沙棘根瘤的形成与固氮能力

与沙棘根系共生结瘤的Ｆｒａｎｋｉａ氏菌可以从根毛和皮层侵染。被侵染的宿主细胞迅速转变为适宜共生生活的传递细胞。宿主细胞的内质网１高尔基体和内生壁物质组成了Ｆｒａｎｋｉａ氏菌的被囊。菌体和被侵染细胞释放激动素，使部分中柱鞘细胞分生，形成根瘤原基。沙棘根瘤是以瘤瓣为基本单位，逐次、逐年连续分枝形成的一个多年生珊瑚状瘤块。沙棘主根一般不结瘤，１级侧根结瘤最多，瘤块最大，２￣３级次之。根瘤在１年中有３个固     

根瘤菌浸根处理对相思苗木接种的效应初报

采用根瘤菌液体菌剂对马占相思、大叶相思和杂交相思苗木进行浸根处理接种试验。结果表明：根瘤菌浸根处理能明显提高相思苗木根系结瘤；苗木生长差异因育苗基质不同而表现不同，河沙基质无施肥条件下接种苗木的苗高、地径和长势均优于无接种苗木；黄心土加草皮灰基质中接种苗木的苗高、地径比无接种苗木略有增加，但不显著；杂交相思和大叶相思比马占相思容易人工接种形成根瘤。     

灭幼脲及B.T制剂处理赤松毛虫的组织病理观察

应用切片技术赤松毛虫幼虫进行组织病理观察。经灭幼脲Ⅲ号处理的赤松毛虫幼虫，其内、外表皮结构松散，内表皮厚度不均匀且明显变薄；６－７龄幼虫体壁几丁质含量降低７０．９％。经Ｂ．Ｔ制剂幼虫，中肠上皮细胞底膜分离，部分上皮细胞被破坏。因食膜变薄，断或溃烂，中肠变黑。     

青海云杉幼树在北疆平原移栽成功的要点

青海云杉（Piceakoraiensis Nakai）常绿针叶乔木，原生长于青海境内丘岭地区。上世纪70年代起引进新疆山区，在苗圃利用青海云杉种子繁殖培育获得成功，培育的幼苗大量供山区人工更新造林用，并且适合新疆山区的环境，生长状况良好。该树种喜阴耐寒，树干通直，无主根，侧根发达，属浅根系，侧枝轮生，层次不明显，其外形呈宝塔形；该树种与新疆雪岭云杉同属同种，但冠形比雪岭云杉更饱满，颜色与其他针叶树种有明显的差异。青海云杉比雪岭云杉颜色较深，呈灰绿色，针叶要短些，其生物学特性（经实际验证）较雪岭云杉更具抗旱性，非常适合新疆山区造林和北部平原、城镇绿化的行道树、观赏树。     

灭幼脲及B．T制剂处理赤松毛虫的组织病理观察

应用石蜡切片技术对赤松毛虫幼虫进行组织病理观察。经灭幼脲Ⅲ号处理的赤松毛虫幼虫，其内、外表皮结构松散，内表皮厚度不均匀且明显变薄；６～７龄幼虫体壁几丁质含量降低７０．９％。经ＫＴ制剂处理的幼虫，中肠上皮细胞与底膜分离，部分上皮细胞被破坏。因食膜变薄，断裂或溃烂，中肠变黑。     

紫外线照射对毛竹茎秆细胞壁超微结构

应用光学显微镜，扫描电子显微镜和色度计，研究了毛竹竹材表面经紫外线照射后细胞壁的破损程度，具木质素组织分解深度以及颜色变化等规律。结果表明：经紫外线照射后，在竹材横切面上，纤维细胞壁的分解始于次生壁各层连接处，接着是细胞角隅处和复合中层，最后纤维细胞壁全部被分解消失，薄壁组织细胞壁的复合层先被分解，随后细胞壁分解变薄，坍塌和消失。竹秆壁表面的分解，最初从表皮细胞的短细胞开始，然后扩展到其它表皮细胞。根据木质素的显色反应显示，紫外线照射竹材样品40d时，薄壁组织比纤维组织分解得更深，其中前者为590μm，而后者只有146μm。另外，经紫外线照射后的竹材样品，其横切面上的颜色和亮度变化最大，径向切面次之，竹秆壁表面变化最小。本文还讨论了经紫外线照射后，竹材中具薄壁组织比纤维组织分解更深的原因，以及样品3个面上颜色和亮度变化的机制。     

