[Effect of Biochar on Soil Enzyme Activity & the Bacterial Community and Its Mechanism].

Biochar-based fertilizers can improve the mineralization of carbon and nitrogen in soil and enhance the soil micro-ecological environment due to particular physical and chemical properties. It is of great significance to explore the underlying mechanism of biochar-based fertilizer in the regulation of soil microorganisms and soil enzyme activity to improve soil quality. Field experiments were conducted to investigate the effects of different biochar-based fertilizer rates[0 (CK2), 0.6 (T1), 0.9 (T2), 1.2 (T3), and 1.5 (T4) t·hm-2]on soil nutrients, soil enzyme activity, and bacterial community structure. The results showed that with the application of biochar-based fertilizer, soil bulk density decreased, while the pH value, available P, available K, organic matter content, and the C/N ratio increased by 0.32%-5.83%, 14.09%-23.16%, 0%-38.70%, 7.49%-14.16%, and 4.06%-10.13%, respectively, compared to that of the CK2 treatment. With increasing rates of biochar-based fertilizer, the enzyme activity first increased and then decreased. Invertase (INV), urease (URE), catalase (CAT), and neutral phosphatase (NPH) activity under the application of biochar-based fertilizer were 63.73%-166.37%, 117.52%-174.03%, 12.98%-23.59%, and 60.84%-119.71% higher than that of CK2, respectively. The corresponding bacterial diversity was significantly improved, especially with regard to the increase in the abundance of growth promoting bacteria, such as Gemmatimonadetes and Proteobacteria, and decreased the abundance of Acidobacteria and Actinobacteria. The correlation analysis showed that soil C/N ratio was the key factor affecting soil enzyme activity, and there was a significant positive correlation between soil enzyme activity and bacterial diversity. There were significantly positive correlations among the activities of the above four soil enzymes and the relative abundance of Gemmatimonadetes (P<0.01), with CAT being the key factor affecting the bacterial community structure. This study revealed a relationship between soil enzyme activity and microbial colonies, which provides a theoretical basis and mechanism for applying biochar to regulate the soil enzyme and micro-ecological environment.

Magnetic Resonance Imaging (MRI) Phenotypes May Provide Additional Information for Risk Stratification for Encapsulated Papillary Carcinoma of the Breast.

BACKGROUND: Encapsulated papillary carcinoma (EPC) of the breast is a rare entity. EPC can be underappreciated on percutaneous biopsy, which may require additional procedures if invasion is not recognized preoperatively. We aimed to investigate the magnetic resonance imaging (MRI) phenotypes correlated with preoperative pathological risk stratification for clinical guidance. MATERIALS AND METHODS: The preoperative MRI scans of 30 patients diagnosed with 36 EPCs in multiple centers between August 2015 and February 2020 were reviewed by two breast radiologists. According to the WHO classification published in 2019, EPCs were classified into two pathological subtypes: encapsulated papillary carcinoma and encapsulated papillary carcinoma with invasion. Clinicopathological analysis of the two subtypes and MR feature analysis were performed. RESULTS: Evaluation of the MRI phenotypes and pathological subtype information revealed that not circumscribed (P=0.04) was more common in EPCs with invasion than in EPCs. There was a significant difference in the age of patients (P=0.05), and the risk increased with age. The maximum diameter of the tumor increased with tumor risk, but there was no significant difference (P=0.36). Nearly half of the EPC with invasion patients showed hyperintensity on T1WI (P=0.19). A total of 63.6% of the EPC with invasion group showed non-mass enhancement surrounding (P=0.85). In addition, 29 patients (96.7%) had no axillary lymph node metastasis, and only one patient with EPC with invasion had axillary lymph node metastasis. Further pathological information analysis of EPCs showed that higher Ki-67 levels were more common in patients with EPCs with invasion (P=0.04). A total of 29 patients (96.7%) had the luminal phenotype, and one patient with EPC with invasion had the Her-2-positive phenotype. CONCLUSION: The margin, age and Ki-67 level were the key features for EPC risk stratification. In addition, these MRI signs, including a larger tumor, non-mass enhancement surrounding and axillary lymph node metastasis, may be suggestive of a high-risk stratification. Therefore, MRI phenotypes may provide additional information for the risk stratification of EPCs.

[Effect of Long-Term Biochar Application on Soil Respiration in Flue-Cured Tobacco Planting Fields in Henan Province].

