Platanus Occidentalis Research Articles

Erythroneura lawsoni abundance and feeding injury levels are influenced by foliar nutrient status in intensively managed American sycamore

Abundance and feeding injury of the leafhopper Erythroneura lawsoni Robinson was measured in an intensively‐managed American sycamore Platanus occidentalis L. plantation. Trees were planted in spring 2000 in a randomized complete block design, and received one of three annual treatments: (i) fertilization (120 kg N/ha/year); (ii) irrigation (3.0 cm/week); (iii) fertilization + irrigation; or (iv) control (no treatment). Foliar nutrient concentrations were significantly influenced by the treatments because only sulphur and manganese levels were not statistically greater in trees receiving fertilization. Over 116 000 E. lawsoni were captured on sticky traps during the study. Leafhopper abundance was highest on nonfertilized trees for the majority of the season, and was positively correlated with foliar nutrient concentrations. Significant temporal variation in E. lawsoni abundance occurred, suggesting five discrete generations in South Carolina. Significant temporal variation occurred in E. lawsoni foliar injury levels, with the highest injury ratings occurring in late June and August. Foliar injury was negatively correlated with foliar nutrient content, and higher levels of injury occurred more frequently on nonfertilized trees. The results obtained in the present study indicated that increased E. lawsoni abundance occurred on trees that did not receive fertilization. Nonfertilized trees experienced greater foliar injury, suggesting that lower foliar nutrient status may have led to increased levels of compensatory feeding.

Methicillin-Resistant Staphylococcus aureus (MRSA)-Active Metabolites from Platanus occidentalis (American Sycamore)

One known and three new potent, selective, and nontoxic anti-MRSA metabolites, kaempferol 3-O-alpha-l-(2'',3''-di-E-p-coumaroyl)rhamnoside (1) (IC(50) 2.0 microg/mL), kaempferol 3-O-alpha-l-(2''-E-p-coumaroyl-3''-Z-p-coumaroyl)rhamnoside (2) (IC(50) 0.8 microg/mL), kaempferol 3-O-alpha-l-(2''-Z-p-coumaroyl-3''-E-p-coumaroyl)rhamnoside (3) (IC(50) 0.7 microg/mL), and kaempferol 3-O-alpha-l-(2'',3''-di-Z-p-coumaroyl)rhamnoside (4) (IC(50) 0.4 microg/mL), were isolated from the leaves of the common American sycamore, Platanus occidentalis. Compounds 2-4 are new. Due to the unusual selectivity, potency, and safety of the pure compounds and the semipure glycoside mixture against MRSA, it is clear that this represents a viable class of inhibitors to prevent growth of MRSA on surfaces and systemically.

Soil microbial communities alter allelopathic competition between Alliaria petiolata and a native species

Allelopathy has been increasingly invoked as a mechanism facilitating exotic plant invasions. However, studies even on the same target species often yield varying results concerning the strength and importance of allelopathic inhibition, suggesting that the process may depend on the specific environmental context. Here I studied how the allelopathic inhibition of sycamore (Platanus occidentalis) seedlings by garlic mustard (Alliaria petiolata) depended on the presence of a soil microbial community. Using three analytical approaches to quantifying allelopathy, I consistently found allelopathic inhibition only in sterilized soils, suggesting that certain microbial taxa inhibit the process, possibly by degrading the allelochemicals. Determining the environmental contexts that reduce or eliminate allelopathic inhibition could lead to a greater understanding of the spatial variation in invasion success and potentially lead to new avenues for management.

A Comparison of Germination and Early Growth of Four Early Successional Tree Species of the Southeastern United States in Different Soil and Water Regimes

To learn more about the basic biology of exotic relative to native tree species we conducted a greenhouse experiment comparing the germination and early seedling growth of four early successional tree species found in the southeastern United States: two exotics (Ailanthus altissima and Paulownia tomentosa) and two natives (Liquidambar styraciflua and Platanus occidentalis). Five soil types and three water regimes were used for the experiment. Liquidambar and Platanus, the native species, germinated significantly more quickly and were more sensitive to soil type than were the exotics, Ailanthus and Paulownia. Platanus grew tallest, and along with Paulownia, accumulated the greatest total biomass. Ailanthus alone exhibited a high root/shoot ratio in all soil types. In addition, species differed in their response to soil types for multiple growth traits. The results suggest that native tree species could be used to help retard the establishment of invasive tree species on bare soil.

