Flooding events tend to destroy the original flood-intolerant vegetation in riparian zones,but the flood-tolerant species can confront the stress,and contribute to the riparian ecosystem.Grass species,Hemarthria altis...Flooding events tend to destroy the original flood-intolerant vegetation in riparian zones,but the flood-tolerant species can confront the stress,and contribute to the riparian ecosystem.Grass species,Hemarthria altissima,are usually dominant in the riparian zones.This species is considered as good forage which is usually grazed by livestock or mowed by local people.Therefore,the apical tissues of the plants are often removed,and the plants have to grow without stem apexes,during their life cycle.In this study,we aimed to examine the differences in growth performance of intact versus apex-cut individuals of H.altissima upon complete submergence.Two groups of H.altissima plants(with and without shoot apexes)were treated with dark non-submergence and dark complete submergence conditions for 200 days.During the experiment,we measured plant growth,biomass changes in plant organs,and the consumption of non-structural carbohydrates(NSC)by different tissues.During submergence,shoot elongation stopped,and around six lateral buds were developed averagely by each plant without apexes.This growth performance finally caused 60%decline of NSC in underground parts.The relatively intensive consumption of carbohydrates in submerged apex-removed plants induced the 21%stem length decreased under water,which indicated the decreasing submergence tolerance of plants with shoot apex removed.Therefore,we suggest that when using H.altissima for restoring degraded riparian ecosystems,the shoot apexes should be protected from grazing by livestock or harvesting by local people in order to maintain the submergence tolerance of H.altissima.展开更多
Aims In a large dam-regulated reservoir with regular hydrological pattern and strong flooding gradients across shore elevations,plants inhabiting in different shore elevations have to confront long-lasting flooding of...Aims In a large dam-regulated reservoir with regular hydrological pattern and strong flooding gradients across shore elevations,plants inhabiting in different shore elevations have to confront long-lasting flooding of differential in tensities every year.Such persistent stress may lead to intraspecific differentiation of flooding tolerance in seeds.Echinochloa crusgalli var.zelayensis is a dominant annual plant in the shores of the Three Gorges Reservoir(TGR),which plays an important role in the shore vegetation.The objective of this study is to check whether intraspecific differentiation of seed flooding tolerance has occurred among E.crusgalli var.zelayensis populations in the TGR shores and whether such differentiation is associated with weak seed dispersal.Methods We collected seeds of E.crusgalli var.zelayensis from different populations in the TGR shores,and then placed them at four elevations in the shores flooded by reservoir impoundment.Parameters reflecting seed flooding tolerance including post-flooding percentage of intact seeds,seed germinability and seedling emergence rate were investigated for the seeds from different populations and undergoing flooding of different intensities.Floating time of seeds and speed of water level rise during impoundment were examined,and used to quantify dispersal potential of seeds in the shores of the TGR when flooded.Important Findings Both intact seed percentage and final seedling emergence rate after flooding significantly declined with increasing shore elevations where the seeds were collected,indicating that intraspecific differentiation in seed flooding tolerance has occurred among E.crusgalli var.zelayensis populations in the TGR shores after 7-year operation of the reservoir.The distanee of seeds transported by rising water during reservoir impoundment was limited due to short-floating time of the seeds and relatively low speed of water level rise in the reservoir.This would be favourable to the development of intraspecific differentiation in seed flooding tolerance.展开更多
基金supported by National Natural Science Foundation of China(grant numbers U22A20448,31800331,31400480,31770465)National Key R&D Program of China(grant number 2023YFF1305204)+2 种基金Chongqing Talents Program(grant number cstc2021ycjh-bgzxm0316)the Fundamental Research Funds for the Central Universities(grant number SWU-KT23001)Science Foundation of School of Life Sciences SWU(grant numbers 20212017050401,20212005393901).
文摘Flooding events tend to destroy the original flood-intolerant vegetation in riparian zones,but the flood-tolerant species can confront the stress,and contribute to the riparian ecosystem.Grass species,Hemarthria altissima,are usually dominant in the riparian zones.This species is considered as good forage which is usually grazed by livestock or mowed by local people.Therefore,the apical tissues of the plants are often removed,and the plants have to grow without stem apexes,during their life cycle.In this study,we aimed to examine the differences in growth performance of intact versus apex-cut individuals of H.altissima upon complete submergence.Two groups of H.altissima plants(with and without shoot apexes)were treated with dark non-submergence and dark complete submergence conditions for 200 days.During the experiment,we measured plant growth,biomass changes in plant organs,and the consumption of non-structural carbohydrates(NSC)by different tissues.During submergence,shoot elongation stopped,and around six lateral buds were developed averagely by each plant without apexes.This growth performance finally caused 60%decline of NSC in underground parts.The relatively intensive consumption of carbohydrates in submerged apex-removed plants induced the 21%stem length decreased under water,which indicated the decreasing submergence tolerance of plants with shoot apex removed.Therefore,we suggest that when using H.altissima for restoring degraded riparian ecosystems,the shoot apexes should be protected from grazing by livestock or harvesting by local people in order to maintain the submergence tolerance of H.altissima.
基金supported by the National Key R&D Program of China(2017YFC0505304)National Natural Science Foundation of China(31770465,31370443)Chongqing Municipal Key R&D Program(cstc2018jszx-zdyfxmX0021-01).
文摘Aims In a large dam-regulated reservoir with regular hydrological pattern and strong flooding gradients across shore elevations,plants inhabiting in different shore elevations have to confront long-lasting flooding of differential in tensities every year.Such persistent stress may lead to intraspecific differentiation of flooding tolerance in seeds.Echinochloa crusgalli var.zelayensis is a dominant annual plant in the shores of the Three Gorges Reservoir(TGR),which plays an important role in the shore vegetation.The objective of this study is to check whether intraspecific differentiation of seed flooding tolerance has occurred among E.crusgalli var.zelayensis populations in the TGR shores and whether such differentiation is associated with weak seed dispersal.Methods We collected seeds of E.crusgalli var.zelayensis from different populations in the TGR shores,and then placed them at four elevations in the shores flooded by reservoir impoundment.Parameters reflecting seed flooding tolerance including post-flooding percentage of intact seeds,seed germinability and seedling emergence rate were investigated for the seeds from different populations and undergoing flooding of different intensities.Floating time of seeds and speed of water level rise during impoundment were examined,and used to quantify dispersal potential of seeds in the shores of the TGR when flooded.Important Findings Both intact seed percentage and final seedling emergence rate after flooding significantly declined with increasing shore elevations where the seeds were collected,indicating that intraspecific differentiation in seed flooding tolerance has occurred among E.crusgalli var.zelayensis populations in the TGR shores after 7-year operation of the reservoir.The distanee of seeds transported by rising water during reservoir impoundment was limited due to short-floating time of the seeds and relatively low speed of water level rise in the reservoir.This would be favourable to the development of intraspecific differentiation in seed flooding tolerance.
