Growth, nitrogen fixation and mineral acquisition of Alnus sieboldiana after inoculation of Frankia together with Gigaspora margarita and Pseudomonas putida

The role of tetrapartite associations among Frankia, Gigaspora margarita (an arbuscular mycorrhizal fungus), Pseudomonas putida (rhizobacterium), and Alnus sieboldiana in growth, nitrogen fixation, and mineral acquisition of A. sieboldiana was investigated. Seedlings of A. sieboldiana were inoculated with Frankia isolated from root nodules of alder, followed by inoculation of G. margarita and P. putida, and were grown for 5 months in a greenhouse. The seedlings inoculated with Frankia and G. margarita together produced the highest biomass of shoots and root nodules. Nitrogen-fixation activity, measured by acetylene reduction assay, was observed when Frankia was inoculated. The activity, on a per-nodule gram basis, decreased after G. margarita inoculation, but on a per-plant basis there was no significant difference in the activity among inoculation treatments. The mineral content in the seedlings changed after inoculation with Frankia, but not after inoculation with P. putida and/or G. margarita. The results showed a synergistic interaction among Frankia, the mycorrhizal fungus, and the rhizobacterium on the growth of A. sieboldiana.     

Different development of pine wilt disease in artificially infectedPinus thunbergii seedlings potted together with different tree species

To evaluate the effect of adjacent tree species on the susceptibility of Japanese black pine (Pinus thunbergii) to pine wilt disease, an inoculation experiment was conducted usingP. thunbergii seedlings potted with seedlings of six tree species,i. e. Alnus sieboldiana, Eurya japonica, Lespedeza bicolor formacutifolia, Pinus thumbergii, Robinia pseudo-acacia andSarothamus scoparius. About ten months after planting, they were inoculated with the pinewood nematode (Bursaphelenchus xylophilus) in early July 1992. After that, the proportion of pine seedlings with completely discolored foliage increased more quickly when the seedlings were potted withR. pseudo-acacia, S. scoparius orA. sieboldiana than when potted withP. thunbergii, L. bicolor orE. japonica. At the end of the study period, 17 weeks after inoculation, it reached 90.6%, 90.0%, 87.5%, 72.7%, 63.3%, and 59.4% when the pine seedlings were potted withR. pseudo-acacia, S. scoparius, A. sieboldiana, P. thunbergii, L. bicolor andE. japonica, respectively. This indicated that the susceptibility ofP. thunbergii seedlings to pine wilt disease was influence by the species of adjacent trees.     

Colonization of Pedunculate oak by the Burgundy truffle fungus is greater with natural than with pelletized lime

European black truffles can be profitable agroforestry crops outside their native ranges. Truffle fungi grow symbiotically as ectomycorrhizae on the roots of host trees, notably hazels and oaks. Conditions in the central USA appear conducive to cultivation of the Burgundy truffle (Tuber aestivum Vitt. syn. T. uncinatum Chatin), but research is needed to determine effects of management practices on truffle establishment and fruiting. In a greenhouse study we tested the effect of lime type, inoculation technique, and two truffle sources on Pedunculate oak (Quercus robur L.) growth and mycorrhizal colonization. We found that the type of lime used to raise potting mix pH can differentially affect the growth rate of root systems inoculated with different selections of Burgundy truffle inoculum. Seedlings inoculated with one selection of the truffle and grown in potting mixes amended with natural crushed dolomitic limestone developed larger root systems with more truffle mycorrhizae compared with potting mix amended with high-calcium pelletized quick-release lime. Seedlings inoculated with a second truffle selection were not affected by lime source and developed root systems as large as those developed with the first truffle source grown with natural lime. Supplemental root dip inoculation did not improve levels of colonization beyond those accomplished by potting mix infestation with truffle ascospores. Use of a hygroscopic polymer to maintain ascospore suspension in the inoculum slurry used to infest the potting mix had no effect on root system development or mycorrhiza formation.     

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.     

