[Effects of water and nitrogen coupling under furrow irrigation on tree growth, absorption and utilization of water and nitrogen of Populus tomentosa]. / 沟灌水氮耦合对毛白杨林木生长及水氮吸收利用的影响.

We explored the coupling effects of water and nitrogen in furrow irrigation on the growth and absorption and utilization of water and nitrogen in young poplar trees (triploid Populus tomentosa), under three irrigation levels (W20, W33, W45; when the soil water potential of 40 cm under the ditch reaches -20, -33 and -45 kPa respectively, irrigate), four N application levels (N120, N190, N260 and N0; the fertilization amount was 120, 190, 260 and 0 kg·hm-2·a-1), and natural conditions (CK). Based on the growth status of trees, the optimal combination of irrigation level and nitrogen application rate under furrow irrigation conditions was determined. The results showed that W20N120 (high water and low fertilizer; soil water potential threshold for initiating irrigation was -20 kPa and N application rate was 120 kg·hm-2·a-1) had the strongest effect on the stand productivity, with a value of 33.37 m3·hm-2·a-1. The significant coupling effect of water and N was detected only for tree height and total individual biomass. The increase of both irrigation amount and N application rate could increase the amount of N uptake, being mainly affected by the latter. The total amount of N uptake was the highest in the W20N260 treatment and reached 112.17 kg·hm-2·a-1, being 74.0% higher than that in CK. Among all the treatments, N uptake efficiency and N fertilizer partial productivity of W20N120 were the highest and significantly higher than those of the other treatments. The N uptake efficiency of the whole plant, aboveground part, and belowground part reached 36.8%, 28.5% and 6.4% in the W20N120 treatment, and its total N partial productivity reached 221.4 kg·kg-1. The effect of irrigation amount under different water-nitrogen coupling treatments on the irrigation water use efficiency was significant. Among them, irrigation water use efficiency in W45N260 was the highest and reached 13.66 g·kg-1. W20N120 had the highest water uptake amount and efficiency, which were 13268.28 t·hm-2 and 129.4%, respectively. To achieve great benefits, adequate irrigation (-20 kPa) and relatively low N application rate (120 kg·hm-2·a-1) should be selected during the young growth of the triploid P. tomentosa.

[Effects of water and nitrogen coupling under drip irrigation on tree growth and soil nitrogen content of Populus ×euramericana cv. 'Guariento'.] / 滴灌水氮耦合对欧美108æ¨æž—æœ¨ç”Ÿé•¿å’ŒåœŸå£¤æ°®ç´ çš„å½±å“.

By using surface drip irrigation, a field experiment including nine drip irrigation and fertigation treatments was carried out, with non-irrigation and non-fertilization as control (CK), to evaluate the integrative effects of water and nitrogen management on the increment of diameter, tree height, and stem volume, and the total nitrogen content in the 0-60 cm soil layer in the poplar (Populus ×euramericana cv. 'Guariento') plantations. There were three irrigation levels (irrigation was initiated when soil water potentials at 20 cm soil depth reached -75, -50 and -25 kPa) and three levels of nitrogen addition (150, 300 and 450 g·tree-1·a-1). Surface drip irrigation and fertigation treatments were applied in the gro-wing seasons of 2012 and 2013. The results showed that the combined treatments of water and nitrogen addition significantly increased growth and stem volume of the poplar plantation. In the first year of the experiment, the annual increment of stem volume was 11.54 m3·hm-2·a-1 in high water and high fertilizer treatment (soil water potentials of -25 kPa + nitrogen addition of 450 g·tree-1·a-1), which was 44.1% higher than that in the CK (8.01 m3·hm-2·a-1). In the second year, the annual increment of stem volume was 27.85 m3·hm-2·a-1 in medium water and high fertilizer treatment (soil water potentials of -50 kPa + nitrogen addition of 450 g·tree-1·a-1), being 36.0% higher than that in CK (20.48 m3·hm-2·a-1). The successive combined treatments signi-ficantly increased the total N content in the 0-20 cm soil layer, with total N content of each soil layer in the first and second year of the experiment being 12.3%-59.4% and 71.1%-81.1% higher than CK, respectively. The increments of diameter and tree height were significantly positively correlated with soil total N content. Nitrogen addition and the interactive effects of water and nitrogen addition significantly affected the diameter and height of trees and soil N content, while irrigation showed no significant effect. In conclusion, the combined drip irrigation and fertigation significantly increased growth and stem volume of the poplar plantation by promoting the soil fertility especially nitrogen availability in the topsoil.

