Predicting the Effectiveness of <Emphasis Type="Italic">Phragmites</Emphasis> Control Measures using a Rhizome Growth Potential Bioassay

In the last century, Phragmites australis (common reed) has expanded from a minor component of the mid-Atlantic tidal wetlands to a dominant species in many locations. Expansion of Phragmites results in decreased plant diversity and alterations to the tidal characteristics of the marsh, resulting in decreased wetland value. Management efforts have used a variety of strategies in an attempt to control its expansion. We tested a greenhouse bioassay that provided insight into the rhizome vitality of six herbicide-treated sites in the Alloway Creek Watershed, NJ well in advance of the growing season. At three sites, rhizomes were exhumed and classified by depth (0–25 cm and 25–75 cm) and appearance (color and firmness). Concurrently, the same protocol was followed, but conducted on an areal basis at three additional sites. Material was grown in sand under greenhouse conditions void of nutrient supplements for 70 days, after which shoots were removed and the rhizomes replanted for 30 days. Effectiveness of control strategies was quantified by examining rhizome color, vitality, and shoot densities in the field. Color was indicative of quality of rhizome reserves. Less than 0.2% of the firm, brown rhizomes produced shoots upon initial planting and none produced shoots upon replanting, whereas 50.9% of white rhizomes produced shoots on initial planting. Rhizome vitality was quantified by examining shoot emergence and the morphology of the shoots. Coupling rhizome vitality with observed field densities resulted in a predictive capability, and shoot density and biomass predictions were compared to field measurements in July 2001. We tested and accurately predicted the relative shoot densities and shoot biomass of the three sites for which we collected rhizome material on an areal basis. The result is a rapid, valuable, and cost-effective monitoring tool that can quickly quantify the effects of past control methods and predict future growth potential.     

姜状三七根茎的皂苷类化学成分研究

为了解姜状三七(Panax zingiberensis)根茎的皂苷类化学成分,采用正相硅胶、反相硅胶和凝胶等色谱方法从其根茎的乙醇提取物中得到9个皂苷类化合物,根据理化性质和波谱数据,其结构分别鉴定为人参皂苷SL₁ (1)、人参皂苷Rh₁ (2)、三七皂苷R₈ (3)、竹节参皂苷IVa (4)、越南人参皂苷R₁₀ (5)、人参皂苷Rg₁ (6)、菠菜皂苷A 28-O-β-d-葡萄糖苷 (7)、齐墩果酸28-O-β-d-葡萄糖苷 (8)和姜状三七苷R₁ (9)。化合物1、3、5、7和8为首次从该植物中分离得到, 其中化合物5为奥克梯隆醇型皂苷,此类皂苷在该植物中未见报道。     

Effect of water depth on the rhizome dynamics of Typha angustifolia

The rhizome dynamics of Typha angustifolia in relation to water depth were investigated. Observations were made in two different stands, namely Akigase from April 2002 to December 2003, and Teganuma from April 2003 to December 2004. The mean rhizome length in the two stands was not significantly different but the mean rhizome diameter and biomass showed a significant difference. The larger rhizome diameter in Teganuma is seemingly an important adaptation to maintain effective aeration of the rhizome by reducing the internal resistance; while larger biomass helps survival under anoxia for longer periods of time, it also provides strong anchorage to the substrate.     

檫树毛竹混交林中毛竹鞭根的研究

采用固定标准地定位观测法,对新造竹林中栽植擦树后形成的檫树（14－15年）毛竹混交林竹鞭根结构和鞭体养分进行了调查和测定,结果表明,檫树在一定的密度范围,混交竹林有利于毛竹鞭根结构的优化和鞭体养分的提高,与毛竹纯林相比,檫树密度为420－615株.hm^-2的混交竹林,其鞭长,鞭径及其整齐度,新鞭年生长量,壮幼鞭比例,健壮芽数量、鞭根体积等,均在不同程度上高于毛竹纯林中的对应部分。当檫树密度超过735株.hm^-2时,混交竹林中的上述指标则低于生毛竹纯林中的对应部分,但单位鞭长的分岔次数明显加大,回归分析表明,鞭总长,鞭节点,新鞭生长量,鞭径、鞭径整齐度及单位鞭长分岔次数与檫树密度之间的关系密切（r=0.92956-0.99530),混交竹林中鞭体的N、P、K,Ca,Mg养分含量高于纯柯的对应值,其中鞭体中N含量较纯林平均高出7．6％、11．6％。     