Ectomycorrhizal inoculation of Douglas-fir transplanted container seedlings with commercially produced inoculum

Commercially produced vegetative inocula of Laccaria laccata and Hebeloma crustuliniforme successfully formed ectomycorrhizae with Douglas-fir transplanted container (plug+1) seedlings. After 4.5 months in containers, 83% and 90%, respectively, of short roots were mycorrhizal. L. laccata- or H. crustuliniforme-inoculated seedlings had significantly more mycorrhizal and total short roots than Pisolithus tinctorius-inoculated (4% mycorrhizal root tips) or uninoculated control seedlings. No significant differences were detected in seedling growth at the end of the container phase.After transplantation and growth in nursery beds for 17 months, mean new short root colonization of all seedlings was 80%. H. crustuliniforme persisted as a dominant mycorrhizal fungus on seedlings initially inoculated with this fungus. L. laccata-inoculated seedlings had 40% of their short roots colonized by L. laccata and another 40% by native fungi Rhizopogon and Thelephora spp. All mycorrhizae of control seedlings and those inoculated with P. tinctorius were formed by fungi native to the nusery beds. A significant fungal treatment effect was detected for shoot height only. Control seedlings were significantly taller than L. laccata-inoculated seedlings after transplanting.This article is part of senior author's thesis in partial fulfillment of the Ph.D. degree in the Department of Forest Science at Oregon State University, Corvallis.     

Effects of Acidic Precipitation and Ectomycorrhizal Inoculation on Growth,Mineral Nutrition,and Xylem Water Potential of Juvenile Loblolly Pine and White Oak

Abstract

Individual and interactive effects of simulated acidic rainfall and mycorrhizal inoculation on growth and nutrient and water relations of loblolly pine (Pinus taedaL.) and white oak (Quercus albaL.) grown in a loam soil were examined. Seedlings of each species inoculated with basidiospores of the ectomycorrhizal fungus Pisolithus tinctorius(Pers.) Coker and Couch, a known my-cobiont of both loblolly pine and white oak, and uninoculated control seedlings received two simulated rains per week of either pH 3.6, 4.2, or 4.8 for 26 weeks. Higher acidity rainfall reduced the growth but increased mycorrhizal colonization of loblolly pine, while both loblolly pine and white oak exposed to these rains exhibited greater foliar injury. Inoculation with P. tinctoriusincreased growth and reduced foliar injury of both species. Foliar concentrations of P, S, and Cu in loblolly pine and white oak, Ca in loblolly pine, and Fe and Zn in white oak decreased with increasing rain acidity while the Al concentration of both species increased. Higher rainfall acidity also reduced soil pH and Ca and Mg concentrations while increasing soil AI. Foliage of inoculated seedlings of both species had higher N and P concentrations and lower Al concentrations than control seedlings. Following the final rain applications, a drought cycle was simulated by withholding irrigation for two weeks during which seedling xylem pressure potential and soil water potential were measured. One day after cessation of irrigation, xylem pressure potential of loblolly pine that had received pH 3.6 rains was lower than that of other treatments. Thereafter, xylem pressure potential and soil water potential of the inoculated treatment decreased below those of the control treatment in both species. These results suggest that acid deposition is detrimental to juvenile loblolly pine and white oak, but the magnitude of this effect is less than the positive response to ectomycorrhizal inoculation.     

Pisolithus tinctorius increases the size of nursery grown red oak seedlings

Inoculation of nursery beds with vegetative mycelia of P. tinctorius (Pt) significantly increased the number of salable 1–0 red oak seedlings produced in two of three years and the average stem height and diameter each year. The percentage of Pt mycorrhizal primary lateral roots on seedlings in the inoculated plots was significantly correlated with stem diameter and weight of lateral roots. The high rates of colonization of short roots by Pt in inoculated plots suggested the test fungus could successfully compete with indigenous fungi in forming mycorrhizae.     

Date of sowing and emergence timing affect growth and development of loblolly pine seedlings

Loblolly pine (Pinus taeda L.) seeds were sown from February to June in Alabama, U.S.A. If sowing was conducted in May or June, seedling emergence was reduced and seedling mortality increased. Seedlings from earlier sowings grew to greater sizes, but seedlings from later sowings grew later into the fall. Within any given sowing date, the earliest seedlings to emerge grew largest. Seedlings from the February sowing formed buds in mid-summer, flushed, and in some instances flushed yet again. However, by early October, not all seedlings from May and June sowings had formed an initial bud.     