EFFECT OF DIFFERENT HEIGHT AND DIAMETER LEVELS THROUGHOUT THE STEM ON VESSELS DIMENTIONS AND SPECIFIC GRAVITY OF Platanus occidentalis L.TREES GROWING AT NINAVAH PLANTATION

Two 10 years old Platanus occidentalis L. trees growing as copies had been fallen to study the variation in vessel element dimensions and specific gravity between and within the trees . Eight discs were cut from each tree from the stump until 14.30 m. with 2 m. interval between each disc. Also ,five wood specimens were taken from each disc from pith to bark at north direction .The results showed that the average vessel element length was 0.566 mm. , mean diameter was 79.45 micron, while mean specific gravity was 0.594. Average vessel elements length and diameter varied throughout stem lengths, there were an increase in these values from base to 2.30 m. height by which the highest mean values were presented (0.504 mm and 58.84 micron respectively ), then these values decreased up to the 8.30 m. height level followed by gradual increase to the 10.30 m. height level then it decrease to the last height level (14.30 m.). Specific gravity mean values decreased by increasing stem height levels , the highest mean was 0.649 at the stump level (0.30 m. ) and lowest value was 0.5541 at 14.30 m. height level. Variation of vessels mean length and diameter among stem diameter level was found to have an increasing values from pith to bark , the lowest mean value was at the pith ( 0.539 ml. And 74.539 micron respectively ), and the highest mean value was near the bark ( 0.612 mm and 85.o66 micron respectively ). There were decreasing in specific gravity mean values from pith toward the bark , the highest mean value was near the pith 0.619 and the lowest value was 0.561 near the bark. Also it was found that there were significant differences between the trees in vessel diameter and specific gravity, but there was no significant differences in vessel length between the trees.

Abundance and Diversity of Seeds in Digestive Tracts of Terrapene carolina and T. ornata in Southwestern Missouri

Box turtles are opportunistic omnivores, and consume a wide variety of fruits. Therefore they might play an important role in dispersal of seeds of a variety of plants. We described the diversity of seeds recovered from feces of Terrapene carolina and T. ornata and made comparisons between them. There was a moderate level of dietary overlap based upon diversity of seeds in the feces. Terrapene carolina had a significantly higher species richness of seeds in its feces than T. ornata. Additionally, we documented seeds of four plants (Celtis, Passiflora, Phytolacca americana, and Platanus occidentalis) that previously were not known to be consumed or dispersed by box turtles.

Effects of Fertilization on Physiological Parameters in American Sycamore (Platanus occidentalis) during Ozone Stress and Recovery Phase

American sycamore seedlings were grown in chambers with two different ozone concentrations (<TEX>$O_3$</TEX>-free air and air with additional <TEX>$O_3$</TEX>) for 45 days. Both the control and the <TEX>$O_3$</TEX> chambers included non-fertilized and fertilized plants. After 18 days of <TEX>$O_3$</TEX> fumigation, seedlings were placed in a clean chamber for 27 days. Seedlings under ozone fumigation showed a significant decrease in pigment contents and photosynthetic activity, and a significant increase in lipid peroxidation. Fertilization enhanced physiological damage such as the inhibition of photosynthetic activity and the increase of lipid peroxidation under ozone fumigation. During the recovery phase, the physiological damage level of seedlings increased with ozone fumigation. In addition, physiological damage was observed in the fertilized seedlings. Superoxide dismutase (SOD) and glutathione reductase (GR) activities of <TEX>$O_3$</TEX>-treated seedlings increased up to 33.8% and 16.3% in the fertilized plants. The increase of SOD activity was higher in the fertilized plants than in the non-fertilized plants. Negative effects of ozone treatment were observed in the biomass of the leaves and the total dry weight of the fertilized sycamore seedlings. The <TEX>$O_3$</TEX>-treated seedlings decreased in stem, root and total dry weight, and the loss of biomass was statistically significant in the fertilized plants. In conclusion, physiological disturbance under normal nutrient conditions has an effect on growth response. In contrast, in conditions of energy shortage, although stress represents a physiological inhibition, it does not seem to affect the growth response.