华山松针叶表皮结构与抗疱锈病关系的初步研究

通过对来自云南4个华山松疱锈病典型发病区的122份华山松针叶样本的解剖结构研究,发现华山松的感病组与健康组之间在针叶表皮结构上有显著差异,其中主要差异为表皮细胞厚度和角质膜厚度,有抗病特性的植株具有显著加厚的针叶表皮结构,抗病的健康组比感病组的角质膜和表皮分别增厚达30.5%和8.0%,而气孔数量和内皮层厚度上差异不明显.结果支持疱锈菌感染华山松是通过主动侵入机制从表皮进入针叶,角质膜厚度和表皮厚度对华山松抵抗疱锈菌感染有重要作用.这一结果为弄清疱锈菌侵入华山松的途径提供了实验证据.     

木兰科6属27种植物的叶片比较解剖学研究

应用石蜡切片技术和光镜观测方法,对采自云南昆明树木园的木兰科6属27种植物的叶片进行了比较解剖学研究。结果表明：（1）木兰科植物的叶片均为异面叶,由表皮、叶肉、叶脉构成;叶肉组织分化为栅栏组织和海绵组织,均具有圆形或近圆形油细胞;叶脉维管束韧皮纤维排列连续或不连续,成环状或轮状。（2）叶片下表皮细胞是否为具明显乳突的细胞和主脉维管束韧皮纤维细胞排列是否连续可明确区分木兰亚科和鹅掌楸亚科。（3）叶片厚度、上表皮厚度、海绵组织厚度可以对秃木兰属和鹅掌楸属进行明确区分,栅栏组织厚度、栅海比、油细胞大小和分布密度等余下性状则在数值上均存在属间重叠现象,不宜作为属间分类性状。（4）基于最大值和最小值进行的聚类结果与传统分类结果吻合度较基于平均值的聚类结果大,最大值和最小值比平均值更能表征研究对象。总之,表皮、下皮、叶肉组织和油细胞等部分叶片解剖学特征在探讨木兰科科下等级如亚科、部分属和部分种的分类地位时具有一定价值。     

苗木掘起后根系吸水与根系再生的生理

苗木根系从土壤中吸收水肥的途径有二:一是经过根毛、表皮、外皮、皮层之类各细胞内部流进中柱导管;另一个是经过细胞间隙被吸进组织内部。前者是主动性吸水,它与细胞质的浓度和活力有关。后者是被动性吸水,是由于地上部分蒸腾引起导管产生负压所致。至于主动性吸水,即使把地上部分切断后,由于根的吸水作用,水分仍被送往地上部分,而由断面流出。如在树木生长期间根系吸水强烈时采伐,或采伐后持续相当长时间内,仍会从伤口流出水分。落叶阔叶树将开叶之前,根的吸水作用开始旺盛,经常可以看到水分从伐桩断     

黄土高原刺槐根系垂直分布特征研究

在中国西北黄土高原地区，水分是树木生长发育的主要限制因子。根系分布特征由于反映了树木对环境条件的利用程度而具有更加特殊的生态意义。本研究选择阳坡和阴坡不同立地上年龄一致的刺槐林调查了根系分布特征。根系垂直分布特征的调查结果表明，在所有立地上，根系生物量随着深度的增加而降低，其中细根的分布深度大于粗根的分布深度。方差分析结果表明：不同立地上不同径级根系的分布特征也有明显的差别，粗根是差异存在的主要原因，阴坡立地上的根系生物量，特别是细根生物量大于阳坡立地上的。对根系消弱系数的分析结果表明，阴坡立地上的根系消弱系数大于0．982，而阳坡立地上的根系消弱系数小于0．982，说明阴坡市地上刺槐根系的生物量在深层土壤中的分布相对量更大一些。其中细根的根系消弱系数大于粗根的，这种根系分布特征有利于根系对深层土壤水分养分的吸收利用，进而促进树木地上部分的生长发育。图3表3参15。     