板栗接种食用菌根真菌的菌根化效果及对幼苗促生效应的研究

[目的]通过板栗幼苗人工接种食用菌根菌固体菌剂,分析其对板栗幼苗生长指标和根系菌根化的效果,以验证大红菇(菌株编号2014-10)、红绒盖牛肝菌(菌株编号2014-14)和美味牛肝菌(菌株编号50559)这3种食用菌根菌固体菌剂作为板栗接种体的有效性及其促生效应,为进一步探索"板栗食用菌根菌新型经济林栽培模式"提供基础。[方法]在板栗播种时分别接种上述3种食用菌根菌固体菌剂,并设空白作对照。对当年生幼苗苗高、地径、根系干质量、侧根数、侧根总长、幼苗侵染率、吸收根侵染率等指标进行调查和分析,并制作菌根石蜡切片进行微观结构观察。[结果]表明:(1)上述3种食用菌根菌在人工接种下均能侵染板栗幼苗根系,平均幼苗菌根化率分别达95.8%、87.0%和96.7%,平均吸收根菌根化率分别达57%、53%和50%,达较高的侵染强度;经微观观察,板栗幼苗根系均形成典型的菌根结构——菌丝套和哈蒂氏网。(2)与对照幼苗相比,3个菌种处理幼苗的平均苗高分别提高32.5%、24.0%和22.7%,平均地径分别提高19.4%、14.1%和5.0%,差异显著(P0.05);平均根系干质量分别提高18.9%、25.3%和14.1%,平均侧根数分别提高16.0%、14.1%和12.1%,平均侧根总长分别提高26.8%、28.9%和44.8%,差异极显著(P0.01)。[结论](1)上述供试食用菌根菌均与板栗根系建立了共生关系,幼苗菌根化效果良好,吸收根菌根化强度高,形成了菌根的典型结构,即菌丝套和哈蒂氏网,验证了上述菌种固体菌剂的有效性,认为其可以作为板栗食用菌根菌栽培的接种体而用于生产实践,为探索"板栗食用菌根菌新型经济林栽培模式"提供了基础。(2)上述供试菌种接种后,对板栗幼苗各项主要生长指标均有不同程度的促进作用,说明上述食用菌根菌对板栗幼苗具有显著的促生效应。     

Pisolithus tinctorius fails to improve plantation performance of inoculated conifers in southwestern Oregon

Bare-root stock of Douglas-fir, lodgepole pine, white fir, and grand fir, inoculated with Pisolithus tinctorius and handled by standard nursery, cold storage and planting practices performed no better than stock which was not intentionally inoculated but which had formed mycorrhizae with indigenous, nursery fungi on a variety of different outplanting sites in southwestern Oregon. Climate, planting sites and nursery practices in the Pacific Northwest differ drastically from those in the southeastern United States, where P. tinctorius has increased plantation survival and growth. Before P. tinctorius can be recommended for nursery inoculation in the Pacific Northwest, its reaction to each phase of the nursery and planting process needs to be carefully analyzed to determine where the problems lie.This article was written and prepared by US Government employees on official time, and is therefore in the public domain.     

Selection of efficient VA mycorrhizal fungi for Casuarina equisetifolia—second screening

An investigation was carried out to screen and select efficient vesicular arbuscular mycorrhizal (VAM) fungi for inoculating the forest tree species, Casuarina equisetifolia. The seedlings were inoculated with 10 different VAM fungi, obtained from various sources. Inoculated seedlings generally had greater plant height, stem girth, biomass and P content than uninoculated plants. They also had more mycorrhizal root colonization and spore numbers in root zone soil. C. equisetifolia seedlings responded best (in biomass) to inoculation with Glomus mosseae (Nicolson and Gerdemann) Gerdemann and Trappe, closely followed by Acaulospora laevis Gerdemann and Trappe and G. fasciculatum (Thaxter Sensu Gerdemann) Gerdemann and Trappe; all the three being statistically on par with each other.     

