●Long-term organic fertilization promoted the positive rhizosphere effects on r-strategist bacteria and K-strategist bacterivorous nematodes.●Long-term inorganic fertilization facilitated the positive rhizosphere ef...●Long-term organic fertilization promoted the positive rhizosphere effects on r-strategist bacteria and K-strategist bacterivorous nematodes.●Long-term inorganic fertilization facilitated the positive rhizosphere effects on K-strategist bacteria and r-strategist bacterivorous nematodes.●The r/K-strategist bacteria interact with r/K-strategist bacterivorous nematodes to suppress herbivorous nematodes abundances.Microbial food web organisms’responses to fertilization are influenced by their r/K-strategies.The roles of r/K-strategist microbes and their associated microbivorous nematodes in regulating herbivorous nematodes abundances remain unexplored,especially under different fertilization regimes.Filling this knowledge gap is critical for enhancing agricultural sustainability through optimization of microbial food web.Here,the microbial food web community structure was analyzed in two soil compartments(bulk/rhizosphere soil)from oilseed rape(Brassica napusL.)season to investigate interactions between r/K-strategist microbes and nematodes under organic and inorganic fertilization regimes.Fertilization regimes,rather than soil compartments,predominantly controlled the microbial food web community structure.Under organic fertilization,the relative abundances of r-strategist bacteria and bacterivores of cp-3 guild were greater in the rhizosphere than in the bulk soil.In contrast,under inorganic fertilization regimes,K-strategist bacteria and bacterivores of cp-2 guild were enriched in the rhizosphere versus the bulk soil.Differential r/K-strategist bacteria controlled the microbial food web network,with r-and K-strategist bacteria predominating under organic and inorganic fertilization,respectively.Soil organic carbon from organic fertilization stimulated the growth of r-strategist bacteria,which interacted with bacterivores of cp-3 guild to reduce the relative abundance of herbivores in the rhizosphere soil.Acidification from inorganic fertilization enriched K-strategist bacteria,which interacted with bacterivores cp-2 or cp-3 guilds to suppress herbivores abundances in the rhizosphere soil.Overall,our findings highlight the importance of cross-kingdom interactions among r/K-strategist organisms for the biocontrol of herbivores,providing guidance for harnessing microbial food web to create a healthy plant rhizosphere.展开更多
The functional performance of soil ecosystems following disturbance determines ecosystem stability,and although contributions of bacterivorous nematodes to soil ecosystems are recognized,their roles in functional stab...The functional performance of soil ecosystems following disturbance determines ecosystem stability,and although contributions of bacterivorous nematodes to soil ecosystems are recognized,their roles in functional stability have received little attention.The objective of this study was to evaluate the roles of bacterivorous nematodes in functional stability following stress.In a factorial laboratory experiment,soil microcosms were prepared with two levels of nematode abundance,either an enriched abundance of bacterivores(Nema soil)or background abundance of nematodes(CK soil),and three levels of stress,copper,heat,or an unstressed control.The resistance and resilience of nematode abundance,as well as soil microbial function by determining decomposition of plant residues and microbial substrate utilization pattern using a BIOLOG microplate,were followed post stress.The relative changes of two dominant bacterivores,Acrobeloides and Protorhabditis,responded differently to stresses.The resistance and resilience of Protorhabditis were greater than that of Acrobeloides to copper stress during the whole incubation period,while both bacterivores only showed higher resilience under heat stress at the end of incubation.The enrichment of bacterivores had no significant effects on the soil microbial resistance but significantly increased its resilience to copper stress.Under heat stress,the positive effect of bacterivores on soil resilience was only evident from 28 days to the end of incubation.The differences in the responses of soil function to stress with or without bacterivores suggested that soil nematodes could be conducive to ecosystem stability,highlighting the soil fauna should be taken into account in soil sustainable management.展开更多
Mixed cultivation of fast-growing grasses and nitrogen(N)-fixing legumes for forage production is widely considered effective for obtaining sustained high forage yields without depleting soil N levels.However,the effe...Mixed cultivation of fast-growing grasses and nitrogen(N)-fixing legumes for forage production is widely considered effective for obtaining sustained high forage yields without depleting soil N levels.However,the effects of monoculture and mixed culture of these species on soil food webs are poorly understood.In this study,soil nematode communities were examined as indicators of the soil food web structure of monoculture and mixed culture of grass and legume at three N levels,i.e.,338(low),450(moderate),and 675(high)kg N ha-1 year-1,across 2 years in wet and dry seasons,using the grass Paspalum