Growth, survival, and root system morphology of deeply planted Corylus colurna 7 years after transplanting and the effects of root collar excavation

Urban trees are frequently planted with their root collars and structural roots buried well below soil grade, either because of planting practices, nursery production practices, or both. These deeply planted structural roots can impair tree establishment and are thought to reduce tree growth, lifespan, and stability, although research has provided few and contradictory results on these questions to date. This study examines container-grown (55 L) Turkish hazel trees (Corylus colurna L.), planted either at grade, 15 cm below grade, or 30 cm below grade into a well-drained silt loam soil, over nearly 8 years. Five years after planting, in 2004, remediation treatments (root collar excavations) were performed on two replicates of each below-ground treatment. Subsequently, all trees were subjected to flooding stress by being irrigated to soil saturation for approximately 6 weeks. In 2006, flooding stress was repeated. Trees root systems were partially excavated in 2007, and root architecture was characterized. Deep planting did not affect trunk diameter growth over 8 years. Survival was 100% for the first 5 years; however, one 30 cm below grade tree died after flooding in 2004 and another died after the 2006 flooding. Photosynthesis was monitored during the 2004 flooding and all trees experienced decline in photosynthetic rates. There was an apparent slight delay in the decline for trees with excavated root collars and those planted at grade. Girdling roots reduced trunk taper and occurred primarily on unremediated trees planted 30 cm below grade.

Selected individual roots were excavated and followed from the root ball and were observed to gradually rise to the upper soil regions. Analysis of roots emerging from excavation trench faces indicated that vertical root distribution at approximately 1.25 m from the tree trunks was the same regardless of planting depth. Longterm consequences of planting below grade are discussed.     

Designing food and habitat trees for urban koalas: Tree height,foliage palatability and clonal propagation of Eucalyptus kabiana

Koalas are iconic Australian tree-dwelling marsupials that are classified as vulnerable because of threatening processes that include urban development, habitat fragmentation and inbreeding. Koalas eat the leaves of specific eucalypt trees but urban planners and landowners often prefer to plant smaller trees that pose less risk from falling limbs. We have conducted a long-term project to develop shorter koala-food trees for planting in parklands, schools, streets and gardens. We identified a little-known and geographically-confined species, Eucalyptus kabiana, that had potential for urban plantings. We assessed the height of E. kabiana trees in cultivation, determined whether their foliage was palatable to koalas, and compared the amenability to vegetative propagation of E. kabiana with that of an extensively-propagated related species, E. tereticornis. Cultivated E. kabiana trees were short, reaching around 3–5 m height after 6 years. Their foliage was highly palatable to koalas, and their cuttings proved to be amenable to propagation. Average rooting percentages for E. kabiana cuttings were 31–46%, similar to values obtained with E. tereticornis cuttings. Over 600 E. kabiana trees have thus far been distributed for planting in wildlife corridors, parklands, schools and gardens. The planting of more koala-food trees will help to alleviate the risks of inbreeding faced by koala populations in fragmented urban landscapes. School plantings also provide opportunities for students to learn about and interact with organisms such as koalas that inhabit the Eucalyptus trees.     

Adventitious root formation in Anacardium occidentale L. in response to phytohormones and removal of roots

Despite advances in tissue culture techniques, propagation by leafy, softwood cuttings is the preferred, practical system for vegetative reproduction of many tree and shrub species. Species are frequently defined as ‘difficult’- or ‘easy-to-root’ when propagated by conventional cuttings. Speed of rooting is often linked with ease of propagation, and slow-to-root species may be ‘difficult’ precisely because tissues deteriorate prior to the formation of adventitious roots. Even when roots form, limited development of these may impair the establishment of a cutting.     

Somatic embryo,adventitious root and shoot regeneration in in vitro grown quince leaves as influenced by treatments of different length with growth regulators

The purpose of this work was to acquire more information on the capacity of in vitro grown quince (Cydonia oblonga Mill.) leaves to simultaneously regenerate somatic embryos, adventitious roots and shoots, and to evaluate the variations induced on regeneration response by treatments of different length with growth regulators. After 2 days of liquid treatment with 2,4-dichlorophenoxyacetic acid, the leaves were cultured for 0, 3, 6, 9, 12, 15, 18 and 21 days on gelled growth medium containing the basal components of Murashige and Skoog and kinetin (Kin) 4.5 μM + naphthaleneacetic acid (NAA) 0.5 μM. At the end of each treatment period, the leaves were cultured on a transfer medium in the absence or in the presence of a growth regulator combination represented by N⁶-benzylaminopurine (BA) 2.66 μM + gibberellic acid 0.58 μM + indole-3-butyric acid 0.3 μM. The culture period for all the treatments was fixed to 52 days.     

