This study was performed to observe the effects of water on photosynthesis and water-related physiology in dominant shrubs in shell sand habitats.Four-year-old Periploca sepium seedlings were used as model species.A g...This study was performed to observe the effects of water on photosynthesis and water-related physiology in dominant shrubs in shell sand habitats.Four-year-old Periploca sepium seedlings were used as model species.A gradient of 12 water levels was established by artificially supplying the shell sand with water up to saturation and then allowing natural evapotranspiration to occur.The photo synthetic,chlorophyll fluorescence and stem sap flow parameters of P.sepium were measured under a range of water conditions.The different soil water conditions were classified according to the responses of these parameters.(1)With the increase in the relative water content(RWC)of the shell sand,the parameters of leaf photosynthesis,chlorophyll fluorescence and water-related physiology in P.sepium showed significant critical responses.The net photo synthetic rate(Pn),transpiration rate(Tr),instantaneous water use efficiency(WUE),potential water use efficiency(WUEi),maximum photochemical efficiency(Fv/Fm),actual photochemical efficiency(ΦPSII)and daily accumulation of stem sap flow all increased first and then decreased with increasing RWC,but the corresponding water conditions associated with their maximum values were not the same.An RWC of 69.40%was determined to be the optimal water condition for photosynthesis and water-related physiological activity in P.sepium.At an RWC of 36.61%,the mechanism of photosynthetic inhibition in P.sepium changed from stomatal limitation to nonstomatal limitation;this was also the minimum water requirement for maintaining normal photo synthetic processes.An RWC of 50.27%resulted in the highest WUE in P.sepium,indicating that moderate drought stress increased WUE.(2)Based on the quantitative relationship between the photo synthetic parameters of P.sepium and the shell sand water gradient,the soil water availability was classified into 6 water grades.The RWC range for maintaining strong photosynthesis and high WUE in P.sepium was 63.22-69.98%.(3)Gas exchange in P.sepium was inhibited under drought and waterlogging stresses.Under these conditions,the photosynthetic electron transport chain was blocked,and the dissipation of light energy as heat increased,which ultimately led to a decline in photo synthetic productivity;moreover,transpiration and dissipation were aggravated,and water transmission and utilization processes in P.sepium were hindered.A significant negative feedback regulation mechanism in the photosynthetic and water-related physiological processes of P.sepium was observed;this mechanism allowed P.sepium growing in shell sand to be highly adaptable to water stress.展开更多
To test the patterns of the root morphology and architecture indexes of Tamarix chinensis in response to water and salt changes in the two media of the groundwater and soil,three-year-old T.chinensis seedlings were ch...To test the patterns of the root morphology and architecture indexes of Tamarix chinensis in response to water and salt changes in the two media of the groundwater and soil,three-year-old T.chinensis seedlings were chosen as the research object.Groundwater with four salinity levels was created,and three groundwater level(GL)were applied for each salinity treatment to measure the root growth and architecture indexes.In the fresh water and brackish water treatments,the topological index(TI)of the T.chinensis roots was close to 0.5,and the root architecture was close to a dichotomous branching pattern.In the saline water and saltwater treatments,the TI of the T.chinensis roots was large and close to 1.0,and the root architecture was close to a herringbone-like branching pattern.Under different GLs and salinities,the total root length was significantly greater than the internal link length,the external link length was greater than the internal link length,and the root system showed an outward expansion strategy.The treatment with fresh water and a GL of 1.5 m was the most suitable for T.chinensis root growth,while the root growth of T.chinensis was the worst in the treatment with saline water and a GL of 0.3 m.T.chinensis can adapt to the changes in soil water and salt by regulating the growth and morphological characteristics of the root system.T.chinensis can adapt to high-salt environments by reducing its root branching and to water deficiencies by expanding the distribution and absorption area of the root system.展开更多
