微波改性木材的超微观察

对微波改性处理后的杨木和水曲柳进行超微观察发现，处理后木材的纹孔膜破裂，导管内的侵填成分明显减少并重新分布。     

Suppression of ectomycorrhizal development in young Pinus thunbergii trees inoculated with Bursaphelenchus xylophilus

In order to study the changes in ectomycorrhizal development during symptom expression of pine wilt disease, root window observations were conducted concurrent with measurements of leaf water potential as well as photosynthetic and transpiration rates of 5‐year‐old Pinus thunbergii trees that were inoculated with the pinewood nematode (PWN) Bursaphelenchus xylophilus. Infected trees were compared with girdled and uninfected control trees. Ectomycorrhizas developed constantly during the experimental period in control trees but did not develop in the girdled trees. Ectomycorrhizal development ceased within 2 weeks in those trees that finally died after PWN infection. In the trees that survived PWN infection, ectomycorrhizal development ceased within 1–4 weeks of inoculation but was resumed thereafter within 3–6 weeks. Ectomycorrhizal development ceased prior to a decrease in both photosynthetic rate and leaf water potential in the inoculated trees.     

Formation of tyloses in felled Quercus rubra L.

Summary Tyloses form in red oak (Quercus rubra L.) sapwood in a period of hours if the wood is cut during the active growth season and stored in green condition in the laboratory. If the wood is cut during dormancy and stored in green condition, tyloses form in a period of months. Electron microscopic examination reveals that the wall of a tylosis forms from a promonths. Electron microscopic examination reveals that the wall of a tylosis forms from a protective layer that develops inside the secondary wall of the ray cell in the vessel-ray pit-pair. Protective layers are also present in fiber-parenchyma pit-pairs. Protective layers may exhibit variable thicknesses, with light and dark layers alternating. A young tylosis wall consists of two layers: An electron-dense outer layer and an electron-transparent inner layer. Tyloses walls may attach to each other and form multilamellate tyloses. Sometimes the individual layers of tyloses walls appear lamellated. Because of the type of formation and structure, the tylosis wall in red oak apparently is a primary wall rather than a secondary. Tyloses walls have simple pits. The findings of this study enable felled hardwoods with potential for forming tyloses to be used without the destructive influence of tyloses.     

Electron microscopic study on the development of the bordered pit in coniferous tracheids

Summary The observations of the inner surface of Japanese red pine (Pinus densiflora Sieb. et Zucc.) earlywood tracheid wall in the various stages of the differentiation allowed the study of the development of the bordered pit. The process of the formation of the bordered pit membrane and the deposition of the cell wall layers in the pit border region were examined in detail by electron microscopy using the replication preparation technique. The microfibrillar structure of the margo and torus, which is characteristic of the bordered pit membrane of this species, was detected in the later stage of primary wall formation. The bordered pit membrane was shown to have the same microfibrillar structure as that of the matured one even at this stage of differentiation, although it was embedded in matrix substances. It appeared that the matrix substances were removed immediately after the warty layer had been formed in the tracheid wall.The initiation of pit border development was observed as the deposition of circularly oriented microfibrils around the vicinity of the pit annulus in the later stage of the primary wall formation. The deposition of the S₁-layer was indicated to contribute to the pit border formation until the diameter of the pit aperture reached its final size, simultaneously with the apposition of the layer of so-called B. T. or initial border thickening. So both the S₁-layer and initial border thickening were assumed to be formed supplementing each other. In the period of the S₁-layer formation, the transversely deposited microfibrils in the tracheid inner surface were detected to generally curve around the pit aperture and some of them extend to the outer surface of the developing pit border beyond the pit aperture. From these observations of replicas of the inner surface of the differentiating tracheid, a concept concerning pit border formation is proposed.The authors are indebted to members in Kyoto University Forest for providing the samples and to Dr. H. Saiki and other members of Wood Structure Laboratory in Department of Wood Science and Technology at Kyoto University for their assistance during this study. They also express their appreciation to Dr. W. A. Cote, Jr. (State University, College of Forestry, N. Y.) and Dr. W. Liese (Universität Hamburg) for their considerate advice.     

