Effects of long-term no-tillage on the functional potential of microorganisms involved in the nitrogen, phosphorus and sulfur cycles of black soil.

Understanding the effects of different tillage practices on functional microbial abundance and composition in nitrogen (N), phosphorus (P) and sulfur (S) cycles are essential for the sustainable utilization of black soils. Based on an 8-year field experiment located in Changchun, Jilin Province, we analyzed the abundance and composition of N, P and S cycling microorganisms and their driving factors in different depths of black soil under no til-lage (NT) and conventional tillage (CT). Results showed that compared with CT, NT significantly increased soil water content (WC) and microbial biomass carbon (MBC) at soil depth of 0-20 cm. Compared with CT, NT significantly increased the abundances of functional and encoding genes related to N, P and S cycling, including the nosZ gene encoding N2O reductase, the ureC gene performing organic nitrogen ammoniation, the nifH gene encoding nitrogenase ferritin, the functional genes phnK and phoD driving organic phosphorus mineralization, the encoding pyrroloquinoline quinone synthase ppqC gene and the encoding exopolyphosphate esterase ppX gene, and the soxY and yedZ genes driving sulfur oxidation. The results of variation partitioning analysis and redundancy analysis showed that soil basic properties were the main factors affecting the microbial composition of N, P and S cycle functions (the total interpretation rate was 28.1%), and that MBC and WC were the most important drivers of the functional potential of soil microorganisms in N, P and S cycling. Overall, long-term no tillage could increase the abundance of functional genes of soil microorganisms by affecting soil environment. From the perspective of molecular biology, our results elucidated that no tillage could be used as an effective soil management measure to improve soil health and maintain green agricultural development.

[Effects of corn and soybean straws returning on CO2 efflux at initial stage in black soil].

In this study, the CO2 emission characteristics and its relationships with C and N concentration in soil amended with different types of residues were studied by thermostatic incubation method to investigate the decomposition characteristics of different types of residues after adding to the soil and the effect of C, N concentration in residues on carbon sequestration. The results showed that during 61 days incubation, the CO2 efflux rates in the soils added with the different residues changed over time and exhibited an initial decrease, followed by a stable low plateau, and then an increase to a high plateau and finally followed by a decrease. The characteristics of CO2 emissions varied with residues, with the differences mainly occurring in the starting and duration of the high plateau CO2 emission period. The cumulative CO2-C emission was significantly affected by residue type. The cumulative CO2-C emissions from soils amended with corn roots, bottom corn stalks, corn leaves, and soybean leaves (about 160 µmol · g(-1) of soil and residue) were significantly greater than those from soils amended with other residues for the initial 21 days. Except for soybean leaves, the cumulative soil CO2 emissions over the 61 day incubation period from soils amended with soybean residues were higher than that from soil amended with corn residues. There were significant linear relationships between the ratio of cumulative CO2-C emission to residue carbon concentration (CR), and both C/N and nitrogen concentration of residues in the initial 21 days incubation, but not for the entire 61 days incubation. Our study suggested that soil CO2 emission was closely dependent upon the type of residue. Soybean residues decomposed more easily than corn residues. However, the decay rate of soybean residues was slower than that of corn residues at the initial stage of incubation. Soil CO2 emission was significantly affected by the C/N ratios and nitrogen concentrations of crop residues only at the early phase of incubation.

[Effects of Different Residue Part Inputs of Corn Straws on CO2 Efflux and Microbial Biomass in Clay Loam and Sandy Loam Black Soils].

The decomposed rate of crop residues is a major determinant for carbon balance and nutrient cycling in agroecosystem. In this study, a constant temperature incubation study was conducted to evaluate CO2 emission and microbial biomass based on four different parts of corn straw (roots, lower stem, upper stem and leaves) and two soils with different textures (sandy loam and clay loam) from the black soil region. The relationships between soil CO2 emission, microbial biomass and the ratio of carbon (C) to nitrogen (N) and lignin of corn residues were analyzed by the linear regression. Results showed that the production of CO2 was increased with the addition of different parts of corn straw to soil, with the value of priming effect (PE) ranged from 215. 53 µmol . g-1 to 335. 17 µmol . g -1. Except for corn leaves, the cumulative CO2 production and PE of clay loam soil were significantly higher than those in sandy loam soil. The correlation of PE with lignin/N was obviously more significant than that with lignin concentration, nitrogen concentration and C/N of corn residue. The addition of corn straw to soil increased the contents of MBC and MBN and decreased MBC/MBN, which suggested that more nitrogen rather than carbon was conserved in microbial community. The augmenter of microbial biomass in sandy loam soil was greater than that in clay loam soil, but the total dissolved nitrogen was lower. Our results indicated that the differences in CO2 emission with the addition of residues to soils were primarily ascribe to the different lignin/N ratio in different corn parts; and the corn residues added into the sandy loam soil could enhance carbon sequestration, microbial biomass and nitrogen holding ability relative to clay loam soil.

