生长素对植物维管分化的信号诱导作用

植物维管系统与植物生长发育关系密切,维管组织的分化机制也因此倍受关注。生长素可诱导植物维管组织分化,它根据自身浓度的高低产生系列信号,从而通过这些信号来控制其所在部位及其周围区域维管组织的分化状况。该文重点论述了生长素在细胞间的极性运输方式及其信号转导途径、生长素对维管组织分化的信号诱导作用及其表现特征,以及生长素诱导植物维管组织分化的分子机理。     

在人工接种和自然感虫情况下美洲黑杨后代对桑天牛抗性的研究

杨树 (Ｐｏｐｕｌｕｓｓｐｐ .)是我国主要造林和工业用材树种之一 ,据统计我国杨树人工林面积达 666×1 0 4ｈｍ2 (王世绩 ,1 995 )。但杨树天牛危害十分猖獗 ,其中光肩星天牛 (Ａｎｏｐｌｏｐｈｏｒａｇｌａｂｒｉｐｅｎｎｉｓ)和黄斑星天牛 (Ａｎｏｐｌｏｐｈｏｒａｎｏｂｉ     

用农杆菌Ri诱导金银花发根培养的研究

通过预培养时间、菌液稀释倍数、浸染时间、共培养时间、抗生素质量浓度5因素4水平的正交实验,得出优化组合,认为组培苗叶片外植体预培养5 d,菌液稀释45倍,浸染4 min,共培养3 d,然后转入含500 mg/L羧苄青霉素的1/2M S培养基上培养,金银花的发根诱导率最高,达54.3%.随机抽取离体培养的发根经PCR检测,证实为转化发状根.     

计算机网络系统感应雷防护研究

介绍了接地、感应雷和直击雷的概念,同时对感应雷的侵入途径和计算机网络系统感应雷防护作了详细阐述,这对其它弱电系统感应雷防护也具有参考价值.     

高效人工湿地构建技术研究进展

人工湿地是人工建设的、可控制的和工程化的湿地系统;它同时也是一个独特的土壤-植物-微生物生态系统。其构建技术是重要的水污染处理共性技术。目前,人工湿地被广泛应用于湖泊、河流、库塘以及湖滨带的重建与恢复以及水污染处理。在这些领域中已显示出极大的发展潜力;可以预见人工湿地一定会具有广阔的应用前景。国内经过多年的研究积累,已经在部分环节中取得了重要进展,这些研究成果可以在我国不同区域,尤其是太湖流域的推广使用。       

大叶榉愈伤组织诱导与继代培养的影响因素

以大叶榉种子的子叶、胚轴、顶芽、嫩枝叶片和茎段等为外植体 ,对大叶榉进行愈伤组织诱导及继代培养研究 .结果表明 :不同外植体的愈伤组织诱导能力有差异 ,其诱导率按高低顺序排列依次为子叶、胚轴、叶片、茎段和顶芽 ;愈伤组织质地、颜色、生长速度与基本培养基、外源激素有很大的关系 ,基本培养基以 WPM培养基最好 ;最佳诱导培养基不适合继代保存 ;在培养基中附加抗氧化剂并调整激素种类 ,可较好地防止褐变现象     

赤桉人工种子制备过程中微芽繁殖体转株的研究

实现包裹后的微芽繁殖体的生根和萌发生长即转株是以微芽为繁殖体制备人工种子中较为重要的环节之一。本试验系统地研究了生长调节剂种类、浓度以及微芽发育状态与赤桉（Ｅｕｃａｌｙｐｔｕｓｃａｍａｌｄｕｌｅｎｓｉｓ）微芽转株的关系,研究了包裹基质中直接添加诱导生根的生长调节剂及微芽生根预诱导对包裹后微芽转株的影响。试验结果表明：ＮＡＡ较ＩＢＡ和ＩＡＡ有较好的诱导微芽生根的效果;选取幼嫩及活跃生长的微芽是获得较高生根率的重要环节;包裹基质中直接添加诱导生根的生长调节剂未能解决包裹后微芽转株的问题;微芽经生根预诱导再附带生根介质包裹对微芽转株有良好的促进作用。微芽包裹后二周生根率可达８１３％,三周后转株率可达８３３％。     

长白落叶松丰产林造林密度及其经济效益初探

本文以长白山落叶松人工林的造林初植密度为研究对象,在5种不同初植密度下,优选出适于黑龙江省利用世界银行贷款集约经营人工林项目合理密度。建筑材林分的合理初植密度为3000株/ha,纤维材林分为3300株/ha。     

Land use change modeling through an integrated Multi-Layer Perceptron Neural Network and Markov Chain analysis(case study: Arasbaran region,Iran)

Temporal land use/land cover (LULC) change information provides a variety of applications for informed management of land resources. The aim of this study was to detect and predict LULC changes in the Arasbaran region using an integrated Multi-Layer Perceptron Neural Network and Markov Chain analysis. At the first step, multi-temporal Landsat images (1990, 2002 and 2014) were processed using ancillary data and were classified into seven LULC categories of high density forest, low-density forest, agriculture, grassland, barren land, water and urban area. Next, LULC changes were detected for three time profiles, 1990–2002, 2002–2014 and 1990–2014. A 2014 LULC map of the study area was further simulated (for model performance evaluation) applying 1990 and 2002 map layers. In addition, a collection of spatial variables was also used for modeling LULC change processes as driving forces. The actual and simulated 2014 LULC change maps were cross-tabulated and compared to ensure model simulation success and the results indicated an overall accuracy and kappa coefficient of 97.79% and 0.992, respectively. Having the model properly validated, LULC change was predicted up to the year 2025. The results demonstrated that 992 and 1592 ha of high and lowdensity forests were degraded during 1990–2014,respectively, while 422 ha were added to the extent of residential areas with a growth rate of 17.58 ha per year. The developed model predicted a considerable degradation trend for the forest categories through 2025, accounting for 489 and 531 ha of loss for high and low-density forests, respectively. By way of contrast, residential area and farmland categories will increase up to 211 and 427 ha, respectively. The integrated prediction model and customary area data can be used for practical management efforts by simulating vegetation dynamics and future LULC change trajectories.     

The use of artificial nest boxes by Siberian flying squirrels (Pteromys volans) in South Korea

In this study, we examined the use of artificial nest boxes by Siberian flying squirrels (Pteromys volans) in three coniferous and mixed forests in Gangwon Province, South Korea. Six hundred and twelve boxes with different sized entry holes (ranging from 3 to 7 cm in diameter) were placed in the forests between 2004 and 2009. Pteromys volans used nine boxes in the coniferous forests and two boxes in the mixed forests. The squirrels only used boxes with entrance holes measuring 3.5, 4, and 5 cm in diameter, showing a strong and moderate preference for boxes with 5 and 4-cm holes, respectively, and a strong avoidance for boxes with 3- and 7-cm holes. Therefore, we suggest placing artificial nest boxes with entrance holes 5 cm in diameter to encourage breeding activity. Most nests made in the artificial boxes were composed of fibrous materials from woody vines. We recommend placing artificial nest boxes with holes of 5-cm diameter in coniferous forests, which support dense populations of P. volans, to survey whether this approach would positively affect the breeding habits and population maintenance of this species.