Seasonal effect on infection and development of lesions caused by Cryphonectria parasitica in Castanea sativa

Seasonal variation in the development of chestnut blight, caused by Cryphonectria parasitica, was investigated by inoculating in situ chestnut trees and in vitro excised chestnut segments, at either monthly or 3‐monthly intervals throughout 30 months. Inoculations were made with conidia and mycelium of a virulent isolate and with mycelium of a hypovirulent isolate. Conidial inoculations of living sprouts or excised segments between May and July resulted in the greatest incidence of infection whereas inoculations in autumn and winter, in vitro as well as in situ, did not reveal any visible disease. However, from these symptomless inoculated stems, C. parasitica was isolated 3 months after inoculation. Inoculations with the mycelium of the virulent isolate always resulted in lesions, except in January 1999, and the greatest rate of lesion development occurred for inoculations made in the spring and summer. There was a significant seasonal effect on lesion development. Lesions caused by the hypovirulent isolate, smaller than those caused by the virulent isolate, followed a similar seasonal pattern. The same seasonal variations were observed for inoculations in vitro of excised segments. Relative water content (RWC) of chestnut bark significantly varied with bark sampling date. The rate of lesion development in sprouts significantly correlated with average minimum (ATn) and maximum (ATx) temperatures and the sum of rainfall during inoculation period, with the rate of lesion development measured in excised segments 10 days after inoculation (R10d) and with RWC measured on the day of inoculation. In multiple regression models, variables ATx and R10d best explained variation in lesion development.     

Profile of bordered pit aspiration in Cryptomeria japonica using confocal laser scanning microscopy: pit aspiration and heartwood color

Nine trees of Cryptomeria japonica from six elite tree clones with a broad range of heartwood colors were selected. The profiles of pit aspiration percentage (ASP) of earlywood and latewood from pith to bark for green and air-dry conditions were determined to study the relationship between heartwood color and pit aspiration. Confocal laser scanning microscopy (CLSM) observations showed that the ASP of earlywood was low in sapwood and high in heartwood in the green condition. Pit aspiration increased in intermediate wood when compared with sapwood. On the other hand, latewood pits did not aspirate during heartwood formation. Comparing the air-dry condition with the green condition, sapwood pits aspirated during drying in both earlywood and latewood; however, there was no significant difference in pit aspiration of heartwood. There was no significant difference between samples with red and black heartwoods for ASP. The difference in ASP between individual trees was larger than that by heartwood color. The general advantage of CLSM over light microscopy is that serial optical sections along the Z axis can be obtained for any moisture condition, without the need for thin sectioning or embedding.     

Influence of Microbial Inoculants on Seedling Production in Teak (Tectona grandis L.f.)

Abstract

An experiment was conducted in forest college campus, Mettupalayam, India with an objective of studying the influence of microbial inoculants on seedling growth of teak. The fruits were collected from the seed production area in top slip (Tamil Nadu) from 63-year mother trees. The microbial inoculants viz., Azospirillum, Azotobacter, phosphobacteria, AMF, Azospirillum + AMF, Azotobacter+ AMF, phosphobacteria + AMF and an uninoculated control formed the treatments. The inoculants were mixed sand and red soil at 1:1:3 ratio, respectively, for preparing nursery mixture for filling the poly pots. The seeds were sown into the poly pots @ two seeds per pot. The experiment was set up in a randomized Block Design with three replications. Biometric observations on various growth attributes were recorded six months after treatment and also their survival in the main field-tested for one year. Azotobacter gave best performance with respect to shoot length, shoot weight and leaf area and combined inoculation of phosphobacteria and AMF gave higher root length and biomass, dry matter production and fine root weight. The survival was better in seedlings that were inoculated with phosphobacteria and AMF. However, below ground biomass and out planting survival during early phase are critical in any tree species. Hence it is concluded that inoculation of phosphobacteria and AMF conjointly be done for better survival and growth of teak seedlings.     

