Background: Soil and vegetation have a direct impact on the process and direction of plant community succession, and determine the structure, function, and productivity of ecosystems. However, little is known about th...Background: Soil and vegetation have a direct impact on the process and direction of plant community succession, and determine the structure, function, and productivity of ecosystems. However, little is known about the synergistic influence of soil physicochemical properties and vegetation features on vegetation restoration. The aim of this study was to investigate the co-evolution of soil physicochemical properties and vegetation features in the process of vegetation restoration, and to distinguish the primary and secondary relationships between soil and vegetation in their collaborative effects on promoting vegetation restoration in a subtropical area of China.Methods: Soil samples were collected to 40 cm in four distinct plant communities along a restoration gradient from herb(4–5 years), to shrub(11–12 years), to Pinus massoniana coniferous and broadleaved mixed forest(45–46 years), and to evergreen broadleaved forest(old growth forest). Measurements were taken of the soil physicochemical properties and Shannon–Wiener index(SD), diameter at breast height(DBH), height(H), and biomass. Principal component analysis, linear function analysis, and variation partitioning analysis were then performed to prioritize the relative importance of the leading factors affecting vegetation restoration.Results: Soil physicochemical properties and vegetation features showed a significant trend of improvement across the vegetation restoration gradient, reflected mainly in the high response rates of soil organic carbon(SOC)(140.76%), total nitrogen(TN)(222.48%), total phosphorus(TP)(59.54%), alkaline hydrolysis nitrogen(AN)(544.65%),available phosphorus(AP)(53.28%), species diversity(86.3%), biomass(2906.52%), DBH(128.11%), and H(596.97%).The soil properties(pH, SOC, TN, AN, and TP) and vegetation features(biomass, DBH, and H) had a clear coevolutionary relationship over the course of restoration. The synergistic interaction between soil properties and vegetation features had the greatest effect on biomass(55.55%–72.37%), and the soil properties contributed secondarily(3.30%–31.44%). The main impact factors of biomass varied with the restoration periods.Conclusions: In the process of vegetation restoration, soil and vegetation promoted each other. Vegetation restoration was the cumulative result of changes in soil fertility and vegetation features.展开更多
Leguminous crops play a vital role in enhancing crop yield and improving soil fertility. Therefore, it can be used as an organic N source for improving soil fertility. The purpose of this study was to(i) quantify the ...Leguminous crops play a vital role in enhancing crop yield and improving soil fertility. Therefore, it can be used as an organic N source for improving soil fertility. The purpose of this study was to(i) quantify the amounts of N derived from rhizodeposition, root and above-ground biomass of peanut residue in comparison with wheat and(ii) estimate the effect of the residual N on the wheat-growing season in the subsequent year. The plants of peanut and wheat were stem fed with 15 N urea using the cotton-wick method at the Wuqiao Station of China Agricultural University in 2014. The experiment consisted of four residue-returning strategies in a randomized complete-block design:(i) no return of crop residue(CR0);(ii) return of above-ground biomass of peanut crop(CR1);(iii) return of peanut root biomass(CR2); and(iv) return of all residue of the whole peanut plant(CR3). The 31.5 and 21% of the labeled 15 N isotope were accumulated in the above-ground tissues(leaves and stems) of peanuts and wheat, respectively. N rhizodeposition of peanuts and wheat accounted for 14.91 and 3.61% of the BG15 N, respectively. The 15 N from the below-ground 15 N-labeled of peanuts were supplied 11.3, 5.9, 13.5, and 6.1% of in the CR0, CR1, CR2, and CR3 treatments, respectively. Peanut straw contributes a significant proportion of N to the soil through the decomposition of plant residues and N rhizodeposition. With the current production level on the NCP, it is estimated that peanut straw can potentially replace 104 500 tons of synthetic N fertilizer per year. The inclusion of peanut in rotation with cereal can significantly reduce the use of N fertilizer and enhance the system sustainability.展开更多