[Impact of tillage practices on microbial biomass carbon in top layer of black soils].

A study was conducted on a long-term (13 years) tillage and rotation experiment on black soil in northeast China to determine the effects of tillage, time and soil depth on soil microbial biomass carbon (MBC). Tillage systems included no tillage (NT), ridge tillage (RT) and mould-board plough (MP). Soil sampling was done at 0-5, 5-10 and 10-20 cm depths in June, August and September, 2013, and April, 2014 in the corn phase of corn-soybean rotation plots. MBC content was measured by the chloroform fumigation extraction (CFE) method. The results showed that the MBC content varied with sampling time and soil depth. Soil MBC content was the lowest in April for all three tillage systems, and was highest in June for MP, and highest in August for NT and RT. At each sampling time, tillage system had a significant effect on soil MBC content only in the top 0-5 cm layer. The MBC content showed obvious stratification under NT and RT with a higher MBC content in the top 0-5 cm layer than under MP. The stratification ratios under NT and RT were greatest in September when they were respectively 67.8% and 95.5% greater than under MP. Our results showed that soil MBC contents were greatly affected by the time and soil depth, and were more apparently accumulated in the top layer under NT and RT.

[Allelopathic effects of aqueous extracts from Panax notoginseng on three maize varieties (Zea mays)].

It has been showed that there were obvious obstacle effects of Panax notoginseng replanting. Crop rotation was the main effective technique to overcome the obstacle. To find a reasonable crop rotation system for P. notoginseng, aqueous extracts from root, stem and leaf of P. notoginseng were analyzed for allelopathic effect on three maize varieties (which are often grown in regions where P. notoginseng grown). The main results were as follows: (1) Allelopathic effect of P. notoginseng stem and leaf extracts on the three other tested plants was stronger than that of root extracts; (2) Corn was more vulnerable to the effects of allelochemicals at seedling stage than at germination stage, and the corn root was more sensitive than aerial part to allelochemicals; (3) Lusan No. 3 and Yunrui No. 1 showed resistance to P. notoginseng allelopathy, with respective comprehensive sensitivity indexes (M3) of - 0.089 3 and -0.159 2, while Bainuo No. 1 is sensitive at M3 = -0.261 0. It then can be concluded that Lusan No. 3 and Yunrui No. 1 may be an alternative rotation plants for overcoming P. notoginseng continuous cropping obstacle.

Nutrition education guided by Dietary Guidelines for Chinese Residents on metabolic syndrome characteristics, adipokines and inflammatory markers.

OBJECTIVE: The objective of this study was to test whether "Dietary Guidelines for Chinese Residents" have beneficial effects on anthropometric and metabolic variables, adipokines and inflammatory markers in metabolic syndrome patients. METHODS AND PROCEDURES: A multi-stage sampling method was applied to select metabolic syndrome patients in two districts of Shanghai. Two hundred and seventy-two metabolic syndrome patients were divided into control and intervention groups according to their district. Nutrition education guided by "Dietary Guidelines for Chinese Residents" was performed in the intervention group for one year. RESULTS: Nutrition-related knowledge, attitudes and behavior were improved in the intervention group. Potassium intake and food to total energy ratio for grain, vegetable and fruit increased while sodium intake as well as fat to total energy ratio decreased in the intervention group compared to the control group (p<0.05). Correspondently, the intervention group significantly improved its waist circumference, waist to hip ratio, high-density lipoprotein cholesterol, adiponectin, leptin and tumor necrosis factor-α compared to the control group (p<0.05). Waist circumference changes from baseline to end of the study in the intervention and the control groups were -3.9±0.3 and -2.3±0.4 cm respectively. There was a significant difference between the two groups (p=0.004). Means of waist circumference, waist to hip ratio, leptin and tumor necrosis factor-α were lower, and high density lipoprotein-cholesterol was higher in the intervention group than the control group (p<0.05). CONCLUSION: This study confirmed "Dietary Guidelines for Chinese Residents" had beneficial effects on anthropometric, lipids, adipokines and inflammatory markers in metabolic syndrome patients.

