Mapping Chinese annual gross primary productivity with eddy covariance measurements and machine learning.

Annual gross primary productivity (AGPP) is the basis for grain production and terrestrial carbon sequestration. Mapping regional AGPP from site measurements provides methodological support for analysing AGPP spatiotemporal variations thereby ensures regional food security and mitigates climate change. Based on 641 site-year eddy covariance measuring AGPP from China, we built an AGPP mapping scheme based on its formation and selected the optimal mapping way, which was conducted through analysing the predicting performances of divergent mapping tools, variable combinations, and mapping approaches in predicting observed AGPP variations.

Generalist Taxa Shape Fungal Community Structure in Cropping Ecosystems.

Fungi regulate nutrient cycling, decomposition, symbiosis, and pathogenicity in cropland soils. However, the relative importance of generalist and specialist taxa in structuring soil fungal community remains largely unresolved. We hypothesized that generalist fungi, which are adaptable to various environmental conditions, could potentially dominate the community and become the basis for fungal coexisting networks in cropping systems.

[Consumption Capacity of NO in Paddy Soil and the Response Mechanism of -containing Communities].

The long-term flooding anaerobic environment in paddy soils is conducive to denitrification, which is one of the most important reasons for NO emissions. NO can be transformed to nitrogen gas (N) by bacteria and archaea containing nitrous oxide reductase (NOR) encoded by the gene, which is the only known biological pathway of NO consumption in soil. is known to be typical in denitrifying bacteria, which is one of the clades of the gene and is mainly possessed a Tat signal peptide motif.

Large-scale patterns of soil antibiotic resistome in Chinese croplands.

Soil is a vital reservoir of antibiotic resistance genes (ARGs), but we still know little about their distribution in cropland soils and the main driving forces. Here we performed an investigation for ARGs patterns in 105 cropland soils (planted with maize, peanut or soybean) along a 2, 200 km transect in China using high-throughput quantitative PCR approaches. Totally, 204 ARGs were detected, with a higher diversity found in central China than that in northeast and south China.

[Differential Responses of Rhizospheric and -type Denitrifier Communities to Different Phosphorus Levels in Paddy Soil].

Phosphorus is an essential life element, which can affect the activities and functions of denitrifiers. Both and genes can code nitrite reductase; however, it remains unclear whether - and -containing denitrifers respond differentially to changes in the availability of phosphorus in paddy soil. In this study, P-deficient paddy soil was used to grow rice plants.

[Impact of Dicyandiamide (DCD) and 3,4-Dimethylpyrazole Phosphate (DMPP) on Ammonia-oxidizing Bacteria and Archaea in a Vegetable Planting Soil].

Nitrification inhibitors (NIs) dicyandiamide (DCD) and 3,4-dimethylpyrazole phosphate (DMPP) showed significant effects in the inhibition of nitrification and the improvement of the utilization efficiency of nitrogen fertilizer in agricultural soils. However, the effects of different NIs on ammonia-oxidizing bacteria (AOB) and archaea (AOA) is still unclear. To verify the inhibitory effect of DCD and DMPP on AOB and AOA, a pot experiment was performed, including Urea, Urea+DCD, and Urea+DMPP treatments.

Multiple factors drive the abundance and diversity of the diazotrophic community in typical farmland soils of China.

Biological nitrogen fixation plays an important role in nitrogen cycling by transferring atmospheric N2 to plant-available N in the soil. However, the diazotrophic activity and distribution in different types of soils remain to be further explored. In this study, 152 upland soils were sampled to examine the diazotrophic abundance, nitrogenase activity, diversity and community composition by quantitative polymerase chain reaction, acetylene reduction assay and the MiSeq sequencing of nifH genes, respectively.

[Variation of community structure and function of rhizospheric denitrifiers at tillering and booting stages of rice].

We investigated the variation of denitrifying communities in rice rhizosphere at tillering and booting stages in comparison with bulk soils with a pot experiment. The techniques of quantitative polymerase chain reaction (qPCR) and terminal restriction fragment length polymorphism (T-RFLP) were used to measure the abundance and community composition of denitrifiers (narG and nosZ), respectively. The results showed that the potential denitrification activity in the rhizosphere at tillering stage was significantly lower than bulk soils.

Protist communities are more sensitive to nitrogen fertilization than other microorganisms in diverse agricultural soils.

Background: Agricultural food production is at the base of food and fodder, with fertilization having fundamentally and continuously increased crop yield over the last decades. The performance of crops is intimately tied to their microbiome as they together form holobionts. The importance of the microbiome for plant performance is, however, notoriously ignored in agricultural systems as fertilization disconnects the dependency of plants for often plant-beneficial microbial processes.

Increased microbial functional diversity under long-term organic and integrated fertilization in a paddy soil.

