利用信息化学物质研究松树小蠹虫的扬飞规律

于2005～2006年在辽宁省千山利用信息化学物质野外诱捕黄色梢小蠹Gryphalus fulvus、红松根小蠹Hylastes plumbeus、横坑切梢小蠹Tomicus minor及纵坑切梢小蠹Tomicus piniperda成虫,结果显示:这4种小蠹在4月18日至8月10日期间都明显出现2次扬飞高峰。第1次扬飞高峰持续均为30d左右,第2次扬飞高峰期约为15d;黄色梢小蠹和红松根小蠹第1次扬飞高峰期在5月上中旬出现,第2次扬飞高峰期分别在7月中下旬和上中旬;横坑切梢小蠹与纵坑切梢小蠹的扬飞高峰期基本一致,第1次扬飞高峰期为4月下旬到5月上旬,第2次扬飞高峰在7月上中旬;结果同时还表明诱虫量第1次扬飞高峰一般都明显大于第2次,只是黄色梢小蠹在首次利用信息化学物质进行监测且密度较高时例外。     

樟树组培苗轻基质育苗技术研究

为提高乡土阔叶树种樟树Cinnamomum camphora的育苗效率,以其新选育的优良无性系组培苗为材料,配置6种以泥炭为主要成分的轻基质组合,开展基质配比、容器规格、空气切根和施缓释肥试验。结果表明,基质配比对苗高、地径、高径比、SPAD值与存活率均有显著影响;泥炭中添加蛭石、木糠或珍珠岩均能显著改善育苗效果,同时添加木糠和珍珠岩时效果最佳;而泥炭中添加椰糠的效果与对照100%黄心土近似,明显劣于其他基质。大穴盘组培苗的苗高、地径、SPAD值和存活率均显著高于小穴盘,但高径比不受容器规格影响;空气切根能明显促进地径生长,抑制主根生长,加快侧根和须根生长,使根系更发达;缓释肥处理能显著提升苗木高生长、高径比和SPAD值,但对存活率影响不大。     

云南松三种同域共存切梢小蠹梢转干期的空间分布格局

分布在我国西南地区的横坑切梢小蠹,云南切梢小蠹和短毛切梢小蠹同域危害寄主云南松,给林业生产带来巨大损失。为探讨同域切梢小蠹种群在共存下对其空间分布格局的影响,采用传统聚集指标法和地统计学方法研究了三者在梢转干期不同受害云南松纯林树冠中的空间分布型。结果表明重度受害样地中云南切梢小蠹种群密度显著高于横坑切梢小蠹,在轻度受害样地则相反;传统聚集指标法结果显示同域共存的3种切梢小蠹种群在不同受害程度云南松中均为聚集分布,横坑切梢小蠹和云南切梢小蠹聚集是由环境因素和昆虫本身的聚集习性引起;地统计学结果表明除重度受害样地中短毛切梢小蠹呈随机分布外,其余切梢小蠹在不同种群密度下均呈聚集分布;除重度受害样地横坑切梢小蠹外,其他小蠹的空间依赖范围为4.01—7.45 m。横坑切梢小蠹和云南切梢小蠹在不同受害林分中拟合的半变异函数模型在球形模型和高斯模型之间转换。同域共存关系不影响不同种群密度下的切梢小蠹种群空间分布类型,但影响其半变异函数模型和理论参数。     

云南横坑切梢小蠹生物学研究

横坑切梢小蠹Tomicus minor (Hartig)是云南松Pinus yunnanensis Franchet的主要次期性害虫之一。1980年以来,该虫与纵坑切梢小蠹T. piniperda（L.）一起在中国西南部大量发生,导致数十万公顷云南松林受害。本文报道了横坑切梢小蠹在云南地区的生活史、生长、发育、繁殖等生物学特征。横坑切梢小蠹年生活史为一代,前后两代在冬春季有部分重叠。成虫羽化于4月下旬开始陆续,5 月下旬结束。成虫羽化后即飞到树冠上蛀食枝梢,直到11月发育成熟,开始繁殖。在此期间,每头成虫可以蛀食4～6个枝梢。横坑切梢小蠹在云南没有越冬习性。繁殖期从11月至次年3月。成虫主要在已经受到纵坑切梢小蠹危害的树木的中、下部产卵。繁殖期较纵坑切梢小蠹约迟1周。由于横坑切梢小蠹从枝梢到树干对云南松持续危害,对树木的危害性较在其它地区更为严重。横坑切梢小蠹利用受到纵坑切梢小蠹蛀害的树木繁殖产卵,加强了蠹虫对云南松树的危害,加速了受害树木的死亡进程。横坑切梢小蠹的上述生物生态学特征是该虫对云南松造成严重危害的重要原因。从横坑切梢小蠹虫体和虫坑中检测到伴生真菌云南半帚孢Leptographium yunnanensis。横坑切梢小蠹对该菌的带菌率在蛀梢期为11.5%;在蛀干中期约为10%～26%。     

