提高葡萄果实品质的关键技术

通过详细阐述在提高葡萄果实品质方面采取的十二项关键性技术措施,如摘心、疏花、疏果、套袋、环剥以及喷打赤霉素、多效唑、吡效隆、烯土、食醋、钙肥等,从而使葡萄生产达到优质、丰产、无公害。     

铅胁迫对4种木本植物酶保护系统的影响

随着工业化、城市化进程的加速，城市铅污染日益严峻。通过植物酶保护系统对铅胁迫的响应研究，可以有效缓解城市铅污染问题。为此，本实验以红檀木（Loropetalum chinese（R．Rr．）Oliv．）、侧柏（Platycladus orientalis（L．）End]1）、金合欢（Acacia famesiana（Linn．）Wind）、杨树（Populusdeltoides×Populus nigara）为材料，采用盆栽试验，分别设置CK（不加Pb）、T1（300mg·kg-1，干土）、T2（450mg·kg-1干土）、T3（600mg·kg-1干土）4个Pb处理浓度，研究了4树种酶保护系统对铅胁迫的响应机理。在铅胁迫下，各树种SOD、POD活性变化显著（P〈0．05），杨树、侧柏、红檀木的POD、SOD均高于对照，其中又以杨树的SOD、POD活性最高，分别为800U·g-1，103U·g-1·min-1，金合欢的酶活性在处理浓度超过300mg·kg-1，后迅速降低。CAT活性在杨树中显著上升（P〈0．05），侧柏中的CAT活性未发生显著变化，金合欢、红檀木中的CAT活性则显著下降（P〈0．05）。木本植物酶保护系统对铅胁迫的响应存在显著的种间差异，其抗铅污染能力依次表现为杨树〉红檀木〉侧柏〉金合欢。     

贮藏温度对藤牧1号苹果果实保鲜效果影响研究

以藤牧1号苹果果实为试材,研究了贮藏温度对果实酶活性及理化性状的影响。结果表明:20℃和5℃温度条件下果实纤维素酶、PG、LOX、淀粉酶活性变化均表现前期逐渐增加,出现峰值后逐渐下降的变化趋势。20℃条件贮藏的果实不但纤维素酶、PG、LOX、淀粉酶活性始终高于5℃条件的果实,酶活性峰值出现时间也较早。果实贮藏期间,果肉原果胶含量逐渐降低,可溶性果胶含量逐渐增加,纤维素含量逐渐下降。20℃条件贮藏的果实的纤维素和果胶物质的含量变化率均高于5℃条件贮藏的果实。随着果实中纤维素和果胶物质的变化,果实逐渐软化,果肉硬度降低,失重率增加,品质下降。     

数字农业技术基础课程网络教学平台研究

在研究了数字农业技术基础教学体系的基础上,分析了目前该课程存在问题,提出了构建网络教学平台的思路,并设计了一个基于后台数据库的数字农业技术基础网络教学平台。该系统具有先进、灵活完善、安全可靠的特点。     

论高等职业技术教育育人模式的创新

传统高等职业技术教育育人模式存在诸多问题.高等职业技术教育育人模式创新是一个崭新的课题.要改变传统的育人模式,建立坚持"以人为本"的育人新模式.要改变传统的育人观念,以市场导向,确定育人的质量和标准等等.     

Detecting dominant landscape objects through multiple scales: An integration of object-specific methods and watershed segmentation

Complex systems, such as landscapes, are composed of different critical levels of organization where interactions are stronger within levels than among levels, and where each level operates at relatively distinct time and spatial scales. To detect significant features occurring at specific levels of organization in a landscape, two steps are required. First, a multiscale dataset must be generated from which these features can emerge. Second, a procedure must be developed to delineate individual image-objects and identify them as they change through scale. In this paper, we introduce a framework for the automatic definition of multiscale landscape features using object-specific techniques and marker-controlled watershed segmentation. By applying this framework to a high-resolution satellite scene, image-objects of varying size and shape can be delineated and studied individually at their characteristic scale of expression. This framework involves three main steps: 1) multiscale dataset generation using an object-specific analysis and upscaling technique, 2) marker-controlled watershed transformation to automatically delineate individual image-objects as they evolve through scale, and 3) landscape feature identification to assess the significance of these image-objects in terms of meaningful landscape features. This study was conducted on an agro-forested region in southwest Quebec, Canada, using IKONOS satellite data. Results show that image-objects tend to persist within one or two scale domains, and then suddenly disappear at the next, while new image-objects emerge at coarser scale domains. We suggest that these patterns are associated to sudden shifts in the entire image structure at certain scale domains, which may correspond to critical landscape thresholds.This revised version was published online in May 2005 with corrections to the Cover Date.     

