草原蘑菇圈对牧草长势影响的初步分析

在白蘑,黄蘑圈上,圈内及圈外分别作测产样方,分析它们之间的差异。结果表明：白蘑,黄蘑圈均可极显著地提高群落地上生物量。其对羊草的影响较显著,圈上羊草的生物量,株高,密度及单株重均明显高于对圈内,圈外;对黄囊苔草和其它植物的影响不明显。白蘑圈对羊草的影响较黄蘑圈小。     

蒙古冰草表型数量性状的变异与生境间的相关性

采用多因变量线性模型方差、变异系数、主成分分析及UPGMA聚类分析的数量统计方法,对来自内蒙古中东部地区的6个天然居群和2个栽培品种(品系)的花序10个数量性状进行了分析。结果表明,蒙古冰草在花序各部的表型性状上存在有居群内及居群间的差异,同时,天然居群的变异程度大于栽培品种,而且居群间的分化与生态环境因子有着密切的相关。     

Biological Control and Use of Adjuvants against Multiple Seeded Cocklebur (Xanthium strumarium) in Comparison with Several Other Cocklebur Types

Common cocklebur has several biotypes including multiple seeded cocklebur (MSC), NCC-TX, and NCC-MS. Alternaria helianthi applied at 2.5×10⁴ conidia mL^-1 in a 50% micro-emulsion of unrefined corn oil (MESUCO) or 0.2% Silwet L 77 caused 60-75% mortality on NCC-TX and MSC. Increasing the conidial concentration to 5×10⁴ mL^-1 increased mortality to 100% on MSC and NCC-TX, and 75% on NCC-MS. At 10×10⁴ conidia mL^-1, A. helianthi caused 100% mortality in all three biotypes. No mortality occurred in any biotype at inoculation rates of 2.5 and 5×10⁴ conidia mL^-1 when applied in water. Increasing the dew period from 0 to 12 h increased mortality from 0 to 100% on all three biotypes at a rate of 2.5×10⁴ conidia mL^-1 in Silwet and MESUCO. MSC appears to be the most sensitive biotype.     

沙地生境沙拐枣(Calligonum mongolicum)种群特征及其扩张

沙拐枣(Calligonum mongolicum)是分布于我国北方荒漠、半荒漠的一种主要固沙植物,研究沙拐枣种群在沙地生境中的扩张对沙漠-绿洲过渡带的生态恢复和重建管理具有重要的实践意义.以巴丹吉林沙漠延伸带与河西走廊中部张临高绿洲过渡带为研究区域,采用踏查与样方调查相结合的方法对4种不同沙地生境(固定沙丘、半流动沙丘迎风坡、背风坡、丘间低地)中沙拐枣种群特征、繁殖规律、种群的扩张域和扩张速率进行了研究.结果表明:(1) 沙地生境中沙拐枣以有性繁殖为主.固定沙丘、半流动沙丘丘间低地、迎风坡和背风坡萌蘖苗密度占总密度的比值分别为35%、45%、2%、9%;实生苗密度比值分别为65%、55%、98%、91%.(2)不同生境中沙拐枣种群都为增长型种群;(3) 固定沙丘、半流动沙丘迎风坡、背风坡、丘间低地中,沙拐枣种群无性繁殖的扩张域和平均扩张速率分别为1～5m和0.67m/a、1～8m和0.64m/a、0～2m和0.15m/a、1～4m和0.41m/a.同时,3种生境中沙拐枣种群密度及其扩张速率都随着年龄的增长而下降.(4)沙拐枣种群在侵入新的生境过程中,开始于有性繁殖,利用无性繁殖拓展生存空间.     

CO2浓度倍增条件下土壤干旱对两种沙生灌木碳氮含量及其适应性的影响

研究利用大型环境生长箱模拟了两种沙地优势灌木柠条和羊柴对 CO2 浓度倍增和土壤干旱交互作用的响应。 CO2 浓度倍增使柠条和羊柴的生物量分别增加了 6 2 .90 %和 5 0 .0 0 % ,使植株叶面积分别增加了 4 1.86 %和 4 5 .84 %。 CO2 浓度的倍增效应随着土壤干旱的增加而下降。 CO2 浓度倍增和土壤干旱都增加单位叶面积质量 (L MA) ,但 CO2 浓度倍增主要增加了水分充足时的 L MA。 CO2 倍增使柠条和羊柴叶片含氮量分别降低了 10 .4 0 %和 5 .0 6 %。柠条叶片含氮量在所有土壤干旱条件下均呈现出增加的趋势 ,而羊柴叶片的含氮量仅在严重干旱条件下增加。 CO2 倍增使叶片的碳氮比显著增加 ,但土壤干旱使之降低。CO2 浓度倍增降低叶肉细胞质膜的过氧化产物丙二醛 (MDA )的含量 ,干旱使之增加。叶片含氮量与 MDA呈显著正相关。研究表明 CO2 倍增有保护叶片免受严重土壤干旱的作用 ,但干旱的负面影响是 CO2 倍增效应所难以弥补的     