纵坑切梢小蠹携带云南半帚孢研究

云南半帚孢 (Leptogramphyunnanensis)是纵坑切梢小蠹Tomicuspiniperda重要的共生真菌 ,在纵坑切梢小蠹危害寄主树木过程中发挥着重要作用。研究揭示 ,纵坑切梢小蠹主要通过与受到感染云南半帚孢的韧皮组织的接触携带上云南半帚孢的。纵坑切梢小蠹卵、幼虫和蛹对云南半帚孢的带菌率较高 ,均大于 90 % ,而成虫的带菌率较低。纵坑切梢小蠹的体表和体内均携带有云南半帚孢 ,但体表带菌是纵坑切梢小蠹带菌的主要途径。通过对纵坑切梢小蠹成虫头、足、翅和腹部带菌率的研究发现 ,云南半帚孢在纵坑切梢小蠹各部位的分布大体相同 ,揭示纵坑切梢小蠹没有携带云南半帚孢的特化构造或器官。     

纵坑切梢小蠹对云南松蛀害研究

在昆明地区,纵坑切梢小蠹Tomicus piniperda L.表现出枝梢聚集、树干蛀害等重要的行为学特征,形成三种基本蛀害模式。横坑切梢小蠹、蓝色伴生真菌参与了纵坑切梢小蠹危害过程,并在其中发挥积极作用。上述因素的综合影响,加强了纵坑切梢小蠹对云南松Pinus yunnanensis寄主树木的危害能力。     

纵坑切梢小蠹对云南松蛀害研究

在昆明地区,纵坑切梢小蠹Tomicus piniperda L.表现出枝梢聚集、树干蛀害等重要的行为学特征,形成三种基本蛀害模式。横坑切梢小蠹、蓝色伴生真菌参与了纵坑切梢小蠹危害过程,并在其中发挥积极作用。上述因素的综合影响,加强了纵坑切梢小蠹对云南松Pinus yunnanensis寄主树木的危害能力。     

云南切梢小蠹对云南松树的蛀干危害及致死机理

蛀干危害是云南切梢小蠹致死云南松树的关键环节。通过控制云南切梢小蠹蛀干密度,对云南切梢小蠹在自然条件下蛀干行为与危害进行了首次探讨。结果表明,云南切梢小蠹蛀干密度与云南松存活率呈负相关,蛀干密度直接决定云南松死亡或存活。研究发现,蛀干密度115坑/m2是云南松树的最低致死密度阈值,云南松树在蛀干密度低于26.4坑/m2情况下存活,在26.4-115坑/m2有部分存活,超过115坑/m2以后将被害致死。云南切梢小蠹对树干攻击形成有卵和无卵两类坑道。形成无卵坑道的蛀干攻击可导致树势衰弱,形成有卵坑道的蛀干危害严重破坏了韧皮组织,是导致云南松死亡的直接原因。     

光照、温度对纵坑切梢小蠹起飞行为的影响

纵坑切梢小蠹有明显的趋光性。在光照为 1～ 4 0 0 lx范围内 ,趋光性随光照强度提高而增强。完全黑暗条件下 ,蠹虫起飞量极少。在光照 10 0 0 lx,温度 2 5℃下 ,蠹虫起飞率达 77.7%。研究认为 ,温度和光照是纵坑切梢小蠹起飞的重要环境因素     

杜尔伯特蒙古族自治县银中杨大苗切根育苗试验初探

试验验证了银中杨造林地大苗切根繁育苗木的可行性,其具有简便易行、节约圃地、减少成本、提高林地生产力等特点。对银中杨的进一步推广利用具有一定意义。     

Axillary bud growth in relation to adventitious root formation in cuttings

Single-node leaf-bud cuttings of Schefflera arboricola Hayata and Stephanotis floribunda Brongn. were set and root formation, onset of axillary bud growth and plant height were measured. An increase in the number of roots in Schefflera, which was achieved with increasing cutting position on the stock plant (measured from top to base) or with increasing stem length below the node, accelerated the onset of axillary bud growth and resulted in an increase in plant height. Increasing the number of roots per cutting in Stephanotis through an increase in basal temperature also accelerated bud and shoot growth. Positional effects on root formation in Stephanotis showed no relationship with axillary bud growth and plant height. A positive relationship between number of roots per cutting and axillary bud growth was found among clones of Stephanotis . In general the results suggest that, with some exceptions, the onset of axillary bud growth is accelerated in cuttings as a result of accelerated root formation and a higher number of roots per cutting.     

