Responses of Greenhouse Tomato and Pepper Yields and Nitrogen Dynamics to Applied Compound Fertilizers

Yield and N uptake of tomato (Lycopersicum esculentum Mill.) and pepper(Capsicum annuum L.) crops in five successive rotations receiving two compound fertilizers (12-12-17and 21-8-11 N-P_2O_5-K_2O) were studied to determine 1) crop responses, 2) dynamics of NO_3-N andNH_4-N in different soil layers, 3) N balance and 4) system-level N efficiencies. Five treatments (2fertilizers, 2 fertilizer rates and a control), each with three replicates, were arranged in thestudy. The higher N fertilizer rate,300 kg N ha^(-1) (versus 150 kg N ha^(-1)), returned highervegetable fruit yields and total aboveground N uptake with the largest crop responses occurring forthe low-N fertilizer (12-12-17) applied at 300 kg N ha^(-1) rather than with the high-N fertilizer(21-8-11). Ammonium-N in the top 90 cm of the soil profile declined during the experiment, whilenitrate-N remained at a similar level throughout the experiment with the lower rate of fertilizer N.At the higher rate of N fertilizer there was a continuous NO_3-N accumulation of over 800 kg Nha^(-1). About 200 kg N ha^(-1) was applied with irrigation to each crop using NO_3-contaminatedgroundwater. In general, about 50% of the total N input was recovered from all treatments. Pepper,relative to tomato, used N more efficiently with smaller N losses, but the crops utilized less than29% of the fertilizer N over the two and a half-year period. Local agricultural practices maintainedhigh residual soil nutrient status. Thus, optimization of irrigation is required to minimizenitrate leaching and maximize crop N recovery.

Effect of Long-Term Straw Incorporation on SoilMicrobial Biomass and C and N Dynamics

A study was performed on the long-term effect of straw incorporation on soil microbial biomass C contents, C and N dynamics in both Rothamsted and Woburn soils. The results showed that for both soils,the microbial biomass C contents were significantly different among all the treatments, and followed the sequence in treatments of straw chopped and incorporated into 10 cm (CI10) > straw burnt and incorporated into 10 cm (BI10) > straw chopped and incorporated into 20 cm (CI20) > straw burnt and incorporated into 20 cm (BI20). Laboratory incubation of soils showed that the cumulative CO2 evolution was closely related to the soil microbial biomass C content. Carbon dioxide evolution rates (CO2-C, μg (g d) -1 ) decreased rapidly in the first two weeks’ incubation, then decreased more slowly. The initial K2SO4-extractable NH4-N and NO3-N contents were low and similar in all the treatments, and all increased gradually with the incubation time. However, net N immobilization was observed in chopped treatments for Rothamsted soils during the first 4 weeks. Nevertheless, more N mineralization occurred in neatment CI10 than any other treatment at the end of incubation for both soils. The Woburn soils could more easily suffer from the leaching of nitrate because the soils were more permeable and more N was mineralized during the incubation compared to the Rothamsted soils.

The Application of Ecosystem Dynamic Model in Xiamen Bay

This paper is to establish a nitrogen and phosphorus nutrients cycle-based numerical model of ecological dynamics for Xiamen Bay on the basis of the existing three-dimensional barocline hydrodynamic model. The calculation results show that the estuarine district of Jiulongjiang estuary has the highest inorganic nitrogen concentration followed by the West Harbor, which demonstrates that Jiulongjiang River is the main input source of inorganic nitrogen in Xiamen Bay. The West Harbor has relatively high concentration of nutrients caused by the huge land pollution emission and its own poor water exchange capacity; while the distribution rules of phytoplankton biomass correspond with those of phosphates, demonstrating Xiamen Bay＇s phytoplankton controlled by phosphorus; the haloplankton biomass differs slightly, presenting the gradual reduction from the interior part to the exterior part of the bay.

Hot Deformation Behavior and Processing Maps of As-cast Mn18Cr18N Steel

Hot deformation behavior of as-cast Mn18Cr18 N austenitic stainless steel was studied in the temperature range of 950-1200 ℃ and strain rate range of 0.001-1 s^（-1） using isothermal hot compression tests. The true stress-strain curves of the steel were characterized by hardening and subsequent softening and varied with temperatures and strain rates. The hot deformation activation energy of the steel was calculated to be 657.4 k J/mol, which was higher than that of the corresponding wrought steel due to its as-cast coarse columnar grains and heterogeneous structure. Hot processing maps were developed at different plastic strains, which exhibited two domains with peak power dissipation efficiencies at 1150 ℃/0.001 s^（-1） and 1200 ℃/1 s^（-1）, respectively. The corresponding microstructures were analyzed by optical microscopy（OM）, scanning electron microscopy（SEM）, and electron backscatter diffraction（EBSD）. It has been confirmed that dynamic recrystallization（DRX） controlled by dislocation slipping and climbing mechanism occurs in the temperature and strain rate range of 1050-1200 ℃ and 0.001-0.01 s^（-1）; And DRX controlled by twinning mechanism occurs in the temperature and strain rate range of 1100-1200 ℃, 0.1-1 s^（-1）. These two DRX domains can serve as the hot working windows of the as-cast steel at lower strain rates and at higher strain rates, respectively. The processing maps at different strains also exhibit that the instability region decreases with increasing strain. The corresponding microstructures and the less tensile ductility in the instability region imply that the flow instability is attributed to flow localization accelerated by a few layers of very fine recrystallized grains along the original grain boundaries.

