nitrogen

摘要： Grain water relations play an important role in grain filling in maize. The study aimed to gain a clear understanding of the changes in grain dry weight and water relations in maize grains by using hybrids with contrasting nitrogen efficiencies under differing nitrogen levels. The objectives were: 1) to understand the changes in dry matter and percent moisture content(MC) during grain development in response to different nitrogen application rates and 2) to determine whether nitrogen application affects grain filling by regulating grain water relations. Two maize hybrids, high N-efficient Zhenghong 311(ZH311) and low N-efficient Xianyu 508(XY508), were grown in the field under four levels of N fertilizer: 0, 150, 300, and 450 kg N ha;during three growing seasons. Dry weight, percent MC and water content(WC) of basal-middle and apical grains were investigated. The difference in the maximum WC and filling duration of basal-middle and apical grains in maize ears resulted in a significant difference in final grain weight. Grain position markedly influenced grain drying down;specifically, the drying down rate of apical grains was faster than that of basal-middle grains. Genotype and grain position both influenced the impact of nitrogen application rate on grain filling and drying down. Nitrogen rate determined the maximum grain WC and percent MC loss rate in the middle and the late grain-filling stages, thus affecting final grain weight. The use of high N-efficient hybrids, combined with the reduction of nitrogen application rate, can coordinate basal-middle and apical grain drying down to ensure yield. This management strategy could lead to a win-win situation in which the maximum maize yield, efficient mechanical harvest and environmental safety are all achieved.

摘要： A variety of wastes are generated due to human activities. Organic waste usage in agriculture plays a significant role in the steady supply of plant nutrients through improving soil quality. An in vitro incubation study was conducted to measure the release of the major nutrients viz. available nitrogen (N), phosphorus (P), and potassium (K) in alkaline soil amended by recycled organic soil conditioners. The soil was amended by compost (Cm) and vermicompost (VC) @ 5 tha?1 and a mixture of compost and vermicompost (Cm + VC) @ 2.5 tha?1. Chemical fertilizers (Cf) were added @ of 98.842 kg⋅ha?1 of urea and 64.99 kg⋅ha?1 of triple superphosphate (TSP), with amended soils being incubated for 120 days maintaining 50% field moisture holding capacity. Due to the sufficient content of potassium in experimental soil for plant growth, extra potassium was not added. Available soil N, P, and K were determined at every 0, 15, 30, 45, 60, 90, and 120 days of incubation. The highest available N and K release was found in VC treated soils at the incubation period of 45 days. On the other hand, the highest P release was recorded in Cm treated soils at the incubation period of 45 days. In this experiment, the addition of Cm, VC and Cm + VC showed better release of cumulative plant available N, P and K than either control (C) or Cf and were arranged as VC > Cm > Cm + VC > Cf > C, Cm > Cm + VC > VC > Cf > C and Cm + VC > VC > Cm > C > Cf for N, P and K, respectively. The results of this experiment revealed that the addition of compost and/or vermicompost is predominant over chemical fertilizer in supplying of major nutrients for crops in alkaline soil.

摘要： Background: Nitrogen(N) is a required macronutrient for cotton growth and productivity. Excessive N fertilizers are applied in agriculture for crop yield maximization, which also generates environmental pollution. Improving crop N use efficiency(NUE) is the most economical and desirable way of reducing fertilizer application and environmental pollution. NUE has been an important issue in cotton. So far there is no report on cotton NUE improvement via transgenic approach. Nin-like proteins(NLP) are transcription factors regulating NUE. We previously demonstrated that At NLP7 improved NUE and biomass when overexpressed in Arabidopsis. However, it is not known whether At NLP7 can be used to improve NUE in crops.Results: To test the feasibility, we expressed At NLP7 in cotton and evaluated NUE and yield of the transgenic cotton in the field. Transgenic cotton showed improved NUE and yield under both low and high N conditions. In addition, plant biomass, amount of absorbed N, N contents, activities of N-assimilating enzymes, and the expression of N-related marker genes were significantly increased in transgenic cotton compared with the wild type control, suggesting that At NLP7 enhances NUE in cotton.Conclusion: Together, our results demonstrate that At NLP7 is a promising candidate to improve NUE and yield in cotton.

