From April to December in 1997 at Northwest Plateau Institute of Biology, Chinese Academy of Science, the effect of predation risk on social behavior, feeding, reproduction and sexual hormones of the root voles (Micro...From April to December in 1997 at Northwest Plateau Institute of Biology, Chinese Academy of Science, the effect of predation risk on social behavior, feeding, reproduction and sexual hormones of the root voles (Microtus oeconomus) was studied when the root voles (Microtus oeconomus ) were exposed to the odor of fitch (Mustila eversmanni). The results showed that the root voles delayed breeding period and the frequency of the copulation significantly lowered (P【0.01). Comparing with the control group, the accumulated time of amicable behavior in females, and general activity of both sexes increased significantly (P【0.01). The frequencies of general activity (P【0.01), investigating activity (females: P【0.05, males: P【0.01), and self-grooming (P【0.01) of both sexes were less significantly. At the same time, the amount of energy intake (P【0.05) and body weight (P【0.01) of the root voles decreased significantly. The litter weight and ovary index of females decreased (P【0.01). For males the sperm count in epididymides also decreased significantly (P【0.01). The progesterone in the blood serum of root voles females increased significantly under fitch odor (P【0.01).展开更多
Three paddy soils were examined for their capacities of dissimilatory reduction of nitrate to ammonium (DRNA). 15 N labelled KNO 3 was added at the rate of 100 mg N kg -1 . Either glucose or rice straw ...Three paddy soils were examined for their capacities of dissimilatory reduction of nitrate to ammonium (DRNA). 15 N labelled KNO 3 was added at the rate of 100 mg N kg -1 . Either glucose or rice straw powder was incorporated at the rate of 1.0 or 2.0 mg C kg -1 respectively. Three treatments were designed to keep the soil saturated with water: A) a 2 cm water layer on soil surface (with beaker mouth open); B) a 2 cm water layer and a 1 cm liquid paraffin layer (with beaker mouth open); and C) water saturated under O 2 free Ar atmosphere. The soils were incubated at 28 oC for 5 days. There was almost no 15 N labelled NH + 4 N detected in Treatment A. However, there was 1.4 to 3.4 mg N kg -1 15 N labelled NH + 4 N in Treatment B and 2.1 to 13.8 mg N kg -1 in Treatment C. Glucose was more effective than straw powder in ammonium production. Because there was sufficient amount of non labelled NH + 4 N in the original soils, 15 N labelled NH + 4 N produced as such should be the result of dissimilatory reduction. Studies on microbial population showed that there were plenty of bacteria responsible for DRNA process (DRNA bacteria) in the soils examined, indicating that number of DRNA bacteria was not a limiting factor for ammonium production. However, DRNA bacteria were inferior in number to denitrifiers. DRNA process in soil suspension seemed to start after 5 days of incubation. Glycerol and sodium succinate, though both are readily available carbon sources to organisms,did not facilitate DRNA process. DRNA occurred only when glucose was available and at the C/NO 3 - N ratio of over 12. It seemed that both availability and quality of the carbon sources affected DRNA.展开更多
The functional diversity of rhizosphere microflora which is also known as the “microbial community” is a sensitive indicator of soil quality subject to the type of winter cover crop and straw returning.In order to e...The functional diversity of rhizosphere microflora which is also known as the “microbial community” is a sensitive indicator of soil quality subject to the type of winter cover crop and straw returning.In order to evaluate the effects of different winter cover crops and returning patterns on the functional diversity of rhizosphere microflora in double-crop rice paddies,we designed five winter cover crops and straw returning combinations to analyze their effects on the functional diversity of rhizosphere microflora in rice paddies: ryegrass (Lolium multiflorumL.)–double-crop rice (Ry),milk vetch (Astragalus sinicus L.)–double-crop rice (Mv),Rape (Brassica napus L.)–Double-crop rice (Ra), Potato (Solanum tuberosum L.)–double-crop rice (Po),and winter fallow–doublecrop rice (CK,the control).In this paper,the average well color development (AWCD) in Biolog-GN plates indicated the capacity for carbon utilization by the rhizosphere microbial community.We analyzed the rhizosphere microbial community functional diversity of the paddy soils with the above five treatments by using the Biolog-GN system.The results showed that applications of winter cover crop and straw returning caused high increases in AWCD compared with CK,and the AWCD values for samples with Po treatment was greater than those with Ry and CK treatments at the early and late rice maturity stages. It was concluded that applications of winter cover crop and straw returning can cause changes in the carbon utilization efficiency of rhizosphere microflora.There were differences in the genetic diversity of the rhizosphere microflora among different treatments at the maturity stage of early and late rice.The richness,Shannon,and McIntosh Index under different winter cover crop and straw returning treatments were significantly different.The highest indexes were observed in the Po treatment and the lowest in the CK at the maturity stage of early and late rice.The richness, Shannon,and McIntosh Index under different treatments ranked in descending order is as follows: Po>Ra>Mv>Ry>CK.Principal Component Analysis (PCA) of substrate reactions were conducted in this research.The results indicated that the pattern of carbon source utilization varied with winter cover crop treatments,and that carbohydrates and amino acids were the main carbon sources of rhizosphere microorganisms.To conclude,the application of winter cover crop and straw returning to paddy fields could significantly increase the carbon source utilization, species richness,and species evenness of rhizosphere microflora in double-crop rice paddies.展开更多
