Global warming is an increasingly serious ecological problem,we examined how the active autotrophic microbes in paddy soils respond to the elevated CO_(2) and temperature.Here we employed stable isotope probing(SIP)to...Global warming is an increasingly serious ecological problem,we examined how the active autotrophic microbes in paddy soils respond to the elevated CO_(2) and temperature.Here we employed stable isotope probing(SIP)to label the active bacteria using the soil samples from a fully factorial Simulated Climate Change(SCC)field experiment where soils were exposed to ambient CO_(2) and temperature,elevated temperature,elevated CO_(2),and both elevated CO_(2) and temperature.Around 28.9% of active OTUs belonged to ammonia-oxidizing bacteria(AOB)and nitrite-oxidizing bacteria(NOB).Nitrosospira taxa was dominant in all soils and 80.4% of carbon-fixing bacteria under elevated temperature were classified as Nitrosomonas nitrosa.While no labeled NOBs were detected when temperature or CO_(2) were elevated independently,diverse NOBs were detected in the ambient conditions.We found that elevated CO_(2) and temperature had contrasting effects on microbial community composition,while relatively small changes were observed when CO_(2) and temperature were elevated simultaneously.Summarily these results suggest that carbon-fixing bacteria can respond positively to elevated CO_(2) concentrations,but when it’s accompanied with increase in the temperature this positive response could be weakened.Multiple abiotic factors thus need to be considered when predicting how microbial communities will respond to multiple climatic factors.展开更多
Less attention has been given to soil enzymes that contribute to beneficial rhizosphere interactions in intercropping systems.Therefore,we performed a field experiment by growing faba bean,lupine,and maize in mono and...Less attention has been given to soil enzymes that contribute to beneficial rhizosphere interactions in intercropping systems.Therefore,we performed a field experiment by growing faba bean,lupine,and maize in mono and mixed cultures in a moderately fertile soil.We measured shoot biomass and the kinetic parameters(maximal velocity(V max)and Michaelis-constant(K m))of three key enzymes in the rhizosphere:Leucine-aminopeptidase(LAP),β-1,4-N-acetylglucosaminidase(NAG),and phosphomonoesterase(PHO).Faba bean benefitted in mixed cultures by greater shoot biomass production with both maize and lupine compared to its expected biomass in monoculture.Next,LAP and NAG kinetic parameters were less responsive to mono and mixed cultures across the crop species.In contrast,both the V max and K m values of PHO increased in the faba bean rhizosphere when grown in mixed cultures with maize and lupine.A positive relative interaction index for shoot P and N uptake for faba bean showed its net facilitative interactions in the mixed cultures.Overall,these results suggest that over-productivity in intercropping is crop-specific and the positive intercropping effects could be modulated by P availability.We argue that the enzyme activities involved in nutrient cycling should be incorporated in further research.展开更多
基金supported by the National Key Research and Development Program of China(2017YFD0200805)the Special Fund for Agriculture Profession(20150312205)the Innovative Research Team Development Plan of the Ministry of Education of China(IRT_17R56).
文摘Global warming is an increasingly serious ecological problem,we examined how the active autotrophic microbes in paddy soils respond to the elevated CO_(2) and temperature.Here we employed stable isotope probing(SIP)to label the active bacteria using the soil samples from a fully factorial Simulated Climate Change(SCC)field experiment where soils were exposed to ambient CO_(2) and temperature,elevated temperature,elevated CO_(2),and both elevated CO_(2) and temperature.Around 28.9% of active OTUs belonged to ammonia-oxidizing bacteria(AOB)and nitrite-oxidizing bacteria(NOB).Nitrosospira taxa was dominant in all soils and 80.4% of carbon-fixing bacteria under elevated temperature were classified as Nitrosomonas nitrosa.While no labeled NOBs were detected when temperature or CO_(2) were elevated independently,diverse NOBs were detected in the ambient conditions.We found that elevated CO_(2) and temperature had contrasting effects on microbial community composition,while relatively small changes were observed when CO_(2) and temperature were elevated simultaneously.Summarily these results suggest that carbon-fixing bacteria can respond positively to elevated CO_(2) concentrations,but when it’s accompanied with increase in the temperature this positive response could be weakened.Multiple abiotic factors thus need to be considered when predicting how microbial communities will respond to multiple climatic factors.
文摘Less attention has been given to soil enzymes that contribute to beneficial rhizosphere interactions in intercropping systems.Therefore,we performed a field experiment by growing faba bean,lupine,and maize in mono and mixed cultures in a moderately fertile soil.We measured shoot biomass and the kinetic parameters(maximal velocity(V max)and Michaelis-constant(K m))of three key enzymes in the rhizosphere:Leucine-aminopeptidase(LAP),β-1,4-N-acetylglucosaminidase(NAG),and phosphomonoesterase(PHO).Faba bean benefitted in mixed cultures by greater shoot biomass production with both maize and lupine compared to its expected biomass in monoculture.Next,LAP and NAG kinetic parameters were less responsive to mono and mixed cultures across the crop species.In contrast,both the V max and K m values of PHO increased in the faba bean rhizosphere when grown in mixed cultures with maize and lupine.A positive relative interaction index for shoot P and N uptake for faba bean showed its net facilitative interactions in the mixed cultures.Overall,these results suggest that over-productivity in intercropping is crop-specific and the positive intercropping effects could be modulated by P availability.We argue that the enzyme activities involved in nutrient cycling should be incorporated in further research.