A five year (2013-2017) experiment was conducted to explore the effects of biochar application on the dynamic changes in soil respiration, soil water, and heat factors under four treatments:CK (without biochar), T1 (with 1.5 t·hm-2biochar), T2 (with 15 t·hm-2biochar), and T3 (with 45 t·hm-2biochar). The results showed that:① the soil respiration rate in the growing season of flue-cured tobacco was significantly reduced by 25.89% under the five year application of medium-dose biochar (T2:15 t·hm-2) in soil, while it was significantly increased by 21.48% when the applied dose increased to 45 t·hm-2(T3) (P<0.05). ② The long-term application of medium-dose biochar in the soil significantly reduced the soil heterotrophic respiration and autotrophic respiration rates by 29.80% and 28.75%, respectively. Meanwhile, the application of high-dose biochar (T3:45 t·hm-2) significantly increased the heterotrophic respiration rate by 28.88%. In addition, the application of low-dose biochar (T1:1.5 t·hm-2) and medium-dose biochar significantly increased the proportion of autotrophic respiration, whereas the high-dose biochar application significantly increased the proportion of heterotrophic respiration (P<0.05). ③ The addition of low-dose biochar to the soil significantly reduced the soil temperature at 5 cm in the growing season of flue-cured tobacco, while the high-dose application significantly reduced the soil humidity. There was a significant index correlation between soil respiration and soil temperature at 5 cm but no significant correlation with soil humidity at 5 cm (P<0.05). Ultimately, the application of low-dose biochar for five years in soil had no effect on soil respiration, and the application of the proper amount of biochar had a carbon sequestration effect. Additionally, large-dose biochar application may be counterproductive. It is recommended that the application range of biochar should be controlled within 15 t·hm-2.

[Effect of Biochar Amendment on Physicochemical Properties and Fungal Community Structures of Cinnamon Soil].

To identify the effect of biochar addition on soil abiotic and biotic properties and provide evidence for the soil improvement with biochar input, the soil physiochemical properties and fungal community were investigated in a cinnamon soil after 3-year biochar additions of 10, 20, and 40 t ·hm-2. The relationship between the fungal community and edaphic physicochemical characteristics was also analyzed. The results showed that soil pH, moisture, total nitrogen (TN), and total organic carbon (TOC) significantly increased but dissolved organic carbon (DOC) content and soil bulk density decreased with biochar addition. High-throughput sequencing results indicated that biochar amendment had little influence on fungal α diversity but significantly changed the fungal community structure. The taxonomic classification showed that the dominant fungal phyla were Ascomycota, Zygomycota, and Basidiomycota, and these phyla accounted for more than 90% of the total sequences. The relative abundance of Ascomycota and Basidiomycota increased, while the abundance of Zygomycota decreased with biochar addition. At the genus level, biochar addition increased the relative abundances of Alternaria, Conocybe, and Aspergillus but decreased the relative abundances of Actinomucor and Gibberella. Redundancy analysis (RDA) showed that soil DOC, pH, and moisture were key environmental factors leading to the shift in the soil fungal community composition. In summary, the application of biochar changed the soil physicochemical properties, which drove the ecological succession of soil fungal communities.

Influence of high-carbon basal fertiliser on the structure and composition of a soil microbial community under tobacco cultivation.

Soil microorganisms play a crucial role in cycling soil nutrients and providing organic nutrients for plant growth and development. Fertilisation balances soil fertility and quality, and affects soil microbial communities. Fertilisation is a frontier subject in agricultural and environmental sciences. Here we showed that the application of high-carbon basal fertiliser treatment could improve the tobacco yield and quality when compared to chemical fertiliser, high-carbon basal fertiliser and mixed high-carbon chemical fertiliser. The potential reason is that different fertiliser treatments influence soil fertility, such as nitrogen, phosphorus, and other contents, besides soil organic matter. Further experiments revealed that populations of bacteria, fungi and actinomycetes fluctuated during tobacco development under different fertilisation treatments. Then we performed high-throughput sequencing of the 16S rRNA gene, and the results showed that the fertilisation treatments had significant effects on the microbial community, particularly within the finer taxonomic divisions or non-dominant taxa. Moreover, proteobacteria and fungal genera had significantly different relative abundances during tobacco growth under various tobacco developmental stages and fertilisation treatments. These results indicated that mixed high-carbon chemical fertiliser could improve soil fertility by influencing the soil microorganism, and that the fertilisation treatments impacted on the structure and composition of the microbial community, and especially the diversity of non-dominant taxa. However, more studies are needed to confirm their reliability.

[Response of photosynthetic characteristics and accumulation and distribution of assimilation products in tobacco to different light environments]. / ä¸åŒå ‰çŽ¯å¢ƒä¸‹çƒŸè‰å ‰åˆç‰¹æ€§åŠåŒåŒ–äº§ç‰©çš„ç§¯ç´¯ä¸Žåˆ†é æœºåˆ¶.

In order to reveal the photosynthetic characteristics and the mechanism about accumulation and distribution of photosynthetic assimilation products under different light environments, potted tobacco was cultivated in a climate control chamber, there were three light intensity treatments (shading: (400±15)-(500±15) µmol·m-2·s-1; natural light: (800±15)-(1000±15) µmol·m-2·s-1; high light: (1500±15)-(1800±15) µmol·m-2·s-1). The results showed that with the decrease of light intensity, the biomass and root allocation, the net photosynthetic rate (Pn), stomata conductance (gs) and transpiration rate (Tr) were decreased, but the intercellular CO2 concentration (Ci) increased. The maximum net photosynthetic rate (Amax), light saturation point (LSP), light saturation point (LCP) and dark respiration rate (Rd) reached the maximum level under high light condition while the apparent quantum efficiency was higher in low light environment. The effects of light intensity on the absorption, accumulation and distribution of 13C in tobacco were significant, with a reduced proportion of enriched 13C distributed to the root under shading. The changes in the external light environment not only significantly affected the photosynthetic cha-racteristics and biomass accumulation of tobacco leaves, but also the distribution pattern of photosynthetic carbon in tobacco plant-soil system.

