 2005 and 2006.Leaf spe-cific hydraulic resistance(Rplant) during the whole growing season,hydraulic resistance of plants(Rp),shoots(Rshoot) and roots(Rroot) in the August of both years were calculated and expressed on leaf area basis.The results showed the proportion of the hydraulic resistance of the aerial part(Rshoot) to the Rp was the same to the proportion of the hydraulic resistance of the soil part(Rroot) to the Rp,indicating that both parts were equivalent important to plant water hydraulic system from soil to leaf.Positive significant corre-lations were found between Rp and Rroot,suggesting that root hydraulics resistance was a major determinant of plant hydraulic resistance(Rp) and transpiration rate.The integrated effect of stomatal control,hy-draulic regulation and morphology adjustment enabled plants at heavy soil site surviving the extreme water deficit period.
基金Supported by Key Projects in the National Science &Technology Pillar Program (2007BAD30B05)Key Project of Science and Tech-nology Department of Guangxi Province of China (0782004-5)the Program for Postgraduates Research Innovattion in GX. Univer-sity (105930903049)~~
文摘[Objective] The aim was to explore the effects of water stress on leaf water and chlorophyll fluorescence parameters of sugarcane seedling,as well as to provide basis for the study on sugarcane production and evaluation. [Method] Seven different sugarcane varieties were studied at the seedling stage under drought stress,and the changes of leaf water and chlorophyll fluorescence parameters under stress conditions were detected. [Result] leaf water potential,leaf relative water content and soil relative water content showed a certain amount of internal relationship,the sugarcane varieties that had more tolerant to drought had higher utilization rate of soil water; the correlation analysis and factor analysis suggested that the survival rate at seedling stage under drought stress,Fv/Fm,leaf water potential and relative water content could be used as drought resistance evaluation indicators. [Conclusion] As a relatively independent influencing factor,water potential had dominating effect on drought resistance,and the reliability of Fv/Fm as drought resistance evaluation indicator had been verified.
基金supported by the National Basic Research Program of China(2009CB825101)the Specialized Research Fund for the Doctoral Program of Higher Education of China(20110008110035)
文摘This paper focused on the water relations of two halophytes differing in photosynthetic pathway, phe- notype, and life cycle: Karelinia caspica (Pall.) Less. (C3, deep-rooted perennial Asteraceae grass) and Atriplex tatarica L. (C4, shallow-rooted annual Chenopodiaceae grass). Gas exchange, leaf water potential, and growth characteristics were investigated in two growing seasons in an arid area of Xinjiang to explore the physiological adaptability of the two halophytes. Both K. caspica and A. tatarica showed midday depression of transpiration, in- dicating that they were strong xerophytes and weak midday depression types. The roots of A. tatarica were con- centrated mainly in the 0-60 cm soil layer, and the leaf water potential (~L) increased sharply in the 0-20 cm layer due to high soil water content, suggesting that the upper soil was the main water source. On the other hand, K. caspica had a rooting depth of about 1.5 m and a larger root/shoot ratio, which confirmed that this species uptakes water mainly from deeper soil layer. Although A. tatarica had lower transpiration water consumption, higher water use efficiency (WUE), and less water demand at the same leaf water potential, it showed larger water stress impact than K. caspica, indicating that the growth of A. tatarica was restricted more than that of K. caspica when there was no rainfall recharge. As a shallow-rooted C4 species, A. tatarica displayed lower stomatal conductance, which could to some extent reduce transpiration water loss and maintain leaf water potential steadily. In contrast, the deep-rooted C3 species K. caspica had a larger root/shoot ratio that was in favor of exploiting groundwater. We concluded that C3 species (K. caspica) tapes water and C4 species (A. tatarica) reduces water loss to survive in the arid and saline conditions. The results provided a case for the phenotype theory of Schwinning and Ehleringer on halophytic plants.
