新疆艾比湖绿洲土地退化遥感动态监测

层次分析法是一种将决策者对复杂系统的决策思维过程模型化、数量化的过程.采用层次分析法,对影响和指示土地退化的生物量、归一化植被指数、土壤水分指数和土壤盐碱化4个影响因子进行分析.通过计算每个影响因子的权重,基于ASTER,SPOT,TM,MODIS产品以及野外调查数据等多源数据,对新疆艾比湖地区2000年8月至2004年8月的土地退化状况进行了评价,并且分析了层次分析法应用于土地退化研究的适用性及其优缺点.研究表明:艾比湖地区耕地退化现象普遍,占耕地总面积的55.78%,分布广,程度重.     

氟铃·辛硫磷20％乳油在棉花上的残留与消解动态

为了评价辛硫磷在棉花上使用的安全性,建立其使用规范.于2010-2012年在杭州和商丘两地进行了氟铃·辛硫磷20％乳油在棉花上的消解动态和最终残留实验.消解动态试验结果表明:在植株和土壤中半衰期分别为0.62～0.81d和2.4～2.8d.最终残留试验表明:氟铃·辛硫磷20％乳油按300g a.i./ha和450g a.i./ha施药,虫害发生期施药3次和4次,末次施药后7、15、21d采集土壤样品和棉花样品,土壤和棉籽中辛硫磷的残留量均＜0.05mg/kg.     

Influence of Portland cement amendment on soil pH and residual soil termiticide performance

Soil adjacent to new brick veneer work is likely to have a higher pH owing to the mixture of cement with the soil. In the Gainesville, FL, area, soil samples taken from such locations had a range of pH values from 9.0 to 10.1; similar soils used in bioassays had a pH of 5.6 before the addition of cement. Addition of 15 mg of Portland cement to 33 g of soil increased the pH to 6, and addition of 291 mg of Portland cement increased the pH to 9. The pH of soil amended with cement was stable for the first 5 months. After 10 months, soil pH values decreased from alkaline to near neutral in all cases. Eastern subterranean termite workers, Reticulitermes flavipes (Kollar), were exposed to the treated soil at pH 6-9 for 24 h, and percentage mortality was recorded at 5 days, 5 months and 10 months. Termite mortality significantly decreased at higher soil pHs for bifenthrin, chlorpyrifos, fipronil and imidacloprid treatments at 5 months and similarly for bifenthrin, permethrin, chlorpyrifos, fipronil and imidacloprid treatments at 10 months. There was an inverse linear relationship between soil pH and mortality. Increased soil pH diminished residual activity of termiticide in the following order: imidacloprid > fipronil > chlorpyrifos = bifenthrin > permethrin > cypermethrin.     

防治桃小食心虫越冬幼虫的有效药剂及其降解动态

研究树下土表施药防治桃小食心虫越冬幼虫的取代药剂。用毒土法测定了分属4类的13种药剂对桃小食心虫越冬幼虫的触杀毒力,其结果以毒死蜱、三唑磷、高效氯氟氰菊酯、甲基对硫磷和辛硫磷毒力较高,LC_(90)值依次为18．38、22．48、35．95、47．63及49．57 mg·kg~(-1),甲氰菊酯、丙溴磷、阿维菌素、甲胺基阿维菌素、氰戊菊酯、马拉硫磷、丙硫克百威和丁硫克百威LC_(90)值处于77．11～205．86mg·kg~(-1)之间。用高效液相色谱法测定了毒力较高的毒死蜱、三唑磷、高效氯氟氰菊酯以及阿维菌素在土壤中的降解动态,半衰期分别为8．28、11．37、10．17及19．70天。欲达30天的有效控制期,按LC_(90)值计算,这4种药剂在土壤中的初施浓度应分别为226．36、139．90、278．03及346．81mg·kg~(-1)。从药剂毒力、降解速率、相同控制期所需剂量及应用成本综合评价,毒死蜱、三唑磷具有较高的应用价值。     