Responses in the bark of Cupressus sempervirens clones artificially inoculated with Seiridium cardinale under field conditions

By 70 days after inoculation, resistant and tolerant clones of field-grown Cupressus sempervirens restricted penetration of the bark by Seiridium cardinale, forming ligno-suberized boundary zones which included four to six layers of cells with suberized cell walls. This response contrasted with that in susceptible clones, where only two to four layers of suberized cells were formed in discontinuous bands around inoculation sites. Detection of multiple layers of thin suberized boundary zones in susceptible clones indicated repeated penetration of the wound/infection-induced barrier by S. cardinale during a single growing season. The methods described will be valuable in the development of rapid, early and accurate screening programmes for durable resistance to Seiridium canker in Cupressus species.     

Infection of Norway spruce container seedlings by Gremmeniella abietina

First‐ and second‐year containerized Norway spruce seedlings were inoculated with conidia of type A (large tree type) and type B (small tree type) of Gremmeniella abietina var. abietina at different times during the summer. The appearance of symptoms after artificial inoculation and natural infection on spruce seedlings were recorded the following spring and compared with the disease symptoms on Scots pine seedlings. The proportion of diseased seedlings after inoculation reached as high as 80%. The susceptible period during the summer began later on the first‐year seedlings than on the second‐year seedlings, and was similar for the pine seedlings. Susceptibility of first‐year seedlings was highest in August and on second‐year seedlings in July. The accumulated temperature sum, relative humidity and height growth for first‐ and second‐year seedlings was assessed. Natural infection in 2002 caused more disease on pine than on spruce seedlings. Experimental thinning of seedlings had no effect on disease incidence. In a preliminary comparison between the ability of A and B types to cause disease in Norway spruce seedlings, type B caused more damage than type A after inoculation. However, type A caused a high disease frequency in other experiments in this study. Symptoms on Norway spruce seedlings often first occurred in the mid‐section of the shoot, and were similar to those observed on pine seedlings: needles turned brown, starting at the needle base, in the spring following inoculation. On first‐year spruce, diseased needles were shed rapidly, in contrast to a slower rate of shedding on first‐year pine seedlings. Pycnidia developed about 2 years after inoculation (on pine 1 year after inoculation). On Norway spruce seedlings the lower part of the shoot, including the lateral shoots, often remained alive. The experiments show that G. abietina can cause disease on containerized Norway spruce seedlings under nursery conditions in Finland. The coincidence of spore dispersal, seedling susceptibility and predisposing factors are important in disease development.     

Effect of Frankia inoculation on the growth of Alnus sieboldiana on unsterilized soil

The effect of inoculation with Frankia, a N-fixing actinomycete, on the growth of Alnus sieboldiana seedlings was studied on unsterilized soil from a nursery and an alder stand (forest of Alnus firma). The seedlings of A. sieboldiana were inoculated with Frankia before or after a 2-month culture on sterilized vermiculite, during which they nodulated, and transplanted to unsterilized soil from the nursery and the alder stand. The control seedlings were also cultured on sterilized vermiculite for about 2 months and transplanted to unsterilized soil without Frankia inoculation. The seedling growth, nodulation and N-fixing activity were measured 3, 10 and 16 weeks after the transplantation. Growth and nodule biomass of the seedlings inoculated with Frankia and those grown on the alder soil were better than those without inoculation with Frankia and grown on the nursery soil, respectively. The seedlings inoculated before spontaneous nodulation grew better than those inoculated at the transplantation. Nitrogen-fixing activity measured by acetylene reduction assay at 16 weeks after the transplantation was higher in the seedlings grown on the soil from the nursery than on the soil from the alder stand.     