The effects of fertilization on activity and composition of soil microbial community depend on nutrient and water availability;however,the combination of these factors on the response of microorganisms was seldom stud...The effects of fertilization on activity and composition of soil microbial community depend on nutrient and water availability;however,the combination of these factors on the response of microorganisms was seldom studied.This study investigated the responses of soil microbial community and enzyme activities to changes in moisture along a gradient of soil fertility formed within a long-term(24 years)field experiment.Soils(0–20 cm)were sampled from the plots under four fertilizer treatments:i)unfertilized control(CK),ii)organic manure(M),iii)nitrogen,phosphorus,and potassium fertilizers(NPK),and iv)NPK plus M(NPK+M).The soils were incubated at three moisture levels:constant submergence,five submerging-draining cycles(S-D cycles),and constant moisture content at 40%water-holding capacity(low moisture).Compared with CK,fertilization increased soil organic carbon(SOC) by 30.1%–36.3%,total N by 27.3%–38.4%,available N by 35.9%–56.4%,available P by 61.4%–440.9%,and total P by 28.6%–102.9%.Soil fertility buffered the negative effects of moisture on enzyme activities and microbial community composition.Enzyme activities decreased in response to submergence and S-D cycles versus low moisture.Compared with low moisture,S-D cycles increased total phospholipid fatty acids(PLFAs)and actinomycete,fungal,and bacterial PLFAs.The increased level of PLFAs in the unfertilized soil after five S-D cycles was greater than that in the fertilized soil.Variations in soil microbial properties responding to moisture separated CK from the long-term fertilization treatments.The coefficients of variation of microbial properties were negatively correlated with SOC,total P,and available N.Soils with higher fertility maintained the original microbial properties more stable in response to changes in moisture compared to low-fertility soil.展开更多
Assessment of soil health requires complexevaluation of properties and functions responsible for abroad range of ecosystem services. Numerous soil qualityindices (SQI) have been suggested for the evaluation ofspecific...Assessment of soil health requires complexevaluation of properties and functions responsible for abroad range of ecosystem services. Numerous soil qualityindices (SQI) have been suggested for the evaluation ofspecific groups of soil functions, but comparison of variousSQI is impossible because they are based on a combinationof specific soil properties. To avoid this problem, wesuggest an SQI-area approach based on the comparison ofthe areas on a radar diagram of a combination of chemical,biological and physical properties. The new approach isindependent of the SQI principle and allows rapid andsimple comparison of parameter groups and soils. Anotherapproach analyzing the resistance and sensitivity ofproperties to degradation is suggested for a detailedevaluation of soil health. The resistance and sensitivityof soil properties are determined through comparison withthe decrease of soil organic carbon (SOC) as a universalparameter responsible for many functions. The SQI-areaand resistance/sensitivity approaches were tested based on quences after the ab and on ment of agricultural soils. Both the SQI-area and the resistance/sensitivity approaches areuseful for basic and applied research, and for decisionmakersto evaluate land-use practices and measure thedegree of soil degradation.展开更多
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
Microplastics provide a new ecological niche for microorganisms,and the accumulation levels of microplastics(MPs)in terrestrial ecosystems are higher than those in marine ecosystems.Here,we applied the zymography to i...Microplastics provide a new ecological niche for microorganisms,and the accumulation levels of microplastics(MPs)in terrestrial ecosystems are higher than those in marine ecosystems.Here,we applied the zymography to investigate how MPs–polyethylene[PE],and polyvinyl chloride[PVC])at two levels(0.01%and 1%soil weight)impacted the spatial distribution of soil hydrolases,nutrient availability,and rice growth in paddy soil.MPs increased the above-ground biomass by 13.0%–15.5%and decreased the below-ground biomass by 8.0%–15.1%.Addition of 0.01%and 1%MPs reduced soil NH4+content by 18.3%–63.2%and 52.2%–80.2%,respectively.The average activities of N-and P-hydrolases increased by 0.8%–4.8%and 1.9%–6.3%with addition of MPs,respectively.The nutrient uptake by rice plants and the enzyme activities in hotspots increased with MP content in soil.The accumulation of MPs in paddy soil could provide an ecological niche that facilitates microbial survival,alters the spatial distribution of soil hydrolases,and decreases nutrient availability.展开更多