[Fitness of sexual reproduction of Toona ciliata var. pubescens natural populations and their sexual reproduction and regeneration]. / æ¯›çº¢æ¤¿å¤©ç„¶ç§ç¾¤æœ‰æ€§ç¹æ®–é€‚åˆåº¦åŠå ¶ç¹æ®–æ›´æ–°.

To examine the reproduction fitness coefficients and individual-level fitness of Toona ciliata var. pubescens, their sexual reproduction and natural regeneration were investigated during 2006-2016, with four natural populations in Jiulianshan National Reserve as test objects. The results showed that there were only 2-10 trees for the natural populations of T. ciliata var. pubescens with a small initial number of fruiting plants (3-9 trees), which were from the initial fruiting plants or their first/second generation. The sexual reproduction of these isolated populations were significantly different, and their seed production capacities tended to decline over time. With the maturing of communities, soil seed banks and seed germinations were extremely poor, and the number of trees that could be growing to mature stage was nearly zero. The optimum maturity age of T. ciliata var. pubescens was about 40 a, and the fitness coefficients (2.0-2.8) rapidly increased in early development stage, but then was sharply reduced (0.3-0.5), and then gradually dropped to almost 0. There were significant differences in the fitness at individual level (0-14 tree·cm-2) among different populations, but their values were low (close to zero). Based on the existing reproduction rate, the actual values of sexual reproduction and regeneration fitness were much lower than the predicted ones. Due to the low level of genetic fitness, the sexual reproductive ability of different populations all showed decreasing trends. The natural sexual regeneration ability tended to decline, while the fitness of T. ciliata var. pubescens further decreased. All those factors suggested higher investment risks. Therefore, the systems of sexual reproduction became unbalanced and deteriorating. We proposed that more studies, including breeding mating, pollination, seed setting, and genetic diversity evaluation, are needed. Moreover, we should provide suitable forest environment through cleaning up litter in the fruiting stage and applying appropriate thinning during the transition period from seedling to young tree growth.

Assessment of phytotoxicity grade during composting based on EEM/PARAFAC combined with projection pursuit regression.

Improper treatment of organic waste may result in environmental pollution and harm to plant growth due to the high concentration of phytotoxin. Composting has widely been used for recycling organic waste and reducing phytotoxin to improve soil properties. Assessing the phytotoxicity grades of compost products is essential for achieving high quality compost to guarantee its marketability. In this study, a technique combined parallel factor (PARAFAC) of excitation-emission matrices (EEMs) spectroscopy with projection pursuit regression (PPR) was applied to improve the sensitivity of phytotoxicity assessment during composting. Results showed that composting reduced the concentration of phytotoxin, and increased the germination index (GI). Composts were divided into four grades based on GI values. Five components containing simple DOM (component C1 and C2) and complex DOM (component C3-C5) were successfully developed by PARAFAC. Correlation analysis between phytotoxicity, chemical indices and fluorescence components demonstrated that C1, C4, complex DOM, and the ratio of simple/complex DOM components were more suitable to assess phytotoxicity of composting products. These results revealed that PARAFAC/PPR enabled a rapid and accurate method to assess the phytotoxicity of compost materials for composting plant.

Dibromoacetic Acid Induces Thymocyte Apoptosis by Blocking Cell Cycle Progression, Increasing Intracellular Calcium, and the Fas/FasL Pathway in Vitro.