[Effects of phosphorus fertilizer on the root system and its relationship with the aboveground part of flue-cured tobacco].

Using 'Yuyan 10' as the material, the effects of different phosphorus fertilizer application on root characteristics of tobacco, such as root dry mass and the difference of dry matter distribution and mineral nutrient accumulation between its above and underground parts were investigated. The results showed that the growth of flue-cured tobacco root system and the distribution of dry matter to the aboveground part were significantly promoted by phosphorus fertilizer application. The application of 30 kg P2O5 · hm(-2) led to the maximums of root dry mass, root volume, root activity and the minimum of root to shoot ratio. The maximum nutrient accumulation rates of root and leaf appeared 57-66 days after transplanting and 44-55 days after transplanting, respectively. Phosphorus could not only promote the mineral nutrition absorption of tobacco and the earlier appearance of maximum nutrient accumulation, but significantly promote the nutrient accumulation of the aboveground part. But, the positive effects described above would be weakened when the amount of phosphorus fertilizer was more than 30 kg P2O5 · hm(-2). Therefore, it's necessary to control the amount of phosphorus application to improve the quality of tobacco leaves.

Differentiation of central lung cancer from atelectasis: comparison of diffusion-weighted MRI with PET/CT.

OBJECTIVE: Prospectively assess the performance of diffusion-weighted magnetic resonance imaging (DW-MRI) for differentiation of central lung cancer from atelectasis. MATERIALS AND METHODS: 38 consecutive lung cancer patients (26 males, 12 females; age range: 28-71 years; mean age: 49 years) who were referred for thoracic MR imaging examinations were enrolled. MR examinations were performed using a 1.5-T clinical scanner and scanning sequences of T1WI, T2WI, and DWI. Cancers and atelectasis were measured by mapping of the apparent diffusion coefficients (ADCs) obtained with a b-value of 500 s/mm(2). RESULTS: PET/CT and DW-MR allowed differentiation of tumor and atelectasis in all 38 cases, but T2WI did not allow differentiation in 9 cases. Comparison of conventional T2WI and DW-MRI indicated a higher contrast noise ratio of the central lung carcinoma than the atelectasis by DW-MRI. ADC maps indicated significantly lower mean ADC in the central lung carcinoma than in the atelectasis (1.83±0.58 vs. 2.90±0.26 mm(2)/s, p<0.0001). ADC values of small cell lung carcinoma were significantly greater than those from squamous cell carcinoma and adenocarcinoma (p<0.0001 for both). CONCLUSIONS: DW-MR imaging provides valuable information not obtained by conventional MR and may be useful for differentiation of central lung carcinoma from atelectasis. Future developments may allow DW-MR imaging to be used as an alternative to PET-CT in imaging of patients with lung cancer.

[Effects of light intensity on photosynthesis and dry matter production of flue-cured tobacco at its seedling stage].

Taking flue-cured tobacco Yunyan 87 as test material, this paper studied its photosynthesis and dry matter production at seedling stage under 100%, 88%, 72%, and 62% natural light intensities. At noon of sunny days, 100% natural light intensity inhibited the photosynthesis, while proper shading (88% natural light intensity) could eliminate the inhibition, and the daily photosynthesis was significantly higher than other treatments. Shading reduced the light saturation point and compensation point, enhanced the apparent quantum yield of photosynthesis and the net photosynthetic rate under weak light, increased the chlorophyll a and chlorophyll b contents, but decreased the chlorophyll a/b and cartenoids contents. Under 88% natural light intensity, tobacco seedlings had higher light saturation point, lower compensation point, higher suitability to the change of light intensity, and higher photosynthetic potentiality. 100% natural light intensity was more advantageous to the transfer of dry matter and soluble sugar to stem, while 88% natural light intensity was more beneficial to the transfer of dry matter and soluble sugar to root. Under the conditions of this experiment, proper shading (88% natural light intensity treatment) could improve the seedling quality of flue-cured tobacco.

[Effects of light intensity on morphological and physiological characteristics of tobacco seedlings].

Through shading with white gauze to simulate different light habitats (100%, 68.2% 35.4% and 16.7% of full sunlight), this paper studied the effects of light intensity on the morphological and physiological characteristics of tobacco seedlings. The results showed that with the decrease of relative light intensity, seedling height increased, while stem circumference, dry weight/fresh weight ratio, leaf thickness, specific leaf weight, and matter accumulation decreased. Less effect of light intensity was observed on the number of seedling leaves. Under weak light condition, the contents of free water, chlorophyll, total nitrogen, and protein in leaves increased, while bound water content, chlorophyll a/b ratio, and invertase activity decreased. The root/shoot ratio, root biomass, and root vitality also decreased. All of these suggested that weak light was unfavorable to the cultivation of strong tobacco seedlings, and the light conditions of seedbed should be improved in tobacco production.