The mechanisms and efficiencies of the removal and remediation of polycyclic aromatic hydrocarbons （PAHs） in soils by different planting patterns with rape （Brassica campestris） and alfalfa （Medicago sativa） wer...The mechanisms and efficiencies of the removal and remediation of polycyclic aromatic hydrocarbons （PAHs） in soils by different planting patterns with rape （Brassica campestris） and alfalfa （Medicago sativa） were studied by pot experiments in a greenhouse. Results showed that the remediation efficiencies under mixed cropping of alfalfa and rape significantly exceeded those under single cropping when the initial concentrations of phenanthrene and pyrene were at 20.05-322.06 mg kg^-1 and 20.24-321.42 mg kg^-1, respectively. After 70 days plantation of crops, the contents of extractable PAHs in soils under mixed cropping were much lower than those under single cropping. About 65.17-83.52% of phenanthrene and 60.09%- 75.34% ofpyrene was removed from the soils under mixed cropping, respectively, which were averagely 43.26 and 40.38% for phenanthrene, and 11.03 and 16.29% for pyren higher than those under single cropping. Alfalfa or rape did absorb and accumulate PAHs from the soils apparently; the PAHs concentrations in plants monotonically increased with the increase of initial PAHs concentrations in soil; the accumulations of PAHs in plants showed following sequence as roots 〉 above parts, phenanthrene 〉 pyrene and single cropping 〉 mixed cropping at same contamination level. Despite the presence of vegetation significantly enhanced the remediation of PAHs in soils, contributions of abiotic loss, plant uptake, accumulation and microbial degradation was much lower than those of plant-microbial interactions in the process of phytoremediation. Thus plant-microbial interactions are the main mechanisms for the remediation enhancement of soil PAHs pollution under mixed cropping models. Results suggested a feasibility of the establishment of multi-species phytoremediation for the improvement of remediation efficiencies of PAHs, which may decrease accumulations of PAHs in crops and thus reduce their risks.展开更多
Nitrogen(N)deposition is a significant aspect of global change and poses a threat to terrestrial biodiversity.The impact of plant-soil microbe relationships to N deposition has recently attracted considerable attentio...Nitrogen(N)deposition is a significant aspect of global change and poses a threat to terrestrial biodiversity.The impact of plant-soil microbe relationships to N deposition has recently attracted considerable attention.Soil microorganisms have been proven to provide nutrients for specific plant growth,especially in nutrient-poor desert steppe ecosystems.However,the effects of N deposition on plant-soil microbial community interactions in such ecosystems remain poorly understood.To investigate these effects,we conducted a 6-year N-addition field experiment in a Stipa breviflora Griseb.desert steppe in Inner Mongolia Autonomous Region,China.Four N treatment levels(N0,N30,N50,and N100,corresponding to 0,30,50,and 100 kg N/(hm2•a),respectively)were applied to simulate atmospheric N deposition.The results showed that N deposition did not significantly affect the aboveground biomass of desert steppe plants.N deposition did not significantly reduce the alfa-diversity of plant and microbial communities in the desert steppe,and low and mediate N additions(N30 and N50)had a promoting effect on them.The variation pattern of plant Shannon index was consistent with that of the soil bacterial Chao1 index.N deposition significantly affected the beta-diversity of plants and soil bacteria,but did not significantly affect fungal communities.In conclusion,N deposition led to co-evolution between desert steppe plants and soil bacterial communities,while fungal communities exhibited strong stability and did not undergo significant changes.These findings help clarify atmospheric N deposition effects on the ecological health and function of the desert steppe.展开更多
Pooideae grasses may be colonized by systemic fungal endophytes.The fitness of endophyte depends entirely on resources and seed transmission from the host plant,while colonized plants may gain increased survival,growt...Pooideae grasses may be colonized by systemic fungal endophytes.The fitness of endophyte depends entirely on resources and seed transmission from the host plant,while colonized plants may gain increased survival,growth,and reproduction relative to their uncolonized conspecifics.Most research of endophyte-grass interactions have been carried out on few cultivars of tall fescue(Schedonorus phoenix)and their symbiont Neotyphodium coenophialum.Lack of studies using wild populations of tall fescue across the species natural distribution range,however,limits the understanding of the ecological and evolutionary role of the symbiosis in nature.We performed a common garden experiment in Southern Finland with three wild,tall fescue populations from northern Europe and the forage cultivar Kentucky-31(KY-31).For each population,we used naturally endophyte-colonized,naturally endophytecolonized but endophyte removed(decolonized),and naturally uncolonized plants to separate effects due to the host genotype from the endophyte.We evaluated growth variables and survival in four environmental treatments of varying water and nutrients.Supply of water and nutrients increased plant biomass and reproductive effort in all populations.This effect was higher for KY-31 plants which produced on average 55%more seeds than wild plants,indicating better adaptation to high resource environments.However,the higher incidence of Claviceps sp.and the low winter survival indicated KY-31 tall fescue is mal-adapted to Northern European conditions.Naturally colonized plants had greater plant biomass(≈12%),reproductive effort(≈22%)and seed mass(≈29%)than naturally uncolonized and decolonized plants.Nonetheless,endophyte colonization did not affect plant survival,and the effects of endophyte colonization on tiller number,panicle/tiller ratio and Claviceps sp.incidence depended on the population origin.In the wild populations,endophyte removal only reduced the number of tillers(≈29%lower),while the difference between naturally colonized and natur展开更多