Dibromoacetic acid (DBAA), a haloacetic acid found in drinking water as a disinfection by-product, can cause many adverse effects, including immunotoxicity. In a previous study, we confirmed that DBAA can induce obvious immunotoxicity in mice but that the underlying mechanisms are not clearly understood. In our current study, we confirmed that DBAA induced cytotoxicity and apoptosis in thymocytes isolated from mice by a range of DBAA concentrations (0, 5, 10, 20, or 40 µM). The data showed that DBAA exposure led to a significant decrease in proliferative responses to T-cell mitogens and obvious inhibition in the production of cytokines interleukin-2 and interleukin-4. We found obvious morphological changes of apoptosis in thymocytes and observed the percentage of apoptotic thymocytes to increase significantly as the DBAA concentration increased. Further investigation showed that DBAA can cause G0/G1 arrest in cell cycle analysis, increase intracellular calcium ([Ca(2+)]i) levels, increase the expression of Fas/FasL proteins, and decrease the expression of Bcl-2 protein. It is concluded that in vitro exposure to DBAA can lead to marked cytotoxicity and apoptosis among thymocytes, and the mechanism involved is strongly related to blocking cell cycle progression, increasing intracellular calcium, and increasing Fas/FasL expressions.

[Effects of fertilization method and nitrogen application rate on soil nitrogen vertical migration in a Populus xeuramericana cv. 'Guariento' plantation].

A field experiment was conducted to investigate the effects of fertilization methods, i.e., drip (DF) and furrow fertilization (GF), and nitrogen (N) application rates (25, 50, 75 g N · plant(-1) · time(-1)) on the dynamics of soil N vertical migration in a Populus x euramericana cv. 'Guariento' plantation. The results showed that soil NH4(+)-N and NO3(-)-N contents decreased with the increasing soil depth under different fertilization methods and N application rates. In the DF treatment, soil NH4(+)-N and NO3(-)-N were mainly concentrated in the 0-40 cm soil layer, and their contents ascended firstly and then descended, reaching their maximum values at the 5th day (211.1 mg · kg(-1)) and 10th day (128.8 mg · kg(-1)) after fertilization, respectively. In the GF treatment, soil NH4(+)-N and NO3(-)-N were mainly concentrated in the 0-20 cm layer, and the content of soil NO3(-)-N rose gradually and reached its maximum at the 20th day (175.7 mg · kg(-1)) after fertilization, while the NH4(+)-N content did not change significantly after fertilization. Overall, N fertilizer had an effect within 20 days in the DF treatment, and more than 20 days in the GF treatment. In the DF treatment, the content and migration depth of soil NH4(+)-N and NO3(-)-N increased with the N application rate. In the GF treatment, the NO3(-)-N content increased with the N application rate, but the NH4(+)-N content was not influenced. Under the DF treatment, the hydrolysis rate, nitrification rate and migration depth of urea were higher or larger than that under the GF treatment, and more N accumulated in deep soil as the N application rate increased. Considering the distribution characteristics of fine roots and soil N, DF would be a better fertilization method in P. xeuramericana cv. 'Guariento' plantation, since it could supply N to larger distribution area of fine roots. When the N application rate was 50 g · tree(-1) each time, nitrogen mainly distributed in the zone of fine roots and had no risk of deep leaching, consequently improving the fertilizer utilization efficiency.

[Regulation of four typical scenic recreational plantations to stand PM2.5 concentration in Beijing, China].

To study the variation of PM2.5 concentration in scenic recreational plantations and its response to meteorological factors, and to analyze the regulation effect of different stands on PM2.5 concentration, in the summer, autumn and winter of 2013, PM2.5 concentration and relevant meteorological factors in four typical scenic recreational plantations (Pinus armandii--Ginkgo biloba mixed plantation, Populus tomentosa--Fraxinus chinensi mixed plantation, Populus tomentosa pure plantation, multiple-species-layered mixed plantation) were simultaneously monitored, in Beijing Olympic Forest Park (the observation was conducted continuously for 28 days). The results showed that the daily variation of PM2.5 concentration in the four stands didn' t represent a unified pattern at different air pollution levels, but were basically consistent at the same pollution level. When the wind force was 0-2 grade, there was no significant difference among daily average PM2.5 concentrations [the average PM2.5 concentration during the observation period (9:00-15:00) ] in the four stands at each pollution level. Stand PM2.5 concentration was positively correlated to air relative humidity (P < 0.01), negatively correlated with air temperature (P < 0.05), but uncorrelated with wind speed. Changed percentage of stand PM2.5 concentration compared to the space varied between -21.4% and 33.2%, and it was negatively correlated with air relative humidity (P < 0.05), but not correlated with the wind speed and air temperature. The regulation effects of the four stands on PM2.5 concentration included both increasing and decreasing effects, and in this study, the critical value of air relative humidity was 67% when this regulation shifted.