Seed source and vesicular-arbuscular mycorrhizal symbiont affects growth of Juglans nigra seedlings

Seedlings of Juglans nigra from three seed sources were grown in fumigated soil without vesicular-arbuscular mycorrhizal (VAM) fungi or inoculated with Gigaspora margarita, Glomus deserticola or Glomus etunicatum. Vesicular-arbuscular mycorrhizal development varied significantly between fungal symbionts within a black walnut source. Glomus deserticola and G. etunicatum produced the highest levels of root colonization in all sources. Significant differences in seedling shoot and root growth were attributed to root colonization by specific VAM fungi in each black walnut source. Glomus deserticola stimulated seedling leaf area and root weight 26 and 52%, respectively, in one seed source. Seedling leaf N, P and K concentrations were significantly improved by VAM in two seed sources. Juglans nigra seedlings respond favorably to VAM colonization. However, differences between seed sources suggest a strong host-symbiont interaction.     

Effect of inoculation with ecto- and arbuscular mycorrhizae and Rhizobium on the growth and nitrogen fixation by black locust,Robinia pseudoacacia

Experiments were made to determine the effect of inoculation withRhizobium, the ectomycorrhizal fungus Hebelomamesophasem and the arbuscular mycorrhizal fungus Glomuscaledonium on the growth and nitrogen fixation of black locust(Robinia pseudoacacia Linn.) seedlings grown invitro and in pot culture. The results showed that both mycorrhizalfungi and Rhizobium stimulated the growth and nitrogenfixing ability of inoculated seedlings. Inoculation with all three microbestogether produced the most beneficial effects on nitrogen fixation, mycorrhizaldevelopment and seedling growth.     

Dual inoculation of a woody legume (Centrolobium tomentosum) with rhizobia and mycorrhizal fungi in south-eastern Brazil

The integration of N₂ fixing trees into stable agroforestry systems in the tropics is being tested due to their ability to produce high biomass N and P yields, when symbiotically associated with rhizobia and mycorrhizal fungi. The growth of Centrolobium tomentosum Guill. ex Benth, a native leguminous tree from the Brazilian Atlantic Forest, was assessed with dual inoculation of Rhizobium spp and mycorrhizal fungi under field conditions. Complete fertilization was compared to treatments of inoculation with selected rhizobia strains BHICB-Ab1 or BHICB-Ab3, associated or not to arbuscular mycorrhizal (AM) fungi. The dual inoculation increased the height and growth in relation to the plants treated with rhizobia alone. Plants inoculated with strain BHICB-Ab1 and arbuscular mycorrhizal fungi (AMF) exhibited an increase of 56% dry matter over uninoculated control and nitrogen accumulation was greater than with BHICB-Ab3 inoculated plants. Strain BHICB-Ab1 presented a synergetic relationship with mycorrhizal fungi since the combined inoculation with BHICB-Ab1 enhanced plant height and dry weight more than single inoculation while the growth of BHICB-Ab3 plants was not modified by AMF inoculation. Arbuscular mycorrhizal fungi enhanced plants survival and seemed to favour the nodule occupation by rhizobia strains as compared to the non-mycorrhizal plants. Inoculation with selected rhizobia and AMF improved the growth of C. tomentosum under field conditions. This revised version was published online in June 2006 with corrections to the Cover Date.     

Promotion of the population growth of pinewood nematode in 4-month-old Japanese black pine seedlings by pretreatment with simulated acid rain

Simulated acid rain (SAR) at three pH levels (pH 4, 3, 2) was applied to only the top or both the top and roots of 4-month-old Japanese black pine seedlings repeatedly for two months. Then the seedlings were inoculated with a virulent isolate (S10) of pinewood nematode,Bursaphelenchus xylophilus. The exposure to SAR at any level did not kill the seedlings. When inoculated with nematodes, however, the nematode population build-up was significantly higher in the seedlings pretreated with SAR at any level than in the control at the 7th and 17th day after inoculation, and subsequent disease symptom development was also significantly accelerated by the exposure to SAR at pH 2 and 3. This result indicates that even acid rain at pH 4 has the potential for promoting population growth of pinewood nematodes in 4-month-old Japanese black pine seedlings.     