文摘Photosynthetic capacity for heritage (Taewa) and modern potato cultivars were compared at different water and nitrogenregimes in the glasshouse and field. The glasshouse was 2*2*4 factorial design with two irrigation: 100% ET and 60% ET;two applied N: 50 kg N ha-1 and 200 kg N ha-1, two Taewa (Moe Moe, Tutaekuri) and two modern potatoes (Moonlight, Agria). The 2009/2010 field experiment was a split-plot, with irrigation and rain-fed regimes as the main treatments: four potatoes above were sub-treatments. The 2010/2011 field experiment was a split-split-plot, with three water regimes as the main treatments: three cultivars (Moe Moe, Tutaekuri, and Agria) were subplots;two N rates were sub-sub-treatments. Gaseous exchange was measured by CIRAS-2 at different days from emergence. Leaf water potential was measured using pressure chamber method. Taewa achieved high photosynthetic WUE in glasshouse and 2010/2011 experiment by maintaining high An, low gs and low Ci compared to modern cultivars (p The An, gs and T increased with irrigation and N increase while decreasing Ci (p < 0.01). Water stress significantly increased VPD resulting in low An and photosynthetic WUE in Moonlight in the glasshouse. The leaf water potential for Taewa was very tolerant while modern potatoes were weakened by water stress. The study indicated that Taewa can be scheduled at partial irrigation without more detrimental effects on photosynthetic capacity while modern potatoes need full irrigation to avoid detrimental effects on photosynthetic capacity.
文摘We performed corrosion case study and corrosion tests to assess the corrosion resistance of stainless steel type 304 pipes in tap water and hot water facilities. Circulating test equipment used for corrosion tests and two types of sample, plates and straight pipe specimens, were examined under different conditions of residual chlorine concentration in the test water. The results of case study analysis indicated that high degrees of pitting corrosion occurred on straight pipes with inner diameter < 50 mm. The results of corrosion tests showed that the residual chlorine concentration around the pitting corrosion of stainless steel type 304 was greater than 0.3 mg/L in the plate, regardless of the remaining chlorine concentration in the straight pipe specimens. These results suggest that straight pipes have higher corrosion susceptibility because of bending during production.
文摘Structural failure of buried cast/ductile iron water mains and tanks due to corrosion attacks manifests in leaks and is common in most cities throughout Nigeria. The appropriate corrective action, which aims to restore pipe/tank integrity is usually based on proper understanding of the degree of corrosiveness of the soil. In an attempt to determine the potential corrosiveness of the soil to buried metallic structures in Bayelsa State, surface geoelectrical sounding was carried out. Twenty-five Schlumberger Vertical Electrical Soundings (VES) was carried out in the freshwater and meander belt geomorphic zone and the salt water mangrove swamp and estuary complex of the state using a maximum current electrode separation ranging from 200 - 400 m. The data obtained was interpreted by computer iterative modeling using a 1D inversion technique software (1X1D, Interpex, USA). The results show a high degree of heterogeneity, both laterally and vertically, which is typical of a complex depositional environment. Generally, the sub-soil condition within the expected depth of installation of water mains and storage tanks (0 - 10 m) is slightly or moderately aggressive (effective aggressivity) in the freshwater and meander belt geomorphic zone but is very strongly aggressive in the salt water mangrove swamp and estuary complex. Corrosion cells which may lead to significant corrosion failures may occur in the vicinities of strongly aggressive stations. This poses a significant corrosion risk to metallic water pipes and storage tanks. Current day design should therefore either mandate the use of a non-metallic piping product (water mains) or cathodic protection system. Prediction of potential corrosiveness of a soil and thus the application of proper corrosion control measures will not only protect the environment from spillages but will also avert cost of repair, clean-up and replacement.
文摘The water resources of rivers and reservoirs with a five-meter drop are used to discuss the technical theory and the cost and practical value of equipment cases.The high-quality development technology of water resources explored in this paper provides a feasible plan for achieving the goal of innovation to zero.
文摘Carex planostachys Kunze (Cyperaceae, Cedar sedge) is an herbaceous species in a genus commonly inhabiting mesic or hydric habitats. Carex planostachys is found in arid and semi-arid Juniperus woodlands. Arid conditions impose survival challenges to plants in dry areas. Some plants have plasticity responses to soil water content and continued normal though reduced functions through droughts, but most herbaceous plants do not survive. Limited previous studies have suggested C. planostachys is tolerant of drought. Physiological responses of C. planostachys from Juniperus woodlands was examined is this study to determine how long plants could survive without water and if they are capable of recovery from very negative water potentials beyond what is considered the permanent wilting point for most herbaceous plants. Plants were placed in pots in partial shade in this experiment. Water loss from the soil with plants was an inverse 2nd order polynomial function with soil water decreasing from 32% to 8% by day 28 of the study. Leaf water potential was also an inverse 2nd order polynomial function but did not decline significantly until 14 days without watering. Leaf water potential was −10.0 MPa after 35 days without watering. Non-watered plants Anet, (photosynthetic rate) was significantly lower compared to the water treatment by day 21 as was stomatal conductance and transpiration. When non-watered plants were watered after 21, 28 or 35 days, full recovery of physiological responses occurred within 7 days. The length of time that C. planostachys was able to withstand drought was greater than the annual trends in lack of precipitation during springtime in this area. Carex planostachys can photosynthesize at water stress between −8 and −10 MPa. Carex planostachys drought and shade tolerance enables it to occupy an understory niche devoid of other herbaceous plants.