During the International Workshop on Soil Erosion and Riverine Sediment in Mountainous Regions held in November 2022,scientists from many countries shared their state-of-the-art knowledge and brainstormed to improve s...During the International Workshop on Soil Erosion and Riverine Sediment in Mountainous Regions held in November 2022,scientists from many countries shared their state-of-the-art knowledge and brainstormed to improve scientific understanding for coping with climate change and anthropogenic impacts.Information summarized in this discussion includes proposed key scientific questions and suggested joint actions to reduce soil erosion and riverine sediment problems in mountainous regions.展开更多
Plant roots are one of the major mediators that allocate carbon captured from the atmosphere to soils as rhizodeposits,including root exudates.Although rhizodeposition regulates both microbial activity and the biogeoc...Plant roots are one of the major mediators that allocate carbon captured from the atmosphere to soils as rhizodeposits,including root exudates.Although rhizodeposition regulates both microbial activity and the biogeochemical cycling of nutrients,the effects of particular exudate species on soil carbon fluxes and key rhizosphere microorganisms remain unclear.By combining high-throughput sequencing,q-PCR,and NanoSIMS analyses,we characterized the bacterial community structure,quantified total bacteria depending on root exudate chemistry,and analyzed the consequences on the mobility of mineral-protected carbon.Using well-controlled incubation experiments,we showed that the three most abundant groups of root exudates(amino acids,carboxylic acids,and sugars)have contrasting effects on the release of dissolved organic carbon(DOC)and bioavailable Fe in an Ultisol through the disruption of organo-mineral associations and the alteration of bacterial communities,thus priming organic matter decomposition in the rhizosphere.High resolution(down to 50 nm)NanoSIMS images of mineral particles indicated that iron and silicon colocalized significantly more organic carbon following amino acid inputs than treatments without exudates or with carboxylic acids.The application of sugar strongly reduced microbial diversity without impacting soil carbon mobilization.Carboxylic acids increased the prevalence of Actinobacteria and facilitated carbon mobilization,whereas amino acid addition increased the abundances of Proteobacteria that prevented DOC release.In summary,root exudate functions are defined by their chemical composition that regulates bacterial community composition and,consequently,the biogeochemical cycling of carbon in the rhizosphere.展开更多
Indigenous grasses have been effectively used to rehabilitate degraded African drylands. Despite their success, studies examining their effects on soil bioindicators such as microbial biomass carbon(C) and enzyme acti...Indigenous grasses have been effectively used to rehabilitate degraded African drylands. Despite their success, studies examining their effects on soil bioindicators such as microbial biomass carbon(C) and enzyme activities are scarce. This study elucidates the effects of drought stress and phenological stages of a typical indigenous African grass, Enteropogon macrostachyus, on microbial biomass and enzyme activities(β-glucosidase, cellobiohydrolase, and chitinase) in the rhizosphere soil. Enteropogon macrostachyus was grown under controlled conditions. Drought stress(partial watering) was simulated during the last 10 d of plant growth, and data were compared with those from optimum moisture conditions. The rhizosphere soil was sampled after 40 d(seedling stage), 70 d(elongation stage), and 80 d(simulated drought stress). A high root:shoot ratio at seedling stage compared with elongation and reproduction stages demonstrated that E. macrostachyus invested more on root biomass in early development, to maximise the uptake of nutrients and water. Microbial biomass and enzyme activities increased with root biomass during plant growth. Ten-day drought at reproduction stage increased the microbial biomass and enzyme activities, accompanying a decrease in binding affinity and catalytic efficiency. In conclusion, drought stress controls soil organic matter decomposition and nutrient mobilization, as well as the competition between plant and microorganisms for nutrient uptake.展开更多