基金supported by National Natural Science Foundation of China (40071049)the National High Technology R&D Program of China (2006AA10z427)the Science and Technology Committee of Chongqing,China(CSTC-2006AC1018)
文摘The mechanisms and efficiencies of the removal and remediation of polycyclic aromatic hydrocarbons （PAHs） in soils by different planting patterns with rape （Brassica campestris） and alfalfa （Medicago sativa） were studied by pot experiments in a greenhouse. Results showed that the remediation efficiencies under mixed cropping of alfalfa and rape significantly exceeded those under single cropping when the initial concentrations of phenanthrene and pyrene were at 20.05-322.06 mg kg^-1 and 20.24-321.42 mg kg^-1, respectively. After 70 days plantation of crops, the contents of extractable PAHs in soils under mixed cropping were much lower than those under single cropping. About 65.17-83.52% of phenanthrene and 60.09%- 75.34% ofpyrene was removed from the soils under mixed cropping, respectively, which were averagely 43.26 and 40.38% for phenanthrene, and 11.03 and 16.29% for pyren higher than those under single cropping. Alfalfa or rape did absorb and accumulate PAHs from the soils apparently; the PAHs concentrations in plants monotonically increased with the increase of initial PAHs concentrations in soil; the accumulations of PAHs in plants showed following sequence as roots 〉 above parts, phenanthrene 〉 pyrene and single cropping 〉 mixed cropping at same contamination level. Despite the presence of vegetation significantly enhanced the remediation of PAHs in soils, contributions of abiotic loss, plant uptake, accumulation and microbial degradation was much lower than those of plant-microbial interactions in the process of phytoremediation. Thus plant-microbial interactions are the main mechanisms for the remediation enhancement of soil PAHs pollution under mixed cropping models. Results suggested a feasibility of the establishment of multi-species phytoremediation for the improvement of remediation efficiencies of PAHs, which may decrease accumulations of PAHs in crops and thus reduce their risks.
基金the National Natural Science Foundation of China(31860136,31560156)the Basic Scientific Research Service Fee Project of Colleges and Universities of Inner Mongolia Autonomous Regionthe Graduate Scientific Research Innovation Project of Inner Mongolia Autonomous Region(B20210158Z).
文摘Nitrogen(N)deposition is a significant aspect of global change and poses a threat to terrestrial biodiversity.The impact of plant-soil microbe relationships to N deposition has recently attracted considerable attention.Soil microorganisms have been proven to provide nutrients for specific plant growth,especially in nutrient-poor desert steppe ecosystems.However,the effects of N deposition on plant-soil microbial community interactions in such ecosystems remain poorly understood.To investigate these effects,we conducted a 6-year N-addition field experiment in a Stipa breviflora Griseb.desert steppe in Inner Mongolia Autonomous Region,China.Four N treatment levels(N0,N30,N50,and N100,corresponding to 0,30,50,and 100 kg N/(hm2•a),respectively)were applied to simulate atmospheric N deposition.The results showed that N deposition did not significantly affect the aboveground biomass of desert steppe plants.N deposition did not significantly reduce the alfa-diversity of plant and microbial communities in the desert steppe,and low and mediate N additions(N30 and N50)had a promoting effect on them.The variation pattern of plant Shannon index was consistent with that of the soil bacterial Chao1 index.N deposition significantly affected the beta-diversity of plants and soil bacteria,but did not significantly affect fungal communities.In conclusion,N deposition led to co-evolution between desert steppe plants and soil bacterial communities,while fungal communities exhibited strong stability and did not undergo significant changes.These findings help clarify atmospheric N deposition effects on the ecological health and function of the desert steppe.
基金supported by Finnish Academy grants 213401 and 209210Turku University Foundation.
文摘Pooideae grasses may be colonized by systemic fungal endophytes.The fitness of endophyte depends entirely on resources and seed transmission from the host plant,while colonized plants may gain increased survival,growth,and reproduction relative to their uncolonized conspecifics.Most research of endophyte-grass interactions have been carried out on few cultivars of tall fescue(Schedonorus phoenix)and their symbiont Neotyphodium coenophialum.Lack of studies using wild populations of tall fescue across the species natural distribution range,however,limits the understanding of the ecological and evolutionary role of the symbiosis in nature.We performed a common garden experiment in Southern Finland with three wild,tall fescue populations from northern Europe and the forage cultivar Kentucky-31(KY-31).For each population,we used naturally endophyte-colonized,naturally endophytecolonized but endophyte removed(decolonized),and naturally uncolonized plants to separate effects due to the host genotype from the endophyte.We evaluated growth variables and survival in four environmental treatments of varying water and nutrients.Supply of water and nutrients increased plant biomass and reproductive effort in all populations.This effect was higher for KY-31 plants which produced on average 55%more seeds than wild plants,indicating better adaptation to high resource environments.However,the higher incidence of Claviceps sp.and the low winter survival indicated KY-31 tall fescue is mal-adapted to Northern European conditions.Naturally colonized plants had greater plant biomass(≈12%),reproductive effort(≈22%)and seed mass(≈29%)than naturally uncolonized and decolonized plants.Nonetheless,endophyte colonization did not affect plant survival,and the effects of endophyte colonization on tiller number,panicle/tiller ratio and Claviceps sp.incidence depended on the population origin.In the wild populations,endophyte removal only reduced the number of tillers(≈29%lower),while the difference between naturally colonized and natur