基金SupportedbytheNationalNaturalScienceFoundationofChina(39970 6 2 2 )andtheTeachingandResearchAwardProgramforYongCadremanTeachersinHigherEducationInstitutionsofMOE P .R .China
文摘To know the annual water consumption of forest, it is necessary to acquire the annual transpiration value of stands. This paper is based on the data measured in the typical weather of the growth season, from 1998 to 2000, with the LI 1600 Steady Porometer and the general weather information. The daily variation of transpiration in black locust forest ( Robinia pesudoacacia L.) is modeled by Penman Monteith equation. As a result of the model, a continuous daily transpiration in the growth season was calculated. The net radiation, intercepted by black locust forest canopy, was acquired from a semi empirical equation of measuring net radiation R n with the extinction coefficient k and leaf area index LAI . The canopy integral stomatic resistance is a mimesis with an empirical equation of measuring data. Compared with measuring data, the relative error of the modeled ones is less than 12% averagely. At last, the total transpiration of black locust forest during the period of 1998 and 2000 in the growth season of May to October, as an average transpiration of the different density stands, were 192 46, 187 07 and 195 59?mm respectively.
基金supported by the National Natural Science Foundation of China(No.51808531)the Major Science and Technology Program for Water Pollution Control and Treatment(No.2018YFE0204101)。
文摘Water transfer is becoming a popular method for solving the problems of water quality deterioration and water level drawdown in lakes. However, the principle of choosing water sources for water transfer projects has mainly been based on the effects on water quality, which neglects the influence in the variation of phytoplankton community and the risk of algal blooms. In this study, algal growth potential(AGP) test was applied to predict changes in the phytoplankton community caused by water transfer projects. The feasibility of proposed water transfer sources(Baqing River and Jinsha River) was assessed through the changes in both water quality and phytoplankton community in Chenghai Lake, Southwest China. The results showed that the concentration of total nitrogen(TN) and total phosphorus(TP) in Chenghai Lake could be decreased to 0.52 mg/L and 0.02 mg/L respectively with the simulated water transfer source of Jinsha River. The algal cell density could be reduced by 60%, and the phytoplankton community would become relatively stable with the Jinsha River water transfer project, and the dominant species of Anabaena cylindrica evolved into Anabaenopsis arnoldii due to the species competition. However, the risk of algal blooms would be increased after the Baqing River water transfer project even with the improved water quality. Algae gained faster proliferation with the same dominant species in water transfer source. Therefore, water transfer projects should be assessed from not only the variation of water quality but also the risk of algal blooms.
基金the Ministry of Science and Technology of China (No. 2017YFE0107300)National Natural Science Foundation of China (Grant Nos. 51478450, 51678551)Xiamen Municipal Bureau of Science and Technology (No. 3502Z20171003).
文摘Dialysis water is directly related to the safety of hemodialysis patients, thus its quality is generally ensured by a stepwise water purification cascade. To study the effect of water treatment on the presence of antibiotic resistance genes (ARGs) in dialysis water, this study used propidium monoazide (PMA) in conjunction with high throughput quantitative PCR to analyze the diversity and abundance of ARGs found in viable bacteria from water having undergone various water treatment processes. The results indicated the presence of 35 ARGs in the eflfluents from the different water treatment steps. Twentynine ARGs were found in viable bacteria from the effluent following carbon filtration, the highest among all of the treatment processes, and at 6.96 Log (copies/L) the absolute abundance of the cphA gene was the highest. Two resistance genes, erm (36) and mtrD-02, which belong to the resistance categories macrolides-lincosamides-streptogramin B (MLSB) and other/efflux pump, respectively, were detected in the effluent following reverse osmosis treatment. Both of these genes have demonstrated the potential for horizontal gene transfer. These results indicated that the treated effluent from reverse osmosis, the final treatment step in dialysis-water production, was associated with potential health risks.