A hydroponic experiment was carried out to study the effect of elevated carbon dioxide(CO2) on root growth of tomato seedlings.Compared with the control(350 μL L-1),CO2 enrichment(800 μL L-1) significantly increased...A hydroponic experiment was carried out to study the effect of elevated carbon dioxide(CO2) on root growth of tomato seedlings.Compared with the control(350 μL L-1),CO2 enrichment(800 μL L-1) significantly increased the dry matter of both shoot and root,the ratio of root to shoot,total root length,root surface area,root diameter,root volume,and root tip numbers,which are important for forming a strong root system.The elevated CO2 treatment also significantly improved root hair development and elongation,thus enhancing nutrient uptake.Increased indole acetic acid concentration in plant tissues and ethylene release in the elevated CO2 treatment might have resulted in root growth enhancement and root hair development and elongation.展开更多
The effects of root activity on microbial response to cadmium(Cd) loading in the rhizosphere are not well understood.A pot experiment in greenhouse was conducted to investigate the effects of low Cd loading and root a...The effects of root activity on microbial response to cadmium(Cd) loading in the rhizosphere are not well understood.A pot experiment in greenhouse was conducted to investigate the effects of low Cd loading and root activity on microbial biomass and community structure in the rhizosphere of pakchoi(Brassica chinensis L.) on silty clay loam and silt loamy soil.Cd was added into soil as Cd(NO_3)_2 to reach concentrations ranging from 0.00 to 7.00 mg kg^(-1).The microbial biomass carbon(MBC) and community structure were affected by Cd concentration,root activity,and soil type.Lower Cd loading rates(<1.00 mg kg^(-1)) stimulated the growth of pakchoi and microorganisms,but higher Cd concentrations inhibited the growth of microorganisms.The content of phospholipid fatty acids(PLFAs) was sensitive to increased Cd levels.MBC was linearly correlated with the total PLFAs.The content of general PLFAs in the fungi was positively correlated with the available Cd in the soil,whereas those in the bacteria and actinomycetes were negatively correlated with the available Cd in the soil.These results indicated that fungi were more resistant to Cd stress than bacteria or actinomycetes,and the latter was the most sensitive to Cd stress.Microbial biomass was more abundant in the rhizosphere than in the bulk soil.Root activity enhanced the growth of microorganisms and stabilized the microbial community structure in the rhizosphere.PLFA analysis was proven to be sensitive in detecting changes in the soil microbial community in response to Cd stress and root activity.展开更多
基金supported by the National Natural Science Foundation of China (No.30871590)the National Key Basic Research Program (973 Program) of China (Nos.2009CB119003 and 2007CB109305)+1 种基金the Major Research Program of Zhejiang Province (No.2008C12061-1)the National "Eleventh Five Years Plan" Key Project on Science and Technology of China (No.2006BAD05B03)
文摘A hydroponic experiment was carried out to study the effect of elevated carbon dioxide(CO2) on root growth of tomato seedlings.Compared with the control(350 μL L-1),CO2 enrichment(800 μL L-1) significantly increased the dry matter of both shoot and root,the ratio of root to shoot,total root length,root surface area,root diameter,root volume,and root tip numbers,which are important for forming a strong root system.The elevated CO2 treatment also significantly improved root hair development and elongation,thus enhancing nutrient uptake.Increased indole acetic acid concentration in plant tissues and ethylene release in the elevated CO2 treatment might have resulted in root growth enhancement and root hair development and elongation.
基金Supported by the Department of Education of Zhejiang Province,China(No.Y200804542)the Innovative Research Team in Higher Educational Institutions of Zhejiang Province,China(No.T200912)+1 种基金the Environmental Protection Research Plana of Hangzhou,China(No.2011008)the Zhejiang Gongshang University,China(No.X13-01)
文摘The effects of root activity on microbial response to cadmium(Cd) loading in the rhizosphere are not well understood.A pot experiment in greenhouse was conducted to investigate the effects of low Cd loading and root activity on microbial biomass and community structure in the rhizosphere of pakchoi(Brassica chinensis L.) on silty clay loam and silt loamy soil.Cd was added into soil as Cd(NO_3)_2 to reach concentrations ranging from 0.00 to 7.00 mg kg^(-1).The microbial biomass carbon(MBC) and community structure were affected by Cd concentration,root activity,and soil type.Lower Cd loading rates(<1.00 mg kg^(-1)) stimulated the growth of pakchoi and microorganisms,but higher Cd concentrations inhibited the growth of microorganisms.The content of phospholipid fatty acids(PLFAs) was sensitive to increased Cd levels.MBC was linearly correlated with the total PLFAs.The content of general PLFAs in the fungi was positively correlated with the available Cd in the soil,whereas those in the bacteria and actinomycetes were negatively correlated with the available Cd in the soil.These results indicated that fungi were more resistant to Cd stress than bacteria or actinomycetes,and the latter was the most sensitive to Cd stress.Microbial biomass was more abundant in the rhizosphere than in the bulk soil.Root activity enhanced the growth of microorganisms and stabilized the microbial community structure in the rhizosphere.PLFA analysis was proven to be sensitive in detecting changes in the soil microbial community in response to Cd stress and root activity.