Influence of tree shelters on seedling success in an afforested riparian zone

The restoration of a natural riparian ecosystem is a key component to improving water quality and restoring stream health in a disturbed watershed. The rate and degree of riparian restoration, and hence stream restoration, depends in part upon afforestation practices. Successful afforestation is determined largely by the rates of survivorship and growth of the tree species planted or recruited in a riparian zone. This study was part of a project involving the restoration of a channelized section of Wilson Creek located in the Bernheim Arboretum and Research Forest, Nelson County, Kentucky. Riparian restoration activities focused on reestablishing a native riparian corridor using American sycamore (Platanus occidentalis), green ash (Fraxinuspennsylvanica var. subintegerrima), and pin oak (Quercus palustris). This study evaluated techniques for improving the growth and survivorship of planted seedlings along Wilson Creek. Specifically, two tree shelter types (Tubex® vs. continental mesh), with or without herbicide treatments, were compared. Additionally, the influence of these techniques on debris retention within the riparian zone was also examined. Results showed that use of tree shelters significantly increased the growth of seedlings (but not survivorship), provided physical protection especially during heavy flooding events, and accelerated woody debris retention. Both Tubex® and continental mesh tree shelters were effective in enhancing seedling growth, with Tubex® shelters yielding significantly better growth when combined with herbicide to control competing vegetation. Thus, the most cost effective choice may depend on the environmental setting and ability to combine the shelters with other growth enhancing treatments.

Assimilation of xylem-transported 13C-labelled CO2 in leaves and branches of sycamore (Platanus occidentalis L.)

Previous reports have shown that CO2 dissolved in xylem sap in tree stems can move upward in the transpiration stream. To determine the fate of this dissolved CO2, the internal transport of respired CO2 at high concentration from the bole of the tree was simulated by allowing detached young branches of sycamore (Platanus occidentalis L.) to transpire water enriched with a known quantity of 13CO2 in sunlight. Simultaneously, leaf net photosynthesis and CO2 efflux from woody tissue were measured. Branch and leaf tissues were subsequently analysed for 13C content to determine the quantity of transported 13CO2 label that was fixed. Treatment branches assimilated an average of 35% (SE=2.4) of the 13CO2 label taken up in the treatment water. The majority was fixed in the woody tissue of the branches, with smaller amounts fixed in the leaves and petioles. Overall, the fixation of internally transported 13CO2 label by woody tissues averaged 6% of the assimilation of CO2 from the atmosphere by the leaves. Woody tissue assimilation rates calculated from measurements of 13C differed from rates calculated from measurements of CO2 efflux in the lower branch but not in the upper branch. The results of this study showed unequivocally that CO2 transported in xylem sap can be fixed in photosynthetic cells in the leaves and branches of sycamore trees and provided evidence that recycling of xylem-transported CO2 may be an important means by which trees reduce the carbon cost of respiration.

First Report of Pierce's Disease of Grape Caused by Xylella fastidiosa in Oklahoma.

Bacterial leaf scorch caused by the bacterium Xylella fastidiosa was first identified in Oklahoma in American elm (Ulmus americanus L.) in the summer of 2004 (2). Subsequently, additional infections of other shade trees and ornamentals including oak (Quercus spp.), mulberry tree (Morus spp.), and sycamore (Platanus occidentalis) have been identified through sample submission to the Oklahoma State University, Plant Disease and Insect Diagnostic Laboratory. As of July 2008, no grape (Vitis spp.) samples positive for infection by X. fastidiosa were identified in Oklahoma. In August of 2008, leaves of four grape vines (Vitis labrusca 'Concord') grown in a home gardener's backyard located in Canadian County, OK were found to be exhibiting chlorosis and green fading colors with marginal browning. These symptoms included an undulating appearance with red-brown bands between the green and scorched areas. Vines exhibited 'matchstick' symptoms where the leaves dropped from the plant, but the petioles remained attached. All symptoms were consistent with those of Pierce's disease (3). Leaves from all four symptomatic vines and leaves from asymptomatic grapes (V. vinifera, unknown cultivar) from the Oklahoma Botanical Gardens located at Oklahoma State University, Stillwater were sampled. Genomic DNA was extracted from all samples with the DNeasy Plant Mini Kit (Qiagen, Germantown, MD). Samples were tested for the presence of X. fastidiosa by real-time PCR with Xylella genus-specific primers XfF1/XfR2 and dual-labeled TaqMan probe XfP2 (4). Infected tissue from a symptomatic oak tree was used as a positive control. Genomic DNA samples extracted from all four symptomatic grape vines and the symptomatic oak tree were PCR positive. Samples from the asymptomatic grape vine were PCR negative. Subsequent analysis was performed on the four symptomatic grape vine samples. X. fastidiosa-specific primers BBXFOUTF1 and BBXFOUTR1 were used to PCR amplify the gyrB gene (2). The amplification product was purified with the QuickClean 5M PCR Purification Kit (GenScript Corporation, Piscataway, NJ) and was subjected to automated sequencing (Oklahoma State University Recombinant DNA/Protein Resource Facility). BLASTN alignment (1) of the 340-bp sequences from the four symptomatic grape samples revealed 99 to 100% homology with the gyrB gene from a Pierce's disease strain of X. fastidiosa, 'Temecula' (GenBank No. AF534960). Remaining petiole tissues from the samples used above were subjected to serological tests for X. fastidiosa by ELISA (Agdia, Inc. Elkhart, IN). These tests confirmed the presence of X. fastidiosa in symptomatic grape tissue. To our knowledge, this is the first report of X. fastidiosa associated with grape and the first report of Pierce's disease in Oklahoma. This suggests that the geographic range for Pierce's disease should be extended to include central Oklahoma.

