The Revised Universal Soil Loss Equation(RUSLE)is widely used to estimate regional soil erosion.However,quantitative impacts of soil and water conservation(SWC)measures on conservation practice factor(P)of the RUSLE r...The Revised Universal Soil Loss Equation(RUSLE)is widely used to estimate regional soil erosion.However,quantitative impacts of soil and water conservation(SWC)measures on conservation practice factor(P)of the RUSLE remain largely unclear,especially for the mountainous and hilly areas.In this study,we improved the RUSLE by considering quantitative impacts of different SWC measures on the P factor value.The improved RUSLE was validated against the long-term(2000-2015)soil erosion monitoring data obtained from 96 runoff plots(15—35°)in mountainous and hilly areas of Hubei Province,China;the result presented a high accuracy with the determination coefficient of 0.89.Based on the erosion monitoring data of 2018 and 2019,the Root Mean Square Error of the result by the improved RUSLE was 28.0%smaller than that by the original RUSLE with decrement of 19.6%—24.0%in the average P factor values,indicating that the soil erosion modelling accuracy was significantly enhanced by the improved RUSLE.Relatively low P factor values appeared for farmlands with tillage measures(P<0.53),grasslands with engineering measures(P<0.23),woodlands with biological measures(P<0.28),and other land use types with biological measures(P<0.51).The soil erosion modulus showed a downward trend with the corresponding values of 1681.21,1673.14,1594.70,1482.40 and 1437.50 t km^(-2)a-1 in 2000,2005,2010,2015 and 2019,respectively.The applicability of the improved RUSLE was verified by the measurements in typical mountainous and hilly areas of Hubei Province,China,and arrangements of SWC measures of this area were proposed.展开更多
Dear Editor,Perennial ryegrass (Lolium perenne) is a globally important forage and turf grass species that commonly forms symbiotic associations with the asexual fungal endophyte—Epichloe festucae var.lolii.Epichloe ...Dear Editor,Perennial ryegrass (Lolium perenne) is a globally important forage and turf grass species that commonly forms symbiotic associations with the asexual fungal endophyte—Epichloe festucae var.lolii.Epichloe endophytes mutualistically interact with host plants by providing major fitness enhancements and protection from both biotic and abiotic stresses (Young et al.,2013).Previous studies have shown that Epichloe festucae var.lolii inhibits the growth of plant pathogenic fungi and fungal spore germination in vitro.Additional studies conducted in the lab or field confirmed that endophytes inhibited pathogen invasion and lesion development in perennial ryegrass.However,endophytes are not always beneficial,and may even weaken the host plant and reduce the disease resistance of the host.Such inconsistent or contrasting results in Festuca spp.,Achnatherum inebrians and Leymus chinensis have also been reported (Wang et al.,2016).展开更多
The three-layered(W-60 vol%Cu/W-40 vol%Cu/W-20 vol%Cu)W/Cu functionally graded material(FGM)containing a Cu network structure was fabricated at different temperatures by hot-pressed sintering produced from copper-coat...The three-layered(W-60 vol%Cu/W-40 vol%Cu/W-20 vol%Cu)W/Cu functionally graded material(FGM)containing a Cu network structure was fabricated at different temperatures by hot-pressed sintering produced from copper-coated tungsten powders.The effects of various sintering temperatures on relative density,microstructure,thermal conductivity,hardness and flexural strength were investigated.Scanning electron microscopy(SEM)and X-ray diffraction(XRD)analysis show that a Cu network extends throughout the W/Cu FGM specimens sintered at 1065℃and the graded structure can be retained perfectly,and W particles are distributed homogeneously.The low-temperature sintering densification of W/Cu FGM arises because the sintering mode of the copper-coated tungsten particles includes just sintering Cu to Cu,rather than Cu to W,Cu to Cu and W to W,as required for conventional powder particles.The relative density of W/Cu FGM sintered at 1065℃for 3 h under a load of25 MPa is 96.1%.The thermal conductivity is up to204 W·m^-1·K^-1 at normal temperature and 150 W·m^-1·K^-1at 800℃.And the Vickers hardness varies with the gradient of different layers from 3.34 to 4.05 GPa.展开更多