入侵植物刺苍耳在新疆的分布及其群落特征

刺苍耳是原产于南美洲的菊科植物,2009年首次在新疆的伊宁县发现。于2010～2011年对新疆南北疆近40个县(市)中刺苍耳可能出现的区域进行调查,并采用样方法,对不同生境中刺苍耳分布相对集中的23个样地所有物种的多度、频度和重要值进行了观测和分析,以明确刺苍耳在新疆的分布区及其群落特征,为有效防治其扩散提供依据。结果显示:(1)刺苍耳分布于新疆的昌吉市、伊宁市、伊宁县、巩留县、特克斯县、新源县、察布查尔县、霍城县和尼勒克县,分布区海拔597～1 834m,生境类型包括荒漠草原和绿洲。(2)刺苍耳在荒漠草原和绿洲生境中的相对多度均处于首位,且在绿洲中达到最大值,为入侵区域最重要的物种;刺苍耳在2种生境中的相对盖度均为第一,且绿洲(46.83%)大于荒漠草原(43.00%)。(3)刺苍耳在2种生境中的综合适应力均最强,在绿洲中尤为突出,是其最易入侵的区域。研究表明,刺苍耳在新疆荒漠草原生境中尚处于局部危害阶段,但在绿洲中已处于蔓延期。     

蒙古口蘑分类地位研究

利用LSU序列分析技术研究蒙古口蘑分类地位,用最大简约法和最大似然法构建系统发育树。结果表明：蒙古口蘑形成一独立分支,与白蘑属Trciholoma亲缘关系较远,蒙古口蘑应从Trciholoma属中划分出来,放入新属———白丽蘑属（新拟）Leucocalocybe,并命名为蒙古白丽蘑（新拟）Leucocalocybe mongolicum（Imai）X.D.Yu＆Y.J.Yao。     

Evaluation of common cocklebur Xanthium strumarium leaf extract as post‐harvest grain protectant of black gram against pulse beetle Callosobruchus chinensis (Coleoptera: Bruchidae) and isolation of crude compound

The pulse beetle Callosobruchus chinensis L. is considered the most important stored grain pest of black gram Vigna mungo Hepper in Bangladesh and other tropical and subtropical countries. Bioactive compounds derived from plants can be used to control of the pulse beetle as a potential alternative to synthetic insecticides. Therefore, aqueous extracts of common cocklebur Xanthium strumarium L. leaf was examined for insecticidal properties against C. chinensis. The extracts showed toxicity, repellent properties, inhibited fecundity and adult emergence of the insects, and protected grains. Insect mortality was accounted highest (72.6%) with 4% extract at 4 days after treatment. The beetles showed highest repellency rate (58.0%) with 4% concentration at 1 hour exposure; however insect repellency decreased with time. The beetles exerted the lowest fecundity and grain damage and produced the lowest number of offspring when they were reared on grains treated with 4% extract. The insecticidal compounds present in common cocklebur leaf were extracted in chloroform and ethanol, and isolated by thin layer chromatography (TLC) and spectral studies (¹H‐NMR and IR), which identified the presence of aromatic ester, n‐hexyl salicylate or o‐hydroxy‐n‐hexyl‐benzoate and a long‐chain ketone. Therefore, naturally occurring X. strumarium and its derivatives may be potential components for integrated management of C. chinensis.     

Accumulation of 6-Azauridine by Mutants of Brevibacterium ammoniagenes

From the inosine producing mutants of Brevibacterium ammoniagenes, KY 13761 was selected as a strain which produced 6-azauridine from 6-azauracil.

The conditions for the conversion were examined and the intermitent feeding of 6-azauracil was found effective for the accumulation.

In order to increase the accumulation, prototrophic revertants were induced from KY 13761 and KY 13021 was selected. By intermitent feeding of 6-azauracil of a final concentration of 6 mg per ml, a maximal accumulation, 12.4 mg/ml, of 6-azauridine was obtained with KY 13021.