English

Reforestation of the Appalachian coalfields with native hardwoods is becoming increasing popular. However, establishing some hardwood species has been difficult due to the poor quality of many mine soils. The purpose of this study was to contrast after 15 years the growth, survival, and overall performance of seven hardwood species planted on three mine sites in Southwestern Virginia. The seven hardwood species were divided into species groups of a non-native fuelwood species, upland hardwoods, riparian species, and a valuable but off-site hardwood species. Overall tree performance was examined as a function of mine soil chemistry and fertility. Eastern cottonwood grew fastest, and black walnut grew slowest. By age 15, the native hardwoods, white and northern red oaks and yellow poplar, grew better than the American sycamore and white ash riparian species. They also responded to a mine soil fertility gradient while the others did not. The overall forest capability of the post-mined condition of these sites was far less than the pre-mined capability. The average weighted site indices (by extent of all soil series) of 10,000 acres in the vicinity of the mined sites are 82 and 77 for yellow poplar and northern red oak, respectively. Reduction in yellow poplar site index between the preand post-mined capability was 26 feet, and the difference for red oak was 15 feet. Northern red oak, white oak, and yellow poplar, all upland native commercial hardwood species, would be better choices for general reforestation than riparian species; however, better reclamation procedures then those used when this study was established (compacted mix of overburden materials with heavy herbaceous ground cover) are needed to restore forest land capability to pre-mining conditions. Additional

Broadleaf species recognition with in situ hyperspectral data

Timely and accurate identification of tree species by spectral methods is crucial for forest and urban ecological management. In this study, a total of 394 reflectance spectra (between 350 and 2500 nm) from foliage branches or canopy of 11 important urban forest broadleaf species were measured in the City of Tampa, Florida, USA with a spectrometer. The 11 species include American elm (Ulmus americana), bluejack oak (Quercus incana), crape myrtle (Lagerstroemia indica), laurel oak (Q. laurifolia), live oak (Q. virginiana), southern magnolia (Magnolia grandiflora), persimmon (Diospyros virginiana), red maple (Acer rubrum), sand live oak (Q. geminata), American sycamore (Platanus occidentalis), and turkey oak (Q. laevis). A total of 46 spectral variables, including normalized spectra, derivative spectra, spectral vegetation indices, spectral position variables, and spectral absorption features were extracted and analysed from the in situ hyperspectral measurements. Two classification algorithms were used to identify the 11 broadleaf species: a nonlinear artificial neural network (ANN) and a linear discriminant analysis (LDA). An analysis of variance (ANOVA) indicates that the 30 selected spectral variables are effective to differentiate the 11 species. The 30 selected spectral variables account for water absorption features at 970, 1200, and 1750 nm and reflect characteristics of pigments and other biochemicals in tree leaves, especially variability of chlorophyll content in leaves. The experimental results indicate that both classification algorithms (ANN and LDA) have produced acceptable accuracies (overall accuracy from 86.3% to 87.8%, kappa from 0.83 to 0.87) and have a similar performance for classifying the 11 broadleaf species with input of the 30 selected spectral variables. The preliminary results of identifying the 11 species with the in situ hyperspectral data imply that with current remote sensing techniques, including high spatial and spectral resolution data, it is still difficult but possible to identify similar species to such 11 broadleaf species with an acceptable accuracy.