Ectomycorrhizal fungi affect the physiological responses of Picea glauca and Pinus banksiana seedlings exposed to an NaCl gradient

We tested the effects of ectomycorrhizal (ECM) inoculation on greenhouse-grown white spruce (Picea glauca (Moench) Voss) and jack pine (Pinus banksiana L.) seedlings to be used for revegetation of salt-affected tailing sands resulting from the exploitation of oil sand in northeastern Alberta, Canada. White spruce and jack pine seedlings were inoculated with three ECM fungi selected for their in vitro tolerance to excess Na+ and Cl-: Hebeloma crustuliniforme (Bull) Quel. UAMH 5247, Laccaria bicolor Maire (Orton) UAMH 8232 and a Suillus tomentosus (Kauff.) Sing., Snell and Dick isolate from a salt-affected site. The physiological responses of the seedlings to a gradient of NaCl concentration (0, 50, 100 and 200 mM) were assessed over four weeks by: (1) Na+ accumulation and allocation; (2) chlorophyll a fluorescence; (3) growth, (4) water content; and (5) organic osmolyte accumulation. Jack pine seedlings were more sensitive than white spruce seedlings to increasing Na+ and Cl- concentrations. Both species showed decreasing biomass accumulation, and increasing concentrations of organic osmotica and Na with increasing NaCl concentration. White spruce seedlings inoculated with the S. tomentosus isolate had the best growth response at all NaCl concentrations tested. Although jack pine seedlings inoculated with the L. bicolor or S. tomentosus isolate exhibited the highest growth in the 50 and 100 mM NaCl treatments, both fungi increased the photochemical stress and dehydration of their hosts in the 200 mM NaCl treatment. At the latter concentration, jack pine seedlings inoculated with H. crustuliniforme showed the greatest tolerance to salt stress. Although the different fungi altered the physiological response of the host in different ways, inoculation with salt-stress-tolerant ECM fungi increased growth and reduced the negative effects of excess NaCl. Use of controlled mycorrhization may increase survival of coniferous seedlings used for revegetation of salt-affected sites.     

Inoculation of ectomycorrhizal fungi contributes to the survival of tree seedlings in a copper mine tailing

To advance our understanding of the effects of inoculation with ectomycorrhizal fungi (EMF) on seedling colonization in mine wastelands, we conducted a field experiment in a copper tailing. Six-month-old seedlings of Japanese red pine (Pinus densiflora) and oak (Quercus variabilis) separately inoculated with three EMF species (Pisolithus sp., Cenococcum geophilum, Laccaria laccata) were transplanted to the copper tailing. The survival rates of tree seedlings were monitored monthly, and growth (biomass and height), contents of nutrients and heavy metals (K, P, Ca, Mg, Cu, Zn), and mycorrhizal infection rates of seedlings were determined 6 months after planting. Oak seedlings exhibited higher survival rates than pine seedlings after 6 months of growth on the tailing. EMF inoculations of pine seedlings significantly enhanced their survival, growth, and nutrient uptake. In contrast, EMF inoculations of oak seedlings improved growth only in terms of biomass. Additionally, EMF inoculation caused pine seedlings to accumulate more Cu and Zn in roots compared to non-inoculated seedlings, whereas inoculation inhibited the accumulation of heavy metals in shoots. However, similar results were not observed in oak seedlings. Observations of roots indicated that the rates of mycorrhizal infection of both tree species had dramatically declined at harvest time. In conclusion, ectomycorrhizal symbioses can improve the survival and performance of pine seedlings in mine tailings. The present study provided direct evidence of the importance of EMF inoculation of seedlings to the reforestation of mine wastelands.     

