豆科树种无性快速繁殖技术研究与进展

豆科树种目前已广泛应用于荒山绿化、饲用及观赏。文中从扦插(嫩枝扦插、硬枝扦插、根插)，组织培养等方面综述了豆科树种无性快速繁殖技术的研究和进展。指出目前豆科树种嫩枝扦插技术研究还局限在对某一树种繁殖途径的探索阶段；硬枝扦插技术研究较为系统和深入，对不同树种扦插生根的影响因素有了比较深入的了解，并因此建立起较为成熟的技术体系；根插方法简单，成活率高，但是研究普遍较少；豆科树种组织培养虽较为困难，但某些树种也已经建立起了较为完善的再生体系。此外，还对豆科树种快速繁殖的生理基础研究进行了讨论，建议加大对豆科树种快速繁殖技术和生理机制的研究力度，为解决优良种质资源快速扩繁奠定基础。     

嫩江沙地几种植物根系垂直分布的研究

采用全部分层挖取法研究了银中杨(Populus alba×Populus berolinensis)、沙棘(Seabuckthorn)、沙枣(Elaeag-nus angustifolia)和山杏(Prunus arm eniaca)4个树种的根系分布情况。结果表明:各树种之间根系的垂直分布差异显著,银中杨根系在0～120 cm土层中均有分布,林龄越大分布越深,但主要集中在0～40 cm的土层中,而且以直径小于7 mm的根系为主;沙棘根系分布较浅,在0～30 cm土层中,分布相对均匀;沙枣根系分布最深仅达20 cm;山杏的根系分布虽可达130 cm,但主要还是集中在10～50 cm土层中。根系总量分布由大到小依次是银中杨、沙棘、沙枣、山杏。     

Tissue culture micropropagation of Douglas-fir

A procedure was developed for plantlet production from embryos of Douglas-fir [Pseudotsuga menziesii (Mirb.) Franco]. The Medium for Conifer Morphogenesis, used at full strength, and supplemented with 10 M benzyladenine for 17 days produced an average of 6.8 shoots on more than 90% of the embryos. The percentage of shoot-forming embryos as well as the average number of shoots per embryo varied significantly among eight seedlots. For secondary multiplication, 89% of the adventitious shoots produced axillary buds on MCM with 5 M benzyladenine. However, 0.5 M BA was more suitable for the elongation of axillaries. Rooting ranged from 0–87% depending upon the treatment. The highest percentage was obtained with a 7-week incubation in peat:perlite containing 1/5-strength medium, 1% sucrose and 2.7 M naphthaleneacetic acid, followed by 5 weeks on peat:perlite with 1/5-strength major and minor salts, full iron and organics, 1% sucrose and 0.1% charcoal.     

Root architecture in relation to tree-soil-crop interactions and shoot pruning in agroforestry

Desirable root architecture for trees differs between sequential and simultaneous agroforestry systems. In sequential systems extensive tree root development may enhance nutrient capture and transfer to subsequent crops via organic pools. In simultaneous systems tree root development in the crop root zone leads to competition for resources.Fractal branching models provide relationships between proximal root diameter, close to the tree stem, and total root length or surface area. The main assumption is that a root branching proportionality factor is independent of root diameter. This was tested in a survey of 18 multipurpose trees growing on an acid soil in Lampung (Indonesia). The assumption appeared valid for all trees tested, for stems as well as roots. The proportionality factor showed a larger variability in roots than in stems and the effects of this variabilily should be further investigated. A simple index of tree root shallowness is proposed as indicator of tree root competitiveness, based on superficial roots and stem diameter.Pruning trees is a major way to benefit from tree products and at the same time reduce above-ground competition between trees and crops. It may have negative effects, however, on root distribution and enhance below-ground competition. In an experiment with five tree species, a lower height of stem pruning led to a larger number of superficial roots of smaller diameter, but had no effect on shoot:root ratios or the relative importance of the tap root.     

林木细根动态及其在矿质养分循环中的作用研究进展

林木细根在森林生态系统能量流动和物质循环中起着重要作用。近年来,随着人们对细根功能的深入认识和研究方法的发展,细根研究成为当今森林生态学的研究热点之一。本文简要介绍了细根研究普遍采用的研究方法及其优缺点、适用性;并综合前人的研究成果,对林分细根生物量、分布、分解和周转以及细根在养分循环中的作用等研究结果进行综述。     

Growth and water potential of j-rooted loblolly and eastern white pine seedlings over three growing seasons

The effects of j-rooting on water stress and growth of loblolly (Pious taeda L.) and eastern white pine (Pious strobus L.) were examined over three growing seasons in the field. Seedlings were planted in an area with severe herbaceous competition with either their roots planted straight or bent into a j shape. All seedlings were planted with their root collars placed at the soil surface. During the first year j-rooted seedlings consistently had lower water potentials but never statistically significant. Since both treatments were planted with the root collar at the soil surface, this trend was likely due to an initial shallower root system in j-rooted seedlings. In year three no differences in water potential were significant and no trends were evident. Growth did not differ significantly by treatment at any time but, by year three, j-rooted plants were consistently larger for both species.     

寒地城市广场设计计划

作者对北方寒冷城市的广场设计问题进行了分析研究,并提出了一些观点和想法,对北方城市广场的设计问题提出一些新的思路。     

窥镜技术在植物根系监测中的应用

窥镜探测技术是传统内窥镜技术与现代计算机技术、微电子技术、图象处理技术等新技术的不断发展和融合的产物,窥镜探测系统由窥镜摄影系统、图象处理和图象分析三部分组成,它采用彩色面阵CCD摄像元件,接收信息后送计算机处理。本文给出了窥镜技术在植物根系系统中的设计要点和实际应用。     

低覆盖度行带式种植模式下赤峰杨根系分布特征

采用根钻法对低覆盖度行带式栽植模式下赤峰杨的根长密度的空间分布特征进行了研究,同时用烘干法对其根质量密度进行了测量。结果表明:赤峰杨的总平均根长密度在不同土层间变化很大,0.0 40 cm土层为根系主要分布区域,其在总平均根长密度中所占比例高达77.1%;不同径级之间的根长密度差异显著,0.0 0.2 mm径级根系的根长密度最大,可达0.61 cm·cm-3。带间根长密度变化出现了先增大后减少而后略有增大的趋势,环境因子影响根系分布,>2.0 mm的粗根根长密度主要分布于带间。低覆盖度行带式配置模式下的赤峰杨吸收根系(<2mm)主要分布于0 40 cm深度区域,粗根(>2.0 mm)主要分布于地表40 cm以下区域,带间是根系的主要分布区域,根系主要利用的是天然降水。