氮肥对盆栽欧洲水青冈生物量和营养分配的影响(英文)

调查了施加氮肥(15NH4和15NO3)处理后在两个连续生长季内欧洲水青冈(Fagus sylvatica L.)幼苗地上部分和地下部分的生物量和营养元素分配。盆栽欧洲水青冈幼苗培养于温室大棚内,培养土样取自相邻的三种林分:欧洲水青冈,挪威赤松,欧洲水青冈-赤松混交林。结果表明,氮肥(15N)处理对欧洲水青冈营养元素分配没有显著影响,施加氮素形式决定自身流入植物库的情况。欧洲水青獭收氮素主要以硝态氮的形式,因此,尽管植物体内保存的硝态氮和氨态氮并没有统计差异,但是叶片中硝态氮明显减少。施加硝态氮对欧洲水青冈氮素恢复的影响要大于施加氨态氮。与欧洲水青冈茎、粗根相比,优质根系对氮素(15N)固定是一个缓慢过程。表8图1参40。     

Decomposition of maize residues after manipulation of colonization and its contribution to the soil microbial biomass

A 28-day incubation experiment at 12°C was carried out on the decomposition of maize leaf litter to answer the questions: (1) Is the decomposition process altered by chemical manipulations due to differences in the colonization of maize leaf litter? (2) Do organisms using this maize material contribute significantly to the soil microbial biomass? The extraction of the maize straw reduced its initial microbial biomass C content by 25%. Fumigation and extraction eliminated the microbial biomass by 88%. In total, 17% of added maize straw C was mineralized to CO₂ during the 28-day incubation at 12°C in the treatment with non-manipulated straw. Only 14% of added C was mineralized in the treatment with extracted straw as well as in the treatment with fumigated and extracted straw. The net increase in microbial biomass C was 79 μg g^?1 soil in the treatment with non-manipulated straw and an insignificant 9 μg g^?1 soil in the two treatments with manipulated straw. However, the net increase did not reflect the fact that the addition of maize straw replaced an identical 58% (≈180 μg g^?1 soil) of the autochthonous microbial biomass C₃-C in all three straw treatments. In the two treatments with manipulated straw, the formation of maize-derived microbial biomass C₄-C was significantly reduced by 25%. In the three straw treatments, the ratio of fungal ergosterol-to-microbial biomass C ratio showed a constant 60% increase compared to the control, and the contents of glucosamine and muramic acid increased by 18%. The average fungal C/bacterial C ratio was 3.6 in the soil and 5.0 in the recovered maize straw, indicating that fungal dominance was not altered by the initial chemical manipulations of the maize straw-colonizing microorganisms.     

Sensitivity of Wheat Powdery Mildew (Blumeria graminis f.sp. tritici) towards Metrafenone

A monitoring study on the current sensitivity situation of wheat powdery mildew (Blumeria graminis f.sp. tritici) towards metrafenone was performed in 2009 with 2509 isolates. Airborne isolates were randomly collected in different regions of the most important European cereal growing regions. The sensitivities of the majority of isolates were comparable to the baseline sensitivity, which was determined in 2000 before market launch of the compound. Ninety-two isolates showed sensitivities outside the baseline. Eighty-four of them were classified as moderately adapted and could still be inhibited with registered rates of metrafenone in glasshouse tests under various preventive or curative conditions. Eight isolates were identified to be resistant, which were not fully inhibited at registered rates. Resistance management strategies and further extensive monitoring studies are indicated for a sustainable use of metrafenone against wheat powdery mildew.     

司马迁《史记》之秦皇与汉武

西方学界对<史记>的篇章结构未给予充分的关注.我们强调了一种分析十二本纪划分的方法.并详尽的论证了秦始皇与汉武帝在儒家的胜利、朝色的选择、封禅之举、政权的膨胀以及封地的废止等方面上的相同处,由此提出"司马迁笔下秦始皇的事迹受到当时汉武帝的影响并作为汉武帝的警示"这样的结论.     

