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1.
Huan Jing Ke Xue ; 40(1): 401-411, 2019 Jan 08.
Artigo em Chinês | MEDLINE | ID: mdl-30628299

RESUMO

Crop straw is an important agricultural source, which can replace chemical fertilizers. A field experiment with six different amounts of fertilization combined with maize straw residues was carried out in purple soil, including the control (CK), conventional fertilizing (F), straw return with conventional fertilizing (100FS), straw return with 70% conventional fertilizing (70FS), straw return with 60% conventional fertilizing (60FS), and straw return with 50% regular fertilizing (50FS), to determine the response of the soil N2O emission and ammonia-oxidizing microorganism community distribution to straw return with reducing fertilizer. The dynamic characteristics of the N2O emission in purple soil were observed using an in situ closed chamber and gas chromatography-based system. The ammonia-oxidizing microorganism community distribution was analyzed with multiple molecular techniques (DNA-based clone library and qPCR) linked to physical-chemical soil properties. The results show that the combination of straw with fertilizer increases the N2O emission and cumulative N2O emission. The highest N2O emission[57.59-6238.02 µg·(m2·h)-1]and cumulative N2O emission (60.76 kg·hm-2) were observed for the 100FS treatment. Compared with the F treatment, the soil ammonium nitrogen and nitrate nitrogen contents are reduced and the soil organic matter increases after crop straw return with chemical fertilizer. However, significant changes of the soil total nitrogen and pH were not observed. The bacterial ammonia oxidizer (AOB) amoA gene abundance is higher than that of the archaeal ammonia oxidizer (AOA). The AOA amoA gene abundance during F treatment (50.9×103 copies·g-1) is significantly higher than that of others, while the AOB amoA abundance gene of the F treatment is the lowest (1.36×105 copies·g-1). The 100FS reduces the community diversity and Pielou index of AOA and AOB amoA gene. Their amoA gene abundance significantly declines during 100FS treatment. However, the increment of the AOA and AOB amoA gene diversity and dominant increment of AOB amoA gene abundance are significant when applying straw with reducing fertilizer. The specific AOA indicator OTU1 may be most important with respect to the direct and indirect production of N2O in purple soil. The redundancy analysis (RDA) shows that the community structure of AOA is remarkably relevant to the soil ammonium nitrogen, organic matter, and available phosphorus (P<0.05) and that the community structure of AOB is remarkably relevant to the soil dissolved organic nitrogen, total nitrogen, available potassium, and available phosphorus (P<0.05). The tolerance to different environments and ecological niches of AOB is weaker than that of AOA. Our results illustrate that the maize straw return with 60%-70% regular fertilizing dramatically increases the community diversity and abundance of the AOA and AOB amoA genes and partly mitigates the soil N2O emission without significantly decreasing the vegetable yields.


Assuntos
Amônia/metabolismo , Fertilizantes , Óxido Nitroso/análise , Microbiologia do Solo , Archaea , Bactérias , Genes Arqueais , Genes Bacterianos , Oxirredução , Filogenia , Caules de Planta , Solo/química , Zea mays
2.
Huan Jing Ke Xue ; 39(10): 4694-4704, 2018 Oct 08.
Artigo em Chinês | MEDLINE | ID: mdl-30229618

RESUMO

Greenhouse gases mainly come from farmland soils. Re-spreading chaff (straw returning) is an effective ecological management in China. Quantitative analysis of straw residues together with reduced fertilization rates can provide a scientific basis for reducing greenhouse gas emissions. A field experiment with six different fertilizer amounts combined with straw residues was carried out in a vegetable field (lettuce-cabbage-chili rotation), including the control (CK), conventional fertilizing (F), straw returning with 100% conventional fertilizing (100FS), straw returning with 70% conventional fertilizing (70FS), straw returning with 60% conventional fertilizing (60FS),and straw returning with 50% conventional fertilizing (50FS). The dynamic characteristics and emission factors of CO2, CH4 and N2O in the soil were analyzed using an in-situ, closed chamber, gas chromatography-based system, from November 2016 to September 2017. The results showed that the emission of CO2, CH4 and N2O has seasonal variation characteristics. The peak value mainly occurred in April to August, and the gas emission peak would appear after fertilizing and irrigating. Compared with F treatment, straw returning with fertilizing treatments reduced the N2O emission fluxes, cumulative emission and emission factor, especially in the 100FS treatment. The N2O cumulative emission and emission factor was 60.76 kg·hm-2, 0.138 kg·kg-1 (N2O-N/N) respectively in 100FS treatment during planting chili was more than that during planting lettuce and cabbage. Moreover, straw returning with reducing conventional fertilizing could reduce the N2O emission factor compared with 100FS treatment. The CO2 emission fluxes 55.28-1831.62[mg·(m2·h)-1] and cumulative emission (7502.13-25988.55 kg·hm-2) in 70FS treatment were lower than that in CK and F treatments, while other treatments increased the CO2 emission fluxes and cumulative emission, especially in 60FS and 50FS treatments. During planting lettuce and cabbage, the CH4 cumulative emission mainly showed negative values in treatments except for CK, indicating that soil could adsorb CH4. Moreover, straw returning with 30%-50% conventional fertilizing treatment could reduce CH4 emission fluxes and cumulative emission during planting chili, but increased in 100FS. Compared with CK and F treatment, generally, straw retuning with conventional fertilizing could significantly increase the global warming potential (GWP) in the study, except for 70FS treatment. 70FS could reduce the CO2, CH4 emission and the GWP of greenhouse gases, but could not significantly affect N2O emission reduction.