Microbes play key roles in diverse biogeochemical processes including nutrient cycling. However, responses of soil microbial community and functional genes to long-term integrated fertilization (chemical combined with organic fertilization) remain unclear. Here, we used pyrosequencing and a microarray-based GeoChip to explore the shifts of microbial community and functional genes in a paddy soil which received over 21-year fertilization with various regimes, including control (no fertilizer), rice straw (R), rice straw plus chemical fertilizer nitrogen (NR), N and phosphorus (NPR), NP and potassium (NPKR), and reduced rice straw plus reduced NPK (L-NPKR).

[Effect of Dicyandiamide on NO Emission in Fallow Paddy Field and Rape Cropping].

The emissions of greenhouse gas in winter are often neglected, and the latest research results showed that NO emissions in fallow paddy field and winter oilseed rape are still large, research on mitigating the NO flux and the mechanism behind them is of significance for mitigating NO emissions from agricultural soil. By using static chamber techniques and molecular biology techniques, the NO emission as well as the community composition and abundance of ammonia oxidizing archaea (AOA) and ammonia oxidizing bacteria (AOB) from fallow paddy field, rape cropping with and without DCD treatment in Taoyuan agricultural ecological experiment station of the Chinese Academy of sciences were measured. The results showed that the addition of DCD significantly inhibited NO emissions in fallow paddy field and rape cropping by 36.

[NO Consumption Ability of Submerged Paddy Soil and the Regulatory Mechanism].

A large number of researches showed that the NO negative emissions from flooding paddy fields, peatlands and other wetlands ecosystem were frequent and considerable, which is of great significance on alleviating the greenhouse gas effect. However, there are few reports about the transformation and microbial mechanism of NO between atmosphere and paddy soil. The slurry of surface paddy soil (0-5 cm) was incubated in laboratory conditions, and the effect of enhanced NO concentrations in headspace on the NO consumption capacity of submerged paddy soil and the response of gene abundance were explored.

[Effect of short-time drought process on denitrifying bacteria abundance and N2O emission in paddy soil].

In order to investigate the impact of drying process on greenhouse gas emissions and denitrifying microorganisms in paddy soil, wetting-drying process was simulated in laboratory conditions. N2O flux, redox potential (Eh) were monitored and narG- and nosZ-containing denitrifiers abundances were determined by real-time PCR. N2O emission was significantly increased only 4 h after drying process began, and it was more than 6 times of continuous flooding (CF) at 24 h.

Long-term balanced fertilization increases the soil microbial functional diversity in a phosphorus-limited paddy soil.

The influence of long-term chemical fertilization on soil microbial communities has been one of the frontier topics of agricultural and environmental sciences and is critical for linking soil microbial flora with soil functions. In this study, 16S rRNA gene pyrosequencing and a functional gene array, geochip 4.0, were used to investigate the shifts in microbial composition and functional gene structure in paddy soils with different fertilization treatments over a 22-year period.

[Effects of rice straw returning on the community structure and diversity of nitrogen-fixing gene (nifH) in paddy soil].

Taking a long-term fertilization experiment in Taoyuan Agro-ecosystem Research Station under Chinese Academy of Sciences as the platform, and selecting four treatments (no fertilization, CK; rice straw returning, C; nitrogen, phosphorus and potassium fertilization, NPK; and NPK+C) as the objects, soil samples were collected at the tillering, booting and maturing stages of rice, and the abundance, composition and diversity of nifH-containing bacterial community were measured by real-time quantitative PCR and terminal restriction fragment length polymorphism (T-RFLP), aimed to understand the effects of rice straw returning on the nifH-containing bacterial community in paddy soil. Compared with CK, treatments NPK+C and NPK increased the abundance of nifH-containing microorganisms significantly (except at tillering stage), and NPK+C had the highest abundance of nifH-containing microorganisms. Under the effects of long-term fertilization, the composition of nifH gene community in CK differed obviously from that in the other three treatments.

[N2O flux in winter and its affecting factors under different land use patterns].

Due to the low temperature in winter, the emissions of greenhouse gas are often neglected. And the latest research results showed that there is continuous N2O emission in winter, therefore, research on understanding the No2O flux regulation is important for evaluating agricultural soil N2O emission. By using static chamber techniques, the N2O emission from soils under different land use patterns including fallow paddy field, rape cropping, honey pomelo orchard and abandon land in Taoyuan agricultural ecological experimental station of Chinese Academy of Sciences was measured.

[Effects of continuous cropping of vegetables on ammonia oxidizers community structure].