[Correlation of plasma adiponectin and components of metabolic syndrome].

OBJECTIVE: To identify the relationship of adiponectin and the components of metabolic syndrome (MS). METHODS: Cluster random sampling was applied in two districts of Shanghai. Two communities were selected. After investigating and physical examination, 235 MS subjects were obtained. Correlation analysis and principle components regression analysis were used to analyze the relationship between adiponectin and components of MS (waist circumference, blood pressure, blood glucose and lipid). RESULTS: Adiponectin in male was (2.82 +/- 1.73) microg/ml, lower than in female [(5.12 +/- 3.51) microg/ml] with statistical difference (Z = -5.25, P = 0.00). Adiponectin levels [(4.38 +/- 3.23) microg/ ml] correlated with abdominal obesity, including waist circumference [(93.37 +/- 7.76) cm] (r(s) = - 0.18, t(r) = -2.79, P = 0.01) and waist hip ratio (0.91 +/- 0.05) (r(s) = -0.28, t(r) = -4.44, P = 0.00), but did not correlate significantly with body mass index (BMI) [(26.85 +/- 3.10) kg/m2] (r(s) = -0.10, t(r) = - 1.45, P = 0. 15). Adiponectin correlated negatively with insulin resistance related indexes, including fasting glucose [(5.48 +/- 1.72) mmol/L] (r(s) = -0.13, t(r) = -2.00, P = 0.05), fasting insulin [(11.52 +/- 5.34) mU/L] (r(s) = -0. 15, t(r) = - 2.31, P = 0.02), homeostasis model assessment of insulin resistance (HOMA-IR) (2.90 +/- 2.07) (r(s) = -0.17, t(r) = -2.63, P = 0.01) and triglyceride [(2.11 +/- 1.24) mmol/L] (r(s) = -0.24, t(r) = -3.77, P = 0.00). The correlations were not observed between adiponectin with total cholesterol [(5.01 +/- 1.19) mmol/L] ( r(s) = -0.05, t(r) = -0.78, P = 0.44), high density lipoprotein-cholesterol (HDL-C) [(1.21 +/- 0.32) mmol/L] (r(s) = 0.06, t(r) = 0.93, P = 0.36), systolic blood pressure [(131.40 +/- 14.93) mm Hg, 1 mm Hg = 0.133 kPa] (r(s) = -0.02, t(r) = -0.34, P = 0.73) and diastolic blood pressure [(86.77 +/- 9.14)mm Hg] (r(s) = -0.02, t(r) = -0.27, P = 0.78). CONCLUSION: Adiponectin should correlate negatively with abdominal obesity and insulin resistance, but not directly correlate with blood pressure in MS.

[Association of peroxisome proliferator-activated-receptors-gamma C161-->T gene polymorphism with metabolic syndrome and dietary predisposition].

OBJECTIVE: To study the genotype frequencies of peroxisome proliferators-activated -receptors-gamma C161-->T gene and its possible association with the metabolic syndrome and dietary intakes. METHODS: The PCR-PFLP method was used to detect the polymorphism of PPARgammaC161-->T gene of 224 adults with metabolic syndrome and 224 normal adults in Shanghai. Their physical examinations, dietary investigation and the serum biochemistry were analyzed. RESULTS: (1) The genotype frequencies of PPARgamma C161-->T CC, CT and TT were 32.4%, 49.6% and 18.0% respectively, which were in agreement with Hardy-Weinberg equilibrium. There was no significant difference in the distribution of genotypes or allele between the metabolic syndrome group and the control group, and the result was the same between male and female subjects. (2) The levels of body mass index,waist width and hip width were significantly different among three genotypes groups. Subjects of the CT genotype had the highest levels. (3) There was significant difference in the negative correlation with the intake of protein and serum TG levels in the metabolic syndrome group. CONCLUSION: The results suggested PPARgamma gene C161-->T should be associated with body mass index, waist width and hip width. It might contribute to the heterogeneity in diet response to TG.