猪德尔塔冠状病毒荧光定量PCR检测方法的建立

根据GenBank登录的猪德尔塔冠状病毒(PDCoV)毒株序列设计特异性引物,建立了检测PDCoV的实时荧光PCR方法。该方法在标准品浓度2.49×10~8~2.49×10~2 copies/μL范围内线性关系良好;特异性试验显示,其他几种常见猪病病毒未见典型扩增曲线;敏感性试验显示,最低检测下限为24.9 copies/μL;重复性试验显示,批内和批间变异系数小于3%。用该方法检测62份猪腹泻粪便样品,相比常规PCR方法,前者的检出率更高;两种方法检测1 168份进境活猪粪便拭子样品,结果均为阴性。结果表明,本研究所建立的方法适用于国内猪场的PDCoV的检测和进境活猪的监控检测,也可作为PDCoV的诊断及分子流行病学调查的技术手段。     

Biochar Mitigates Salinity Stress in Potato

A pot experiment was conducted in a climate‐controlled greenhouse to investigate the growth, physiology and yield of potato in response to salinity stress under biochar amendment. It was hypothesized that addition of biochar may improve plant growth and yield by mitigating the negative effect of salinity through its high sorption ability. From tuber bulking to harvesting, the plants were exposed to three saline irrigations, that is 0, 25 and 50 mm NaCl solutions, respectively, and two levels of biochar (0 % and 5 % W/W) treatments. An adsorption study was also conducted to study the Na⁺ adsorption capability of biochar. Results indicated that biochar was capable to ameliorate salinity stress by adsorbing Na⁺. Increasing salinity level resulted in significant reductions of shoot biomass, root length and volume, tuber yield, photosynthetic rate (A_n), stomatal conductance (g_s), midday leaf water potential, but increased abscisic acid (ABA) concentration in both leaf and xylem sap. At each salinity level, incorporation of biochar increased shoot biomass, root length and volume, tuber yield, A_n, g_s, midday leaf water potential, and decreased ABA concentration in the leaf and xylem sap as compared with the respective non‐biochar control. Decreased Na⁺, Na⁺/K⁺ ratio and increased K⁺ content in xylem with biochar amendment also indicated its ameliorative effects on potato plants in response to salinity stress. The results suggested that incorporation of biochar might be a promising approach for enhancing crop productivity in salt‐affected soils.     

广州石门国家森林公园野生观赏植物资源调查

通过野外调查和查阅文献资料,得出石门国家森林公园共有野生观赏植物122科267属377种,其中蕨类植物19科23属28种,裸子植物4科5属7种,被子植物99科239属342种。分析了石门国家森林公园野生观赏植物资源的基本特征和用途,并探讨其保护和开发利用。     

基质浇施黄腐酸钾对黄瓜幼苗的影响

对基质栽培的黄瓜幼苗浇施不同浓度的黄腐酸钾,通过研究其对黄瓜幼苗形态指标(株高、茎粗、根体积、最大根长、地上、地下部干鲜质量)、壮苗指数、叶绿素含量、根系活力等的影响。试验结果表明,在较低浓度水平下,黄腐酸钾可以显著提高黄瓜地下部干物质积累,增加根体积和根长,提高根系活力;高浓度的黄腐酸钾可抑制幼苗生长;而60~120 mg/L黄腐酸钾处理有利于培育壮苗。     

鳢肠对棉铃虫生长发育的影响

通过饲料混毒法测定鳢肠对棉铃虫生长发育的影响。结果表明,随饲料中鳢肠比例的加大和棉铃虫幼虫取食时间的延长,鳢肠对棉铃虫幼虫的生长发育具有明显的抑制作用。幼虫取食鳢肠比例高的饲料后,棉铃虫蛹质量显著降低,但羽化率和单雌日均产卵量与对照处理差异不显著;给棉铃虫幼虫饲喂鳢肠明显延长了幼虫和成虫历期,但对蛹历期的影响较小。     

超声振动时效的机理及实验研究

随着小型精密零件的广泛应用,消除小型零件的残余应力成为一个重要研究课题。本文提出了采用超声振动对小型零件时效处理。讨论了超声振动时效技术消除残余应力的机理。提出在时效过程中激振应力与工件残余应力之和大于材料疲劳极限时,即可对残余应力有消除作用。建立了圆截面杆件的残余应力计算模型。试验研究了激振应力和激振时间对消除构件残余应力效果的影响。结果表明,最佳激振时间为10min~15min,工件内残余应力消除率随着振幅的增大而增加。     

Response of labile organic C and N pools to plastic film removal from semiarid farmland soil

To examine the effects of plastic film removal on grain yield and soil organic matter (SOM), a spring maize (Zea may L.) field experiment was conducted for 5 yr at Changwu Agricultural and Ecological Experimental Station of Northwest China. Compared with traditional plastic film mulching during entire growing stages (FM), plastic film removal at the silking stage (RM) resulted in a 6.3% higher average maize yield. Under the RM treatment, soil organic carbon and total nitrogen significantly increased after the 5‐yr cultivation in the 0‐ to 20‐cm layer. Significant increases in extractable organic C (EOC), KMnO₄‐oxidizable C (KMnO₄‐C) and C management index (CMI) in the 0‐ to 20‐cm layer, and light fraction organic C and EOC in the 20‐ to 40‐cm layer were observed in response to plastic film removal after the 1‐yr treatment; the responses were more significant after 5 yr. Under the RM treatment, significant increases in microbial biomass C, light fraction organic N, extractable organic N, KMnO₄‐C and CMI were also observed after five years in the 20‐ to 40‐cm layer. Moreover, KMnO₄‐C and EOC were much more sensitive than other labile SOM fractions to the application of RM, even after only 1 yr of cultivation. Therefore, compared with mulching for the whole growing season, plastic film removal at the maize silking stage is an effective option for increasing yields and enhancing SOM concentration and soil sustainability in the regions with semiarid monsoon climates that have sufficient rainfall during maize reproductive stages.     

Proton accumulation accelerated by heavy chemical nitrogen fertilization and its long-term impact on acidifying rate in a typical arable soil in the Huang-Huai-Hai Plain

Cropland productivity has been signiifcantly impacted by soil acidiifcation resulted from nitrogen (N) fertilization, especialy as a result of excess ammoniacal N input. With decades’ intensive agricul...