[Exploration of a quantitative methodology to characterize the retention of PM2.5 and other atmospheric particulate matter by plant leaves: taking Populus tomentosa as an example].

Taking Populus tomentosa as an example, a methodology called elution-weighing-particle size-analysis (EWPA) was proposed to evaluate quantitatively the ability of retaining fine particulate matter (PM2.5, diameter d ≤ 2.5 µm) and atmospheric particulate matter by plant leaves using laser particle size analyzer and balance. This method achieved a direct, accurate measurement with superior operability about the quality and particle size distribution of atmospheric particulate matter retained by plant leaves. First, a pre-experiment was taken to test the stability of the method. After cleaning, centrifugation and drying, the particulate matter was collected and weighed, and then its particle size distribution was analyzed by laser particle size analyzer. Finally, the mass of particulate matter retained by unit area of leaf and stand was translated from the leaf area and leaf area index. This method was applied to a P. tomentosa stand which had not experienced rain for 27 days in Beijing Olympic Forest Park. The results showed that the average particle size of the atmospheric particulate matter retained by P. tomentosa was 17.8 µm, and the volume percentages of the retained PM2.5, inhalable particulate matter (PM10, d ≤ 10 µm) and total suspended particle (TSP, d ≤ 100 µm) were 13.7%, 47.2%, and 99.9%, respectively. The masses of PM2.5, PM10, TSP and total particulate matter were 8.88 x 10(-6), 30.6 x 10(-6), 64.7 x 10(-6) and 64.8 x 10(-6) g x cm(-2) respectively. The retention quantities of PM2.5, PM10, TSP and total particulate matter by the P. tomentosa stand were 0.963, 3.32, 7.01 and 7.02 kg x hm(-2), respectively.

[Simulation of soil water dynamics in triploid Populus tomentosa root zone under subsurface drip irrigation].

Based on the observed data of triploid Populus tomentosa root distribution, a one-dimensional root water uptake model was proposed. Taking the root water uptake into account, the soil water dynamics in triploid P. tomentosa root zone under subsurface drip irrigation was simulated by using HYDRUS model, and the results were validated with field experiment. Besides, the HYDRUS model was used to study the effects of various irrigation technique parameters on soil wetting patterns. The RMAE for the simulated soil water content by the end of irrigation and approximately 24 h later was 7.8% and 6.0%, and the RMSE was 0.036 and 0.026 cm3 x cm(-3), respectively, illustrating that the HYDRUS model performed well in simulating the short-term soil water dynamics in triploid P. tomentosa root zone under drip irrigation, and the root water uptake model was reasonable. Comparing with 2 and 4 L x h(-1) of drip discharge and continuous irrigation, both the 1 L x h(-1) of drip discharge and the pulsed irrigation with water applied intermittently in 30 min periods could increase the volume of wetted soil and reduce deep percolation. It was concluded that the combination of 1 L x h(-1) of drip discharge and pulsed irrigation should be the first choice when applying drip irrigation to triploid P. tomentosa root zone at the experiment site.

Colonoscopic and histologic features of colonic Crohn's disease in Chinese patients.