Two Burkholderia strains from nodules of Dalbergia odorifera T. Chen in Hainan Island, southern China

Two Burkholderia strains 8111 and 8201 were isolated from root nodules of Dalbergia odorifera, an endemic woody legume in southern China. Phylogenetic analysis of 16S rRNA gene and 16S-23S gene intergenic spacer (ITS) showed that these two bacterial strains were closely related to Burkholderia cepacia and they were also similar in carbon source utilization using Biolog GN2 plate tests. The DNA G+C content of strains 8111 and 8201 were 65.8 and 65.5?mol%. Inoculation tests demonstrated that both strains 8111 and 8201 formed functional root nodules in their original host D. odorifera, and significantly enhanced plant growth (as measured by plant biomass and nitrogen content), compared to the no-inoculated control plants. Sequencing of 16S rRNA gene in nodules of D. odorifera seedlings inoculated with strains 8111 and 8201 confirmed their identity. However, these two strains did not induce root nodulation in Acacia auriculiformis and Erythrophleum fordii. This implies that the nodulation capacity between Burkholderia strains 8111 or 8201 and their legume hosts may be specific. Our results show that both Burkholderia strains 8111 and 8201 are able to form functional nodules on D. odorifera and are potentially beneficial inoculants for seedling propagation to be used in large scale D. odorifera plantations.     

Nitrogen transfer between N2-fixing plant and non-N2-fixing plant

IntroductionNitrogenisanelementthatcyclesthroughanecosyst6mandneedstobepresentatacertain'minimumIeveItosust8inthatsystem.lnaninterspe-ciesconteXt,thebeneficiaIeff6ctsofN2-fixingpIantsinecosyst6ms,duetOtheirc0ntributionofnitr0gen,havebeenobservedbysucceedinggenerationsofagronomists,f0rest6rs,andecoIogists.Thein-terpIantsofN2-fixingplantsandnon-N2-fixingplantsarepraCticedtoincreasetotaIyieldandreducetheneedfOrf6Ftilizersinput,andithasbeenshownthatpartoftheassimiIatedNinthenon-N2-fixingpIa…     

Seasonal fluctuations of starch in root and stem tissues of coppiced Salix viminalis plants grown under two nitrogen regimes

Seasonal changes in starch were studied at the tissue and cellular levels in roots and stems of Salix viminalis L. cuttings. Cuttings were planted in pots containing sand and grown in a controlled environment chamber in which seasons were artificially induced by changes in temperature and photoperiod. Nitrogen was supplied at optimum and low rates, and during dormancy, one-half of the plants were decapitated. Starch concentrations in root and stem tissues were determined regularly during shoot extension growth, dormancy and resprouting after dormancy. We used light microscopy (LM) combined with image analysis (IA) to determine the cellular localization and amount of starch in different cell types of stem and root tissues. Chemical analysis confirmed that starch concentrations were lower in plants receiving a high-N supply rate than in plants receiving a low-N supply rate. In all plants, the highest concentration of starch was in the roots. Light microscopy and IA showed that starch accumulated mainly in the phloem and cortical cells of both root and stem tissues. Starch grains were also regularly found in ray parenchyma cells. The amount of starch as well as the size of the grains showed strong seasonal fluctuations. In both roots and stems, starch concentrations were highest during predormancy and lowest during periods of shoot extension growth. At the time of resprouting, root cells of decapitated plants were more depleted of starch than root cells of intact plants, supporting the hypothesis that starch reserves in roots are important during the early phase of resprouting in coppice systems.     