wetsfeteini and the legume Medicago sativa(alfalfa),both commonly cultivated worldwide.Repeated-measures analysis of covariance showed that compared with grass monoculture,legume monoculture and grass-legume mixture increased abundances of herbivorous,bacterivorous,and fungivorous nematodes in the soil food web under the low and moderate N fertilization levels.Principal response curve results showed that the abundance of Helicotylenchus,a plant parasite,was significantly higher under legume monoculture than other planting systems at the low N fertilization level.Structural equation model analysis indicated that the legume increased bacterivore abundance,while increasing N fertilization decreased omnivore abundance.The legume might increase the quantity and quality of food resources for soil biota,resulting in the bottom-up control of soil nematode communities.Our results indicate that targeted control of a soilborne pathogen,Helicotylenchus,is required in alfalfa-based planting systems.In addition,high inorganic N application,which is detrimental to legume-rhizobia symbiosis,nullified the otherwise positive effects of legumes on soil nematodes.展开更多
Prescribed fire produced a landscape with two types of severely burned patches: charred shrub patches and charred patches with tree trunks at the center. Soil nematodes were more abundant in burned and unburned junipe...Prescribed fire produced a landscape with two types of severely burned patches: charred shrub patches and charred patches with tree trunks at the center. Soil nematodes were more abundant in burned and unburned juniper (Juniperus monosperma) tree patches than in yucca-shrub patches. There were no differences in nematode abundance between burned and unburned patches during the late spring and summer samples. Nematode abundance was significantly (p < 0.05) higher in unburned patches than in burned patches in the early spring samples, reflecting large differences in soil moisture between unburned and burned patches. There were no differences in soil nematode abundance between burned and unburned patches at oneyear post-burn and three-year post-burn sites. When all samples were pooled, taxonomic diversity, ecological indices, and abundance of trophic groups (bacteria-feeders, fungi-feeders, and omnivore-predators) were higher in unburned than burned patches. These results suggest that the long-term (up to three years post-burn) effects of fire on soil nematodes are indirect, i.e., by loss of tree canopies, litter accumulation, and shrub foliage, which affects soil temperatures and water redistribution.展开更多
基金supported by the National Key Research and Development Program of China(Grant No.2018YFD0800202)the Fundamental Research Funds for the Central Universities(Grant No.226-2024-00052)+2 种基金supported by the National Natural Science Foundation of China(Grant No.42007083)the China Postdoctoral Science Foundation(Grant No.2020M671736)supported by a Royal Society University Research Fellowship(Grant No.URF150571)。
文摘●Long-term organic fertilization promoted the positive rhizosphere effects on r-strategist bacteria and K-strategist bacterivorous nematodes.●Long-term inorganic fertilization facilitated the positive rhizosphere effects on K-strategist bacteria and r-strategist bacterivorous nematodes.●The r/K-strategist bacteria interact with r/K-strategist bacterivorous nematodes to suppress herbivorous nematodes abundances.Microbial food web organisms’responses to fertilization are influenced by their r/K-strategies.The roles of r/K-strategist microbes and their associated microbivorous nematodes in regulating herbivorous nematodes abundances remain unexplored,especially under different fertilization regimes.Filling this knowledge gap is critical for enhancing agricultural sustainability through optimization of microbial food web.Here,the microbial food web community structure was analyzed in two soil compartments(bulk/rhizosphere soil)from oilseed rape(Brassica napusL.)season to investigate interactions between r/K-strategist microbes and nematodes under organic and inorganic fertilization regimes.Fertilization regimes,rather than soil compartments,predominantly controlled the microbial food web community structure.Under organic fertilization,the relative abundances of r-strategist bacteria and bacterivores of cp-3 guild were greater in the rhizosphere than in the bulk soil.In contrast,under inorganic fertilization regimes,K-strategist bacteria and bacterivores of cp-2 guild were enriched in the rhizosphere versus the bulk soil.Differential r/K-strategist bacteria controlled the microbial food web network,with r-and K-strategist bacteria predominating under organic and inorganic fertilization,respectively.Soil organic carbon from organic fertilization stimulated the growth of r-strategist bacteria,which interacted with bacterivores of cp-3 guild to reduce the relative abundance of herbivores in the rhizosphere soil.Acidification from inorganic fertilization enriched K-strategist bacteria,which interacted with bacterivores cp-2 or cp-3 guilds to suppress herbivores abundances in the rhizosphere soil.Overall,our findings highlight the importance of cross-kingdom interactions among r/K-strategist organisms for the biocontrol of herbivores,providing guidance for harnessing microbial food web to create a healthy plant rhizosphere.
