小麦化感作用物的提取,分离及其对白茅的杀除效果

小麦颖壳提取物经3520树脂分离后,对所得甲醇洗脱物离心,分得油类似物、上清液及沉淀物。前两个组分在300mg/L的浓度下,对白茅生长抑制率分别为100％和98％。上清液经硅胶柱分离,得7个亚组分,其中第1、3和7号亚组分在500mg/L浓度下对白茅生长的抑制率分别为95％、91％和95％。第3亚组分经葡聚糖凝胶柱分离,又分得A、B、C 3个组分,褐色粉末状的B组分在1000mg/L浓度下使白茅的生长量下降81％。从而证明小麦颖壳对白茅的化感作用是由多个化感物共同作用的结果。室内和温室及大田的测定结果表明,小麦颖壳中的甲醇洗脱物在24mg/株的剂量下对白茅生长的抑制率可达90％以上。这暗示,小麦颖壳中的甲醇可溶物可望开发成为防治白茅的生物除草剂。     

Global occurrence and spread of highly pathogenic avian influenza virus of the subtype H5N1

Highly pathogenic avian influenza viruses of the subtype H5N1 (HPAIV-H5N1) have circulated continuously in Asia, Europe, and Africa since 2003. Investigations on the environmental preference and global spread processes of the virus are needed. We compiled 16 environmental variables to assess their correlation with HPAIV-H5N1 occurrences by using a niche-based model called Maxent. We found the virus had the strongest positive association with the human footprint index, as well as the presence of certain types of wetlands and mild temperature (10-30 C). Outbreaks of HPAIV-H5N1 in poultry or wild birds were also more frequent in certain major habitat types (e.g., tropical and subtropical moist broadleaf forests, temperate broadleaf and mixed forests, and flooded grasslands and savannas) and ecoregions. We conducted trend surface analysis to generate the travelling wave of the virus' global spread from 2003 to 2009, which indicated that high mountains or plateaus did not affect the spread speed and direction.     

9种药剂对斜纹夜蛾的室内毒力与田间应用效果

通过室内毒力测定和田间药效试验,测定当前9种主流杀虫剂产品对斜纹夜蛾的防治效果。结果表明,甲维盐、茚虫威、虫螨腈和虫酰肼对斜纹夜蛾具有优良的防效,可作为防治斜纹夜蛾的首选药剂。Bt与多杀菌素的效果次之。阿维菌素、高效氯氰菊酯和毒死蜱对斜纹夜蛾已逐渐失去控制作用,在生产中应尽量少用、慎用。     

新疆果树多毛小蠹生物学特性及防治

多毛小蠹是新疆果树重要害虫，危害杏树甚为严重。在库尔勒一年发生2～3代，主要以幼虫和少数成虫、卵在树皮内越冬，世代重叠。在自然变温下，卵历期4～11天，幼虫20～31天；蛹期6～9天；成虫10～35天。完成一世代需40～86天，主要以幼虫在寄主树表面活动。采用农业和药剂防治相结合效果显著。     

美洲斑潜蝇发育始点及有效积温研究

室内设置５种温度对美洲斑潜蝇卵、幼虫、蛹、成虫和全世代的发育速率进行了观察,测得其发育始点和有效积温分别为１４．４、１２．８、１１．１．１５．０、１２．５℃和２９．０、４８．９、１３６．６、２３．７、２３５．２日度,同时对１９９７年进行了发生检验。     

