Infection of Populus alba var. hickeliana by Melampsora medusae Thüm.

The first record of infection of Populus alba var. hickeliana by the American rust, Melampsora medusae Thum. is reported. The morphology of uredospores of rust on P. alba is compared with that of other Melampsora spp. infecting white poplars. The implications of these observations for the widespread establishment in the future of white × black hybrid poplars are discussed.     

Temperature-light sensitivity of infection types expressed by cultivars of Populus deltoides Marsh. to races of Melampsora medusae Thüm.

Infection types were assessed when four cultivars of Populus deltoides Marsh. were inoculated with six races of Melampsora medusae Thüm. and incubated in combinations of light intensity (100, 500 and 1000 μEm^-2s^-1) and temperature (15 and 25°C). Resistance in the cultivars was always at a maximum when the race/cultivar complexes were incubated in the light intensity (1000 μ^-2s^-1)/high temperature (25°C) regime. Inereasing light intensity was generally associated with reduced infection type in the cultivars; the reduction was more pronounced in an incubation temperature of 25 than 15°C. The potential epidemiological significance of the results is discussed.     

Induction of rapid and synchronous germination of urediniospores of Melampsora medusae

A method to obtain high (> 95 %) and uniform germination of urediniospores of Melampsora medusae on a niembrano filter is described. Such levels of gormination are essential in electrophorotie and other physiological studios of rust fungi.     

Effect of Cladosporium aecidiicola Thum. on the viability of urediniospores of Melampsora medusae Thum. in storage

The viability of urediniospores of Melampsora medusae decreased markedly when stored in mixture with the conidia of Cladosporium aecidiicola. The rate of decrease was more rapid in samples stored at 16°C with high concentration of Cladosporium (ratio of urediniospores to conidia 10:1 by weight) than at ?12°C and low concentration (20:1 by weight).     

Direct genotyping of the poplar leaf rust fungus,Melampsora medusae f. sp. deltoidae,using codominant PCR‐SSCP markers

Two anonymous DNA markers that are revealed by single‐strand conformational polymorphism (SSCP) analysis were developed for detection of polymorphisms in Melampsora medusae f. sp. deltoidae (Mmd). Mono‐uredinial isolates of Mmd were first obtained, DNA was extracted from urediniospores and random amplified polymorphic DNA (RAPD) products of eight mono‐uredinial isolates were separated on a SSCP gel to identify differences among them. Bands representing putative polymorphic loci among the eight isolates tested were excised from the SSCP gel and re‐amplified by polymerase chain reaction (PCR), and then cloned and sequenced. A primer pair was designed to amplify a DNA fragment of a size suitable for SSCP analysis (<600 bp) for two out of three DNA fragments sequenced. Each set of primers amplified a PCR product for all eight isolates that were initially used to generate them and the resulting PCR products were analysed by SSCP. Polymorphisms among isolates were identified for both putative loci. The two primer pairs amplified a PCR product of the expected size on an additional 32 mono‐uredinial isolates of Mmd tested. From the overall 40 mono‐uredinial isolates tested, 5 and 11 alleles were detected, and 12 and 34 isolates showed to be heterozygous, as indicated by the presence of more than two bands on the SSCP gel, at loci A and B, respectively. The primer pairs were tested for specificity against 106 fungal isolates belonging to various taxa, including other rusts, and against DNA extracted from greenhouse‐grown healthy poplar leaves. DNA amplification products of the expected size were obtained only when Mmd DNA was present. Optimization of PCR conditions with these two primer pairs allowed genotyping directly from single uredinia extracted from infected leaves, thus alleviating the need to culture the fungus to characterize individuals, hence making it possible to process large numbers of samples for population studies.     

Effect of Melampsora medusae leaf rust infection on yield of hybrid poplars in the north-central United States

Melampsora medusae Thuem. is a hazard to cultivation and fiber production of hybrid poplars grown under short rotations, particularly when the alternate host is present. This rust can be controlled with biweekly fungicide applications but resistant clones are the best method of control.     