To clarify the changes in plant photosynthesis and mechanisms underlying those responses to gradually increasing soil drought stress and reveal quantitative relationships between photosynthesis and soil moisture,soil ...To clarify the changes in plant photosynthesis and mechanisms underlying those responses to gradually increasing soil drought stress and reveal quantitative relationships between photosynthesis and soil moisture,soil water conditions were controlled in greenhouse pot experiments using 2-year-old seedlings of Forsythia suspensa(Thunb.) Vahl. Photosynthetic gas exchange and chlorophyll fluorescence variables were measured and analyzed under 13 gradients of soil water content. Net photosynthetic rate(PN), stomatal conductance(gs), and water-use efficiency(WUE) in the seedlings exhibited a clear threshold response to the relative soil water content(RSWC). The highest PNand WUEoccurred at RSWCof51.84 and 64.10%, respectively. Both PNand WUEwere higher than the average levels at 39.79% B RSWCB 73.04%. When RSWCdecreased from 51.84 to 37.52%,PN, gs, and the intercellular CO2 concentration(Ci)markedly decreased with increasing drought stress; the corresponding stomatal limitation(Ls) substantially increased, and nonphotochemical quenching(NPQ) also tended to increase, indicating that within this range of soil water content, excessive excitation energy was dispersed from photosystem II(PSII) in the form of heat, and the reduction in PNwas primarily due to stomatal limitation.While RSWCdecreased below 37.52%, there were significant decreases in the maximal quantum yield of PSII photochemistry(Fv/Fm) and the effective quantum yield of PSII photochemistry(UPSII), photochemical quenching(qP), and NPQ; in contrast, minimal fluorescence yield of the dark-adapted state(F0) increased markedly. Thus,the major limiting factor for the PNreduction changed to a nonstomatal limitation due to PSII damage. Therefore, an RSWCof 37.52% is the maximum allowable water deficit for the normal growth of seedlings of F. suspensa, and a water content lower than this level should be avoided in field soil water management. Water contents should be maintained in the range of 39.79% B RSWCB 73.04% to ensure normal function of the photosynthetic apparatus and high levels of photosynthesis and efficiency in F.suspensa.展开更多
Soil moisture is a major limiting factor for plant growth on shell ridge islands in the Yellow River Delta.However, it is difficult to carry out situ experiment to study dominant plant photosynthesis physiological on ...Soil moisture is a major limiting factor for plant growth on shell ridge islands in the Yellow River Delta.However, it is difficult to carry out situ experiment to study dominant plant photosynthesis physiological on the shell ridge islands under extreme soil water stress. To evaluate the adaptability of plants to light and moisture variations under extreme soil moisture conditions present on these islands, we measured photosynthetic gas exchange process,chlorophyll fluorescence, and stem sap flow variables for3-year-old trees of Tamarix chinensis Lour, a restoration species on these islands, subjected to three types of soilwater levels: waterlogging stress(WS), alternating dry–wet(WD), and severe drought stress(SS) to inform decisions on its planting and management on shell ridge islands. Gas exchange, chlorophyll fluorescence, and stem sap flow in T.chinensis were then measured. Net photosynthetic rate(PN), transpiration rate(E), and water use efficiency(WUE)were similar under WS and alternating dry–wet conditions,but their mean E and WUEdiffered significantly(P \ 0.05).Under SS, the PN, E and WUEof T. chinensis leaves varied slightly, and mean PN, E and WUEwere all low. Apparent quantum efficiency(AQY), light compensation point(LCP),light saturation point(LSP), and maximum net photosynthetic rate(PNmax) of leaves were not significantly different(P [ 0.05) under WS and dry–wet conditions; however,under extreme drought stress, compared with the dry–wet conditions, LCPwas higher, LSPwas lower, and AQYand PNmaxwere both at the lowest level. Therefore, drought stress weakened light adaptability of leaves, and the efficiency of light transformation was poorer.(3) Maximum photochemical efficiency(Fv/Fm) and the actual photochemical efficiency(UPSII) were similar under waterlogged stress and dry–wet conditions, indicating a similar healthy photosynthetic apparatus and photosynthetic reaction center activity, respectively. Under SS, Fv/Fmwas 0.631, and the coefficient of non-photochemical quenching(NPQ) was0.814, which indicated that while the photosynthetic mechanism was damaged, the absorbed light energy was mainly dissipated in the form of heat, and the potential photosynthetic productivity was significantly reduced. The daily cumulants of sap flow of T. chinensis under dry–wet alternation and severe drought stress were 22.25 and63.97% higher, respectively, than under waterlogging stress. Daily changes in sap flow velocity for T. chinensis differed under the three soil water levels. Stem sap flow was weak at night under severe drought stress. Under dry–wet alternation, daytime average stem sap flow velocity was the highest, and night stem flow accounted for 10.26%of the day cumulants, while under waterlogged stress, the average nightly stem flow velocity was the highest,accounting for 31.82% of the day cumulants. These results provide important information for regional vegetation restoration and ecological reconstruction.展开更多