基于条件植被温度指数的冬小麦主要生育时期干旱监测效果评价——I.因子权重排序法和熵值法组合赋权

选取关中平原冬小麦越冬后2002—2009年每年3—5月共9旬的条件植被温度指数（VTCI）遥感干旱监测结果,将冬小麦越冬后分为四个主要生育时期,分别运用因子权重排序法、熵值法及组合赋权法确定各生育时期干旱对产量的影 响权重,计算关中平原各市冬小麦每年的加权VTCI,并建立加权VTCI与冬小麦单产间的一元线性回归模型。结果表明,关中平原大部分地区的加权VTCI与小麦单产密切相关。其中,熵值法确定的加权VTCI与小麦单产的线性相关性不显著,渭南、咸阳及铜川的决定系数R²值均低于0.5;因子权重排序法和组合赋权法确定的加权VTCI与小麦单产的线性相关性显著,咸阳、宝鸡及西安的R²值接近或高于0.6,渭南接近 0.5,铜川较差。且组合赋权法的结果中宝鸡和西安的R²值接近0.7,优于因子权重排序法和熵值法的结果。     

Field evaluation of insect-resistant transgenic Populus nigra trees

The performance of insect-resistant transgenic poplar trees (Populusnigra) expressing a Cry1Ac gene from Bacillus thuringiensis subsp. Kurstaki HD-1 against poplar defoliators was evaluated in the field at the Manas Forest Station in Xinjiang Uygur Autonomous Region during1994–1997. The results showed that the average percentage of highly damaged leaves on the transgenic trees was 10% while that on the control trees in nearby plantations reached 80–90%. The average number of pupae per m² of soil at 20cm depth in transgenic poplar plantation was 18 which was only 20% of that found in the non-transgenic control field. The number of pupae and the leaf-damage on transgenic trees described above are all far below the threshold set for chemical protection measures. The non-transformed poplar trees grown in the same plantation with the transgenic trees were also protected indicating that cross protection occurred between these two kinds of trees. Insect-resistant transgenic poplar trees have a potential application value in afforestation. This revised version was published online in August 2006 with corrections to the Cover Date.     

病原菌诱导后黄瓜叶片中脂氧合酶活性与茉莉酸积累的关系

通过酶活性测定和高效液相色谱分析,研究经病原菌诱导后黄瓜叶片中脂氧合酶(LOX)活性与茉莉酸(JA)积累量的关系。结果表明,黄瓜经褐斑菌诱导后,叶片中茉莉酸(JA)大量积累,同时脂氧合酶(LOX)活性上升,接种叶片的上位叶中LOX活性和JA含量于诱导接种褐斑菌12h后开始升高,并于诱导接种24h后达到峰值,接种叶片的下位叶中LOX活性和JA含量在诱导接种12h后变化不大,但在24h后显著升高,并于48h达到峰值,此后逐渐平稳下降。相关分析表明,LOX与JA呈显著正相关,相关系数r为0.92。同时通过喷施脂氧合酶抑制剂(NDGA)和添加茉莉酸的试验证实LOX是JA合成的关键酶。     

Effect of stachyose supplementation on growth performance, nutrient digestibility and caecal fermentation characteristics in broilers

1. The objective of this study was to evaluate whether the oligosaccharide stachyose enhances gastrointestinal tract health by fermentation and proliferation of desirable bacteria species and thus affects growth performance and nutrient digestibility in broilers. 2. A total of 432 1-d-old male Arbor Acres (AA) broilers were randomly allocated to one of 6 treatments, with 12 replicate pens per treatment and 6 birds per pen. Chicks were fed a maize-hamlet protein 300 (HP300) basal diet with 0, 4.0, 8.0, 12.0 or 16.0 g/kg stachyose. A sixth diet contained no HP300 but soybean meal (SBM) and provided 8.7 g/kg stachyose and 3.1 g/kg raffinose. The duration of the study was 42 d. 3. Stachyose contents above 12.0 g/kg depressed group body weights, average daily gain and feed/gain but not feed intake during the whole experimental period. Broiler growth decreased linearly and quadratically with increasing stachyose content. No differences were detected between diets supplemented with 12.0 g/kg stachyose and SBM. 4. Nutrient digestibility tended to decrease but not significantly with increasing stachyose. 5. Stachyose content had no significant positive effects on caecal pH, microflora population and the resulting short-chain fatty acid (SCFA) metabolites during the 42 d experiment, with only butyrate differing significantly in the initial period.