Background:Epichloësinensis is a newly found endophyte species that is frequently involved in symbiosis with Festuca sinensis.There are a little reports on the characteristics of E.sinensis in vitro.Methods:In th...Background:Epichloësinensis is a newly found endophyte species that is frequently involved in symbiosis with Festuca sinensis.There are a little reports on the characteristics of E.sinensis in vitro.Methods:In the present study,five E.sinensis endophyte strains(strain ID 1,2,41D,57D,111D)isolated from different F.sinensis ecotypes were used to evaluate their antioxidant capacities and enzyme activities.Also,the growth of E.sinensis on potato dextrose agar(PDA)with different additives was investigated.Results:The five strains had significantly different(p<0.05)total antioxidant capacities and radical-scavenging abilities.In most cases,the growth rate of strain 1 was the fastest(p<0.05),and that of strain 57D was the slowest(p<0.05).The growth rates of these five strains on PDA with vitamins significantly(p<0.05)increased with increasing vitamin concentration.The growth rates of these five strains on PDA with plant growth regulators also significantly(p<0.05)increased;however,the increase was inconsistent at different concentrations of indole-3-acetic acid and gibberellin.Low concentrations(5 and 10 mg L−1)of forchlorfenuron(KT-30)significantly promoted the growth of all five strains,whereas high concentrations(20 and 40 mg L−1)of KT-30 significantly inhibited their growth(p<0.05).The Na+,Cd2+,Zn2+,and Cr6+ions all inhibited the growth of these five strains,and their growth rates were significantly decreased with an increase in ion concentrations(p<0.05).Under Na+stress,strain 41D grew the fastest and had the strongest tolerance(p<0.05);under Cd2+,Zn2+,and Cr6+stresses,strain 111D grew the fastest and had the strongest tolerance(p<0.05).Conclusions:The results indicated that the E.sinensis had antioxidant activities and hydrolase activities.Additives could promote or inhibit the growth of the strains in different degrees.All these evaluations in the present study improve our understanding of the E.sinensis endophyte and provide referenced information for further studies.展开更多
基金funded by the Natural Science Foundation of China Project(41907061)the National Key Research and Development Program(2016YFC0503506)+1 种基金the Research Program from the State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau(A314021402-2005)the Research Center on Mountain Torrent&Geologic Disaster Prevention of the Ministry of Water Resources,Changjiang River Scientific Research Institute(CKWV2019761/KY).
文摘The Revised Universal Soil Loss Equation(RUSLE)is widely used to estimate regional soil erosion.However,quantitative impacts of soil and water conservation(SWC)measures on conservation practice factor(P)of the RUSLE remain largely unclear,especially for the mountainous and hilly areas.In this study,we improved the RUSLE by considering quantitative impacts of different SWC measures on the P factor value.The improved RUSLE was validated against the long-term(2000-2015)soil erosion monitoring data obtained from 96 runoff plots(15—35°)in mountainous and hilly areas of Hubei Province,China;the result presented a high accuracy with the determination coefficient of 0.89.Based on the erosion monitoring data of 2018 and 2019,the Root Mean Square Error of the result by the improved RUSLE was 28.0%smaller than that by the original RUSLE with decrement of 19.6%—24.0%in the average P factor values,indicating that the soil erosion modelling accuracy was significantly enhanced by the improved RUSLE.Relatively low P factor values appeared for farmlands with tillage measures(P<0.53),grasslands with engineering measures(P<0.23),woodlands with biological measures(P<0.28),and other land use types with biological measures(P<0.51).The soil erosion modulus showed a downward trend with the corresponding values of 1681.21,1673.14,1594.70,1482.40 and 1437.50 t km^(-2)a-1 in 2000,2005,2010,2015 and 2019,respectively.The applicability of the improved RUSLE was verified by the measurements in typical mountainous and hilly areas of Hubei Province,China,and arrangements of SWC measures of this area were proposed.