The 9-cis-epoxycarotenoid dioxygenase(NCED)gene is rate-limiting in abscisic acid(ABA) biosynthesis.In this study, an NCED gene, designated FvNCED3(KY008746), was cloned from velvet ash(Fraxinus velutina Torr.) with a...The 9-cis-epoxycarotenoid dioxygenase(NCED)gene is rate-limiting in abscisic acid(ABA) biosynthesis.In this study, an NCED gene, designated FvNCED3(KY008746), was cloned from velvet ash(Fraxinus velutina Torr.) with a RACE method. The full length c DNA of FvNCED3 encodes a 573-amino acid polypeptide.Sequencing analysis showed that the FvNCED3 protein was highly homologous to other NCED proteins. The expression patterns of FvNCED3 in different ash organs were analyzed by real-time PCR which revealed that FvNCED3 expression levels were highest in leaves and lowest in roots. The gene expression patterns of FvNCED3 under abiotic stress indicated that its expression increased under drought, salt and ABA stress and decreased due to high and low temperatures. There were no obvious changes under ultraviolet light. The 1094-bp upstream sequence 5' flank regulation region of the FvNCED3 gene was also cloned from ash using the Genome Walking method. To assess the activity of the FvNCED3 promoter, a p FvNCED3 p::GUS plant expression vector was constructed for tobacco transformation. GUS expression of the FvNCED3 GUS enzyme activity was detected in almost all transgenic tobacco tissues, especially in the young leaves,stigma, anther, ovule and ovary. After treating the transgenic tobacco with NaCl and placing it under drought stress, GUS staining of tobacco leaves increased compared with that under normal growth conditions. This result indicates that gene expression driven by the FvNCED3 promoter can be induced by salt and drought stress.展开更多
Chromium is a common harmful pollutant with high toxicity and low bearing capacity of soil and water.Excellent salinity resistance,a wide pH range,and high regeneration capacity were essential for qualified adsorbents...Chromium is a common harmful pollutant with high toxicity and low bearing capacity of soil and water.Excellent salinity resistance,a wide pH range,and high regeneration capacity were essential for qualified adsorbents used in removing hexavalent chromium(Cr(VI))from polluted water.Herein,iron oxalate modified weak basic resin(IO@D301)for the removal of Cr(VI)was prepared by the impregnation method.The IO@D301 was characterized by scanning electron microscope(SEM),Fourier transform infrared spectroscopy(FTIR),X-Ray diffraction(XRD)and X-ray photoelectron spectroscopy(XPS).Owing to abundant amine,carboxyl groups and iron ions existing on the surface,IO@D301 possesses high adsorption and salinity resistance capacity for Cr(VI).The maximum adsorption capacity of IO301 towards Cr(VI)reached 201.30 mg·g^(-1) at 293 K and a pH of 5.The adsorption equilibrium was well fitted by the Freundlich model,and the adsorption process was described by the pseudofirst-order kinetics model as spontaneous and exothermic.The mechanism may be identified as electrostatic attraction,coordination,and reduction,which was confirmed by FT-IR and X-ray photoelectron spectroscopy.展开更多
vegetation restoration is a main ecological remediation technology for greening saline and alkaline soils.The objectives of this study were to determine the effect of1-aminobenzotriazole(ABT-1) on the growth and physi...vegetation restoration is a main ecological remediation technology for greening saline and alkaline soils.The objectives of this study were to determine the effect of1-aminobenzotriazole(ABT-1) on the growth and physiology of Tamarix chinensis under salt stress and to determine a suitable ABT-1 concentration and soil salinity(Sc) for propagating T.chihehsis-cuttings.Cuttings were soaked in water and ABT-1 solutions at three concentrations(50,100,and 200 mg L^(-1)) and propagated in pots containing four soil salinity levels,mild(0.3%),moderate(0.6%),and severe(0.9% and 1.2%),and compared with a control.The cuttings were measured to determine growth indices and physiological and biochemical indices(e.g.,chlorophyll content,superoxide dismutase activity,peroxidase activity,and malondialdehyde content).ABT-1 was effective in improving survival,growth,and physiological processes of cuttings under salt stress.However,there was a threshold effect when using ABT-1 to facilitate propagation under salt stress.ABT-1 effects were insignificant when applied at low concentrations(<100 mg L^(-1)).At a high concentration(> 100 mg L^(-1)),ABT-1 limited growth and physiological activities.Under a salt stress level(Sc ≤0.9%),ABT applied at a 100 mg L^(-1)concentration increased chlorophyll content and superoxide dismutase and peroxidase activities in the leaves and reduced malondialdehyde accumulation and membrane lipid peroxidation effects.As a result,ABT-1 enhanced the resistance of T.chinensis to salt stress.However,under high salt stress(>0.9%) and ABT-1 concentration(> 100 mg L^(-1)),the physiological regulatory ability of T.chinensis seedlings weakened.T.chinensis grew well at a salt stress ≤0.9% and ABT ≤100 mg L^(-1) and exhibited relatively high physiological regulatory ability and high salt adaptability.展开更多