OBJECTIVE: An attempt was made to provide a better insight into endoscopic and histological features and to enhance the understanding of the diagnostic value of colonoscopy combined with biopsy for colonic Crohn's disease. METHODS: As presented in our 27 cases of colonic Crohn's disease (Crohn's colitis), the endoscopic findings and histological changes of biopsy specimens were analyzed. As collated with correspondent results of biopsy and surgical specimens, the diagnostic accuracy of endoscopy was evaluated. RESULTS: Of these patients, 26 involvements of the colon (often combined with other sites of the bowel) were observed (96.3%). However, involvements limited to the colon alone were seen in only four cases (14.8%). Endoscopically, diverse patterns of multi-staged-segmental distributed and multi-sited inflammatory lesions, both destructive and proliferative/regenerative changes were observed in the bowel of the same patient. The diagnostic accuracy of colonoscopy, as confirmed by the histological examination of biopsy and resected specimens, was 66.7%. The major characteristic features of mucosal biopsy were the focal distribution of inflammatory infiltration and lymphoid aggregate. Otherwise, it may include edematous and widened submucosa, deep fissuring ulcers and hyperplasia, fibrosis and granulomas (detected in 30% of the group), among others. CONCLUSION: The colonic involvement of Crohn's disease was common. Colonoscopy may be valuable in establishing a diagnosis and in assessing the extent and severity of such colonic involvement. Biopsy is helpful to confirm a diagnosis conducted by colonoscopy. Colonoscopy combined with biopsy may replace radiology as the initial test of choice in many clinical situations.

[Importance of colonoscopy combined with biopsy in the diagnosis of colonic Crohn's disease].

OBJECTIVE: An attempt was made to provide a better insight into endoscopic and histological features and/or problems encountered when establishing a diagnosis of colonic Crohn's disease (Crohn's colitis). METHODS: As presented in our 27 cases with Crohn's colitis, the endoscopic findings and histological changes of biopsy specimens were summarized. As collated with correspondent results of biopsy and surgical specimens, the diagnostic accuracy of endoscopy was evaluated. RESULTS: twenty-six involvements of the large intestine (combined with other sites of the intestine) was found (96.3%). However, involvement limited to the colon alone was seen in only 4 cases (14.8%). Endoscopically, overlapped lesions with multistaged-segmental distributed and multi-sited diverse patterns (destructive and proliferative/regenerative) of inflammatory changes were observed. Endoscopic accuracy was 66.7%. The characteristic features of mucosal biopsy include focal distribution of the lesions, a thickened and edematous submucosa, deep fissuring ulcers, lymphoid aggregate, and hyperplasia, fibrosis and granulomas (detected in 30% of the group), etc. CONCLUSIONS: Colonic involvement of Crohn's disease is common. Colonoscopy may be valuable in establishing the diagnosis and in assessing the extent and severity of colonic involvement, and CDEIS was value in the follow up of patients. Colonoscopic biopsies are helpful for verification of the diagnosis in difficult cases. Colonoscopy has replaced radiology as the initial test of choice in many clinical situations.

Clinical features and management of Crohn's disease in Chinese patients.

BACKGROUND: An increasing incidence of Crohn's disease has been found in China in recent years. Our study has been focused on evaluating the diversity of the clinical manifestations of Crohn's disease in order to improve early diagnostic accuracy and therapeutic efficacy. METHODS: Thirty patients with active Crohn's disease were enrolled and their clinical data, including diagnostic and therapeutic results, were analyzed. Endoscopy combined with histological examination of biopsy specimens provided characteristic features of the disease. Transabdominal bowel sonography (TABS) was used for detecting intestinal complications. Nutritional supportive therapy was given to 20 subjects with active cases of the disease. RESULTS: Most patients were young adults with a higher proportion of females to males (ratio: 1.14:1). The disease affects any segment or a combination of segments along with the alimentary tract (from the mouth to the anus). In this study, the colon and small bowel were the major sites involved. Recurrent episodes of abdominal pain in the right lower quadrant and watery diarrhea were the most common symptoms. Granulomas were identifiable in nearly one-third (30.8%) of all biopsy specimens. In moderate cases of the disease, remission was achieved more quickly through the use of oral prednisone therapy than with SASP or 5-ASA. Beneficial effects on the host's nutritional status were observed. Immunosuppressives were used on an individual basis and showed variable therapeutic effects. Sixteen patients had surgery due to intestinal obstruction or failure to respond to drug therapies. Rapid improvement after surgery was reported. CONCLUSION: Endoscopy (with biopsy) and TABS were both crucial procedures for diagnosis. SASP (or 5-ASA) and prednisone were effective as inductive therapies. Azathioprine has demonstrable benefits after induction therapy with prednisone. Surgery, as an alternative treatment, provided another effective choice in selected patients.