半根供铁对苹果砧木幼苗生长的影响

利用分根技术在水培条件下研究了半根供铁对苹果砧木幼苗生长的影响。结果表明,一半根系供铁不仅未影响植株对铁营养的需求,甚至在处理初期植株的铁吸收总量和铁吸收速率还略有提高。一半根系供铁苹果砧木小金海堂和山定子叶片活性铁质量分数均未降低,而且与对照相比无叶片黄化的现象。因此,通过半根供铁的方式来改善苹果砧木幼苗的生长,为进一步研究砧木缺铁适应性反应的调控部位打下基础,也为今后缺铁的矫正和提高铁素利用效率提供了一条新的思路。     

葡萄果实始熟机理的研究——缓慢生长期外施激素和环剥的效应

在巨峰葡萄果实缓慢生长期对果实外施激素和对枝条环剥处理，结果表明，外源ＡＢＡ单独处理、果穗下方环剥与外源ＩＡＡ或ＡＢＡ联合处理均使始熟期提前到来；外源ＩＡＡ（３００ｍｇ／Ｌ）处理并没有推迟果实的始熟期，而外源ＧＡ３处理则使始熟延迟。分析各种处理果实的内源激素变化后认为，虽然果肉ＡＢＡ浓度的升高并不总与始熟期相一致，但ＡＢＡ做为始熟启动信息几乎是可以肯定的。ＩＡＡ浓度在始熟期毫无例外地下降到低谷，说明ＩＡＡ数量的减少也是始熟的必要条件之一。ＧＡ３处理在延迟始熟的同时减缓了ＩＡＡ的下降而并未影响ＡＢＡ的变化。果穗上下方环剥试验表明果实中启动成熟的ＡＢＡ可以不来源于叶片。讨论了果实中内外源激素的相互关系及其对始熟启动的调控机制     

Understanding the stability of Samanea saman trees through tree pulling,analytical calculations and numerical models

There have been several cases of tree failure in Singapore. Many studies have shown that soil properties and root architecture of trees are important factors that govern tree stability. Twenty Samanea saman trees were planted in different soil media, which were original in situ soil, top soil, mixture of 50% granite chips and 50% top soil, and mixture of 80% granite chips and 20% top soil. The objectives of this study were to investigate tree overturning processes and also to compare the results of tree pulling tests with results from an analytical calculation and numerical modeling for different soil types. The results showed that stability of the trees were not governed by the shear strength of the soil. Factors that affected tree stability included cross-sectional area of the roots and root plate area. Tree pulling test and numerical modeling results showed that there were two modes of failure which occurred when a tree was overturned. The first mode was the shear failure of soil and the second was a combination of shear failure of soil and root breakage. The maximum overturning force obtained from the tree pulling test was in the same order of magnitude as the maximum overturning forces obtained from the analytical calculation and numerical modeling.     

水分胁迫对荔枝幼树根系与梢生长的影响

以盆栽沙培1年生荔枝空中压条苗为试材,研究了水分胁迫对荔枝幼树根系和梢生长的影响以及二者的相互关系。3个处理为:沙体积含水量为7.5%(严重缺水),15.0%(一般缺水),22.5%(充分供水)。结果表明:水分胁迫严重抑制荔枝幼树地上部分和各级侧根的生长,使地上部枝梢生长严重受阻,叶片数量、平均叶面积、叶片厚度均显著变小;根总干重、侧根长度、根表面积显著减少。水分胁迫下促进须根的生长,须根的长度、根表面积比水分充足时显著增加。水分胁迫时叶片淀粉含量下降,而根系积累更多的淀粉。比较不同处理的根梢比发现,干旱对根系生长的抑制作用比枝梢更显著。     

EDTA对铅胁迫下香根草生长及铅积累特性的影响

以香根草为试材,采用水培方法,研究了EDTA对铅胁迫下香根草生长及铅积累特性的影响。结果表明:单一Pb处理可明显抑制植株的生长,香根草体内的Pb含量随Pb处理浓度的增加而显著增加,根系Pb含量明显高于地上部。与单一处理相比,添加EDTA处理后,在一定程度上抑制了Pb污染下香根草的生长。EDTA处理14d植株内Pb的积累总量比单一Pb处理显著增加,地上部与植株总吸收量Pb的比值均明显上升,表明EDTA可促进香根草对Pb的吸收和积累,同时促进Pb向香根草地上部运输。     

铜胁迫对萝卜种子萌发和幼苗生长的影响

为探讨铜对植物的毒害机理,研究了不同浓度铜对萝卜种子萌发及幼苗生长的影响.研究结果表明,随着铜浓度的增加,萝卜种子的发芽率、幼苗株高和根长都受到抑制.超氧化物歧化酶(SOD)和过氧化物酶(POD)活性随着铜浓度的增加先升高后降低.     