In this study,pot experiments were conducted on the seedlings of Pinus sylvestris var.mongolica to study the influence of Trichoderma(Trichoderma harzianum E15)and Ectomycorrhizal fungi(Suillus luteus N94)on the growt...In this study,pot experiments were conducted on the seedlings of Pinus sylvestris var.mongolica to study the influence of Trichoderma(Trichoderma harzianum E15)and Ectomycorrhizal fungi(Suillus luteus N94)on the growth of these seedlings.In particular,the effects of these fungi on the fungal community structure in the rhizosphere soil of the seedlings were investigated.Inoculation with Trichoderma harzianum E15 and Suillus luteus N94 significantly(P<0.05)promoted the growth of the Pinus sylvestris seedlings.The non-metric multidimensional scaling(NMDS)results indicated a significant difference(P<0.05)between the fungal community structures in the rhizosphere soil of the annual and biennial seedlings.In the rhizosphere soil of annual seedlings,the main fungi were Ascomycota,Basidiomycota,Zygomycota.Ascomycota,Basidiomycota,Mortierellomycota,and p-unclassified-k-Fungi were the main fungi in the rhizosphere soil of biennial seedlings.The dominant genus in the rhizosphere soil and a key factor promoting the growth of the annual and the biennial seedlings was Trichoderma,Suillus,respectively.Both of them were negatively correlated with the relative abundance of microbial flora in the symbiotic environment.Trichoderma had a significant promoting effect on the conversion of total phosphorus,total nitrogen,ammonium nitrogen,nitrate nitrogen,and the organic matter in the rhizosphere soil of the seedlings,while Suillus significantly promoted the conversion of organic matter and total phosphorus.展开更多
To explore the critical relationships of photosynthetic efficiency and stem sap flow to soil moisture,two-year-old poplar saplings were selected and a packaged stem sap flow gauge,based on the stem-heat balance method...To explore the critical relationships of photosynthetic efficiency and stem sap flow to soil moisture,two-year-old poplar saplings were selected and a packaged stem sap flow gauge,based on the stem-heat balance method,and a CIRAS-2 portable photosynthesis system were used.The results show that photosynthetic rates(P_(n)),transpiration rates(T_(r)),instantaneous water use efficiency(WUE)and the stem sap flow increased initially and then decreased with decreasing soil water,but their critical values were different.The turning point of relative soil water content(W_(r))from stomatal limitation to nonstomatal limitation of P_(n)was 42%,and the water compensation point of P_(n)was 13%.Water saturation points of P_(n)and T_(r)were 64%and 56%,respectively,and the WUE was 71%.With increasing soil water,the apparent quantum yield(AQY),light saturation point(LSP)and maximum net photosynthetic rate(P_(n)max)increased first and then decreased,while the light compensation point(LCP)decreased first and then increased.When W_(r)was 64%,LCP reached a lower value of 30.7µmol m^(-2)s^(-1),and AQY a higher value of 0.044,indicating that poplar had a strong ability to utilize weak light.When W_(r)was 74%,LSP reached its highest point at 1138.3µmol·m^(-2)s^(-1),indicating that poplar had the widest light ecological amplitude and the highest light utilization efficiency.Stem sap flow and daily sap flow reached the highest value(1679.7 g d^(-1))at W_(r)values of 56%and 64%,respectively,and then declined with increasing or decreasing W_(r),indicating that soil moisture significantly affected the transpiration water-consumption of poplar.Soil water was divided into six threshold grades by critical values to maintain photosynthetic efficiency at different levels,and a W_(r)of 64-71%was classified to be at the level of high productivity and high efficiency.In this range,poplar had high photosynthetic capacity and efficient physiological characteristics for water consumption.The saplings had characteristics of water tolerance and were not drought resistant.Full attention should be given to the soil water environment in the Yellow River Delta when planting Populus.展开更多