干旱区绿洲荒漠交错带土地退化及生态重建

由于经济的发展，土地资源受到越来越大的压力。当这种压力超过了土地资源的承载能力，就导致了土地退化的发生。作为陆地生态系统的基础，土地资源的退化表现为：土壤肥力降低，生物多样性降低，以及伴随的经济发展的落后。当前世界范围内对土地退化的治理，基本方法仍是基于生态学理论的生物方法。但对土地退化的恢复与生态系统的重建的研究，需要经过谨慎设计的长期实验。绿洲荒漠交错带的重要性，不仅表现为是绿洲的保护屏障，而且在绿洲经济的发展中也起到巨大的作用。通过对国内外大量研究的回顾，讨论了在不同地区进行的长期实验所采用的方法。有人为因素参与的退化土地恢复与生态重建，可以在短期内取得明显效果。产生土地退化的原因，不仅仅是土地资源特点与自然环境这样一些自然因素，还包括一些社会与经济因素。因此退化土地的恢复与生态重建的成功，需要一种考虑自然、社会和经济因素的综合的方法。     

Importance of Cell Wall Degrading Enzymes Produced by Fusarium graminearum during Infection of Wheat Heads

Cytological studies were carried out to elucidate the importance of cell wall degrading enzymes (CWDE) during infection of wheat spikes by Fusarium graminearum. Scanning electron micrographs revealed that at 6–24 hours after inoculation (hai) of single spikelets with macroconidia of F. graminearum, the fungus germinated by forming several germ tubes and developed a dense hyphal network in the cavity of the spikelet. At 24–36hai, the fungus formed infection hyphae which invaded the ovary and inner surface of the lemma and palea. Transmission electron microscopical studies revealed that the fungus extended inter- and intracellularly in the ovary, lemma and rachis and caused considerable damage and alterations to the host cell walls. In different tissues of healthy and F. graminearum-infected wheat spikes the cell wall components cellulose, xylan and pectin were localized by means of enzyme-gold and immuno-gold labelling techniques. Localization of cellulose, xylan and pectin showed that host cell walls which were in direct contact with the pathogen surface had reduced gold labelling compared to considerable higher labelling densities of walls distant from the pathogen–host interface or in non-colonized tissues. The reduced gold labelling densities in the infected host cell walls indicate that these polysaccharide degrading enzymes might be important pathogenicity factors of F. graminearum during infection of wheat spikes. The results revealed that, infection and colonization of wheat spikes by F. graminearum and reactions of infected host tissue were similar to those reported for F. culmorum.     

呼伦贝尔草甸草原羊草群落不同退化程度土壤理化指标

文中对放牧干扰下不同退化程度呼伦贝尔草甸草原羊草群落土壤理化性质进行了研究。结果发现,土壤含水量、土壤全氮、土壤有机物、土壤速效氮随着退化程度的增加显著下降,而土壤容重、土壤(1-2mm)粗粒百分含量、土壤速效钾随着退化程度的增加而显著提高。土壤速效磷和pH值没有规律性变化。通过研究表明:土壤含水量、土壤容重、土壤(1-2mm)粒径粗粒、土壤有机物、全氮、速效氮和速效钾在不同退化程度之间都具有显著性差异,因此,这些指标可做为草甸草原羊草群落确定土壤退化程度的退化指标。     

三种新烟碱类杀虫剂在土壤中的残留降解及影响因子

建立了吡虫啉、啶虫脒和噻虫嗪在土壤中的高效液相色谱-串联质谱（HPLC-MS/MS）检测方法。样品经乙腈提取和QuEChERS法净化后,采用HPLC-MS/MS检测,外标法定量,在0.01~1.0 mg/kg添加水平下,3种新烟碱类杀虫剂在土壤中的回收率在89%~103%之间,相对标准偏差（RSD）在1.3%~10.3%之间,定量限均为0.01 mg/kg。采用建立的方法,在室内模拟条件下,研究了土壤微生物、温度、土壤含水量及农药初始浓度对土壤中吡虫啉、啶虫脒和噻虫嗪降解的影响。结果表明:土壤微生物是影响农药残留降解的首要因素,灭菌处理土壤中农药残留降解速率明显低于非灭菌土壤。此外,环境温度、土壤含水量、初始浓度等因素也会对农药残留降解产生不同影响,土壤含水量为最大持水量的60%左右时降解最快,半衰期分别为15.6、7.2和25.8 d;农药初始浓度越高,降解速度越慢;在5~35℃范围内,随着温度的升高,降解速度加快。