氮钾互作对春玉米养分吸收动态及模式的影响

采 用田间试 验与 植株 分 析等 方 法 研究 了 不 同氮 钾 配比 下 春 玉 米养 分 吸 收 动 态及 模式，结 果表明，不 同氮钾 配比下春 玉米氮磷 钾绝对 量的积累 均符合 Ｌｏｇｉｓｔｉｃ 方程，肥 料用量与 比例可明显影响 到玉米 养分吸收 最大速 率及 其 出现 日 期。用 量 及比 例适 宜 可获 得较 高 的养 分最 大 吸收速率， 且其最大 速率出现 日期相 对较早；玉 米氮素 最大吸收 速率 出现 在中 后期， 应注 意氮 肥的 分次施用 。每生产１００ ｋｇ 玉 米子粒， 适宜氮（ Ｎ） 、磷（ Ｐ） 、钾（ Ｋ） 的吸收 量分别为１９５４ 、０３７６ 和１３９０ ｋｇ 。植株养 分吸收 适宜比例 为１∶０１９∶０７１ 。

Decomposition of Different Litter Fractions in a Subtropical Bamboo Ecosystem as Affected by Experimental Nitrogen Deposition

As an important component of the global carbon （C） budget, litter decomposition in terrestrial ecosystems is greatly affected by the increasing nitrogen （N） deposition observed globally. We hypothesized that different litter fractions derived from a single tree species may respond to N deposition differently depending on the quality of the litter substrate. To test the hypothesis, a two-year field experiment was conducted using the litterbag method in a Pleioblastus amarus plantation in the rainy region of Southwest China. Four N treatment levels were applied： control （no N added）, low-N （50 kg N ha-1 year-1）, medium-N （150 kg N ha-a year-1）, and high-N （300 kg N ha-1 year-l）. We observed different patterns of mass loss for the three P. amarus litter fractions （leaves, sheaths, and twigs） of varying substrate quality in the control plots. There were two decomposition stages with different decay rates （fast rate in early stages and slow rate in the later stages） for leaves and sheaths, while we did not observe a slower phase for the decay of twigs during the 2-year study period. The annual decomposition rate （k） of twigs was significantly lower than that of leaves or sheaths. Addition of N slowed the decomposition of leaves and twigs in the later stages of decomposition by inhibiting the decay of lignin and cellulose, while addition of N did not affect the mass loss of sheaths during the study period. In the decomposition of all three litter fractions, experimental N deposition reduced the net N accumulation in the early stages and also decreased the net N release in the later stages. The results of this study suggest that litter substrate quality may be an important factor affecting litter decomposition in a bamboo ecosystem affected by N deposition.

Designing Cyclopentapeptide Inhibitor of Neuraminidase H5N1 Virus Through Molecular and Pharmacology Simulations

Highly Pathogenic Avian Influenza（HPAI） H5N1 has attracted much attention as a potential pandemic virus in humans, which makes death inevitable in humans. Neuraminidase（NA） has an important role in viral replication. Thus, it is an attractive target when designing anti-influenza virus drug. However, evolving viruses cause some anti-viral drugs to be ineffective, as they show resistance to them. Selection of peptides as drug candidates is important for the peptide-receptor activity and good selectivity. Cyclic bonds in the peptide ligand design aim to improve the stability of the system and remove the obstacles in drug metabolism. The design is based on the polarity of the ligand and amino acid residues in the active site of NA. The results are 4200 cyclic pentapeptides as potential lead compounds. Docking simulations were conducted using MOE 2008.10 and were screened based on the value of the binding energy（？Gbinding）. ADME-Tox prediction assay was conducted on the selected ligands.Intra- and inter-molecular interactions, as well as changes in the form of bonds, were tested by molecular dynamics simulations at temperatures of 310 K and 312 K. The results of the docking simulations and toxicity prediction assay show that there are two ligands that have a residual interaction with the target protein： CLDRC and CIWRC. These two ligands have ？Gbindingvalues of –40.5854 and –39.9721 kcal/mol（1 kcal/mol = 4.18 k J/mol）. These ligands are prone to be mutagenic and carcinogenic, and they have a good oral bioavailability. The results show that the molecular dynamics of both ligand CLDRC and CIWRC are more feasible at the temperature of 312 K. At the end,both CIWRC and CLDRC ligands can be used as the drug candidates against H5N1 virus.