基金supported by the Forestry Science and Technology Innovation Project of Shandong Province(No.2019LY006)the National Natural Science Foundation of China(No.31770761)+1 种基金Open Research Fund Program of Shandong Key Laboratory of Eco-Environmental Science for Yellow River Delta(Binzhou University)(No.2020KFJJ03)the Taishan Scholars Program of Shandong ProvincemChina(No.TSQN201909152)。
文摘This study was performed to observe the effects of water on photosynthesis and water-related physiology in dominant shrubs in shell sand habitats.Four-year-old Periploca sepium seedlings were used as model species.A gradient of 12 water levels was established by artificially supplying the shell sand with water up to saturation and then allowing natural evapotranspiration to occur.The photo synthetic,chlorophyll fluorescence and stem sap flow parameters of P.sepium were measured under a range of water conditions.The different soil water conditions were classified according to the responses of these parameters.(1)With the increase in the relative water content(RWC)of the shell sand,the parameters of leaf photosynthesis,chlorophyll fluorescence and water-related physiology in P.sepium showed significant critical responses.The net photo synthetic rate(Pn),transpiration rate(Tr),instantaneous water use efficiency(WUE),potential water use efficiency(WUEi),maximum photochemical efficiency(Fv/Fm),actual photochemical efficiency(ΦPSII)and daily accumulation of stem sap flow all increased first and then decreased with increasing RWC,but the corresponding water conditions associated with their maximum values were not the same.An RWC of 69.40%was determined to be the optimal water condition for photosynthesis and water-related physiological activity in P.sepium.At an RWC of 36.61%,the mechanism of photosynthetic inhibition in P.sepium changed from stomatal limitation to nonstomatal limitation;this was also the minimum water requirement for maintaining normal photo synthetic processes.An RWC of 50.27%resulted in the highest WUE in P.sepium,indicating that moderate drought stress increased WUE.(2)Based on the quantitative relationship between the photo synthetic parameters of P.sepium and the shell sand water gradient,the soil water availability was classified into 6 water grades.The RWC range for maintaining strong photosynthesis and high WUE in P.sepium was 63.22-69.98%.(3)Gas exchange in P.sepium was inhibited under drought and waterlogging stresses.Under these conditions,the photosynthetic electron transport chain was blocked,and the dissipation of light energy as heat increased,which ultimately led to a decline in photo synthetic productivity;moreover,transpiration and dissipation were aggravated,and water transmission and utilization processes in P.sepium were hindered.A significant negative feedback regulation mechanism in the photosynthetic and water-related physiological processes of P.sepium was observed;this mechanism allowed P.sepium growing in shell sand to be highly adaptable to water stress.
基金financially supported by the Joint Funds of the National Natural Science Foundation of China(U2006215)the National Natural Science Foundation of China(31770761)+2 种基金the Shandong Key Laboratory of Coastal Environmental Processes,YICCAS(2019SDHADKFJJ16)the Natural Science Foundation of Shangdong Province(ZR2020QD003)Taishan Scholars Program of Shandong Province,China(TSQN201909152)。
文摘To test the patterns of the root morphology and architecture indexes of Tamarix chinensis in response to water and salt changes in the two media of the groundwater and soil,three-year-old T.chinensis seedlings were chosen as the research object.Groundwater with four salinity levels was created,and three groundwater level(GL)were applied for each salinity treatment to measure the root growth and architecture indexes.In the fresh water and brackish water treatments,the topological index(TI)of the T.chinensis roots was close to 0.5,and the root architecture was close to a dichotomous branching pattern.In the saline water and saltwater treatments,the TI of the T.chinensis roots was large and close to 1.0,and the root architecture was close to a herringbone-like branching pattern.Under different GLs and salinities,the total root length was significantly greater than the internal link length,the external link length was greater than the internal link length,and the root system showed an outward expansion strategy.The treatment with fresh water and a GL of 1.5 m was the most suitable for T.chinensis root growth,while the root growth of T.chinensis was the worst in the treatment with saline water and a GL of 0.3 m.T.chinensis can adapt to the changes in soil water and salt by regulating the growth and morphological characteristics of the root system.T.chinensis can adapt to high-salt environments by reducing its root branching and to water deficiencies by expanding the distribution and absorption area of the root system.