Selecting trees for urban paved sites in Scandinavia – A review of information on stress tolerance and its relation to the requirements of tree planners

Urban paved sites are complex stress environments and when selecting trees for such sites, tree planners must prioritise stress tolerance above aesthetic appeal and functional aspects. This requires detailed information about the tolerance of tree species to environmental stresses, so as to support urban tree planners in selecting a wide range of trees. In Scandinavia there is currently no overview of the extent to which the character of information about stress tolerance and its dissemination in books and papers support urban tree planners in selecting a wide range of species for paved sites. Books on dendrology, literature on plant use in cities, tree nursery catalogues and scientific papers were therefore reviewed. For the review, eight tree species were selected along a gradient representing their intensity of use in Northern Europe. We examined the character of information and assessed it relative to tree planners’ requirements for information to be; contextual, local to Scandinavia, referring to existing plantings in paved sites and recommendations for use of the species in paved sites. The results showed that existing information is piecemeal and that most is either too general (dendrology literature) or too specific or contradictory (scientific literature) to meet the requirements of urban tree planners, while books intended for plant use in cities do not sufficiently integrate the local perspective. Moreover, contextual information local to the Scandinavian region is mainly provided for already much used species. These findings led to suggestions on how future urban forestry and arboriculture research and dissemination efforts in Scandinavia can encourage tree planners to use a greater variety of tree species in urban paved sites.     

土壤铅胁迫对旱柳生长及相关生理特性的影响

采用盆栽试验方法研究了不同铅胁迫浓度下旱柳幼苗的生长及相关生理指标的变化。结果表明:随着重金属铅胁迫浓度的增加,旱柳的比叶重、株高与地径生长受到抑制;叶绿素含量及根系活力呈下降的趋势;叶片游离脯氨酸含量与细胞膜透性呈逐渐增加趋势。在浓度为300mg/kg时,游离脯氨酸、细胞膜透性及根系活力与对照相比达到显著差异(P<0.05);在浓度600mg/kg时,株高、地径与对照相比达到极显著差异(P<0.01);叶绿素a与对照相比达到显著差异(P<0.05);不同铅胁迫浓度对叶绿素b、叶绿素a/b值没有显著的影响。     

不同胁迫处理对甜瓜苗期生长发育的影响

为了研究不同胁迫处理对甜瓜苗期生长发育的影响,在F18、F20两个甜瓜品种的苗期分别施以低温胁迫、水分胁迫、盐胁迫处理,分别对F18、F20的株高、茎粗、叶面积、地上部和地下部干质量、叶绿素含量等指标进行了测定。结果表明,不同胁迫处理对甜瓜幼苗的株高及地下部干质量有显著影响,说明其可作为甜瓜苗期抗早衰鉴定的形态指标;F18比F20较耐低温胁迫和盐胁迫,F20较耐水分胁迫,这与形态指标的表现一致。     

盐胁迫对锦带花生长及光合特性的影响

以锦带花为试材,采用盆栽法,研究不同土壤含盐量对锦带花生长及光合特性的影响。结果表明:随着盐含量的增加,锦带花的相对新梢生长量在盐含量为0.1%时有所增加,当盐含量≥0.2时才显著降低。盐害指数也随着盐含量的增加而逐渐增加,在盐含量≤0.2%时增加不显著,当盐含量≥0.3%时才显著增加。随着盐含量的增加,锦带花的净光合速率、气孔导度、蒸腾速率在盐含量为0.1%时有所增加,当盐含量≥0.2%时才逐渐降低,胞间CO2浓度变化趋势与其相反,在盐含量为0.1%时降低,随着盐含量的增加又逐渐增加。在盐含量≤0.3%,锦带花的水分利用效率变化不明显,这说明锦带花可以通过降低蒸腾速率维持自身的水分利用效率,当盐含量为0.4%时,锦带花的水分利用效率显著降低。在光响应过程中,随着光强的增加,各盐含量的净光合速率都逐渐增加,盐含量越大,其增加的幅度越小。此外盐胁迫增加了锦带花的光补偿点,降低锦带花的光饱和点。     

不同灌水量对温室夏茬樱桃番茄植株生长和果实品质的影响

在土壤和基质栽培方式下,通过控制每株每天灌水量将土壤水分控制在不同水平下,研究水分胁迫对樱桃番茄植株生长和果实品质的影响.结果表明:随水分胁迫强度的增强,番茄的株高、茎粗、叶面积、产量、单果重都逐渐下降;水分胁迫提高了番茄果实可溶性固形物、总糖、有机酸、维生素C等含量,并明显提高了水分生产率.     

