武义县古树名木资源调查

武义县有古树名木１４５４株,４３种,隶属于２５科３８属。其中树龄最大者达１２００ａ,径最粗者为２７０ｃｍ,在调查的基础上,提出了古树名木的保护管理与开发利用建议。     

老龄芒果树截干换种新技术

报道云南保山市新城农场采取截干换种新技术更新老龄三年芒芒果树,提高芒果产量、质量,增加经济效益,并详细介绍了芒果树截干换种新技术     

北京市潮关西沟流域华北落叶松林分结构分析

着眼北京市密云县古北口镇潮关西沟流域内华北落叶松代表性样地,分别对其不同密度下林木直径和树高结构进行分析,从而找出其林分分布规律。结果表明:华北落叶松人工林的不同林分密度下林分结构相似,基本遵从于正态分布。随着林分密度的增加,林分平均胸径分布范围增加,林分内的树高分布范围也增大,且不同密度林分的树高分布都有一个高峰。     

苦楝研究现状及发展前景

论述了苦楝(Melia azedarach)的国内外研究现状,包括化学成分,药理作用及其在农林上的杀虫作用,并提出了今后研究开发的方向。     

稳态气孔计与其它3种方法蒸腾测值的比较研究

１９８９－１９９２年,分别在山东（鲁克斯扬）与宁夏（合作杨）人工林中,用３种方法（快速称量法、热脉冲法和整树容器法）多次对比了气孔计测值的变化。结果表明,气孔计测值恒大于实际蒸腾值。根据１０次１０２６个样本比较,气孔计测值约为自然蒸腾值的１．３－３．２倍,平均为２．６４９倍,其平均校正系数为０．３７７５,干旱地区为０．６４５２,较湿润地区为０．３４０７,此值可作为蒸腾耗水研究的参考。     

阔叶树小径材热压干燥工艺的研究

通过对荷木和米槠两种华南地区常用阔叶树小径材薄板材热压干燥工艺的研究，探讨热压干燥工艺参数对小径材板材干燥质量（包括密度，厚度压缩率，尺寸稳定性及部分力学性能）的影响，试验结果表明，热压干燥工艺可以大大改善小径材的物理力学性能。     

Soil nutrient supply and biomass production in a mixed forest on a skeleton‐rich soil and an adjacent beech forest

In the natural forest communities of Central Europe, beech (Fagus sylvatica L.) predominates in the tree layer over a wide range of soil conditions. An exception with respect to the dominance of beech are skeleton‐rich soils such as screes where up to 10 broad‐leaved trees co‐exist. In such a Tilia‐Fagus‐Fraxinus‐Acer‐Ulmus forest and an adjacent mono‐specific beech forest we compared (1) soil nutrient pools and net nitrogen mineralization rates, (2) leaf nutrient levels, and (3) leaf litter production and stem increment rates in order to evaluate the relationship between soil conditions and tree species composition. In the mixed forest only a small quantity of fine earth was present (35 g l^—1) which was distributed in patches between basalt stones; whereas a significantly higher (P < 0.05) soil quantity (182 g l^—1) was found in the beech forest. In the soil patches of the mixed forest C and N concentrations and also concentrations of exchangeable nutrients (K, Ca, Mg) were significantly higher than in the beech forest. Net N mineralization rates on soil dry weight basis in the mixed forest exceeded those in the beech forest by a factor of 2.6. Due to differences in fine earth and stone contents, the volume related soil K pool and the N mineralization rate were lower in the mixed forest (52 kg N ha^—1 yr^—1, 0—10 cm depth) than in the beech forest (105 kg N ha^—1 yr^—1). The leaf N and K concentrations of the beech trees did not differ significantly between the stands, which suggests that plant nutrition was not impaired. In the mixed forest leaf litter fall (11 %) and the increment rate of stem basal area (52 %) were lower than in the beech forest. Thus, compared with the adjacent beech forest, the mixed forest stand was characterized by a low volume of patchy distributed nutrient‐rich soil, a lower volume related K pool and N mineralization rate, and low rates of stem increment. Together with other factors such as water availability these patterns may contribute to an explanation of the diverse tree species composition on Central European screes.     

林木种衣剂使用技术的研究

通过室内外试验,林木种子经过浸种后包衣是提高其成活率的必要手段,浸种48h把种子晾干后包衣效果最好。各树木种子经包衣后播种保存率均比时照提高。使用种衣剂包衣的樟子松和落叶松,2年生时,在密度基本一致的条件下,Ⅰ、Ⅱ级苗比时照增加。     

Phylogenetic relationships between rice dwarf phytoreovirus isolates from five countries

Rice dwarf virus isolates were collected from several locations in Japan, the Philippines, China, Nepal and Korea. Genomic dsRNA segment profiles in polyacrylamide gel electrophoresis differed among the isolates. There were less differences in the profiles between isolates from Japan and Korea than in those between these two Countries and others. Nucleic acid hybridization was used to examine the extent of genomic variation. Full-length cDNAs to all genomic segments encoding non-structural proteins (S4, S6, S9, S10, S11 and S12) were synthesized from two Japanese isolates, and were used for dot-blot hybridization. Hybridizations using probes generated from the full-length cDNA clones failed to differentiate isolates from different geographical areas. However, cDNA probes covering a variable region of S12 were able to distinguish Japanese and Korean isolates from those of other countries. Phylogenetic tree analysis based on the amino acid sequence of P12 encoded by S12 grouped Japanese and Korean isolates together. The Chinese isolates from two different locations (Yunnan and Fujian) were closely related to each other, and were the most distantly related to Japanese and Korean isolates.     

安徽药用牡丹炭疽病病原菌鉴定

<正>牡丹(Paeonia suffruticosa Andr.)是芍药科植物,为多年生落叶灌木,具有很高的观赏和药用价值。因其风姿华丽、色彩艳丽、品种繁多、深受大家喜爱,是中国传统名花和世界著名花卉之一。其根皮也被称为丹皮,具有抗炎、抑制血小板、止痛、清热等作用,是六味地黄丸等著名中成药的主要配方,也是饮片中的常用品[1-2]。近年来,随着牡丹种植面积的不断扩大,造成牡丹病害的大面积发生,已给牡丹生产带来严重影响。