基金supported by the National Natural Science Foundation of China(Nos.41621061,31500511)the Natural Science Foundation of Shandong Province of China(No.ZR2015CL044)
文摘To clarify the changes in plant photosynthesis and mechanisms underlying those responses to gradually increasing soil drought stress and reveal quantitative relationships between photosynthesis and soil moisture,soil water conditions were controlled in greenhouse pot experiments using 2-year-old seedlings of Forsythia suspensa(Thunb.) Vahl. Photosynthetic gas exchange and chlorophyll fluorescence variables were measured and analyzed under 13 gradients of soil water content. Net photosynthetic rate(PN), stomatal conductance(gs), and water-use efficiency(WUE) in the seedlings exhibited a clear threshold response to the relative soil water content(RSWC). The highest PNand WUEoccurred at RSWCof51.84 and 64.10%, respectively. Both PNand WUEwere higher than the average levels at 39.79% B RSWCB 73.04%. When RSWCdecreased from 51.84 to 37.52%,PN, gs, and the intercellular CO2 concentration(Ci)markedly decreased with increasing drought stress; the corresponding stomatal limitation(Ls) substantially increased, and nonphotochemical quenching(NPQ) also tended to increase, indicating that within this range of soil water content, excessive excitation energy was dispersed from photosystem II(PSII) in the form of heat, and the reduction in PNwas primarily due to stomatal limitation.While RSWCdecreased below 37.52%, there were significant decreases in the maximal quantum yield of PSII photochemistry(Fv/Fm) and the effective quantum yield of PSII photochemistry(UPSII), photochemical quenching(qP), and NPQ; in contrast, minimal fluorescence yield of the dark-adapted state(F0) increased markedly. Thus,the major limiting factor for the PNreduction changed to a nonstomatal limitation due to PSII damage. Therefore, an RSWCof 37.52% is the maximum allowable water deficit for the normal growth of seedlings of F. suspensa, and a water content lower than this level should be avoided in field soil water management. Water contents should be maintained in the range of 39.79% B RSWCB 73.04% to ensure normal function of the photosynthetic apparatus and high levels of photosynthesis and efficiency in F.suspensa.
基金supported by the National Natural Science Foundation of China(No.31370702)the Key Project of Natural Science Foundation of Shandong Province(No.ZR2015JL014)+2 种基金the Key Research and Development Project of Shandong Province(No.2015GNC111022)Science and Technology Plan of Universities in Shandong Province(No.J13LC03)Natural Science Foundation of Shandong Province(No.ZR2015CL044)
文摘Soil moisture is a major limiting factor for plant growth on shell ridge islands in the Yellow River Delta.However, it is difficult to carry out situ experiment to study dominant plant photosynthesis physiological on the shell ridge islands under extreme soil water stress. To evaluate the adaptability of plants to light and moisture variations under extreme soil moisture conditions present on these islands, we measured photosynthetic gas exchange process,chlorophyll fluorescence, and stem sap flow variables for3-year-old trees of Tamarix chinensis Lour, a restoration species on these islands, subjected to three types of soilwater levels: waterlogging stress(WS), alternating dry–wet(WD), and severe drought stress(SS) to inform decisions on its planting and management on shell ridge islands. Gas exchange, chlorophyll fluorescence, and stem sap flow in T.chinensis were then measured. Net photosynthetic rate(PN), transpiration rate(E), and water use efficiency(WUE)were similar under WS and alternating dry–wet conditions,but their mean E and WUEdiffered significantly(P \ 0.05).Under SS, the PN, E and WUEof T. chinensis leaves varied slightly, and mean PN, E and WUEwere all low. Apparent quantum efficiency(AQY), light compensation point(LCP),light saturation point(LSP), and maximum net photosynthetic rate(PNmax) of leaves were not significantly different(P [ 0.05) under WS and dry–wet conditions; however,under extreme drought stress, compared with the dry–wet conditions, LCPwas higher, LSPwas lower, and AQYand PNmaxwere both at the lowest level. Therefore, drought stress weakened light adaptability of leaves, and the efficiency of light transformation was poorer.(3) Maximum photochemical efficiency(Fv/Fm) and the actual photochemical efficiency(UPSII) were similar under waterlogged stress and dry–wet conditions, indicating a similar healthy photosynthetic apparatus and photosynthetic reaction center activity, respectively. Under SS, Fv/Fmwas 0.631, and the coefficient of non-photochemical quenching(NPQ) was0.814, which indicated that while the photosynthetic mechanism was damaged, the absorbed light energy was mainly dissipated in the form of heat, and the potential photosynthetic productivity was significantly reduced. The daily cumulants of sap flow of T. chinensis under dry–wet alternation and severe drought stress were 22.25 and63.97% higher, respectively, than under waterlogging stress. Daily changes in sap flow velocity for T. chinensis differed under the three soil water levels. Stem sap flow was weak at night under severe drought stress. Under dry–wet alternation, daytime average stem sap flow velocity was the highest, and night stem flow accounted for 10.26%of the day cumulants, while under waterlogged stress, the average nightly stem flow velocity was the highest,accounting for 31.82% of the day cumulants. These results provide important information for regional vegetation restoration and ecological reconstruction.