Assuntos
Agricultura/métodos , Fertilizantes , Gases de Efeito Estufa/análise , Dióxido de Carbono , China , Efeito Estufa , Metano , Óxido Nitroso , Caules de Planta , Solo , Verduras
3.
Huan Jing Ke Xue ; 39(9): 4338-4347, 2018 Sep 08.
Artigo em Chinês | MEDLINE | ID: mdl-30188079

RESUMO

The effects of different straw and biochar applications on the carbon balance of a farmland ecosystem were studied under a rape-maize rotation planting system. The study explored impact of straw and biochar addition on soil carbon sequestration. A field experiment was carried out at the National Monitor Station of Soil Fertility and Fertilizer Efficiency of Purple Soils (Chongqing, China). Five treatments, i.e., control (CK, no organic material), straw only (CS), straw and microorganism (CSD), half straw and half biochar (CSBC), and biochar only (BC), were applied. In-situ cumulative emissions of soil total carbon were subsequently monitored. Based on field experiment and survey data, carbon emissions, carbon sequestration, and and economic and environmental benefits were analyzed for soil respiration, soil carbon pool, crop carbon pool, as well as the cost of agricultural inputs after straw and biochar application. The main results were:①Accumulative emissions of soil carbon during two planting seasons were all higher with treatment than in CK, and the differences between CS, CSD, and CK were significant (P<0.05). ②Compared with CK, both straw and biochar treatments increased crop yield (by 1.49%-3.92%) and crop net primary productivity (NPP) increased by 4.44%-17.90%. Largest yields and NPP during both seasons were achieved with CSD.③Net carbon sequestration was positive during both seasons in all treatments without CK, indicating a carbon sink effect. The highest net carbon sequestration was obtained with CSD (9.05 t·hm-2) and BC (10.75 t·hm-2) treatments. The lowest carbon emissions were obtained with the BC treatment, with emissions 62.69%-81.86% lower than CK. ④The highest production to cost ratio was obtained with CS treatments during the rape planting season. Application of only biochar reduced the production to cost ratio but increased the carbon trading income (466.95-561.22 yuan·hm-2).⑤BC treatment increased carbon productivity (CP) in both seasons, while the economic (CJ) and ecological benefits(CE) of BC treatment were significantly lower than with other treatments. The addition of straw increases economic and ecological benefits; however, addition of biochar reduces such benefits.


Assuntos
Agricultura/métodos , Brassica rapa/crescimento & desenvolvimento , Carbono/análise , Carvão Vegetal , Solo/química , Zea mays/crescimento & desenvolvimento , China , Fertilizantes , Caules de Planta
4.
Huan Jing Ke Xue ; 39(1): 355-362, 2018 Jan 08.
Artigo em Chinês | MEDLINE | ID: mdl-29965702