Susceptibility and lesion development in Scots pine saplings infected with Peridermium pini in northern Finland

Susceptibility of Pinus sylvestris provenances from northern Finland to Peridermium pini and lesion development caused by the rust were investigated by inoculating 768 saplings. Resin‐top disease symptoms on the stem including stem swelling, occurrence of spermatial fluid and rust aecia, were recorded over a period of 9 years. The disease incidence was low (3.6%), varying within the range of 0–9.4% among pine provenances and 3.4–3.9% among spore sources in 1994–2002. Aecia were produced for the first time 2–4 years after inoculation, appearing mainly in early June, 2–9 years after inoculation. The aecia ruptured in late July to early August, and the overall sporulation lasted for 1–8 years among the pine provenances. Spermatial fluid was observed regularly in the year prior to aecia development 2–7 years after inoculation. Annual fresh swelling was observed for 1–6 years after inoculation. No statistically significant differences occurred neither between the pine provenances, the spore sources nor the years with regard to all the major disease variables. The results suggest that Scots pine provenances from northern Finland are highly resistant to P. pini regardless of the pine provenance or spore source.     

Pre‐ and post‐inoculation water stress affects Sphaeropsis sapinea canker length in Pinus halepensis seedlings

In order to assess the influence of water stress on the development of Sphaeropsis sapinea cankers in Pinus halepensis, the stems of 4‐ to 5‐year‐old potted seedlings were artificially inoculated with the fungus before and after being kept at controlled water regimes from April 1997 to March 1998. In the pre‐water‐stress inoculation experiment, the canker length, measured 5 months after inoculation (September 1997), was greater in seedlings predisposed to extreme water deficit (midday needle water potential between ?4.5 and ?5.5 MPa). In the post‐water‐stress inoculation experiment, the fungus was inoculated in April 1998, after irrigation had enabled the seedlings to resume normal needle water potential. In this case also, at 5 months after inoculation, longer cankers were visible in seedlings that had been subjected to extreme water deficit. These findings suggest that the occurrence of marked water stress, although apparently tolerated by Aleppo pine, can enhance the development of S. sapinea cankers in this species, regardless of whether the stress occurs before or after infection by the fungus.     

Host status effect of cowpea and sunflower on the populations ofMeloidogyne javanica andRotylenchulus reniformis

A highly susceptible cowpea,Vigna sinensis cv. Baladi plants were tested as trap plants for eitherMeloidogyne javanica orRotylenchulus reniformis under greenhouse conditions. The plants were gathered by cutting them above the surface of the soil or by uprooting them, 1/2, 1, 3, 6, 12, 24, 36 and 48 days after nematode inoculation. Both of the mentioned nematodes began to mature and lay eggs after the 12th day from their inoculation. Hence, it is advised to pull up cowpea plants from 3–12 days after nematode inoculation. After planting sunflower,Helianthus annus cv. Miak replacing cowpea, the nematode populations were higher, in most cases, on sunflower plants replacing cutting cowpea than those on sunflower replacing uprooted cowpea. The highest percentages of nematode reduction were 98.55 and 99.57 forM. javanica and 95.09 and 92.90% forR. reniformis on sunflower plants replacing cutting and uprooted cowpea plants after 12 days from nematode inoculation, respectively.M. javanica andR. reniformis decreased the length and weight of sunflower plants as affected by planting time and method of cowpea harvest. This method of nematode control is cheaper, easy and pollution free.     

Fluorescein-labeled wheat germ agglutinin stains the pine wood nematode, <Emphasis Type="Italic">Bursaphelenchus </Emphasis><Emphasis Type="Italic">xylophilus</Emphasis>

Pine wilt disease, caused by the pine wood nematode (PWN, Bursaphelenchus xylophilus), is a major threat to pine forests throughout East Asia. Nonetheless, its mechanism of invasion has not yet been described in detail. To better understand the pathology of this disease, it is important to examine the distribution of PWNs within pine tissue during the course of disease development. We attempted to stain nematodes with fluorescein-conjugated wheat germ agglutinin (F-WGA) as a means to locate and track the spread of PWNs. Although PWNs proliferated on Botrytis cinerea fungus were successfully stained only on their vulvas and spicule holes, PWNs extracted from inoculated Pinus thunbergii seedlings were stained on their surface. Stainability, or the percentage of PWNs stained with F-WGA over more than half of their surface, was about 20% by 1 day after inoculation, but increased to 80% at 10 days. The stainability of PWNs extracted from a 5-cm main stem segment that included the inoculation site was less than that of PWNs extracted from other parts of the main stem farther away (i.e., those that had dispersed). These results suggest that stainability is related to dispersal activity in time. Thus, to raise the stainability of PWNs at shorter timeframes after inoculation, PWNs with more than 80% stainability were re-inoculated into pine seedlings. This resulted in more than 70% stainability from 1 to 6 days after inoculation. In F-WGA stained thin paraffin sections of pine tissue of re-inoculated seedlings, PWNs brightly fluoresced under epifluorescence and were easily detected against the dark background of pine tissue. This staining technique with F-WGA is an excellent tool for detecting PWNs in pine tissue.     