Investigations were conducted on the effects of intensive application of chemical fertilizers in crop production on soil nitrifier communities and the relationship between nitrifier communities and soil nitrification ability. Two series of vegetable soils were selected from Huangxing, Changsha, reflecting continuous vegetable cropping with about 20 years and new vegetable field with only about 2 years vegetable growing history. In each series five independent topsoils (0-20 cm) were sampled and each soil was a mixture of 10 cores randomly taken in the same field.

[Discussion of laboratory diagnosis for echinococcosis].

Laboratory diagnosis is one of the main means for diagnosis of echinococcosis. With the continuing evolvement of immunology and immunology technology, the laboratory diagnosis of echinococcosis obtained an encouraging progress, and the sensitivity and specificity of diagnostic tests for echinococcosis further improved. This review summarizes the current information concerning stool test, diagnostic antigen, and immunological diagnostic methods of echinococcosis.

[Change characteristics of soil available nitrogen and phosphorus and heavy metal contents after long-term cultivation of vegetables].

Soil samples were collected from three vegetable fields under different years of cultivation in Changsha suburbs of Hunan Province, South-central China to study the accumulation characteristics, risks, and sources of soil available nitrogen and phosphorus and heavy metals in the fields. With the increasing year of vegetable cultivation, the soil NO3(-)-N, Olsen-P, and heavy metals contents in the fields increased significantly. The average contents of soil NO3(-)-N, Olsen-P, and Cd in the vegetable fields having been cultivated for 1-2 years in Ningxiang County, 10-15 years in Changsha County, and 30 years in Kaifu District were 21.

[Effect of long-term application of nitrogen fertilizer on the diversity of nitrifying genes (amoA and hao) in paddy soil].

The aim of this study was to determine the effect of long-term (16 years) application of nitrogen fertilizer on the diversity of nitrifying genes (amoA and hao) in paddy soil on the basis of long-term paddy field experimental station (started in 1990) located in Taoyuan, with the molecular approaches of PCR, constructing libraries and sequencing. The fertilizer was urea and no fertilizer was as control. The Shannon index showed that long-term application of nitrogen fertilizer made the diversity of amoA gene descend while no effect on the diversity of hao gene.

[Effects of rice straw on the diversity of nitrifying genes (amoA and hao) in paddy soil].

The effects of long-term (16 years) fertilization on the diversity and community structure of soil ammonia-oxidizing gene (amoA) and hydroxylamine-oxidizing gene (hao) in paddy soil were evaluated using the methods of polymerase chain reaction, cloning and sequencing. The soil samples were collected from the treatments of NPK (CK) and NPK plus rice straw (SR) of the long-term field fertilization experiment in Taoyuan Agro-ecological Experimental Station. The Shannon Indices showed that the diversity of amoA and hao in SR treatment was lower than that in CK, and LUBSHUFF statistical analyses demonstrated that the sequence compositions of both amoA and huo libraries were significantly different between CK and SR.

[Comparing study on different methods for RNA extraction from paddy soils].

Four different methods were evaluated for extracting RNA from microorganisms of a paddy soil and a upland soil, the RNA quality and quantity were examined. The results showed that method 1 applying liquid nitrogen for grinding gave the highest yield but poor purity, and the additional purification was necessary for further RT-PCR. Method 2 using bead beating yielded the RNA with high purity which could be directly used for RT-PCR, but the RNA yield was lower than that of method 1.

[Effect of long-term fertilization on the diversity of nitrite reductase genes (nirK and nirS) in paddy soil].

In order to investigate the effects of long-term application of nitrogen fertilizer on soil denitrifying communities, the diversities of nir genes (nirK and nirS) were studied using molecular approaches in the long-term paddy field experiment (started in 1990) located in Taoyuan. Analysis of clone sequences indicated that the nirK fragments from paddy soil showed close similarity (90.7%) to the nirK sequences registered in GenBank database, but were not related to any known strain.

[Soil bacterial community structure in primeval forest and degraded ecosystem in Karst region].

By using PCR-RFLP, this paper studied the 16S rDNA gene diversity and phylogenesis of soil bacteria in primeval forest and degraded ecosystem in Karst region of Northwest Guangxi. More genotypes and higher diversity index were observed in the soil of primeval forest than in that of degraded ecosystem, and only two common genotypes were observed in the two soils. A clone from each genotype was randomly selected as representative for sequencing.

Effects of top excision on the potassium accumulation and expression of potassium channel genes in tobacco.

The effects of the removal of the shoot apex of tobacco on the relative transcript levels of potassium channel genes, determined by real-time PCR, and on the relationship between the expression of genes encoding potassium channels and potassium concentration, were studied. The results from the study indicated that comparatively more assimilates of photosynthesis were allocated to the apex in control plants than in both decapitated and IAA-treated decapitated plants. By contrast, dry matter in the upper leaves, roots, and stems in both decapitated and IAA-treated plants was significantly increased relative to control plants.