盾叶薯蓣根状茎的发育解剖学和组织化学研究

盾叶薯蓣根状茎顶端的生长点由鳞片包被,其衍生细胞分化为原表皮、基本分生组织和散生的原形成层束,以后分化为表皮、基本组织和散生的维管束构成的初生结构。根状茎顶端下方的原表皮内存在初生增厚分生组织,其细胞不断向内分裂和其衍生细胞的体积增大使根状茎能够迅速增粗。分化完成的根状茎主要由周皮、基本组织和散生的维管束构成。周皮由木栓层、木栓形成层和栓内层组成;基本组织由薄壁细胞组成;维管束属于有限维管束。薯蓣皂甙主要存在于基本组织薄壁细胞中。原分生组织和原形成层不含薯蓣皂甙,维管束的木质部和韧皮部中的韧皮纤维也无薯蓣皂甙的分布,韧皮部的生活细胞和维管束鞘细胞有薯蓣皂甙的积累。近顶端的基本分生组织细胞内薯蓣皂甙不形成液滴,随着细胞分裂逐渐停止,细胞内开始形成含薯蓣皂甙的液滴,反映皂甙是在成熟细胞内积累。其中,有小型维管束分布的基本组织中薯蓣皂甙的积累与分布最丰富,两年生根状茎中薯蓣皂甙的含量比一年生的高。     

Clonal plasticity in response to rhizome severing and heterogeneous resource supply in the rhizomatous grass Psammochloa villosa in an Inner Mongolian dune, China

In a field experiment, Psammochloa villosa plants were subjected to rhizome severing. Severing rhizomes reduced growth in the young, detached rhizome segments compared to the controls in terms of all measured clonal growth-related characters, i.e. number of rhizomes and shoots, total rhizome length and total number of rhizome nodes. In a container experiment, the control ramets received uniform water and nutrient supply but in heterogeneous treatments high and low levels of water and nutrient supply, respectively were established. The number of ramets, total rhizome length, dry weight per ramet and biomass allocation to the rhizome had higher values at high water and nutrient supply, while spacer length (length of rhizome between shoots) and rhizome internode length were not affected. The local response of ramets given low water supply was enhanced due to connection to a well watered parent ramet in terms of number of ramets, total rhizome length and dry weight per ramet. A remote effect was not observed in the other treatments or in the other measured characters.     

切断根茎对根茎禾草沙鞭和赖草克隆生长的影响

为了研究半干旱内陆沙化生境中植物克隆整合对克隆植物基株扩展能力和对克隆植物分株定居逆境能力的贡献,在内蒙古鄂尔多斯高原毛乌素沙地对根茎禾草沙鞭（Rsammochloavillosa（Trin．）Bor）和赖草（Leymussecali－nus（Georgi．）Tzvel．）进行了以切断根茎为处理的野外实验。实验结果表明,切断根茎处理使根茎禾草沙鞭基株的幼小部分（观测单元）在实验期间根茎数量增量、地上技数量增量、地上枝总长度增量、主根茎节数增量、根茎节总数增量、主根茎长度增量和根茎总长度增量显著地减少。然而,切断根茎处理对另一根茎禾草赖草基株幼小部分（观测单元）的上述7个特征在实验期间的增量没有影响。这些结果指示着在克隆整合及其对克隆生长贡献方面的种间差异。沙鞭的克隆整合特性和克隆生长特性对它在水分短缺、蒸散剧烈、养分贫瘠、生境斑块化和扰动经常的沙化草地环境中的生存能力有重要贡献。     

荷花分蔤栽培繁殖研究

在正常栽培条件下,钵或缸栽荷花的花期是从6月中旬到8月。但用分蔤栽培繁殖技术,可使花期延长到10月上旬。这是延长花期的一种栽培繁殖方法。本文介绍了这一技术的要点和试验结果。     

生姜根际茎腐病拮抗菌的筛选及鉴定

从生姜根际土样分离获得的86个细菌分离物中,通过离体拮抗试验,筛选出2株对生姜茎腐病有良好拮抗效果的细菌,编号分别为JF24和JF3。通过对它们进行形态学观察、生理生化测定以及16S rRNA序列分析,初步确定,JF24为荧光假单胞菌(Pseudomonas fluorescens),JF3为粪产碱菌(Alcaligenes faecalis)。JF24和JF3的16S rRNA序列的GenBank登录号分别为FJ999730和FJ999731。