基金supported by the National Forestry Public Welfare Industry Research Project (grant no. 201504411)the National Natural Science Foundation of China (grant nos. 31570447 and 31300524)。
文摘Background: Soil and vegetation have a direct impact on the process and direction of plant community succession, and determine the structure, function, and productivity of ecosystems. However, little is known about the synergistic influence of soil physicochemical properties and vegetation features on vegetation restoration. The aim of this study was to investigate the co-evolution of soil physicochemical properties and vegetation features in the process of vegetation restoration, and to distinguish the primary and secondary relationships between soil and vegetation in their collaborative effects on promoting vegetation restoration in a subtropical area of China.Methods: Soil samples were collected to 40 cm in four distinct plant communities along a restoration gradient from herb(4–5 years), to shrub(11–12 years), to Pinus massoniana coniferous and broadleaved mixed forest(45–46 years), and to evergreen broadleaved forest(old growth forest). Measurements were taken of the soil physicochemical properties and Shannon–Wiener index(SD), diameter at breast height(DBH), height(H), and biomass. Principal component analysis, linear function analysis, and variation partitioning analysis were then performed to prioritize the relative importance of the leading factors affecting vegetation restoration.Results: Soil physicochemical properties and vegetation features showed a significant trend of improvement across the vegetation restoration gradient, reflected mainly in the high response rates of soil organic carbon(SOC)(140.76%), total nitrogen(TN)(222.48%), total phosphorus(TP)(59.54%), alkaline hydrolysis nitrogen(AN)(544.65%),available phosphorus(AP)(53.28%), species diversity(86.3%), biomass(2906.52%), DBH(128.11%), and H(596.97%).The soil properties(pH, SOC, TN, AN, and TP) and vegetation features(biomass, DBH, and H) had a clear coevolutionary relationship over the course of restoration. The synergistic interaction between soil properties and vegetation features had the greatest effect on biomass(55.55%–72.37%), and the soil properties contributed secondarily(3.30%–31.44%). The main impact factors of biomass varied with the restoration periods.Conclusions: In the process of vegetation restoration, soil and vegetation promoted each other. Vegetation restoration was the cumulative result of changes in soil fertility and vegetation features.
基金supported by the National Natural Science Foundation of China(31671640)the Special Fund for Agro-scientific Research in the Public Interest,China(201503121-11)the National Key Research and Development Program of China(2016YFD0300205-01)
文摘Leguminous crops play a vital role in enhancing crop yield and improving soil fertility. Therefore, it can be used as an organic N source for improving soil fertility. The purpose of this study was to(i) quantify the amounts of N derived from rhizodeposition, root and above-ground biomass of peanut residue in comparison with wheat and(ii) estimate the effect of the residual N on the wheat-growing season in the subsequent year. The plants of peanut and wheat were stem fed with 15 N urea using the cotton-wick method at the Wuqiao Station of China Agricultural University in 2014. The experiment consisted of four residue-returning strategies in a randomized complete-block design:(i) no return of crop residue(CR0);(ii) return of above-ground biomass of peanut crop(CR1);(iii) return of peanut root biomass(CR2); and(iv) return of all residue of the whole peanut plant(CR3). The 31.5 and 21% of the labeled 15 N isotope were accumulated in the above-ground tissues(leaves and stems) of peanuts and wheat, respectively. N rhizodeposition of peanuts and wheat accounted for 14.91 and 3.61% of the BG15 N, respectively. The 15 N from the below-ground 15 N-labeled of peanuts were supplied 11.3, 5.9, 13.5, and 6.1% of in the CR0, CR1, CR2, and CR3 treatments, respectively. Peanut straw contributes a significant proportion of N to the soil through the decomposition of plant residues and N rhizodeposition. With the current production level on the NCP, it is estimated that peanut straw can potentially replace 104 500 tons of synthetic N fertilizer per year. The inclusion of peanut in rotation with cereal can significantly reduce the use of N fertilizer and enhance the system sustainability.