RESUMO

The aim of this work is to understand the effects of straw and biochar return in soil on the content, distribution, stability, and relative contribution rate of organic carbon for soil aggregates, which could be used to better understanding the stability of the soil carbon pool and the protection mechanisms under straw and biochar return. In this study, a field experiment was conducted to study the effects of straw and biochar return on soil aggregates and carbon sequestration characteristics in a rape-maize rotation planting system. Five treatments, including a control (no organic material added, CK), straw (CS), straw and microorganism (CSD), Biochar (BC), half straw and half biochar (CSBC), were used. The results indicated that ① Straw and biochar could improve the content of soil organic carbon, and the BC and CSBC treatments increased it by 16.88-17.37 g·kg-1, values higher than those with the CS and CSD treatments (13.76-14.68 g·kg-1); ② Compared with the CK treatment, CS and CSD treatments could increase the stability of the aggregates through significantly increasing the content of macro-aggregate by 94.00%-117.78% and significantly increasing the mean weight diameter (MWD), geometric mean diameter (GMD), and R0.25 of water stable aggregates, but reducing the D value (P<0.05); and ③ With the increase in aggregate particle size, the content of organic carbon in the aggregates decreased first and then increased. The contribution rate of soil organic carbon in silt and clay was the highest (29.61%-42.18%), and the contribution rate of organic carbon in the macro-aggregate was the lowest (9.19%-17.81%). In addition to the CSD treatment, the CS, BC, and CSBC treatments reduced the contribution of larger aggregates (2-0.25 mm) and micro-aggregates (0.25-0.053 mm). In general, the benefit of straw return was better than that of biochar in promoting soil aggregation. However, the application of biochar was better than straw in improving the aggregates organic carbon content. The newly generated carbon from straw degradation was mainly distributed in large aggregates. Straw with microorganisms could promote the combination of carbon by different components in the larger aggregates. The carbon from biochar and straw with biochar treatments were mainly concentrated in micro-aggregates.


Assuntos
Sequestro de Carbono , Carvão Vegetal , Solo/química , Carbono , Caules de Planta
5.
Artigo em Chinês | MEDLINE | ID: mdl-22164611

RESUMO

A total of 205 dialysis patients with renal insufficiency were selected as an experiment group, and 360 healthy people were selected as a control group. The specific IgG antibodies of Toxoplasma gondii of the objects in the 2 groups were detected by ELISA. The positive rates of the experiment and control groups were 27. 3% and 3. 6% ,respectively, with a significant difference between them (P < 0.05). Among the dialysis patients with renal insufficiency, the positive rates of the patients with or without a history of blood transfusion were 31.2% and 19.2% , respectively, and there was a significant difference between them (P < 0.05). In conclusion, the infection rate of T. gondii in dialysis patients with renal insufficiency is higher than that of common people, and dialysis and/or blood transfusion may be potential risk(s) for Toxoplasma gondii infection.


Assuntos
Anticorpos Antiprotozoários/sangue , Diálise Renal/efeitos adversos , Insuficiência Renal/terapia , Toxoplasma/fisiologia , Toxoplasmose/diagnóstico , Adulto , Idoso , Estudos de Casos e Controles , China , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Insuficiência Renal/complicações , Toxoplasma/imunologia , Toxoplasma/isolamento & purificação , Toxoplasmose/sangue , Toxoplasmose/etiologia , Toxoplasmose/parasitologia
6.
Protoplasma ; 248(2): 257-66, 2011 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-20461420

RESUMO

The distribution and development of secretory cells and crystal cells in young shoot apexes of water hyacinth were investigated through morphological and cytological analysis. The density of secretory cells and crystal cells were high in parenchyma tissues around the vascular bundles of shoot apexes. Three developmental stages of the secretory cells can be distinguished under transmission electron microscopy. Firstly, a large number of electron-dense vesicles formed in the cytoplasm, then fused with the tonoplast and released into the vacuole in the form of electron-dense droplets. As these droplets fused together, a large mass of dark material completely filled the vacuole. To this end, a secretion storage vacuole (SSV) formed. Secondly, an active secretion stage accompanied with degradation of the large electron-dense masses through an ill-defined autophagic process at periphery and in the limited internal regions of the SSV. Finally, after most storage substances were withdrawn, the materials remaining in the spent SSV consisted of an electron-dense network structure. The distribution and development of crystal cells in shoot apical tissue of water hyacinth were also studied by light and electron microscopy. Crystals initially formed at one site in the vacuole, where tube-like membrane structures formed crystal chambers. The chamber enlarged as the crystal grew in bidirectional manner and formed needle-shaped raphides. Most of these crystals finally occurred as raphide bundles, and the others appeared as block-like rhombohedral crystals in the vacuole. These results suggest that the formation of both secretory cells and crystal cells are involved in the metamorphosis of vacuoles and a role for vacuoles in water hyacinth rapid growth and tolerance.


Assuntos
Diferenciação Celular , Eichhornia/ultraestrutura , Brotos de Planta/ultraestrutura , Feixe Vascular de Plantas/ultraestrutura , Eichhornia/crescimento & desenvolvimento , Microscopia Eletrônica de Transmissão , Brotos de Planta/crescimento & desenvolvimento , Feixe Vascular de Plantas/crescimento & desenvolvimento , Vacúolos/ultraestrutura
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