Effect of some chemicals employed in the detached leaf culture of Populus on the infection of Melampsora larici-populina

A study was made on the effect of certain chemicals and their combinations on the longevity of the leaf disks cut from Populus × euramericana‘1-488’and P. alba cv. hickeliana. Benzimidazole and gibberellic acid maintained (up to a maximum of 80 days) the leaf disks better than the others, however, the longevity was dependent on the chemical and the concentration employed. In a factorial experiment of 3 chemicals × 2 concentrations × 2 cultivars × 2 races of the fungus, it was found that. all these factors contributed significantly (P<0.05) to the experimental variance. However, differential effects of the chemicals or the concentrations on the cultivar × race interaction were not observed.     

四种杨属植物的热值及灰分含量的比较

对新疆克拉玛依地区的胡杨(P.euphraticaOliv.)、俄罗斯杨(Populus.Russkii)、新疆杨(P.albavar.pyramidalis)、银×新杨(Populus alba×Populus bolleana),茎、枝、根热值和灰分含量进行研究。结果表明:(1)4种杨属植物不同组分灰分含量变化趋势没有一定的规律性,但各组分皮的灰分含量均大于木质的灰分含量;(2)4种杨属植物不同组分的干质量热值和去灰分热值变化相同,均为枝茎根;(3)4种杨属植物不同部位木质的干重热值和灰分含量没有显著的线性相关(P0.01),不同部位皮的干重热值和灰分含量具有显著的线性相关(P0.01);(5)4种杨属植物热值各组分木质和皮的差异不显著(P0.01)。     

Genetic relationships among genetically distinct forms of Melampsora larici‐epitea and related species based on AFLP data

Amplified Fragment Length Polymorphism (AFLP) was used to study genetic relationship among leaf rust fungi (Melampsora spp.) occurring on Salix species in short‐rotation coppice. Special interest was paid to a newly identified rust fungus found on S. viminalis in southern Sweden, morphologically similar to M. larici‐epitea but with a distinct DNA profile. Genetic distances among 40 Melampsora isolates collected from S. viminalis, S. dasyclados, S. viminalis x dasyclados, S. daphnoides, S. acutifolia and M. larici‐populina were calculated based on 101 AFLP markers. Neighbour‐joining analysis revealed the presence of six clusters, which corresponded exactly to predefined groups, namely three formae speciales of M. larici‐epitea, a stem‐infecting form of Melampsora on S. viminalis, the newly identified Melampsora on S. viminalis and a group consisting of two isolates from the poplar rust M. larici‐populina. All six clusters were well supported by bootstrap analysis (84 to 100% support). The newly identified Melampsora on S. viminalis was indicated to be genetically separated from M. larici‐epitea as well as from the stem‐infecting form of Melampsora.     

Detection of phytoplasma infections in declining Populus nigra ‘Italica’ trees and molecular differentiation of the aster yellows phytoplasmas identified in various Populus species

A disease of Populus nigra‘Italica’ associated with foliar yellowing, sparse foliage, stunting, dieback, and decline was observed in south-western Germany; a witches’ broom disease of Populus alba that is known in other countries was also detected in Hungary and Germany. The aetiology of the diseases was studied by fluorescence microscopy and polymerase chain reaction (PCR) amplification. Using fluorescence microscopy, phytoplasmas could be detected only in P. alba. However, most diseased trees of P. nigra‘Italica’ tested phytoplasma-positive by PCR. In some of the trees the phytoplasma numbers were so low that nested PCR was required to detect the infection. Very low phytoplasma numbers were also observed in diseased Populus tremula. The identity of phytoplasmas from P. nigra‘Italica’ sampled in Germany and France, P. alba and also P. tremula was examined by restriction fragment length polymorphism (RFLP) analysis of PCR-amplified ribosomal DNA. In all poplars, phytoplasmas of the aster yellows group were detected. However, three different RFLP groups were identified that consisted of (1) French strains from P. nigra‘Italica’, (2) German strains from P. nigra‘Italica’ and (3) strains from P. alba and P. tremula. The profile observed in the last group was probably the result of sequence heterogeneity in the two 16S RNA genes.     

The Status of Melampsora pinitorqua Rostr. in Italy1

Present knowledge of host range and distribution of Melampsora pinitorqua Rostr. in Italy is reported. Melampsora larici-tremulae, which occurs at high altitude in the Apennines and the Alps and infects only larch, can infects pine also in artificial conditions.     