摘要： High yields of wheat are mainly obtained through a high level of nitrogen and irrigation supplementation.However,excessive nitrogen and irrigation supplication increase the risk of lodging.The main objectives of this work were to clarify the capacity of lodging resistance of wheat in response to nitrogen and irrigation,as well as to explore the effective ways of improving lodging resistance in a high-yield wheat cultivar.In this study,field experiments were conducted in the 2015-2016 and 2016-2017 growing seasons.A wheat cultivar Jimai 22(JM22),which is widely planted in the northern of Huang-Huai winter wheat region,was grown at Tai’an,Shandong Province,under three nitrogen rates and four irrigation treatments.The lodging risk was increased with increased nitrogen rate,as indicated by increasing lodging index(LI)and lodging rate across both growing seasons.With nitrogen increasing,the plant height,the basal internode length and the center of gravity height,which were positively correlated with LI,increased significantly.While the density of the basal 2nd internode(for culm and leaf sheath)and cell wall component contents,which were negatively correlated with LI,decreased conspicuous along with nitrogen increased.Increasing irrigation supplementation increased the 2nd internode culm wall thickness,breaking strength and leaf sheath density within limits which increased stem strength.Among the treatments,nitrogen application at a rate of 240 kg ha^(-1) and irrigation application at 600 m^(3)ha^(-1) at both the jointing and anthesis stages resulted in the highest yield and strongest stem.A suitable plant height ensures suffcient biomass for high yield,and higher stem stiffness,which was primarily attributed to thicker culm wall,greater density of the culm and leaf sheaths and higher cell wall component contents are the characteristics that should be taken into account to improving wheat lodging resistance.

摘要： [Objectives]This study was conducted to explore the rational formula for rice fertilization in Jianghan Plain.[Methods]An experiment on the combined application of nitrogen,phosphorus and potassium fertilizers was carried out in Jianghan Plain,an important rice producing area in Hubei,with a total of five treatments to study the effects of nitrogen,phosphorus and potassium fertilizers on the fertilizer use efficiency and yield of rice.[Results]Fertilization had a significant effect on improving rice yield,and nitrogen fertilizer had the greatest effect on rice yield,followed by potassium fertilizer and phosphorous fertilizer.[Conclusions]This study provides a scientific basis for the application of rice fertilizers and the reduction and efficiency improvement of chemical fertilizers in Jianghan Plain.

摘要： Nitrogen-15 isotope-modified compounds are widely used in medicine, pharmacology, agriculture and various fields of science and their nomenclature is gradually increasing. Their widespread use depends on the availability of inexpensive and simple isotope analysis methods. The present article is an attempt to determine the nitrogen-15 isotope content directly in organic compounds without their conversion. The general principle of possibility of determination of the isotopes of nitrogen directly in organic compounds is proposed. Based on the study of mass-spectra of Carbamide Carbonyldiamide, isocyanic acid and nitrobenzene the mass peaks are selected, by which it is possible to determine the atomic fraction of the isotopes of nitrogen. The respective formulas are proposed.

摘要： The nitrogen(N)requirements of cotton are well understood and have been extensively studied since 1887,with practical guides,decision support systems,models and recent reviews providing information on the importance of providing cotton crops with a sufficient supply of nutrients and improving nitrogen use efficiency.Given that the financial return to the grower depends on both the cotton quantity and quality and the growing importance of the latter,this review focusses specifically on information and knowledge about the effect of nitrogen application level on fibre quality.

