辣椒种生镰刀菌及其病理学意义的研究

 采用吸水纸检验法,对北京地区22份辣椒(Capsicum annuum)种子样品的分析结果是:木贼镰刀菌(Fusarium equiseti)、串珠镰刀菌(F. moniliforme)、尖孢镰刀菌(F.oxysporum)、半裸镰刀菌(F. semitectum)和茄病镰刀菌(F. solani)是5种常见的辣椒种生镰刀菌,其平均带菌率分别为1.0%,2.6%,0.1%,0.8%和0.2%。经发芽试验观察,在自然带菌的情况下,木贼镰刀菌,串珠镰刀菌、尖孢镰刀菌、半裸镰刀菌和茄病镰刀菌能分别使种子发芽率降低98.6%,39.8%、62.1%、2.7%和52.1%。经土壤接种法进行致病性测定,除半裸镰刀菌对植株无明显致病性反应外,其它4种镰刀菌均能不同程度地引起植株枯萎和其它病理症状。     

Effects of foliar- and root-applied silicon on the enhancement of induced resistance to powdery mildew in Cucumis sativus

Two cucumber ( Cucumis sativus ) cultivars differing in their resistance to powdery mildew, Ningfeng No. 3 (susceptible) and Jinchun No. 4 (resistant), were used to study the effects of foliar- and root-applied silicon on resistance to infection by Podosphaera xanthii (syn. Sphaerotheca fuliginea ) and the production of pathogenesis-related proteins (PRs). The results indicated that inoculation with P. xanthii significantly suppressed subsequent infection by powdery mildew compared with noninoculation, regardless of Si application. Root-applied Si significantly suppressed powdery mildew, the disease index being lower in Si-supplied than in Si-deprived plants, regardless of inoculation treatment. The resistant cultivar had a more constant lower disease index than the susceptible cultivar, irrespective of inoculation or Si treatment. Moreover, with root-applied Si, activities of PRs (for example peroxidase, polyphenoloxidase and chitinase) were significantly enhanced in inoculated lower leaves or noninoculated upper leaves in inoculated plants of both cultivars. Root-applied Si significantly decreased the activity of phenylalanine ammonia-lyase in inoculated leaves, but increased it in noninoculated upper leaves. However, Si treatment failed to change significantly the activity of PRs in plants without fungal attack. Compared to the control (no Si), foliar-applied Si had no effects either on the suppression of subsequent infection by P. xanthii or on the activity of PRs, irrespective of inoculation. Based on the findings in this study and previous reports, it was concluded that foliar-applied Si can effectively control infections by P. xanthii only via the physical barrier of Si deposited on leaf surfaces, and/or osmotic effect of the silicate applied, but cannot enhance systemic acquired resistance induced by inoculation, while continuously root-applied Si can enhance defence resistance in response to infection by P. xanthii in cucumber.     

基于DEM的水系对城市化空间格局机制研究——以兰州-西宁区域为例

利用兰州-西宁区域的DEM数据,采用ArcGIS9.3技术,通过水文分析、三维仿真模拟、格网法等空间分析方法和分形模型研究,结果表明河流对兰州-西宁区域城市化空间格局形成的自然机制,包括：地势高低决定了人口城市化空间聚集的方向性;水系的空间形态奠定了城市点-轴分布格局;水系分维和城市体系分形具有相似性,并且水系的分维数...     

表达犬瘟热病毒H基因重组新城疫病毒的构建及其免疫原性研究

为研制安全、有效的新型犬瘟热疫苗,本研究利用新城疫病毒(NDV) LaSota弱毒疫苗株反向遗传操作系统,构建出表达犬瘟热病毒(CDV)弱毒疫苗株Rockborn-20/8血凝素(H)蛋白的重组病毒rLa-CDV-H,并对其生物学特性进行鉴定,评估其作为犬瘟热活载体疫苗的安全性和有效性.通过免疫荧光和western blot试验证明了CDV H蛋白的正确表达;重组病毒株保持了LaSota亲本株的低致病性和高滴度鸡胚生长特性;重组病毒rLa-CDV-H接种12周龄比格犬后,可以诱导显著的CDV中和抗体反应.本研究表明重组病毒rLa-CDV-H具有作为犬瘟热重组病毒活载体疫苗的潜力.     

节能日光温室内保温幕铺卷机构的设计

节能日光温室的保温性能决定着在深冬农业生产的安全和成败.为此,针对节能日光温室的结构特点,结合铺卷节能日光温室内保温幕的技术要求,在吸收温室内保温先进技术的基础上,设计了一种用于无立柱节能日光温室内保温幕铺卷的机构,选择了合理的工作参数,以满足北方冬季对节能日光温室保温设备的需求.     