刈割对紫花苜蓿根系生长影响的初步分析

研究了不同刈割次数对紫花苜蓿根系发育能力的影响。结果表明：刈割抑制紫花苜蓿主根的纵向(垂直)生长,而促进其横向(直径)生长,并使紫花苜蓿侧根发生总数减少和垂直分布的总体格局向表层集中,随着刈割次数的增加,侧根集中分布在土壤表层的比例也增加;刈割使根系生物量和体积总量减少,并随着刈割次数的增加,这种减少趋势更加明显,同时在土壤中的垂直分布变浅。     

不同地理种源桔梗种子性状及苗期生长分析

对来源于不同产地的43份桔梗[Platycocon grandiflorus（Jaeq．）A．DC．]种子的地理变异、种子特性及幼苗生长状况进行了分析。根据不同种源桔梗种子的特性、发芽率及幼苗的生长状况,利用聚类分析方法可将供试的桔梗种源大致分为南方和北方2个地理种源,其中北方种源的种子颗粒较大,千粒重达1．21～1．35g;南方种源的种子发芽率高（65％～71％）,种子千粒重为1．15～1．20g,幼苗生长健壮,根系较发达。此外,桔梗种子的发芽率与纬度呈明显的负相关,桔梗幼苗地上部分的生长与根茎的生长存在显著的相关性,可作为早期间苗及幼苗筛选的标准。研究结果表明,来源于安徽毫州及安徽太和的桔梗种源适合在浙江富阳地区栽培。     

模拟水分胁迫对不同种源麻楝种子萌发能力的影响

以麻楝6个种源种子为试验材料,用不同浓度的聚乙二醇(PEG)溶液模拟干旱胁迫,探讨干旱胁迫对种子发芽率、发芽势、发芽指数、活力指数以及幼苗苗高和胚根长及根苗比的影响,为麻楝的引种和推广种植提供依据。结果显示:(1)不同水势胁迫处理均降低了麻楝种子的发芽率和发芽势,当水势为-0.40MPa时延缓了种子萌发进程;种子的发芽率、发芽势、发芽指数和活力指数均随干旱胁迫强度的增加呈明显下降的趋势;当胁迫水势为-0.86MPa时,干旱胁迫处理的种子在试验结束时仍未能萌发,即-0.86MPa是麻楝种子萌发的临界水势。(2)当胁迫水势高于-0.40MPa时,麻楝幼苗的胚根长度与对照组差异不显著且长于对照组,说明高于-0.40MPa的水势有利于麻楝种子胚根的生长;麻楝幼苗苗高生长则是随着PEG浓度的升高而逐渐减缓。(3)适当的干旱胁迫可以增大各种源麻楝幼苗根苗比,且在胁迫水势高于-0.20MPa时都达到最大值。研究表明,麻楝种子具有一定的抗干旱胁迫的萌发能力,并以来自缅甸的Khin Aye Pale和泰国的Phu Wiang材料较强,来源于中国三亚和马来西亚Ulu Tranan的较弱。     

Cr6+胁迫对小麦幼苗根系生长的影响及DNA损伤效应研究

研究了Cr6+胁迫对3 d和10 d龄小麦幼苗根系生长的影响及DNA损伤效应.结果表明(1)>5 mg/L的Cr6+均显著或极显著降低幼苗根长、根数及根系鲜重、干重,3 d龄幼苗根系生长比10 d龄幼苗对Cr6+胁迫更敏感;(2)所试浓度Cr6+均降低两苗龄幼苗根系DNA含量;5～20 mg/L Cr6+浓度范围内,3 d龄幼苗根系DNA含量下降幅度大于10 d龄幼苗,Cr6+浓度>20 mg/L时,3 d龄幼苗根系DNA含量低于10 d龄幼苗;(3)Cr6+对两苗龄幼苗根系DNA增色效应的影响均呈现随浓度增大先升高后下降的趋势;3 d龄幼苗根系DNA增色效应在5～60 mg/L Cr6+浓度范围内大于对照,Cr6+浓度>60 mg/L时则小于对照;在所试Cr6+浓度范围内,10 d龄幼苗根系DNA增色效应均大于对照.     

