Effects of nitrogen rate and ratio of base fertilizer and topdressing on uptake, translocation of nitrogen and yield in wheat

Application of nitrogen (N) fertilizer is one of the most important measures to increase grain yield and protein content in winter wheat (Triticum aestivum L.) production. However, misuse of N Tertilizer will not only affect gram yield and quality, but also cause the decline of economic benefits and related negative environmental effects. It is essential to study reasonable N application regimes for profitable yields, efficient N utilization and reduction in possible environmental pollution. The objective of this study was to determine the N uptake and translocation in wheat plants by using ¹⁵N isotope tracers in PVC cylinders (2.05 m long, ϕ 0.2 m, without bottom) in seven treatments: without N fertilizer application (N0); N application rate of 168 kg/hm² (0.527 g/pot), with ratios of base fertilizer to topdressing of 1:1 (N1), 1:2 (N2) and 0:1 (N3); N application rate of 240 kg/hm² (0.753 g/pot), with ratios of base fertilizer to topdressing of 1:1 (N4), 1:2 (N5) and 0:1 (N6). The ¹⁵N tracer experiment showed that the main basal N absorbed by plant from sowing to jointing stage accounted for 78.04%–89.67%; fertilizer N use efficiency (FNUE, N fertilizer accumulation in plant/N supplied) of topdressing was significantly higher than that of basal N; reducing basal N amount and increasing topdressing N amount could appropriately promote the plant’s absorption of more N fertilizer and enhance FNUE, of which treatment N2 had the highest values. Under the high-yield condition, when N fertilizer rate was increased from 168 to 240 kg/hm², there were no significant differences in the amount of N accumulation in plants and in grains between treatments with the same ratio of base fertilizer to topdressing; by reducing basal N amount and increasing topdressing N amount accordingly, the translocation efficiency (TE, accumulation amount from vegetative organs to gram/N accumulation in vegetative organs during anthesis) increased, and the amount of N assimilation to grains after anthesis and its contribution proportion (the amount of N assimilation to grains after anthesis/N accumulation in grain) also increased. In other words, grain N accumulation amount increased with increasing amount of topdressing N at the same N fertilizer rate. There were no significant differences among treatments N2, N3, N5 and N6 in grain N accumulation. Appropriate N fertilizer rate with a reduction in basal N amount and an increase in topdressing N amount such as in N2, N5 and N6 increased grain yield and protein content. In conclusion, under conditions used in this experiment, as far as grain yield, protein content and FNUE are concerned, the recommended appropriate N fertilizer application regime is treatment N2, with a N fertilizer rate of 168 kg/hm² and a ratio of base fertilizer to topdressing of 1:2. Translated from Journal of Acta Agronomica Sinica, 2006, 32(12): 1860–1866 [译自: 作物学报]     

住宅小区绿化中短工期高质量的施工技术

根据某楼盘景观绿化工程施工过程,从进场前准备、苗木品种选择、绿地土壤翻新、大型乔木预培育和预种植等方面,围绕短工期、高质量的要求,总结庭院景观高效施工技术.     

论生态景观吸引力空间异化模型的应用——以江苏环太湖国际旅游区规划为例

以江苏环太湖国际旅游区规划为实验对象,重点探讨生态景观吸引力空间异化过程,即从要素磁场分化开始,经由同质景观间的引力异化,导致同类景观片区间的引力空间异化,最终推导出另一种同质相斥、异质相吸的新型生态景观吸引力空间结构。     

人工模拟自然醇化的库房设施建设与应用

笔者通过对烟叶人工模拟自然醇化的可行性和优势及今后的发展趋势的分析,引进了人工模拟自然醇化的先进库房建设及技术应用,它采用国际先进的技术对烟叶醇化库的温湿度进行实时监测,实现了对监测数据的对比、分析、存储、显示、打印、报警等多项功能。改变了以往手工抄表的状况,减轻了工作人员的劳动强度,在仓库监控管理领域具有很高的推广和应用价值。     

杜洛克生长猪理想氨基酸平衡的研究

通过对４８头杜洛克生长猪的饲养试验及６头阉公猪的代谢试验，探讨了１７％，１５％两种蛋白水平及０．８％、０．９５％和１．０５％三种赖氨酸水平的６种饲粮对杜洛克生长猪日增重、氮沉积和能量代谢的影响。结果表明，两种蛋白水平对增重影响差异不大（Ｐ＞０．０５），高蛋白时，以１．０５％的赖氨酸、赖蛋比６．２饲粮获得最好的增重和饲料利用率；低蛋白时，以０．９５％赖氨酸、赖蛋比６．３增重最好。尿Ｎ与日食Ｎ量呈极显著正相关（Ｐ＜０．０１）；６组饲粮Ｎ沉积量差异不显著（Ｐ＞０．０５）；但低蛋白饲粮的Ｎ沉积率和ＭＥ／ＤＥ值显著高于高蛋白饲粮（Ｐ＜０．０５）。     

A review of the role of excess soil moisture conditions in constraining farm practices under Atlantic conditions