四季杨、南抗杨扦插育苗技术

四季杨(Populus spp.美洲黑杨×智利黑杨),1978年由中国林科院引入我国[1]。近于常绿,但在霜冻严重的寒冷地区落叶;该品种萌芽早,生长期长,生长速度快,产量高,尚未发现天牛危害,对食叶害虫抗性强,是短周期工业原料林、绿化防护林的优良树种。南抗杨(Populus deltoids Marsh)是我国自己选育出来的优良品种。具有生长快、成林易、成材早、产量高、质量好,适应性、抗逆性强、抗病虫害能力优,栽培技术简单等特点,是营造速生丰产、农田防护林、退耕还林、平原绿化、生态林等绿化美化的优良树种。随着短周期工业原林、农田防护林等多项工程建设…     

Gas exchange characteristics of Populus trichocarpa, Populus deltoides and Populus trichocarpa x P. deltoides clones

Responses of net photosynthesis, dark respiration, photorespiration, transpiration, and stomatal conductance to irradiance, temperature, leaf-to-air vapor density difference (VDD), and plant water stress were examined in two Populus trichocarpa clones (one from a moist, coastal climate in western Washington and one from a dry, continental climate in eastern Washington), one P. deltoides clone, and two P. trichocarpa x P. deltoides clones. Light saturation of photosynthesis in greenhouse-grown trees occurred at about 800 micromol m(-2) s(-1) for P. deltoides, P. trichocarpa x P. deltoides, and the eastern Washington ecotype of P. trichocarpa, but at about 600 micromol m(-2) s(-1) for the western Washington ecotype of P. trichocarpa. Average net photosynthesis (at saturating irradiance and the optimum temperature of 25 degrees C) was 20.7, 18.8, 18.2 and 13.4 micromol CO(2) m(-2) s(-1) for P. deltoides, P. trichocarpa x P. deltoides, and the eastern and western Washington clones of P. trichocarpa, respectively. In all clones, net photosynthesis decreased about 14% as VDD increased from 3 to 18 g H(2)O m(-3). Stomatal conductance decreased sharply with decreasing xylem pressure potential (XPP) in all clones except the western Washington clone of P. trichocarpa. Stomata in this clone were insensitive to changes in XPP and did not control water loss. Complete stomatal closure (stomatal conductance < 0.05 cm s(-1)) occurred at about -2.0 MPa in the eastern Washington clone of P. trichocarpa and around -1.25 MPa in the P. deltoides and P. trichocarpa x P. deltoides clones. Transpiration rates were highest in the P. trichocarpa x P. deltoides clone and lowest in the western Washington clone of P. trichocarpa. The P. deltoides clone and eastern Washington clone of P. trichocarpa had the highest water use efficiency (WUE) and the western Washington clone of P. trichocarpa had the lowest WUE. The hybrids were intermediate. It was concluded that: (1) gas exchange characteristics of eastern and western Washington clones of P. trichocarpa reflected adaptation to their native environment; (2) crossing the western Washington clone of P. trichocarpa with the more drought resistant P. deltoides clone produced plants better adapted to the interior Pacific Northwest climate, although the stomatal response to soil water deficits in the hybrid was conservative compared with that of the eastern Washington clone of P. trichocarpa; and (3) introducing eastern Washington clones of black cottonwood into breeding programs is likely to yield lines with favorable growth characteristics combined with enhanced WUE and adaptation to soil water deficits.     

Relationship of water to adventitious rooting in stem cuttings of Populus species

Populus species, characterized by fast growth and easy vegetative propagation, are widely used in agroforestry practices. The substantial water requirement of poplars make them interesting subjects for water balance studies. No information exists on soil moisture requirements for initial root and shoot growth of Populus cuttings. This study on leafless hardwood cuttings of Populus x euramericana (Dode) Guinier cv. Robusta examined the dynamics of water use during propagation, as influenced by two initial soil water potentials (–0.006 and –0.06 MPa). Differences in the initial water potential of the cuttings was achieved by three pretreatments i.e., fresh, soaked and dried. Initial _shoot was –1.45, –0.10 and –2.10 MPa in fresh, soaked and dried cuttings, respectively. Soil moisture had a major effect on rooting. Water-stressed cuttings took a longer time to root and had fewer roots. Pre-soaking of cuttings stimulated rooting, particularly under the drier soil moisture conditions. Initially the water potential of cuttings decreased with time and with the formation of roots it stabilized in all the pretreatments. The reduction in water potential of cuttings after planting was related to an increase in resistance to water flow in the xylem.This revised version was published online in November 2005 with corrections to the Cover Date.     