基金supported by National Key R&D Program of China(2017YFC0505904)the National Natural Science Foundation of China(31400525)+2 种基金the Natural Science Foundation of Shandong Province,China(ZR2014CQ028)Project funded by China Postdoctoral Science Foundation(2016M592235)the Postdoctoral Foundation of Shandong Agricultural University
文摘The 9-cis-epoxycarotenoid dioxygenase(NCED)gene is rate-limiting in abscisic acid(ABA) biosynthesis.In this study, an NCED gene, designated FvNCED3(KY008746), was cloned from velvet ash(Fraxinus velutina Torr.) with a RACE method. The full length c DNA of FvNCED3 encodes a 573-amino acid polypeptide.Sequencing analysis showed that the FvNCED3 protein was highly homologous to other NCED proteins. The expression patterns of FvNCED3 in different ash organs were analyzed by real-time PCR which revealed that FvNCED3 expression levels were highest in leaves and lowest in roots. The gene expression patterns of FvNCED3 under abiotic stress indicated that its expression increased under drought, salt and ABA stress and decreased due to high and low temperatures. There were no obvious changes under ultraviolet light. The 1094-bp upstream sequence 5' flank regulation region of the FvNCED3 gene was also cloned from ash using the Genome Walking method. To assess the activity of the FvNCED3 promoter, a p FvNCED3 p::GUS plant expression vector was constructed for tobacco transformation. GUS expression of the FvNCED3 GUS enzyme activity was detected in almost all transgenic tobacco tissues, especially in the young leaves,stigma, anther, ovule and ovary. After treating the transgenic tobacco with NaCl and placing it under drought stress, GUS staining of tobacco leaves increased compared with that under normal growth conditions. This result indicates that gene expression driven by the FvNCED3 promoter can be induced by salt and drought stress.
基金The research has been funded by the National Key Research&Development Program of China(2017YFC0505904)National Natural Science Foundation of China(51808040)Taishan Scholars Program of Shandong Province.
文摘Chromium is a common harmful pollutant with high toxicity and low bearing capacity of soil and water.Excellent salinity resistance,a wide pH range,and high regeneration capacity were essential for qualified adsorbents used in removing hexavalent chromium(Cr(VI))from polluted water.Herein,iron oxalate modified weak basic resin(IO@D301)for the removal of Cr(VI)was prepared by the impregnation method.The IO@D301 was characterized by scanning electron microscope(SEM),Fourier transform infrared spectroscopy(FTIR),X-Ray diffraction(XRD)and X-ray photoelectron spectroscopy(XPS).Owing to abundant amine,carboxyl groups and iron ions existing on the surface,IO@D301 possesses high adsorption and salinity resistance capacity for Cr(VI).The maximum adsorption capacity of IO301 towards Cr(VI)reached 201.30 mg·g^(-1) at 293 K and a pH of 5.The adsorption equilibrium was well fitted by the Freundlich model,and the adsorption process was described by the pseudofirst-order kinetics model as spontaneous and exothermic.The mechanism may be identified as electrostatic attraction,coordination,and reduction,which was confirmed by FT-IR and X-ray photoelectron spectroscopy.
基金supported financially by the National Natural Science Foundation of China (No.31770761)the Forestry Science and Technology Innovation Project of Shandong province (2019LY006)+1 种基金the Natural Science Foundation of Shandong province (No.ZR2017LEE023)the Taishan Scholars Program of Shandong province,P.R.China(No.TSQN201909152)。
文摘vegetation restoration is a main ecological remediation technology for greening saline and alkaline soils.The objectives of this study were to determine the effect of1-aminobenzotriazole(ABT-1) on the growth and physiology of Tamarix chinensis under salt stress and to determine a suitable ABT-1 concentration and soil salinity(Sc) for propagating T.chihehsis-cuttings.Cuttings were soaked in water and ABT-1 solutions at three concentrations(50,100,and 200 mg L^(-1)) and propagated in pots containing four soil salinity levels,mild(0.3%),moderate(0.6%),and severe(0.9% and 1.2%),and compared with a control.The cuttings were measured to determine growth indices and physiological and biochemical indices(e.g.,chlorophyll content,superoxide dismutase activity,peroxidase activity,and malondialdehyde content).ABT-1 was effective in improving survival,growth,and physiological processes of cuttings under salt stress.However,there was a threshold effect when using ABT-1 to facilitate propagation under salt stress.ABT-1 effects were insignificant when applied at low concentrations(<100 mg L^(-1)).At a high concentration(> 100 mg L^(-1)),ABT-1 limited growth and physiological activities.Under a salt stress level(Sc ≤0.9%),ABT applied at a 100 mg L^(-1)concentration increased chlorophyll content and superoxide dismutase and peroxidase activities in the leaves and reduced malondialdehyde accumulation and membrane lipid peroxidation effects.As a result,ABT-1 enhanced the resistance of T.chinensis to salt stress.However,under high salt stress(>0.9%) and ABT-1 concentration(> 100 mg L^(-1)),the physiological regulatory ability of T.chinensis seedlings weakened.T.chinensis grew well at a salt stress ≤0.9% and ABT ≤100 mg L^(-1) and exhibited relatively high physiological regulatory ability and high salt adaptability.