The Less Favoured Area (LFA) scheme is a major element of the EU Rural Development Policy, aimed at supporting farming in areas with natural handicaps or low soil productivity. It has been in place since 1975 and accounts for 14% of total Community funding. In 2003, the European Court of Auditors recommended that the socio‐economic criteria on which the current scheme is based be replaced by biophysical criteria. Reviews of the proposals suggest that in Atlantic climates of Northwest Europe, the new criteria do not delineate adequately areas where agricultural productivity is constrained by the biophysical environment and that such areas are instead demarcated by the occurrence of excess soil moisture conditions. In this paper, we review the impact of excess soil moisture conditions on the sustainability of farming systems and their role in constraining strategic and tactical farm management practices. In particular, we review the scientific evidence on the impact of excess soil moisture conditions on herbage growth, herbage utilization, farm operations and environmental sustainability. On the basis of this, we propose an additional biophysical criterion for the new delineation of LFAs, namely the length of time that soil water is in excess of field capacity (‘field capacity days’). While there is no clear threshold for field capacity days above which agricultural sustainability is acutely constrained, the evidence reviewed in this paper suggests that the sustainability of intensive livestock farming and tillage systems is particularly challenging in scenarios where the 80 percentile of field capacity days exceeds 220–230 days.     

银杏干叶球磨法超微粉碎的试验研究

根据几种常见的超微粉碎技术特点,结合银杏干叶超微粉碎必须保持其药用功能因子不损失的技术要求,选择球磨超微粉碎法对银杏干叶进行了超微粉碎试验．结果表明,以m（研磨球）：m（银杏叶）=15：1进行干法球磨3h,所得粉末粒度均匀,平均粒径3．367μm．电子显微镜下能观察到单个细胞破壁后破碎的粒子团,且干结不透明,表明银杏干叶细胞已破裂．     

Basal internode elongation of rice as affected by light intensity and leaf area

Short basal internodes are important for lodging resistance of rice(Oryza sativa L.).Several canopy indices affect the elongation of basal internodes,but uncertainty as to the key factors determining elongation of basal internodes persists.The objectives of this study were(1)to identify key factors affecting the elongation of basal internodes and(2)to establish a quantitative relationship between basal internode length and canopy indices.An inbred rice cultivar,Yinjingruanzhan,was grown in two split-plot field experiments with three N rates(0,75,and 150 kg N ha−1 in early season and 0,90,and 180 kg N ha−1 in late season)as main plots,three seedling densities(16.7,75.0,and 187.5 seedlings m−2)as subplots,and three replications in the 2015 early and late seasons in Guangzhou,China.Light intensity at base of canopy(Lb),light quality as determined from red/far-red light ratio(R/FR),light transmission ratio(LTR),leaf area index(LAI),leaf N concentration(NLV)and final length of second internode(counted from soil surface upward)(FIL)were recorded.Higher N rate and seedling density resulted in significantly longer FIL.FIL was negatively correlated with Lb,LTR,and R/FR(P<0.01)and positively correlated with LAI(P<0.01),but not correlated with NLV(P>0.05).Stepwise linear regression analysis showed that FIL was strongly associated with Lb and LAI(R2=0.82).Heavy N application to pot-grown rice at the beginning of first internode elongation did not change FIL.We conclude that FIL is determined mainly by Lb and LAI at jointing stage.NLV has no direct effect on the elongation of basal internodes.N application indirectly affects FIL by changing LAI and light conditions in the rice canopy.Reducing LAI and improving canopy light transmission at jointing stage can shorten the basal internodes and increase the lodging resistance of rice.     

大豆不同株龄及不同的叶龄、荚龄对灰斑病的反应

本研究用人工接种方法探讨了大豆不同株龄及不同的叶龄和荚龄对灰斑病的反应。结果表明,株龄越大的大豆其灰斑病愈轻,反之则重。完全展开叶和正在扩展叶易感灰斑病,嫩叶（叶缘未分离）和老化叶不易感病。荚龄大于１ｃｍ的最易感病、病粒率高,０．５ｃｍ以下的荚不易感病。     

Comparative diagnostic test characteristics of oscillometric and Doppler ultrasonographic methods in the detection of systolic hypertension in dogs

Comparison of test characteristics allows a clinician to choose the optimal diagnostic test method for an individual patient. This study assessed the comparative test characteristics of noninvasive (NI) blood pressure measurement methods (oscillometric and Doppler) and used this information to develop optimal cutoff values for diagnosis of systolic hypertension in dogs by these NI methods. Simultaneous NI (oscillometric or Doppler methods) and invasive (arterial puncture [AP]) systolic blood pressure (SBP) measurements were obtained prospectively from normal dogs and dogs suspected of having systemic hypertension based on clinical signs. Oscillometric SBP readings were obtained from the distal hind limb (Osc-L, n = 54) or the proximal tail (T. n = 27). Doppler BP measurements were obtained using a forelimb cuff (n = 57). AP-SBP was categorized as hypertensive if > or = 160 mmHg, and sensitivity (Se). specificity (Sp), and likelihood ratios (LR) were calculated for diagnostic cutoff values ranging from 130 to 220 mmHg. Receiver operator characteristic (ROC) curves were analyzed to determine optimal cutoff values for diagnosis of AP-SBP > or = 160 mmHg. Optimal NI SBP cutoff values considered to reflect AP values > or = 160 mmHg were: Osc-L = 160 mmHg (Se: 65%, Sp: 85%. LR = 4.33: 1), Osc-T = 150 mmHg (Se: 84%, Sp: 75%, LR = 3.36: 1), and Doppler = 160 mmHg (Se: 71%,