Nitrogen transfer between N2-fixing plant and non-N2-fixing plant

The transfer mechanisms, calculating methods and ecological significance of nitrogen transfer between legumes and non-legumes are briefly reviewed. There are three pathways of nitrogen transfer from legumes to neighboring non-legumes: (1) the nitrogen pass in soluble form from the donor legume root into the soil solution, move by diffusion or/and mass flow to the receiver root and be taken up by the latter; (2) nitrogen pass into the soil solution as before, be taken up and transported by mycorrhizal hyphae attached to the receiver roots; (3) if mycorrhizal hyphae form connections (bridges) between the two root systems, the nitrogen could pass into the fungus within the donor root and be transported into the receiver root without ever being in the soil solution. The mechanisms of nitrogen transfer between N₂-fixing plants and non-N₂-fixing plants are reviewed in terms of indirect and direct pathways. The indirect N-transfer process is related to the release of nitrogen from legumes (donor plants), the possible interaction of this nitrogen with soil, the decomposition and mineralization of legumes and turnover of nitrogen, the nitrogen absorbing and competing abilities of the legume and the non-legume (receiver plant). The direct nitrogen transfer process is generally considered to be related to the nitrogen gradient and physiological imbalance between legumes and non-legumes, and when the donor legume lies in stressful stage (i.e. removal of shoots or attacked by insects), the nitrogen transfer can be improved significantly. The methods of determining nitrogen transfer (indirect¹⁵N-isotope dilution method and direct¹⁵N determination method) are evaluated, and their advantages and shortcomings are shown in this review. Foundation Item: This paper was funded by National Science Foundation and Doctor Foundation of China. Biography: J{upang} San-na (1970-), male. Ph. doctor, engineer in Collage of Resource and Environment. Beijing Forestry University Responsible editor: Chai Ruihai     

豆科树种根瘤菌与四种豆科植物的接种试验

从５１种豆科树种根瘤中分离获得的６６个菌株与４种豆科植物进行接种试验，幼苗经５０ｄ培养，刺槐，合欢，大豆，豌豆的结瘤率分别为１００％，８７．９％，６９．７％，２５．８％。其中有１２个菌株可同时在这４种豆科植物上结瘤，２９个菌株可同时在刺槐，合欢和大豆上结瘤，４个可同时在刺槐，合欢和豌豆上结瘤，说明豆科对种根瘤菌具有较广泛的共生寄主范围。     

红豆树苗木根瘤及其对生长的影响

红豆树根瘤的形成时间和根瘤的数量与圃地土壤的质量有关,在土壤水肥条件好的环境中,1 a生苗木中的根瘤少见,且根瘤个体极小;在土壤较贫瘠的圃地中,红豆树根瘤十分发达,数量多且形成时间早。红豆树根瘤能够促进苗木生长,有根瘤生长比无根瘤生长的1年生红豆树植株中,根系的干物质增长率46%、根系鲜重的增长率41.9%、茎干物质增长率40.3%、植株总干物质的增长率35.0%、植株总鲜重增长率22.4%、植株叶的干物质增长率14.8%。截根处理有助于根瘤菌感染苗木植株,苗木生长更健壮:截根处理的苗木径高比为4.1%,未截根处理的为3.4%;截根处理促进根系的发育,截根处理的侧根总长度47cm/株、未截根处理的侧根总长度为26cm/株、侧根增加率为80.8%,截根处理的须根总长度228cm/株、未截根处理的侧根总长度为102cm/株、须根增加比率123.5%;截根处理促进苗木根幅的扩大,比未截根处理的根幅增大27.3%。     

Intraspecific variation in <Emphasis Type="Italic">Trifolium pratense</Emphasis>: impact on feeding and host location by <Emphasis Type="Italic">Sitona lepidus</Emphasis> (Coleoptera,Curculionidae)

Red clover (Trifolium pratense L.) is becoming increasingly important in grassland systems because of its high productivity, protein content and nitrogen-fixing ability, but its use has been constrained by losses due to pests and diseases, and this contributed to the decline of red clover usage allowing white clover (T. repens L.) to become the dominant legume of UK grasslands. One of the major pests of red clover is the clover root weevil (Sitona lepidus Gyllenhal, Coleoptera, Curculionidae) which attacks both the shoots and roots, particularly the N-fixing root nodules, of clover plants. This current work investigates the feeding preferences of S. lepidus with respect to 11 varieties (Pawera, Kuhn, Astra, Norseman, Norseman low, Norseman high, Marcom, Merviot, Milvus, Britta, Sabtoron) and 5 lines (AA30, AA31, AA4493, AA4494 and AA4495) of red clover in order to identify relationships between the variation in attractiveness of different red clover varieties for both adult and larval stages of the weevil. Of those tested Norseman high showed potential resistance, being less favoured by both adults and larvae of the weevil. This may be attributed to the potentially high phyto-oestrogen levels in this variety.     