盐胁迫对罗布麻种子萌发及幼苗生长的影响

研究了不同浓度盐胁迫对罗布麻种子萌发及幼苗生长的影响。结果表明:对照及盐浓度为20%条件下种子萌发率最高;随着盐胁迫增加,SOD、POD活性及脯氨酸含量先增大后减小,在盐浓度60%处达到最大值;MDA的含量先减小后增大,在40%处达到最小值。表明一定浓度的盐胁迫可以促进罗布麻幼苗的生长,种子萌发以无盐及低盐环境最好。     

铜污染对芹菜生长及生理特性的影响

以芹菜定植苗为试材,通过设CuSO4.5H2O 05、、10、204、0 mg/L营养液水培试验,研究Cu污染对芹菜生长的影响及生理胁迫伤害。结果表明:低浓度CuSO45 mg/L对芹菜生长有促进作用,随浓度递增20~40 mg/L对生长有抑制作用;根系活力在CuSO4浓度为5 mg/L时较对照上升,随浓度递增而下降;叶绿素a含量在低浓度CuSO45 mg/L含量上升,随浓度递增含量下降,对叶绿素a的影响大于叶绿素b及类胡萝卜素;硝酸还原酶在CuSO4浓度为5 mg/L时较对照上升,再随浓度递增而不断下降;POD活性随Cu浓度升高先上升后下降再上升;SOD和CAT活性先上升后下降;叶细胞膜渗透性丙二醛(MDA)及含量相对电导率随CuSO4浓度升高而不断上升。     

盐胁迫对滨梅幼苗生长和渗透调节物质含量的影响

以滨梅幼苗为试材,研究了不同浓度盐(NaCl)胁迫下植株生长及渗透调节物质的响应。结果表明:0.5%NaCl能显著促进滨梅幼苗的生长及水分代谢,但相对膜透性与对照比无显著差异;1.0%NaCl与对照无显著差异,2.0%NaCl显著抑制滨梅幼苗生长及水分代谢,相对膜透性显著增加;随着NaCl浓度的增加,滨梅叶内的可溶性蛋白、可溶性糖含量及有机渗透调节物质总量显著增加,而脯氨酸含量的变化不明显。     

低盐锻炼对苗期番茄生长及抗氧化酶活性的影响

摘要：为了探究低盐锻炼对盐胁迫环境下番茄幼苗生长及抗氧化酶活性的影响,以“KT636”番茄品种为供试材料,设置5个低盐锻炼水平,NaCl浓度分别为0、25、50、75、100 mmol/L,7 d后模拟重度盐胁迫（NaCl浓度为100 mmol/L）,分别标记为NS-100、T25-100、T50-100、T75-100、T100-100,以1/2霍格兰德营养液正常培养的幼苗为对照,分析番茄幼苗的生长指标和抗氧化酶活性。结果表明：与未经低盐锻炼处理相比较,低盐锻炼各处理番茄幼苗的株高、茎粗、叶片干质量均无显著变化;25 mmol/L的低盐锻炼可以提高盐胁迫下植株的株高和茎粗,且显著提高了叶面积、地上部干质量、地下部干质量、植株干质量以及叶片过氧化物歧化酶（POD）、抗坏血酸过氧化物酶（APX）、谷胱甘肽还原酶（GR）的活性,在一定程度上提高了番茄幼苗的耐盐性。     

盐胁迫和干旱胁迫对蓝花子种子萌发和幼苗生长的影响

将蓝花子培养在含有不同浓度的NaCl和甘露醇的MS培养基上,研究蓝花子在不同浓度的NaCl和甘露醇处理下的发芽势、发芽率、相对发芽率、叶绿素含量以及过氧化物酶活性等,揭示蓝花子对盐胁迫和干旱胁迫的耐受能力。结果表明:蓝花子的发芽率、株高、根长、叶绿素以及过氧化物酶活性都随NaCl浓度的升高而显著下降;在甘露醇胁迫时,蓝花子幼苗的根长、叶绿素含量以及POD酶活性都随甘露醇浓度的升高表现为先升高后降低的趋势。说明同十字花科其它植物相比蓝花子对盐胁迫十分敏感,而对干旱胁迫却能表现出比较明显的耐受性。