Field performance of conifer and hardwood species 5 years after nursery inoculation in the Canadian Prairie Provinces

The field performance of conifer and hardwood species inoculated with different inoculation treatments was evaluated 5 or 3 years after outplanting in the field trials established in the Canadian Prairie Provinces. In conifer trials, the growth of white spruce, black spruce, lodgepole pine, and larch seedlings observed on different sites varied greatly to different inoculation treatments depending on plant and fungal species involved. Five years after outplanting, most of the introduced fungi were replaced by several indigenous ectomycorrhizal fungal species except for Laccaria bicolor strain. Survival rates of most of the inoculated seedlings were not significantly different from control seedlings naturally colonized by other resident fungi. In hardwood trial, the effects of nursery inoculation of different poplar clones, aspen and balsam poplar were very limited. Growth and survival data were combined into seedling volume and plot volume index (PVI) for measurement of total growth response of seedlings. Our results demonstrated that certain inoculated plant-fungus combinations have played a positive role during the initial establishment of these seedlings in the field, which was reflected on significantly greater stem volume and PVI compared to non-inoculated control seedlings. The results from this study provided useful information on field evaluation for potential benefits of mycorrhizal inoculation in nursery.     

Histopathology of primary needles and mortality associated with white pine blister rust in resistant and susceptible Pinus strobus

White pine blister rust caused by Cronartium ribicola is a damaging non‐native disease of five‐needled pines in North America. Efforts to control the disease and mitigate damage to date have been only somewhat effective. Recent efforts to improve the health of eastern white pine and reestablish the tree as a dominant species in the North Central United States have focused on identification and propagation of disease‐free eastern white pine (Pinus strobus) growing in areas with a high incidence of blister rust. Many of these selections have been shown to resist infection following artificial inoculation with C. ribicola. In this study, 13 eastern white pine families derived from controlled pollination of selections previously determined to possess putative resistance as well as susceptible selections were inoculated with C. ribicola. Mortality data from inoculation studies show superior survivability in three families with over 60% of seedlings able to survive the 52 week post‐inoculation monitoring period compared to 0–10% survival of the most susceptible families. Primary needles were collected for histological analysis from all inoculated families 4 weeks after inoculation and from selected families 6.5 weeks and 38 weeks after inoculation. Histological observations of infection sites show distinct resistance reactions in the families more likely to survive infection based on mortality data. Analysis of the reactions in susceptible families revealed extensive hyphal colonization of the vascular bundle and adjacent mesophyll cells that appear uninhibited by tree responses. In resistant families, collapsed cells adjacent to infection sites, heavy deposition of phenolic compounds and abnormal cell growth were documented more frequently and appear to play an integral role in the ability of these eastern white pine families to impede growth of C. ribicola in primary needle tissue.     

In vitro ectomycorrhizal formation of Pinus patula, P. pseudostrobus, P. oocarpa and P. elliotii grown in southern India

In vitro syntheses of ectomycorrhizas of Pinus patula, P. pseudostrobus, P. oocarpa and P. elliotii with Amanita muscaria, Laccaria fraterna, L. laccata, Pisolithus tinctorius, Rhizopogon luteolus, Scleroderma citrinum and Thelephora terrestris were attempted. Most of the fungi initiated mycorrhizal formation within 2 weeks after inoculation. Laccaria fraterna and S. citrinum formed mycorrhizas after 6 weeks of inoculation. Amanita muscaria failed to form mycorrhizas during the 12 week period of observation. The degree of colonization of different mycorrhizal fungi varied with different species of Pinus.     