Estimating the ‘critical’ distance at which adjacent land-use degrades wetland water and sediment quality

Conversion of forested lands to agriculture or urban/residential areas has been associated with declines in stream and lake water quality. Less attention has been paid to the effects of adjacent land-uses on wetland sediment and water quality and, perhaps more importantly, the spatial scales at which these effects occur. Here we address these issues by examining variation in water and sediment nutrient levels in 73 southeastern Ontario, Canada, wetlands. We modeled the relationship between water and sediment nutrient concentrations and various measures of adjacent land-use such as forest cover and road density, measured over increasing distances from the wetland edge. We found that water nitrogen and phosphorous levels were negatively correlated with forest cover at 2250 meters from the wetland edge, while sediment phosphorous levels were negatively correlated with wetland size and forest cover at 4000 meters and positively correlated with the proportion of land within 4000 meters that is itself wetland. These results suggest that the effects of adjacent land-use on wetland sediment and water quality can extend over comparatively large distances. As such, effective wetland conservation will not be achieved merely through the creation of narrow buffer zones between wetlands and more intensive land-uses. Rather, sustaining high wetland water quality will require maintaining a heterogeneous regional landscape containing relatively large areas of natural forest and wetlands.     

Carbaryl induced alterations in the reproduction and metabolism of freshwater snail Lymnaea acuminata

When the freshwater snail Lymnaea acuminata was exposed to sub-lethal doses (2.0, 5.0, and 8.0 mg/L) of carbaryl, fecundity was significantly reduced and even stopped at higher sub-lethal doses and altered metabolic activity in the body tissue of the snail was observed. The change from aerobic to anaerobic metabolism results in lesser energy production in the body tissues of the snails, causing paralysis and finally death. This reduced fecundity and altered metabolism suggests that it would be better to avoid the use of carbaryl pesticides in the water bodies or fields adjoining the water bodies particularly in the rainy season.     

种猪场猪生殖和呼吸系统综合征血清抗体检测

应用ELISA试剂诊断盒对青海省几个主要种猪场的103份血清进行了PRRS的血清抗体检测，共检出阳性血清6份，阳性率为5．83％，表明青海省几个主要种猪场存在PRRS。     

Effects of Melia azedarach on nutritional physiology and enzyme activities of the rice leaffolder Cnaphalocrocis medinalis (Guenée) (Lepidoptera: Pyralidae)

Laboratory assays were done to evaluate the effect of Melia azedarach L. (Rutales: Meliaceae) seed extract on nutritional indices and gut enzymes acid phosphatases, alkaline phosphatases, adenosinetriphosphatases, and lactate dehydrogenase of the rice leaffolder (RLF) Cnaphalocrocis medinalis (Guenée) (Lepidoptera: Pyralidae). Larvae were fed a treated rice-leaf diet containing the seed extract and their midgut was used for enzyme determination. Laboratory experiments showed that the seed extract suppressed the larval activity of C. medinalis even at a low dose. Gross dietary utilization (efficiency of conversion of ingested and digested food) of RLF decreased after ingesting the treated rice-leaf diet. Food consumption, digestion, relative consumption rate, efficiency of conversion of ingested food, efficiency of conversion of digested food, and relative growth rate values declined significantly. As compared to the control, consumption of the extract containing rice-leaf diet resulted in a 69% reduction of the acid phosphatases activity, a 71% reduction of the alkaline phosphatases activity, a 46% reduction of the adenosine triphosphatases activity, and a 52% inhibition of the lactate dehydrogenase activity.