Fine Scale Patterns in Microbial Extracellular Enzyme Activity during Leaf Litter Decomposition in a Stream and its Floodplain

Microorganisms mediate the decomposition of leaf-litter through the release of extracellular enzymes. The surfaces of decomposing leaves are both chemically and physically heterogeneous, and spatial patterns in microbial enzyme activity on the litter surface should provide insights into fine-scale patterns of leaf-litter decomposition. Platanus occidentalis leaves were collected from the floodplain of a third-order stream in northern Mississippi, enclosed in individual litter bags, and placed in the stream channel and in the floodplain. Replicate leaves were collected approximately monthly over a 9-month period and assayed for spatial variation in microbial extracellular enzyme activity and rates of organic matter (OM) decomposition. Spatial variation in enzyme activity was measured by sampling 96 small discs (5-mm diameter) cut from each leaf. Discs were assayed for the activity of enzymes involved in lignin (oxidative enzymes) and cellulose (beta-glucosidase, cellobiohydrolase) degradation. Rates of OM loss were greater in the stream than the floodplain. Activities of all enzymes displayed high variability in both environments, with severalfold differences across individual leaves, and replicate leaves varied greatly in their distribution of activities. Geostatistical analysis revealed no clear patterns in spatial distribution of activity over time or among replicates, and replicate leaves were highly variable. These results show that fine-scale spatial heterogeneity occurs on decomposing leaves, but the level of spatial variability varies among individual leaves at the measured spatial scales. This study is the first to use geostatistical analyses to analyze landscape patterns of microbial activity on decomposing leaf litter and in conjunction with studies of the microbial community composition and/or substrate characteristics, should provide key insights into the function of these processes.

Non‐native grass alters growth of native tree species via leaf and soil microbes

Summary Non‐native plants can alter both native microbe communities and ecosystem processes. These changes may indirectly affect native plant communities. We tested whether an invasive plant influences other plant species through above‐ and below‐ground microbial associations. These factors have received less attention than direct competition for resources in research on plant invasions. Previous work in the mid‐western US revealed that the above‐ground fungal endophyte (Neotyphodium coenophialum) in non‐native tall fescue grass (Lolium arundinaceum) reduced establishment of native tree species, slowing plant succession from grassland to forest relative to communities lacking the symbiont. Here, we examined potential soil‐mediated mechanisms underlying these negative impacts on trees. We challenged nine tree species with soil conditioned by tall fescue grass either with (E+) or without (E–) the symbiotic endophyte. We collected field soil from replicated, experimental E+ and E– field plots, sterilized half to eliminate soil microbes, then conditioned the soil in the greenhouse with either E+ or E– tall fescue. Individual tree seeds received one of five soil treatments: E– live, E– sterile, E+ live, E+ sterile, or no tall fescue conditioning (control). Tree survival and biomass were assessed after approximately 80 days. Soil conditioning by E+ tall fescue reduced the biomass of three tree species (Elaeagnus umbellata, Fraxinus pennsylvanica, Platanus occidentalis) and the survival of P. occidentalis relative to conditioning by E– tall fescue. However, decreased biomass occurred only in live soil, suggesting indirect effects of the endophyte via altered soil microbes. In addition, two species (F. pennsylvanica, Prunus serotina) grew larger in both unconditioned soils and E– live soil relative to all other soil treatments, and two species (Ailanthus altissima, P. occidentalis) performed poorly in all soil treatments relative to unconditioned soil. Finally, three species did not significantly respond to any soil treatment (Acer negundo, Quercus palustris, Cercis canadensis). Synthesis. Our results show that negative impacts of a non‐native grass on native trees can depend on both above‐ and below‐ground microbial associations. Because tree species responded divergently to soil conditioning, the endophyte symbiosis has the potential to alter plant succession and the future composition of forest communities.