摘要： Membrane separation is a high-efficiency,energy-saving,and environment-friendly separation technology.Covalent organic framework(COF)-based mixed-matrix membranes(MMMs)have broad application prospects in gas separation and are expected to provide new solutions for coal-bed methane purification.Herein,a high-throughput screening method is used to calculate and evaluate COF-based MMMs for CH_(4)/N_(2) separation.General design rules are proposed from thermodynamic and kinetic points of view using the computation-ready,experimental COFs.From our database containing 471,671 generated COFs,5 COF membrane materials were screened with excellent membrane selectivities,which were then used as the filler of MMMs for separation performance evaluation.Among them,BAR-NAP-Benzene_CF_(3) combined with polydimethylsiloxane and styrene-b-butadiene-b-styrene show high CH_(4) permeability of 4.43×10^(-13) mol·m·s^(-1)·Pa^(-1)·m^(-2) and high CH_(4)/N_(2) selectivity of 9.54,respectively.The obtained results may provide reasonable information for the design of COF-based membranes for the efficient separation of CH_(4)/N_(2).

摘要： The DD33 superalloy with ultra-low nitrogen (N) content was prepared by vacuum induced melting, and the effect of N on micro-pores in the DD33 single crystal nickel-base superalloy during solidification and homogenization was investigated by in-situ X-ray computed tomography (XCT). Results indicate that the volume fraction of micro-pores, including shrinkage pores and gas pores, increases from 0.08% to 0.11% with increasing N content from 5 ppm to 45 ppm during solidification. Correspondingly, the level of micro-pores in the sample with high N content is higher than that in the sample with low N content during homogenization at 1,330 °C for different time periods. However, the evolution behaviors of gas pores is different from that of shrinkage pores during solidification and homogenization. The number of gas pores is obviously larger in the high N sample during solidification, while the number of shrinkage pores and gas pores is almost the same in both samples after 1 h homogenization. Quantitative results show that the annihilation of micro-pores is associated with bubble diffusion, while the growth behavior of micro-pores during further exposure is dominated by Kirkendall-Frenkel effect.

摘要： Wheat flour products are the main dietary component of the Qinghai-Tibetan Plateau(QTP)population in China.However,the high altitude restricts the local wheat quality and quantity,and the applied nitrogen rate is higher than the optimal rate for wheat planting.In this study,we considered whether reducing the amount of nitrogen fertilizer and introducing the superior varieties from the North China Plain(NCP)are viable ways to increase the wheat quality and quantity in the QTP.Three and four winter wheat cultivars from QTP and NCP,respectively,were planted in Lhasa at an altitude of 3647 m with reduced topdressing nitrogen application at the jointing stage.The wheat from NCP exhibited higher grain hardness index and test weight,and better flour and dough quality.Reducing the topdressing nitrogen fertilizer from 135 to 75 kg N ha^(-1) at the jointing stage(with the same basal fertilization of 105 kg N ha^(-1) did not significantly(P<0.05)affect the grain yield,grain quality,flour quality or dough quality in any of the cultivars.In summary,introducing high-quality winter wheat varieties from the NCP to the Lhasa plateau is a viable way to enhance the wheat supply and quality in the QTP.Reducing a certain amount of the nitrogen fertilizer is an economic and feasible approach for the QTP region.

摘要： As nitrogen, particularly ammonium nitrogen is one of the main problems during thelandfill of municipal solid waste. Aerobic pretreatment could effectively reduce the nitrogenpollution during landfill. Nitrogen balance during various degrees of aerobic pretreatmentfollowed by anaerobic degradation was investigated. The function of aerobic pretreatment for the fateof nitrogen was to transfer the long, manifold and uncontrollable nitrogen pollution into the short, purified andcontrollable one. The nitrogen content in the pretreated waste was not linearly correlated with the time for thestability of waste. Considering the energy consumption during aerobic pretreatment, leachate characteristicsand stabilization time during the following landfill, the operation mode of R2 was optimized.