Ectomycorrhizal development in a Pinus thunbergii stand in relation to location on a slope and effect on tree mortality from pine wilt disease

The relationship between ectomycorrhizal development and mortality from pine wilt disease was studied in an artificial Pinus thunbergii Parl. stand on a slope. The development of ectomycorrhizae and the survival of the trees showed the same tendency, which suggests a correlation between mycorrhizal development and resistance to pine wilt disease. The development of pine roots and mycorrhizae was greater in the upper part of the slope. The ratio of mycorrhizae to the total of mycorrhizae and fine taproots was also higher in the upper part of the slope. Tree mortality was clearly biased and more trees survived in the upper part of the slope than in the middle and the lower parts. There was no significant difference between the upper and the lower part of the slope in the number of feeding wounds made by the pine sawyer beetle, which demonstrates the opportunity of infection with this disease. There was no clear correlation between the development of mycorrhizae and the composition of the soil substrate such as total carbon, nitrogen, and phosphorus. The abundant mycorrhizae in the upper part of the slope, which mitigate drought stress, may also have decreased the rate of tree mortality.     

Effects of single and dual inoculation with selected microsymbionts (rhizobia and arbuscular mycorrhizal fungi) on field growth and nitrogen fixation of <Emphasis Type="Italic">Calliandra calothyrsus</Emphasis> Meissn

Our study aimed to assess the effect of dual inoculation with the selected Rhizobium strain KWN35 and the arbuscular mycorrhizal isolate BEG 176 (Glomus etunicatum) on the growth of Calliandra calothyrsus cultivated under irrigation in the field in Senegal (Dakar) over a period of 24 months. Although plants inoculated with both microsymbionts grew better (height and root collar diameter) than plants from three other inoculation treatments (control, single inoculation with KWN35 or BEG 176), these results were not statistically different except at 1 and 5 months after field transplantation. KWN35 was present in a relatively high percentage of nodules harvested from plants inoculated with this rhizobial strain either alone or with mycorrhiza (approximately 60% and 40% 1 and 2 years after field transplantation respectively). The percentage of mycorrhizal root infections was around 60% in the inoculated plants after 12 months with significantly higher N, P and K foliar contents of trees compared with the non-inoculated controls. However, as for nodulation, by 24 months after transplantation, there were no significant differences between treatments. We conclude that field inoculation of C. calothyrsus with Rhizobium strain KWN35 and arbuscular mycorrhizal isolate BEG 176 did not have a long-lasting effect on the growth of trees, even when a majority of nodules were occupied by the inoculated rhizobia and the roots infected by the mycorrhiza. Several reasons can be postulated for these results, such as a possible effect of soil fertility on the efficiency of the nodules.     

Effect of nursery storage and site preparation techniques on field performance of high-elevation Pinus contorta seedlings

After five years of growth at high-elevations (∼3000 m) in Utah, container lodgepole pine (Pinus contorta Dougl. var. latifolia Engelm.) seedlings survived well (80–95%) and grew to similar heights regardless of nursery storage method and site preparation technique. Seedlings received one of three storage treatments: (1) spring-sown in the nursery, overwintered in cooler storage and outplanted in July; (2) spring-sown, overwintered in freezer storage, and outplanted in July; or (3) winter-sown, no storage, and hot-planted in late August. We outplanted seedlings at two locations that were clearcut and had received two treatments of surface organic matter (coarse wood, logging slash, and forest floor) removal: surface organic matter (OM) piled with a bulldozer and burned or surface OM remaining in situ. Compared to adjacent uncut stands, both site preparation treatments increased total soil bulk density, but retaining surface OM in situ maintained soil OM, carbon, and nitrogen levels. After one growing season, seedlings planted where surface OM had been bulldozed were taller and had more biomass, although survival was similar (≥96%) across site preparation treatments. The height growth advantage disappeared after five growing seasons and although overall survival was good, survival was highest where site preparation involved removal of surface OM and freezer-stored seedlings were planted. Total non-structural carbohydrates tended to be higher in roots than in shoots and were also higher in hot-planted seedlings than in stored seedlings. Our results indicate that nursery and forest managers have several options for successful nursery production and outplanting of container lodgepole pine seedlings in the central Rocky Mountains. Using hot-planted seedlings allows for a faster turnaround time (from seed to plantable seedling) and maintaining surface OM may be a cost-effective alternative to dozer piling and burning.