Changes in phenolic metabolites of Scots-pine phloem induced by Ophiostoma brunneo-ciliatum,a bark-beetle-associated fungus

Changes in soluble phenol contents of Scots-pine (Pinus sylvestris) phloem were studied after inoculation with Ophiostoma brunneo-ciliatum, a fungus associated with Ips sexdentatus. They were compared to the length of the fungus-induced reaction zone of the phloem, taken as an estimation for the trees' response efficiency against aggression. Five clones consisting of 14 trees were studied, and eight soluble phenolic metabolites were analysed in detail in reaction zones and in unwounded phloem sampled 3 weeks after inoculation. The stilbenes pinosylvin and pinosylvin monomethylether, and the flavonoid pinocembrin, were detected in reaction zones only. Concentrations of two p-coumaric-acid esters and an acetophenone glycoside decreased after inoculation. Variations of the flavonoids taxifolin and 3' taxifolin glucoside were inconsistent. One tree had longer reaction zones and a phenolic content different from the others. In unwounded phloem, concentrations of some phenolic compounds and in particular the ratio between the two p-coumaric-acid esters could be markers for trees' response efficiency. In the reaction zone, markers could be the ratios between concentrations of certain preformed compounds and concentrations of newly synthesized pinosylvin and pinocembrin.     

Relative susceptibility of oaks to seven species of Phytophthora isolated from oak forest soils

Isolates of Phytophthora cambivora, P. cinnamomi, P. citricola, P. europaea, P. quercetorum and two unidentified species were tested for their pathogenicity to eastern US oak species by root and stem inoculations. Experiments were conducted during two different periods and included 1‐, 2‐ and 20‐year‐old oaks grown under greenhouse and field conditions. Species of Phytophthora were pathogenic in varying degrees to the oak species tested. All species were pathogenic to fine and taproots of at least one oak species. The fine root damage caused by the species of Phytophthora ranged from 9 to 55% when compared to the controls. Roots were more susceptible during the fall inoculation period than the summer. With exception of Phytophthora sp1 and P. quercina‐like, all species of Phytophthora were pathogenic to oak stems with P. cinnamomi and P. citricola being the most aggressive. Quercus montana and Q. rubra were the most susceptible oak species to stem inoculation. Lesion sizes were considerably larger when 20‐year‐old trees were inoculated. Generally, no significant differences in lesion sizes were detected in greenhouse tests when the summer and fall inoculation periods were compared. However, on 2‐year‐old field‐grown seedlings, lesion sizes were considerably smaller or not significantly different from controls during the fall inoculation period, suggesting lower, late season temperatures may restrict lesion development.     

Effect of Thinning and Phlebiopsis gigantea Stump Treatment on the Growth of Heterobasidion parviporum Inoculated in Picea abies

The spread of Heterobasidion parviporum Niemelä & Korhonen in roots of Norway spruce was studied in three unthinned first rotation stands of Norway spruce [Picea abies (L.) Karst.] on former agricultural land in south-western Sweden. Heterobasidion parviporum was inoculated at stump height into the trunk of 135 standing trees in a randomized block design. One year after inoculation, two-thirds of the trees were thinned out and one-third was left standing. Half of the stumps left by thinning were treated with spores of Phlebiopsis gigantea (Fr.) Jül and half were left untreated. The spread of H. parviporum was examined both 3 and 5 yrs after inoculation. The rate of spread of H. parviporum and the proportion of infected roots were found to be significantly higher in the root systems of the stumps than in those of the standing trees. Treatment with P. gigantea had no significant effect on the development of H. parviporum in the stumps. There was a tendency 5 yrs after inoculation, however, for a lower proportion of H. parviporum-infected roots in the stumps treated with P. gigantea than in the untreated stumps. In conclusion, thinning of infected Norway spruce was found to increase the rate of spread of H. parviporum in the root systems of the infected trees, which could increase the risk of a rapid build-up of infection in the remaining stand.