鹅掌楸苗期动态生命表

报道了鹅掌楸在苗圃播种后的出苗率和幼苗存活率,根据定期观察数据编制了苗期动态生命表。结果表明,4个种源的出苗率都很低(1.64%～3.05%),比其各自的饱满种子率低得多;天然种源的出苗率高于栽培的种源,但前者的出苗数占饱满种子数的比例却低于后者。至一个生长季以后,幼苗存活率仅占出苗数的16%～27%,而黄山种源与庐山种源的交配后代则高达60%,明显地高于其亲本和其它种源。种子大小对于出苗率和幼苗存活率没有直接影响。最后讨论了遗传因素和生存环境对幼苗存活的影响,并认为种子和幼苗适合度低是鹅掌楸致濒的重要原因之一。     

Chemotaxis of deleterious rhizobacteria to velvetleaf (Abutilon theophrasti Medik.) seeds and seedlings

Abstract Intact seeds and seed and seedling root exudates of velvetleaf ( Abutilon theophrasti Medik.) were used as chemoattractants in experiments to determine the relative importance of chemotaxis in spermosphere and rhizosphere colonization by selected rhizobacteria. Results for soft-agar, capillary tube and soil chemotaxis assays indicated that selected deleterious rhizobacteria were specifically attracted to seed and seedling root exudates. Several amino acids and sugars detected in exudates were chemoattractants for these rhizobacteria. Using soil-chemotaxis assemblies, migration of rhizobacterial isolates through 2-cm distances of soil toward velvetleaf seeds or exudates was detected within 24 h. Isolates were not detected at the same site in soils without seeds or exudates until 72 h after inoculation. These results suggest that attraction of delecterious rhizobacteria toward seeds and seedling roots mediated by exudates (chemotaxis) might be the first step in establishment and subsequent colonization of biological control bacteria on weed seeds and seedling roots in soil.     

DPC浸种对花生幼苗根系和叶片生理功能的影响

在田间条件下,研究了DPC浸种对花生（Arachis hypogaeaL.)幼苗根系和叶片生理功能的影响。结果表明,DPC可提高花生幼苗根系中IAA和Z ZR的含量,促进根系的生长,提高根系活力;DPC可促进花生苗期叶片叶绿素的合成,提高叶绿素含量,提高苗期叶片的光合速率。在实践中,用150mg/LDPC浸种是取得花生壮苗丰产的有效措施。     

Inorganic Nutrient Supplements Constrain Restoration Potential of Seedlings of the Seagrass,Posidonia australis

Seed represents a potentially ecologically sustainable source of planting units for restoring seagrasses, particularly for seagrasses where transplanting negatively impacts donor beds. However, newly germinated seeds may be nutrient limited as their underdeveloped root systems may constrain capacity to access sediment‐based resources. We conducted a study in land‐based aquaculture tanks to determine whether early growth of newly germinated Posidonia australis seedlings could be enhanced by adding inorganic nutrients to the sediment. Sediments were supplemented with nitrogen and phosphorus in a factorial design (no nutrients, N, P, N + P). Shoot survival, whole shoot biomass, root morphology, root architecture, and nutrient concentration of seedlings were assessed monthly for the first 4 months after germination. More than 90% of seedlings survived during the 4 months of the experiment, irrespective of nutrient treatment. Growth of P. australis seedlings was not enhanced by addition of N or P to the sediment despite nutrient uptake occurring. Seedling growth was found to be more dependent on seed nutrient reserves rather than external nutrient sources for at least the first 4 months after germination. Adding inorganic nutrients to the sediment also significantly reduced the development of the seedling root system in terms of biomass, length, and density of lateral root branches. This study demonstrated that inorganic nutrient supplements constrain root development and therefore capacity for successful anchorage of seagrass seedlings, and pose a significant limitation on seedling establishment when transferred to the field, as well as potentially limiting natural and transplanted seedling establishment in eutrophic sediments.     

Effect of Fluoride on Nucleic Acids and Growth in Germinating Corn Seedling Roots

Corn seeds were treated with 0.01 M sodium fluoride for various time periods. The treated seeds were germinated and grown until the seedling roots reached a standard size of 12±3 mm. Analyses were made for RNA and DNA contents of 3-mm seedling root tips. Determinations also were made for growth rate, rate of cell elongation, cell multiplication, and tissue maturity of 12-mm roots. RNA contents of 3-mm root tips were found to be directly proportional to the growth rates of the entire seedling root of corn seeds treated with sodium fluoride for various periods of time. The RNA content was reduced on a cell basis and was independent of the root tip cell number. The amount of DNA was not related to the growth rate of the intact seedling roots. Since fluoride reduced the number of mitotic figures, it was likely that fluoride inhibited DNA synthesis during the interphase of the mitotic cycle. Growth by cell multiplication was inhibited more than that by cell elongation in the sample treated with fluoride for a shorter period. The two types of growth, however, showed a similar level of growth reduction in the sample treated with fluoride for a longer period. Fluoride seemed to reduce the rates of cellular elongation and multiplication not more than about 40 per cent of the control value in these tissues under present experimental conditions. Fluoride also induced maturity in the seedling roots in proportion to the periods of fluoride treatment.