年产5000m3意杨LVL主材及设备量的计算与配置

LVL已成为当今木材加工行业发展速度最快的一种木质复合材料产品.介绍了苏北一家年产5000m3意杨LVL企业的加工材料与设备配置情况,着重对单板、胶黏剂主材及压机等主要设备进行了相关的设计计算与配置,为我国制造胶合板的中小型企业做好意杨LVL产品的主材及其设备的设计工作提供参考.     

Development of Melampsora ciliata rust on nursery‐grown poplars in north‐western Himalayas

Development of leaf rust (Melampsora ciliata) in different species, hybrids and cultivars of poplar (Populus spp.) was studied in nursery‐grown plants. Five different criteria were used to assess the disease development. The mean disease index on 10 August was 9.4% which increased to 70.0% on 10 October. The lowest disease index (5.5%) was recorded in P. yunnanensis whereas the maximum was recorded in P. × euramericana‘Rubra‐Poiret’ (59.5%). The apparent infection rate per unit per day was highest in P. nigra × P. trichocarpa (9.7 × 10^–2) whereas the minimum occurred in P. maximowiczii × P. berolinensis‘Oxford’ (3.3 × 10^–2). The area under the disease progress curve was a maximum in P. × euramericana‘Rubra‐Poiret’ (26.7) and a minimum in P. yunnanensis (1.6). Complete defoliation by the first half of October occurred in P. nigra × P. trichocarpa, which also had the maximum apparent infection rate and area under the disease progress curve. Inoculum production was highest in P. nigra × P. trichocarpa and lowest in P. maximowiczii × P. berolinensis‘Oxford’.     

Role of cell wall degrading enzymes in the interaction of poplar and Melampsora larici-populina Kleb.

The activity of cell wall-degrading enzymes, produced in poplar cultivars infected Melampsora laricipopulina Kleb., was studied. The results show that PMG, PMTE, C_X and β-glucosidase played roles during the infection. After inoculation, the activity of PMG in both susceptible and resistant cultivars had two peak values in 2 dpi and 5 dpi. The activities of PMTE and β-glucosidase had a peak value in 3 dpi, and C_X in 2 dpi. Among these cell wall-degrading enzymes, the activities of PMG and PMTE were higher and the activities of C_X and β-glucosidase were relatively lower. The activities of these cell wall-degrading enzymes were significantly higher in susceptible cultivars than those in resistant cultivars. All these demonstrated that these cell wall-degrading enzymes played certain roles in the infection of M. larici-populina. __________ Translated from Scientia Silvae Sinicae, 2008, 44(5): 79–83 [译自: 林业科学]     

洞庭湖区杨树主要害虫种类及灾害控制策略

对湖南省杨树害虫的调查结果表明:害虫种类多,主要害虫是天牛类和舟蛾类。我们针对杨树主要害虫发生为害的特点,提出了相应的虫灾控制策略,提倡生物防治和可持续控制。     

科尔沁沙地小叶杨和杂交杨一些生理生态特性的比较研究

采用ＡＰ４气孔计和ＰＶ曲线研究了小叶杨和杂交杨气孔导率和水分状况在不同季节的变化特征，结果表明：（１）在干旱的５、６月份，小叶杨的气孔导率远远高于杂交杨；在湿润的７月又低于杂交场；在生长近结束的８月底二者气地度近等；（２）小叶杨和杂交杨各在干旱的５月渗透调节抗旱能力相差不多，以后各月杂交杨则高于小叶杨，６月最明显；随着植物枝条木质化程度的提高，二者渗透调节能力和抗旱性均呈上升趋势。