基金supported by the National Foundation of Sciences in China(No.41877056)China Agriculture Research System-Green Manure(No.CARS-22-G-10).
文摘The functional performance of soil ecosystems following disturbance determines ecosystem stability,and although contributions of bacterivorous nematodes to soil ecosystems are recognized,their roles in functional stability have received little attention.The objective of this study was to evaluate the roles of bacterivorous nematodes in functional stability following stress.In a factorial laboratory experiment,soil microcosms were prepared with two levels of nematode abundance,either an enriched abundance of bacterivores(Nema soil)or background abundance of nematodes(CK soil),and three levels of stress,copper,heat,or an unstressed control.The resistance and resilience of nematode abundance,as well as soil microbial function by determining decomposition of plant residues and microbial substrate utilization pattern using a BIOLOG microplate,were followed post stress.The relative changes of two dominant bacterivores,Acrobeloides and Protorhabditis,responded differently to stresses.The resistance and resilience of Protorhabditis were greater than that of Acrobeloides to copper stress during the whole incubation period,while both bacterivores only showed higher resilience under heat stress at the end of incubation.The enrichment of bacterivores had no significant effects on the soil microbial resistance but significantly increased its resilience to copper stress.Under heat stress,the positive effect of bacterivores on soil resilience was only evident from 28 days to the end of incubation.The differences in the responses of soil function to stress with or without bacterivores suggested that soil nematodes could be conducive to ecosystem stability,highlighting the soil fauna should be taken into account in soil sustainable management.
基金supported by the National Natural Science Foundation of China(Nos.41877055,31870454,and 41930652)the Strategic Priority Research Program of Chinese Academy of Sciences(No.XDA23060103)+3 种基金the Guangxi Natural Science Foundation,China(No.2018GXNSFAA281008)the Program of the Youth Innovation Promotion Association of Chinese Academy of Sciences(No.Y201969)the Foundation for Young Scholars in Western China of Chinese Academy of Sciences given to Dr.Jie Zhaothe Youth Innovation Team Project of Institute of Subtropical Agriculture,Chinese Academy of Sciences(No.2017QNCXTD_ZJ)
文摘Mixed cultivation of fast-growing grasses and nitrogen(N)-fixing legumes for forage production is widely considered effective for obtaining sustained high forage yields without depleting soil N levels.However,the effects of monoculture and mixed culture of these species on soil food webs are poorly understood.In this study,soil nematode communities were examined as indicators of the soil food web structure of monoculture and mixed culture of grass and legume at three N levels,i.e.,338(low),450(moderate),and 675(high)kg N ha-1 year-1,across 2 years in wet and dry seasons,using the grass Paspalum wetsfeteini and the legume Medicago sativa(alfalfa),both commonly cultivated worldwide.Repeated-measures analysis of covariance showed that compared with grass monoculture,legume monoculture and grass-legume mixture increased abundances of herbivorous,bacterivorous,and fungivorous nematodes in the soil food web under the low and moderate N fertilization levels.Principal response curve results showed that the abundance of Helicotylenchus,a plant parasite,was significantly higher under legume monoculture than other planting systems at the low N fertilization level.Structural equation model analysis indicated that the legume increased bacterivore abundance,while increasing N fertilization decreased omnivore abundance.The legume might increase the quantity and quality of food resources for soil biota,resulting in the bottom-up control of soil nematode communities.Our results indicate that targeted control of a soilborne pathogen,Helicotylenchus,is required in alfalfa-based planting systems.In addition,high inorganic N application,which is detrimental to legume-rhizobia symbiosis,nullified the otherwise positive effects of legumes on soil nematodes.
文摘Prescribed fire produced a landscape with two types of severely burned patches: charred shrub patches and charred patches with tree trunks at the center. Soil nematodes were more abundant in burned and unburned juniper (Juniperus monosperma) tree patches than in yucca-shrub patches. There were no differences in nematode abundance between burned and unburned patches during the late spring and summer samples. Nematode abundance was significantly (p < 0.05) higher in unburned patches than in burned patches in the early spring samples, reflecting large differences in soil moisture between unburned and burned patches. There were no differences in soil nematode abundance between burned and unburned patches at oneyear post-burn and three-year post-burn sites. When all samples were pooled, taxonomic diversity, ecological indices, and abundance of trophic groups (bacteria-feeders, fungi-feeders, and omnivore-predators) were higher in unburned than burned patches. These results suggest that the long-term (up to three years post-burn) effects of fire on soil nematodes are indirect, i.e., by loss of tree canopies, litter accumulation, and shrub foliage, which affects soil temperatures and water redistribution.