Growth and physiology of olive pioneer and fibrous roots exposed to soil moisture deficits

In woody plants, pioneer roots are the main roots used to expand the root system horizontally and vertically whereas fibrous 'feeder' roots are chiefly used in the absorption of water and nutrients. Because of their different roles, we expected newly emerged pioneer and fibrous roots to respond differently to restrictions in soil moisture. We hypothesized that fibrous roots would exhibit greater growth plasticity and greater physiological impairment from soil moisture deficits, especially under heterogeneous conditions. We compared the responses of fibrous and pioneer roots of olive seedlings (Olea europaea) to localized and uniform soil moisture deficits in transparent containers in the greenhouse. In comparison with uniformly wet conditions, uniformly dry conditions caused reduced shoot photosynthesis and reduced shoot growth, but no significant effect on root morphology, root respiration (measured in aerated buffer solution using excised roots) or electrolyte leakage as a function of root age. Under heterogeneous soil moisture conditions, root growth tended to preferentially occur in the moist sector, especially in the pioneer roots. In comparison with pioneer roots in the moist sector, pioneer roots in the dry sector had higher tissue density and higher suberin content, but no shift in root respiration, non-structural carbohydrates or electrolyte leakage. In contrast, fibrous roots in the dry sector exhibited evidence of impaired physiology in older (>38 days) roots compared with similar age fibrous roots in the moist sector. While we anticipated that, compared with pioneer roots, fibrous roots would be more sensitive to soil moisture deficits as expressed by higher electrolyte leakage, we did not expect the strong growth plasticity of pioneer roots under heterogeneous soil moisture conditions. Differentiating the responses of these two very different root types can improve our understanding of how different portions of the root system of woody plants cope with soil moisture deficits.     

Influence of ground flora on Fraxinus mandshurica seedling growth on abandoned land and beneath forest canopy

A better understanding of root/shoot interactions influencing seedling growth on abandoned land could yield insight into seedling regeneration and restoration of the abandoned lands. Field work had been conducted for 2 years (2008–2009) to investigate the impacts of neighbouring plants on Manchurian Ash (Fraxinus mandshurica) seedling growth under the canopy of an old secondary forest and on the abandoned land exposed to full solar radiation in North-eastern China. Four different interaction treatments were designed for the study: neither shoot nor root interaction, shoot interaction only, root interaction only, and both shoot and root interaction. The presence of either the shoots or roots of neighbours had a competitive effect, reducing the growth of the target seedlings at each site. The total competitive effect of roots and shoots of neighbouring plants was significantly less than the sum of root and shoot competition separately on the abandoned land, but this difference was not significant beneath the forest canopy. Root competition was more restraining than shoot competition on the abandoned land. Target seedlings adjusted their root morphology and growth rates in response to the competitive effects from different parts of the neighbouring plants. Our results indicated that the root:shoot ratios of the target seedlings at the end of the experiment were affected by neither initial tree size nor the competition from either above- or belowground at either site. The results also highlight the importance of reducing root competition in boosting seedling regeneration and forest rehabilitation on the abandoned land.     

Root growth in Sitka spruce and Douglas-fir transplants: dependence on the shoot and stored carbohydrates

When dormant Sitka spruce (Picea sitchensis (Bong.) Carr.) transplants were lifted from the nursery in March and transferred to favorable growing conditions in a controlled environment chamber, new roots emerged and elongated even when the plants were bark-ringed so that the roots could not receive metabolites from the shoot by phloem translocation. Carbohydrate analysis showed that starch reserves in the roots of the bark-ringed plants were depleted, indicating that these reserves provided the energy source for new root growth. The shoot also had a role in new root growth as excised root systems showed greatly reduced root growth. This response is compared to that of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) in which bark-ringing prevented root growth indicating that current photosynthate is needed for new root growth. The findings are discussed in relation to the problems of establishing these species in forest plantations.