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Zhang F.-P.,Key Laboratory of Huazhong Crop Physiology | Zhang F.-P.,Huazhong Agricultural University | Li C.-F.,Key Laboratory of Huazhong Crop Physiology | Li C.-F.,Huazhong Agricultural University | And 6 more authors.
Applied Soil Ecology | Year: 2010

Soil microbial activity plays a crucial role in soil microbiological processes, which can be used as a useful indicator to determine the ecological effects of heavy metal pollution on soils. The objective was to determine the effects of heavy metal pollution on mining soils at the Lawu mine of central Tibet, China on soil enzyme activities (sucrase, urease and acid phosphatase), microbial biomass C, N and P (MBC, MBN, and MBP), basal respiration, metabolic quotients, and N mineralization. Sixteen soil samples around the mine were sampled, and one soil sample, 2km from the mine center, was taken as the control. Compared to the control, mining soils were polluted by heavy metals, Cu, Zn, Pb and Cd, resulting in decreases of sucrase activities, urease activities, acid phosphatase activities, MBC, MBN, MBP, and N mineralization, and increases of basal respiration and qCO 2. Multivariate analysis (cluster analysis [CA], principle component analysis [PCA] and canonical correlation analysis [CCA]) indicated nine microbial variables were only reduced to one principal component explaining 72% of the original variances, and MBC (R 2=0.93) had the highest positive loadings on the principal component. Mining soils polluted by heavy metals were perfectly clustered into four groups, which were highly distinguished by MBC. There were significant canonical correlations between soil heavy metals and microbial indexes on two canonical variates (R1=0.99, p<0.001; R2=0.97, p<0.01), which further demonstrated significant correlations between soil heavy metal contents and microbial characteristics. Hence, our results suggested that MBC may be used a sensitive indicator for assessing changes in soil environmental quality in metal mine of central Tibet. © 2010.

Li C.-F.,Key Laboratory of Huazhong Crop Physiology | Li C.-F.,Huazhong Agricultural University | Kou Z.-K.,Key Laboratory of Huazhong Crop Physiology | Kou Z.-K.,Huazhong Agricultural University | And 8 more authors.
Atmospheric Environment | Year: 2010

Agricultural practices affect the production and emission of carbon dioxide (CO2) from paddy soils. It is crucial to understand the effects of tillage and N fertilization on soil CO2 flux and its influencing factors for a better comprehension of carbon dynamics in subtropical paddy ecosystems. A 2-yr field study was conducted to assess the effects of tillage (conventional tillage [CT] and no-tillage [NT]) and N fertilization (0 and 210 kg N ha-1) on soil CO2 fluxes during the 2008 and 2009 rice growing seasons in central China. Treatments were established following a split-plot design of a randomized complete block with tillage practices as the main plot and N fertilizer level as the split-plot treatment. The soil CO2 fluxes were measured 24 times in 2008 and 17 times in 2009. N fertilization did not affect soil CO2 emissions while tillage affected soil CO2 emissions, where NT had similar soil CO2 emissions to CT in 2008, but in 2009, NT significantly increased soil CO2 emissions. Cumulative CO2 emissions were 2079-2245 kg CO2-C ha-1 from NT treatments, and 2084-2141 kg CO2-C ha-1 from CT treatments in 2008, and were 1257-1401 kg CO2-C ha-1 from NT treatments, and 1003-1034 kg CO2-C ha-1 from CT treatments in 2009, respectively. Cumulative CO2 emissions were significantly related to aboveground biomass and soil organic C. Before drainage of paddy fields, soil CO2 fluxes were significantly related to soil temperature with correlation coefficients (R) of 0.67-0.87 in 2008 and 0.69-0.85 in 2009; moreover, the Q10 values ranged from 1.28 to 1.55 and from 2.10 to 5.21 in 2009, respectively. Our results suggested that NT rice production system appeared to be ineffective in decreasing carbon emission, which suggested that CO2 emissions from integrated rice-based system should be taken into account to assess effects of tillage. © 2010.

Li-Jun L.,Key Laboratory of Huazhong Crop Physiology | Di-Luo T.,Key Laboratory of Huazhong Crop Physiology | Xiao-Bing D.,Key Laboratory of Huazhong Crop Physiology | Run-Qing Y.,Key Laboratory of Huazhong Crop Physiology | Ding-Xiang P.,Key Laboratory of Huazhong Crop Physiology
International Journal of Agriculture and Biology | Year: 2012

To resolve the bottleneck problems hindering the development of the ramie (Boehmeria nivea L. Gaud) cultivation industry, the feasibility of a new harvesting mode was investigated. This allows a continuous supply of ramie within a growing season and provided theoretical and technical support for industrialized production of ramie. Huazhu 4 was used and harvesting times were within 28 May to 21 October 7 days interval. Five harvesting modes were designed with 3 replications, with traditional harvesting mode as the control. The results showed that the range in fiber fineness among the five harvesting modes was 1659-1958 m/g. The mean in mode 1 was the highest of the five modes (1958 m/g) and was 6.47% higher than in controls. Compared to controls, the average fiber fineness in mode 5 was 1.96% higher, and that of mode 4 was the same as the controls. However, modes 2 and 3 had 9.79 and 5.55% lower mean fiber fineness compared with controls, respectively. The harvested yields of raw fiber in modes 2 and 3 were 21.50 and 5.04%, respectively higher than controls - with no increases in other modes. This suggested that 1-30 June was the most suitable time for continuous harvesting producing higher yields. The latest that ramie should be harvested is mid-late October. Continuous harvesting mode was feasible for ramie production, and provides a novel harvesting method for perennial crop, which is mainly harvested from nutritive organs. © 2012 Friends Science Publishers.

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