There is an increasing concern about rice (Oryza sativa L.) soil microbiomes under the influence of mixed heavy metal contamina- tion. We used the high-throughput Illumina MiSeq sequencing approach to explore the ba...There is an increasing concern about rice (Oryza sativa L.) soil microbiomes under the influence of mixed heavy metal contamina- tion. We used the high-throughput Illumina MiSeq sequencing approach to explore the bacterial diversity and community composition of soils in four paddy fields, exhibiting four degrees of mixed heavy metal (Cd, Pb and Zn) pollution, and examined the effects of these metals on the bacterial communities. Our results showed that up to 2 104 to 4 359 bacterial operational taxonomic units (OTUs) were found in the bulk and rhizosphere soils of the paddy fields, with the dominant bacterial phyla (greater than 1% of the overall community) including Proteobacteria, Actinobacteria, Firmicutes, Acidobacteria, Gemmatimonadetes, Chlorofiexi, Bacteroidetes and Nitrospirem. A number of rare and candidate bacterial groups were also detected, and Saprospirales, HOC36, SC-I-84 and Anaerospora were rarely detected in rice paddy soils. Venn diagram analysis showed that 174 bacterial OTUs were shared among the bulk soils with four pollution degrees. Rice rhizosphere soils displayed higher bacterial diversity indices (ACE and Chao 1) and more unique OTUs than bulk soils. Total Cd and Zn in the soils were significantly negatively correlated with ACE and Chao 1, respectively, and the Mantel test suggested that total Pb, total Zn, pH, total nitrogen and total phosphorus significantly affected the community structure. Overall, these results provided baseline data for the bacterial communities in bulk and rhizosphere soils of paddy fields contaminated with mixed heavy metals.展开更多
To measure the contribution of root respiration (Rr) to total soil respiration (Rt) in arid cotton fields, eighteen plots, nine for girdling and nine control, were built in an arid cotton field in the Aksu National Ex...To measure the contribution of root respiration (Rr) to total soil respiration (Rt) in arid cotton fields, eighteen plots, nine for girdling and nine control, were built in an arid cotton field in the Aksu National Experimental Station of Oasis Farmland Ecosystem, Xinjiang of China. Given the difference of soil respiration between girdled plots and non-girdled control plots, the components of soil respiration, root respiration (Rr) and respiration originating from decomposition (Rd) were divided. The temperature sensitivities of R r and R d were analyzed, respectively. The results showed that the average contribution of R r to R t in arid cotton field was about 32% during the study period. The temperature-response curve of R r differed from that of Rd . The dynamic variation of R d was more related to the change of soil temperature as compared to Rr . Rr and Rd had different responses to the variation of environment, and thus new models capable of differentiating between Rr and Rd are needed for evaluating the different factors controlling these two components of soil respiration in arid cotton field.展开更多
Biosolids application in periurban agroecosystems could mitigate climate change by sequestering C, while improving plant net primary production(NPP). Monitoring NPP is useful for studying ecological responses to human...Biosolids application in periurban agroecosystems could mitigate climate change by sequestering C, while improving plant net primary production(NPP). Monitoring NPP is useful for studying ecological responses to human management. The values of NPP and C input in periurban agroecosystems are insufficient or missing. The objective was to use local databases to estimate NPP and C input in periurban areas(south, north and west) of Buenos Aires City, Argentina, using different biosolids application scenarios(low and high effects). The NPP varied with crop and vegetable types(P < 0.05), with maize(Zea mays) and wheat(Triticum aestivum) presenting the highest production, soybean(Glycine max) medium and sunflower(Helianthus annuus) the lowest. Tomato(Lycopersicon esculentum Mill.) presented the highest production in the south area(La Plata). West and north areas, where Vertic and Typic Argiudolls are the main soils, presented the lowest NPP and C input. According to the low and high effect scenarios,only vegetables presented significant differences(P < 0.05) in average and cumulative NPP and C input between areas. Vegetables contributed with the highest proportion(> 70%) to NPP in both projected scenarios. For both scenarios, average C input by crops and vegetables presented similar proportions. Biosolids addition in periurban agroecosystems could be a viable practice to elevate NPP and C input.展开更多
文摘From April to December in 1997 at Northwest Plateau Institute of Biology, Chinese Academy of Science, the effect of predation risk on social behavior, feeding, reproduction and sexual hormones of the root voles (Microtus oeconomus) was studied when the root voles (Microtus oeconomus ) were exposed to the odor of fitch (Mustila eversmanni). The results showed that the root voles delayed breeding period and the frequency of the copulation significantly lowered (P【0.01). Comparing with the control group, the accumulated time of amicable behavior in females, and general activity of both sexes increased significantly (P【0.01). The frequencies of general activity (P【0.01), investigating activity (females: P【0.05, males: P【0.01), and self-grooming (P【0.01) of both sexes were less significantly. At the same time, the amount of energy intake (P【0.05) and body weight (P【0.01) of the root voles decreased significantly. The litter weight and ovary index of females decreased (P【0.01). For males the sperm count in epididymides also decreased significantly (P【0.01). The progesterone in the blood serum of root voles females increased significantly under fitch odor (P【0.01).