文摘In this study,pot experiments were conducted on the seedlings of Pinus sylvestris var.mongolica to study the influence of Trichoderma(Trichoderma harzianum E15)and Ectomycorrhizal fungi(Suillus luteus N94)on the growth of these seedlings.In particular,the effects of these fungi on the fungal community structure in the rhizosphere soil of the seedlings were investigated.Inoculation with Trichoderma harzianum E15 and Suillus luteus N94 significantly(P<0.05)promoted the growth of the Pinus sylvestris seedlings.The non-metric multidimensional scaling(NMDS)results indicated a significant difference(P<0.05)between the fungal community structures in the rhizosphere soil of the annual and biennial seedlings.In the rhizosphere soil of annual seedlings,the main fungi were Ascomycota,Basidiomycota,Zygomycota.Ascomycota,Basidiomycota,Mortierellomycota,and p-unclassified-k-Fungi were the main fungi in the rhizosphere soil of biennial seedlings.The dominant genus in the rhizosphere soil and a key factor promoting the growth of the annual and the biennial seedlings was Trichoderma,Suillus,respectively.Both of them were negatively correlated with the relative abundance of microbial flora in the symbiotic environment.Trichoderma had a significant promoting effect on the conversion of total phosphorus,total nitrogen,ammonium nitrogen,nitrate nitrogen,and the organic matter in the rhizosphere soil of the seedlings,while Suillus significantly promoted the conversion of organic matter and total phosphorus.
基金This study was supported by the National Natural Science Foundation of China(No.31770761,No.31870379)the Forestry Science and Technology Innovation Project of Shandong Province(No.2019LY006)+1 种基金the Science and Technology Projects of Shandong Province(No.2017CXGC0316)the Taishan Scholars Program of Shandong Province,P.R.China(No.TSQN201909152).
文摘To explore the critical relationships of photosynthetic efficiency and stem sap flow to soil moisture,two-year-old poplar saplings were selected and a packaged stem sap flow gauge,based on the stem-heat balance method,and a CIRAS-2 portable photosynthesis system were used.The results show that photosynthetic rates(P_(n)),transpiration rates(T_(r)),instantaneous water use efficiency(WUE)and the stem sap flow increased initially and then decreased with decreasing soil water,but their critical values were different.The turning point of relative soil water content(W_(r))from stomatal limitation to nonstomatal limitation of P_(n)was 42%,and the water compensation point of P_(n)was 13%.Water saturation points of P_(n)and T_(r)were 64%and 56%,respectively,and the WUE was 71%.With increasing soil water,the apparent quantum yield(AQY),light saturation point(LSP)and maximum net photosynthetic rate(P_(n)max)increased first and then decreased,while the light compensation point(LCP)decreased first and then increased.When W_(r)was 64%,LCP reached a lower value of 30.7µmol m^(-2)s^(-1),and AQY a higher value of 0.044,indicating that poplar had a strong ability to utilize weak light.When W_(r)was 74%,LSP reached its highest point at 1138.3µmol·m^(-2)s^(-1),indicating that poplar had the widest light ecological amplitude and the highest light utilization efficiency.Stem sap flow and daily sap flow reached the highest value(1679.7 g d^(-1))at W_(r)values of 56%and 64%,respectively,and then declined with increasing or decreasing W_(r),indicating that soil moisture significantly affected the transpiration water-consumption of poplar.Soil water was divided into six threshold grades by critical values to maintain photosynthetic efficiency at different levels,and a W_(r)of 64-71%was classified to be at the level of high productivity and high efficiency.In this range,poplar had high photosynthetic capacity and efficient physiological characteristics for water consumption.The saplings had characteristics of water tolerance and were not drought resistant.Full attention should be given to the soil water environment in the Yellow River Delta when planting Populus.