Establishment of an ELISA for Measuring Bovine Pregnancy-Associated Glycoprotein in Serum or Milk and Its Application for Early Pregnancy Detection

It has been shown in several mammalian species that during pregnancy, trophoblast cells express a range of pregnancy-associated glycoproteins (PAG). The presence of PAG in the maternal serum of cows may serve as an indicator of pregnancy from day 28 after AI onward. The present study addresses (1) conversion of an existing PAG-RIA to a competitive double antibody ELISA using a polyclonal anti-bPAG-IgG and an anti-rabbit-IgG raised in sheep for coating and (2) application of newly established ELISA to test its suitability for pregnancy detection by measuring PAG in serum or milk. The intraassay coefficients of variation (CV) for the PAG-ELISA were 2–14% for serum and 10–12% for milk; the corresponding interassay CVs were 8–22% and 12–22%, respectively. Pregnancy-associated glycoprotein profiles established in milk and serum of 12 pregnant cows showed a characteristic pattern with measurable amounts from approximately day 20 onwards in serum and from day 60 onwards in milk. In a field trial, serum PAG was determined in 397 cows sampled between 20 and 50 days after insemination. The outcome was that, pregnancy could reliably be diagnosed from day 28 onwards in serum and from day 150 onwards in milk. In conclusion, it may be stated that the established ELISA provides an efficient and reliable means of pregnancy diagnosis that will, in our judgement, gain in popularity with cattle breeding. The ELISA proved to be an adequate and efficient way of measuring PAG in maternal serum or milk and will be a useful means of pregnancy detection in cows.     

Substituted alpha-(phenylhydrazono)phenylacetonitrile derivatives. Part 1: A new class of uncoupler of oxidative phosphorylation

Substituted alpha-(phenylhydrazono)phenylacetonitrile derivatives have been discovered which constitute a series of potent uncouplers of oxidative phosphorylation. Systematic variation of substituents on both benzene rings has clearly demonstrated the importance of steric congestion around the ionisation site and delocalisation of negative charge in the anionic form. Replacement of the cyano group by other electron-withdrawing groups leads to a dramatic decrease in uncoupling activity. The sub-nanomolar levels of uncoupling activity found in certain members indicate that these compounds are the most potent uncouplers yet reported.     

Evaluation of Erysiphe graminis f sp tritici field isolates for resistance to strobilurin fungicides with different SNP detection systems

A single nucleotide polymorphism (snp) in the cytochrome b gene confers resistance to strobilurin fungicides in Erysiphe graminis DC fsp tritici Marchal. On the basis of this point mutation three different types of molecular markers have been developed. Cleaved amplified polymorphic sequences and allele-specific PCR were used to score resistant and sensitive isolates from specifically selected regional populations across Europe. The results of molecular tests were in total agreement with the resistance phenotypes revealed by in vivo tests. Serial dilutions of mixed samples (resistant/sensitive) delimited the detection for strobilurin-resistant alleles to a range of 10-50% for both marker classes. Due to these detection limits no mixture of mitochondria within individual isolates was found. Denaturing high performance chromatography was used to increase the detection sensitivity for the mutant allele. Although the detection limit was lowered to 5-10%, there was no evidence for the existence of mixed mitochondrial genotypes.     

Quinoxyfen--resistance management and sensitivity monitoring in wheat: 1995-2000

Wheat powdery mildew, Blumeria (= Erysiphe) graminis DC f sp tritici Marschal is one of the most important foliar diseases of cereals in Europe, and has shown a high potential for adaptability in sensitivity towards modern fungicides during the last 20 years. Quinoxyfen is a surface-mobile fungicide from a new chemical class that has been commercially used for the control of B graminis in Europe since 1997. When the compound was launched, a Resistance Management Strategy was implemented which included: no seed treatments, no autumn use, a specified window of application and recommendations for appropriate tank-mixing. To assess the success of this Management Strategy, a European-wide resistance monitoring programme was carried out between 1995 and 2000 using spore trap sampling, and a whole plant assay. The mean EC50 values found by year were 0.060 mg litre-1 in 1995, 0.052 mg litre-1 in 1996, 0.071 ml litre-1 in 1997, 0.039 mg litre-1 in 1998, 0.039 mg litre-1 in 1999 and 0.063 mg litre-1 in 2000. No new sensitivity classes were found. The slight shift to lower sensitivity in 1998 and 1999 was correlated with similar shifts in three wildtype isolates, and was ascribed to experimental variation. The monitoring programme will continue to assess the long-term impact of the management recommendations on the resistance status of quinoxyfen.