文摘The effects of fertilization on activity and composition of soil microbial community depend on nutrient and water availability;however,the combination of these factors on the response of microorganisms was seldom studied.This study investigated the responses of soil microbial community and enzyme activities to changes in moisture along a gradient of soil fertility formed within a long-term(24 years)field experiment.Soils(0–20 cm)were sampled from the plots under four fertilizer treatments:i)unfertilized control(CK),ii)organic manure(M),iii)nitrogen,phosphorus,and potassium fertilizers(NPK),and iv)NPK plus M(NPK+M).The soils were incubated at three moisture levels:constant submergence,five submerging-draining cycles(S-D cycles),and constant moisture content at 40%water-holding capacity(low moisture).Compared with CK,fertilization increased soil organic carbon(SOC) by 30.1%–36.3%,total N by 27.3%–38.4%,available N by 35.9%–56.4%,available P by 61.4%–440.9%,and total P by 28.6%–102.9%.Soil fertility buffered the negative effects of moisture on enzyme activities and microbial community composition.Enzyme activities decreased in response to submergence and S-D cycles versus low moisture.Compared with low moisture,S-D cycles increased total phospholipid fatty acids(PLFAs)and actinomycete,fungal,and bacterial PLFAs.The increased level of PLFAs in the unfertilized soil after five S-D cycles was greater than that in the fertilized soil.Variations in soil microbial properties responding to moisture separated CK from the long-term fertilization treatments.The coefficients of variation of microbial properties were negatively correlated with SOC,total P,and available N.Soils with higher fertility maintained the original microbial properties more stable in response to changes in moisture compared to low-fertility soil.
基金We are most grateful for the state assignment AAAA-A18-118013190177-9the Russian Foundation for Basic Research(18-04-00773 and 19-29-05260).
文摘Assessment of soil health requires complexevaluation of properties and functions responsible for abroad range of ecosystem services. Numerous soil qualityindices (SQI) have been suggested for the evaluation ofspecific groups of soil functions, but comparison of variousSQI is impossible because they are based on a combinationof specific soil properties. To avoid this problem, wesuggest an SQI-area approach based on the comparison ofthe areas on a radar diagram of a combination of chemical,biological and physical properties. The new approach isindependent of the SQI principle and allows rapid andsimple comparison of parameter groups and soils. Anotherapproach analyzing the resistance and sensitivity ofproperties to degradation is suggested for a detailedevaluation of soil health. The resistance and sensitivityof soil properties are determined through comparison withthe decrease of soil organic carbon (SOC) as a universalparameter responsible for many functions. The SQI-areaand resistance/sensitivity approaches were tested based on quences after the ab and on ment of agricultural soils. Both the SQI-area and the resistance/sensitivity approaches areuseful for basic and applied research, and for decisionmakersto evaluate land-use practices and measure thedegree of soil degradation.
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.
基金We are grateful for financial support from the National Key Research and Development Plan(2019YFC1805100)the National Natural Science Foundation of China(42107341,21767012)+2 种基金the UK Natural Environment Research Council and the Global Challenges Research Fund(NE/V005871/1)sponsorship by K.C.Wong Magna Fund in Ningbo Universitythe Science and Technology Plan of Ganzhou City(GSKF201850).
文摘Microplastics provide a new ecological niche for microorganisms,and the accumulation levels of microplastics(MPs)in terrestrial ecosystems are higher than those in marine ecosystems.Here,we applied the zymography to investigate how MPs–polyethylene[PE],and polyvinyl chloride[PVC])at two levels(0.01%and 1%soil weight)impacted the spatial distribution of soil hydrolases,nutrient availability,and rice growth in paddy soil.MPs increased the above-ground biomass by 13.0%–15.5%and decreased the below-ground biomass by 8.0%–15.1%.Addition of 0.01%and 1%MPs reduced soil NH4+content by 18.3%–63.2%and 52.2%–80.2%,respectively.The average activities of N-and P-hydrolases increased by 0.8%–4.8%and 1.9%–6.3%with addition of MPs,respectively.The nutrient uptake by rice plants and the enzyme activities in hotspots increased with MP content in soil.The accumulation of MPs in paddy soil could provide an ecological niche that facilitates microbial survival,alters the spatial distribution of soil hydrolases,and decreases nutrient availability.