基金funded by the National Basic Research Program of China (2014CB138702)the National Natural Science Foundation of China (31502001)China Agriculture Research System (CARS-22 Green Manue)
文摘Dear Editor,Perennial ryegrass (Lolium perenne) is a globally important forage and turf grass species that commonly forms symbiotic associations with the asexual fungal endophyte—Epichloe festucae var.lolii.Epichloe endophytes mutualistically interact with host plants by providing major fitness enhancements and protection from both biotic and abiotic stresses (Young et al.,2013).Previous studies have shown that Epichloe festucae var.lolii inhibits the growth of plant pathogenic fungi and fungal spore germination in vitro.Additional studies conducted in the lab or field confirmed that endophytes inhibited pathogen invasion and lesion development in perennial ryegrass.However,endophytes are not always beneficial,and may even weaken the host plant and reduce the disease resistance of the host.Such inconsistent or contrasting results in Festuca spp.,Achnatherum inebrians and Leymus chinensis have also been reported (Wang et al.,2016).
基金financially supported by the Wenzhou Public Welfare Technology Research Industry Project(No.G20140042)。
文摘The three-layered(W-60 vol%Cu/W-40 vol%Cu/W-20 vol%Cu)W/Cu functionally graded material(FGM)containing a Cu network structure was fabricated at different temperatures by hot-pressed sintering produced from copper-coated tungsten powders.The effects of various sintering temperatures on relative density,microstructure,thermal conductivity,hardness and flexural strength were investigated.Scanning electron microscopy(SEM)and X-ray diffraction(XRD)analysis show that a Cu network extends throughout the W/Cu FGM specimens sintered at 1065℃and the graded structure can be retained perfectly,and W particles are distributed homogeneously.The low-temperature sintering densification of W/Cu FGM arises because the sintering mode of the copper-coated tungsten particles includes just sintering Cu to Cu,rather than Cu to W,Cu to Cu and W to W,as required for conventional powder particles.The relative density of W/Cu FGM sintered at 1065℃for 3 h under a load of25 MPa is 96.1%.The thermal conductivity is up to204 W·m^-1·K^-1 at normal temperature and 150 W·m^-1·K^-1at 800℃.And the Vickers hardness varies with the gradient of different layers from 3.34 to 4.05 GPa.
基金National Nature Science Foundation of China(31971768)Gansu Transportation Department Science and Technology Project(2021-07 and 2021-28).
文摘Background:Epichloësinensis is a newly found endophyte species that is frequently involved in symbiosis with Festuca sinensis.There are a little reports on the characteristics of E.sinensis in vitro.Methods:In the present study,five E.sinensis endophyte strains(strain ID 1,2,41D,57D,111D)isolated from different F.sinensis ecotypes were used to evaluate their antioxidant capacities and enzyme activities.Also,the growth of E.sinensis on potato dextrose agar(PDA)with different additives was investigated.Results:The five strains had significantly different(p<0.05)total antioxidant capacities and radical-scavenging abilities.In most cases,the growth rate of strain 1 was the fastest(p<0.05),and that of strain 57D was the slowest(p<0.05).The growth rates of these five strains on PDA with vitamins significantly(p<0.05)increased with increasing vitamin concentration.The growth rates of these five strains on PDA with plant growth regulators also significantly(p<0.05)increased;however,the increase was inconsistent at different concentrations of indole-3-acetic acid and gibberellin.Low concentrations(5 and 10 mg L−1)of forchlorfenuron(KT-30)significantly promoted the growth of all five strains,whereas high concentrations(20 and 40 mg L−1)of KT-30 significantly inhibited their growth(p<0.05).The Na+,Cd2+,Zn2+,and Cr6+ions all inhibited the growth of these five strains,and their growth rates were significantly decreased with an increase in ion concentrations(p<0.05).Under Na+stress,strain 41D grew the fastest and had the strongest tolerance(p<0.05);under Cd2+,Zn2+,and Cr6+stresses,strain 111D grew the fastest and had the strongest tolerance(p<0.05).Conclusions:The results indicated that the E.sinensis had antioxidant activities and hydrolase activities.Additives could promote or inhibit the growth of the strains in different degrees.All these evaluations in the present study improve our understanding of the E.sinensis endophyte and provide referenced information for further studies.