文摘Three paddy soils were examined for their capacities of dissimilatory reduction of nitrate to ammonium (DRNA). 15 N labelled KNO 3 was added at the rate of 100 mg N kg -1 . Either glucose or rice straw powder was incorporated at the rate of 1.0 or 2.0 mg C kg -1 respectively. Three treatments were designed to keep the soil saturated with water: A) a 2 cm water layer on soil surface (with beaker mouth open); B) a 2 cm water layer and a 1 cm liquid paraffin layer (with beaker mouth open); and C) water saturated under O 2 free Ar atmosphere. The soils were incubated at 28 oC for 5 days. There was almost no 15 N labelled NH + 4 N detected in Treatment A. However, there was 1.4 to 3.4 mg N kg -1 15 N labelled NH + 4 N in Treatment B and 2.1 to 13.8 mg N kg -1 in Treatment C. Glucose was more effective than straw powder in ammonium production. Because there was sufficient amount of non labelled NH + 4 N in the original soils, 15 N labelled NH + 4 N produced as such should be the result of dissimilatory reduction. Studies on microbial population showed that there were plenty of bacteria responsible for DRNA process (DRNA bacteria) in the soils examined, indicating that number of DRNA bacteria was not a limiting factor for ammonium production. However, DRNA bacteria were inferior in number to denitrifiers. DRNA process in soil suspension seemed to start after 5 days of incubation. Glycerol and sodium succinate, though both are readily available carbon sources to organisms,did not facilitate DRNA process. DRNA occurred only when glucose was available and at the C/NO 3 - N ratio of over 12. It seemed that both availability and quality of the carbon sources affected DRNA.
文摘The functional diversity of rhizosphere microflora which is also known as the “microbial community” is a sensitive indicator of soil quality subject to the type of winter cover crop and straw returning.In order to evaluate the effects of different winter cover crops and returning patterns on the functional diversity of rhizosphere microflora in double-crop rice paddies,we designed five winter cover crops and straw returning combinations to analyze their effects on the functional diversity of rhizosphere microflora in rice paddies: ryegrass (Lolium multiflorumL.)–double-crop rice (Ry),milk vetch (Astragalus sinicus L.)–double-crop rice (Mv),Rape (Brassica napus L.)–Double-crop rice (Ra), Potato (Solanum tuberosum L.)–double-crop rice (Po),and winter fallow–doublecrop rice (CK,the control).In this paper,the average well color development (AWCD) in Biolog-GN plates indicated the capacity for carbon utilization by the rhizosphere microbial community.We analyzed the rhizosphere microbial community functional diversity of the paddy soils with the above five treatments by using the Biolog-GN system.The results showed that applications of winter cover crop and straw returning caused high increases in AWCD compared with CK,and the AWCD values for samples with Po treatment was greater than those with Ry and CK treatments at the early and late rice maturity stages. It was concluded that applications of winter cover crop and straw returning can cause changes in the carbon utilization efficiency of rhizosphere microflora.There were differences in the genetic diversity of the rhizosphere microflora among different treatments at the maturity stage of early and late rice.The richness,Shannon,and McIntosh Index under different winter cover crop and straw returning treatments were significantly different.The highest indexes were observed in the Po treatment and the lowest in the CK at the maturity stage of early and late rice.The richness, Shannon,and McIntosh Index under different treatments ranked in descending order is as follows: Po>Ra>Mv>Ry>CK.Principal Component Analysis (PCA) of substrate reactions were conducted in this research.The results indicated that the pattern of carbon source utilization varied with winter cover crop treatments,and that carbohydrates and amino acids were the main carbon sources of rhizosphere microorganisms.To conclude,the application of winter cover crop and straw returning to paddy fields could significantly increase the carbon source utilization, species richness,and species evenness of rhizosphere microflora in double-crop rice paddies.