文摘During the International Workshop on Soil Erosion and Riverine Sediment in Mountainous Regions held in November 2022,scientists from many countries shared their state-of-the-art knowledge and brainstormed to improve scientific understanding for coping with climate change and anthropogenic impacts.Information summarized in this discussion includes proposed key scientific questions and suggested joint actions to reduce soil erosion and riverine sediment problems in mountainous regions.
基金supported by National Natural Science Foundation of China(Grants No.31902107 and 41977271)Natural Science Foundation of Jiangsu Province(Grant No.BK20211577)+3 种基金the Innovative Research Team Development Plan of the Ministry of Education of China(Grant No.IRT_17R56)supported by Qing Lan Project of Jiangsu Provincethe support by the RUDN University Strategic Academic Leadership Programthe WeChat subscription ID“meta-Genome”and“Micro-Bioinformatics and microflora”for the analysis methods.
文摘Plant roots are one of the major mediators that allocate carbon captured from the atmosphere to soils as rhizodeposits,including root exudates.Although rhizodeposition regulates both microbial activity and the biogeochemical cycling of nutrients,the effects of particular exudate species on soil carbon fluxes and key rhizosphere microorganisms remain unclear.By combining high-throughput sequencing,q-PCR,and NanoSIMS analyses,we characterized the bacterial community structure,quantified total bacteria depending on root exudate chemistry,and analyzed the consequences on the mobility of mineral-protected carbon.Using well-controlled incubation experiments,we showed that the three most abundant groups of root exudates(amino acids,carboxylic acids,and sugars)have contrasting effects on the release of dissolved organic carbon(DOC)and bioavailable Fe in an Ultisol through the disruption of organo-mineral associations and the alteration of bacterial communities,thus priming organic matter decomposition in the rhizosphere.High resolution(down to 50 nm)NanoSIMS images of mineral particles indicated that iron and silicon colocalized significantly more organic carbon following amino acid inputs than treatments without exudates or with carboxylic acids.The application of sugar strongly reduced microbial diversity without impacting soil carbon mobilization.Carboxylic acids increased the prevalence of Actinobacteria and facilitated carbon mobilization,whereas amino acid addition increased the abundances of Proteobacteria that prevented DOC release.In summary,root exudate functions are defined by their chemical composition that regulates bacterial community composition and,consequently,the biogeochemical cycling of carbon in the rhizosphere.
文摘Indigenous grasses have been effectively used to rehabilitate degraded African drylands. Despite their success, studies examining their effects on soil bioindicators such as microbial biomass carbon(C) and enzyme activities are scarce. This study elucidates the effects of drought stress and phenological stages of a typical indigenous African grass, Enteropogon macrostachyus, on microbial biomass and enzyme activities(β-glucosidase, cellobiohydrolase, and chitinase) in the rhizosphere soil. Enteropogon macrostachyus was grown under controlled conditions. Drought stress(partial watering) was simulated during the last 10 d of plant growth, and data were compared with those from optimum moisture conditions. The rhizosphere soil was sampled after 40 d(seedling stage), 70 d(elongation stage), and 80 d(simulated drought stress). A high root:shoot ratio at seedling stage compared with elongation and reproduction stages demonstrated that E. macrostachyus invested more on root biomass in early development, to maximise the uptake of nutrients and water. Microbial biomass and enzyme activities increased with root biomass during plant growth. Ten-day drought at reproduction stage increased the microbial biomass and enzyme activities, accompanying a decrease in binding affinity and catalytic efficiency. In conclusion, drought stress controls soil organic matter decomposition and nutrient mobilization, as well as the competition between plant and microorganisms for nutrient uptake.