优良鸟类食源植物冬红Holmskioldia sanguinea的生态景观营造实践

为在华南区更好吸引乡土鸟类,利用鸟类食源灌木冬红Holmskioldia sanguinea及棚架、生态雨水沟、用于遮挡的灌木与景石等配套措施,在短时间内构建一套生态景观,有效为食蜜鸟类提供冬季食源,吸引了叉尾太阳鸟Aethopyga christinae、暗绿绣眼鸟Zosterops japonicus、朱背啄花鸟Dicaeum cruentatum、红胸啄花鸟Dicaeum ignipectus、北红尾鸲Phoenicurus auroreus等鸟类到此栖息。经实践深圳市梅林公园的冬红生态景观点已成为全国摄影圈和观鸟圈经典的定点拍摄地。最后还对冬红的栽培管护技术、公园生态声景观构建、公园科普系统建设等提出建议,并讨论了该外来种对城市生态系统的可能影响。     

Induction of antiviral resistance and stimulary effect by oligochitosan in tobacco

Oligochitosan was applied by spraying it on tobacco leaves for inhibition of tobacco mosaic virus (TMV). The maximum inhibition of TMV by oligochitosan was observed when inoculation occurred at 24 h after spraying 50 μg ml⁻¹ oligochitosan. The production of H₂O₂ and NO in epidermal tobacco cells induced by oligochitosan was investigated by epidermal strip bioassay and LSCM, using cell permeable fluorophore diaminofluorescein diacetate (DAF-2D) and 2′,7′-dichlorofluorescin diacetate (H₂DCF-DA), respectively. Epidermal tobacco cells treated with oligochitosan resulted in a strong increase of intracellular NO and H₂O₂. Oligochitosan and NO donor sodium nitroprusside (SNP) induced the defense reaction against tobacco mosaic virus (TMV), and increased phenylalanine ammonia-lyase (PAL) activity. Co-treatment of the tobacco cells with oligochitosan and NO scavenger CPTIO blocked the inducing resistance. The results indicated that the defense response induced by oligochitosan was connected with NO pathway.     

双重排水条件下控制措施对银南灌区水稻田水盐关系的影响分析

针对宁夏银南灌区目前存在的排水过量问题,研究者提出了利用控制排水措施,在适当时段减少排水量的建议。然而,灌区在农沟以及更深层的支、干沟及黄河(低地)的影响下,受着深层排水和浅层排水的双重作用。其中深层排水一般不会受到田间措施的影响,它的存在“淡化或中和”了由于浅层排水的减少引起的田间含盐量的增加。本文在对双重排水情况下的水盐运动进行概化的基础上,建立了基于特定地区排水特性的“浅层排水与深层排水比-浅层排水控制率-排水含盐量增加率”的关系。最后结合根据地下水洗淋的临界情况,确定了达到这一目标控制指标以及浅层地下水控制率。结果显示,对于研究的典型情况,当地下水的盐分含量达到临界的1.62 g/l时,可以将1m深的农沟控制至30cm深;这时的浅层地下水仅为现状的14%,即从731mm减少到了102mm。     

我国农药禁限用政策实施情况及建议

本文研究了农药禁限用政策历史沿革、颁布实施情况、运行成效以及所面临问题的评价,提出了加强农药管理的意见与建议。     

青海海北高寒湿地近地层大气CO_2浓度的变化特征

采用快速响应红外气体分析仪对青海海北高寒湿地大气CO2浓度进行连续监测,分析2004年CO2浓度变化特征表明,CO2浓度存在明显的日、季变化,日、年内均表现“U”型变化特征。这些变化与植被生理活动、土壤呼吸、大气逆温层、及湍流交换强度等有关。自1月到7月CO2浓度的日变化过程中,日最高值出现时间在日出前后的5:00到9:00,并随7月的到来逐渐提早,日出后下降,约在下午15:00左右为最低,日落后又逐步升高。7月以后日最高值出现时间随时间推移又滞后,最低提早。一年中,月平均浓度最低值出现在7月份,最高值则在10月。观测表明,2004年海北高寒湿地CO2年平均浓度为315.3μmol/mol,月平均最高为335.0μmol/mol(10月),月平均最低值为270.1μmol/mol(7月)。统计海北高寒湿地旬平均CO2浓度与气象因素线性相关关系表明,海北高寒湿地CO2浓度与大多数气象因子有显著的负相关关系,但与土壤温度、气压、相对湿度等的相关关系不明显。