基金supported by the Research Grants Council of the Hong Kong Special Administrative Region, China (No. 28100014)the Research and Development Office of the Education University of Hong Kong, China (No. RG84/2012-2013R)the NSFC-Guangdong United Foundation, China (No. U1501232)
文摘There is an increasing concern about rice (Oryza sativa L.) soil microbiomes under the influence of mixed heavy metal contamina- tion. We used the high-throughput Illumina MiSeq sequencing approach to explore the bacterial diversity and community composition of soils in four paddy fields, exhibiting four degrees of mixed heavy metal (Cd, Pb and Zn) pollution, and examined the effects of these metals on the bacterial communities. Our results showed that up to 2 104 to 4 359 bacterial operational taxonomic units (OTUs) were found in the bulk and rhizosphere soils of the paddy fields, with the dominant bacterial phyla (greater than 1% of the overall community) including Proteobacteria, Actinobacteria, Firmicutes, Acidobacteria, Gemmatimonadetes, Chlorofiexi, Bacteroidetes and Nitrospirem. A number of rare and candidate bacterial groups were also detected, and Saprospirales, HOC36, SC-I-84 and Anaerospora were rarely detected in rice paddy soils. Venn diagram analysis showed that 174 bacterial OTUs were shared among the bulk soils with four pollution degrees. Rice rhizosphere soils displayed higher bacterial diversity indices (ACE and Chao 1) and more unique OTUs than bulk soils. Total Cd and Zn in the soils were significantly negatively correlated with ACE and Chao 1, respectively, and the Mantel test suggested that total Pb, total Zn, pH, total nitrogen and total phosphorus significantly affected the community structure. Overall, these results provided baseline data for the bacterial communities in bulk and rhizosphere soils of paddy fields contaminated with mixed heavy metals.
基金Supported by the National Natural Science Foundation of China(Nos.31000208 and 40830640)the National Basic Research Program(973 Program) of China(No.2009CB421302)
文摘To measure the contribution of root respiration (Rr) to total soil respiration (Rt) in arid cotton fields, eighteen plots, nine for girdling and nine control, were built in an arid cotton field in the Aksu National Experimental Station of Oasis Farmland Ecosystem, Xinjiang of China. Given the difference of soil respiration between girdled plots and non-girdled control plots, the components of soil respiration, root respiration (Rr) and respiration originating from decomposition (Rd) were divided. The temperature sensitivities of R r and R d were analyzed, respectively. The results showed that the average contribution of R r to R t in arid cotton field was about 32% during the study period. The temperature-response curve of R r differed from that of Rd . The dynamic variation of R d was more related to the change of soil temperature as compared to Rr . Rr and Rd had different responses to the variation of environment, and thus new models capable of differentiating between Rr and Rd are needed for evaluating the different factors controlling these two components of soil respiration in arid cotton field.
文摘Biosolids application in periurban agroecosystems could mitigate climate change by sequestering C, while improving plant net primary production(NPP). Monitoring NPP is useful for studying ecological responses to human management. The values of NPP and C input in periurban agroecosystems are insufficient or missing. The objective was to use local databases to estimate NPP and C input in periurban areas(south, north and west) of Buenos Aires City, Argentina, using different biosolids application scenarios(low and high effects). The NPP varied with crop and vegetable types(P < 0.05), with maize(Zea mays) and wheat(Triticum aestivum) presenting the highest production, soybean(Glycine max) medium and sunflower(Helianthus annuus) the lowest. Tomato(Lycopersicon esculentum Mill.) presented the highest production in the south area(La Plata). West and north areas, where Vertic and Typic Argiudolls are the main soils, presented the lowest NPP and C input. According to the low and high effect scenarios,only vegetables presented significant differences(P < 0.05) in average and cumulative NPP and C input between areas. Vegetables contributed with the highest proportion(> 70%) to NPP in both projected scenarios. For both scenarios, average C input by crops and vegetables presented similar proportions. Biosolids addition in periurban agroecosystems could be a viable practice to elevate NPP and C input.