Pollen allergenic potential nature of some trees species: A multidisciplinary approach using aerobiological, immunochemical and hospital admissions data

Trees are considered producers of allergenic pollen. The aims of this work were to characterize the aerobiology of the Platanus, Acer, Salix, Quercus, Betula and Populus pollen, linking it with monthly emergency hospital admissions and to identify the different reactivity levels in sensitized patients. This information would be of great importance to evaluate the convenience of changing the inventory of pollen producer trees related to the risk of allergenic reactions. The study was conducted in Porto, Portugal, from 2005 to 2007. Airborne pollen was sampled using a Hirst-type volumetric trap. The antigenic and allergenic properties of Acer negundo, Betula pendula, Platanus occidentalis, Populus hybrida, Quercus robur and Salix babylonica pollen, collected in public gardens or sidewalks, were investigated by sodium dodecyl sulphate-polyacrylamide gel electrophoresis (SDS-PAGE) and immunological techniques using polysensitized-patient sera. Monthly hospital admissions of asthma or dyspnea related with respiratory diseases were obtained from the Emergency Room database of Hospital Geral de Santo António. Tree pollen and hospital admissions were positively correlated. Tree pollen peaked in March which coincides with the hospital admissions maximum. The highest binding affinity was observed with A. negundo, S. babylonica and P. occidentalis pollen extracts and the lowest with P. hybrida. Consistently, Acer and Platanus maximum airborne pollen concentrations were observed during March attaining levels considered moderate to high risk for allergenic reactions. Prominent bands with approximately 71, 35, 31, 22, 19, 16, 14, 13 and 11 kDa were revealed. A 52 kDa band was shared by all analyzed sera. High levels of airborne pollen and emergency hospital admissions were related. High binding affinity of specific IgE to pollen extracts of the most abundant tree pollen present in the atmosphere was observed. Patient sera revealed multiple similar allergenic bands shared by the different extracts. This multidisciplinary approach is useful in day-to-day medical practice to help in diagnostic, therapeutic and allergy alerting system adjusting.

Oriental plane pollen allergy: Identification of allergens and cross-reactivity between relevant species

Pollen from different tree and grass species represent the greatest inducers of type I allergy worldwide. Oriental plane trees, as Platanus orientalis, are an important source of airborne allergens in cities of the southwest Asia and southeast Europe. This study was aimed to identify relevant allergens of P. orientalis pollen and to ascertain whether P. orientalis allergens have cross-reactivity with related plane trees, such as Platanus acerifolia and Platanus occidentalis pollen components. Nineteen patients with a clinical history of reaction to P. orientalis pollen and a positive skin-prick test (SPT) to P. orientalis pollen extract were included in this study. Identification of IgE-binding proteins in Platanus pollen extracts was elucidated by immunoblotting using sera from P. orientalis pollen-sensitive patients. Cross-reactivity studies among P. orientalis allergens and relevant species was evaluated by immunoblot-inhibition and ELISA inhibition assays. All the patients were polysensitive and exhibited positive SPT to grass and tree pollen allergens. The IgE-binding pattern of P. orientalis pollen extract was well defined. The inhibition experiments showed that the capacity of P. occidentalis was greater than P. acerifolia pollen extract in preventing the reactivity of immobilized P. orientalis pollen extract with the IgE antibodies of patients. The 28-kDa molecule was the most frequent allergen among nine IgE-binding proteins of P. orientalis pollen. The IgE-reactive components of P. orientalis pollen showed a higher level of cross-reactivity with P. occidentalis pollen in comparison with P. acerifolia pollen.

Adventitious bud regeneration from leaf explants of Platanus occidentalis L. and genetic stability assessment

The aim of this work is to develop a method of plant regeneration from leaf explants of Platanus occidentalis L. successfully. Woody plant medium (HortScience 16:453–459, 1981) and Murashige and Skoog (Physiol Plant 15:473–497, 1962) medium were used as induced and rooted basal medium, respectively. The effects of combinations of 6-BA, IBA, NAA and KT with different concentrations on adventitious bud regeneration from P. occidentalis leaf explants were compared. The results showed that the highest shoot regeneration frequency (90%) and maximum number (13.72 ± 0.44) of shoots per explant was recorded on WPM medium supplemented with 22.20 mmol l−1 6-BA and 0.49 mmol l−1 IBA. A 40-day-old explants were much more productive for shoot formation than others in this study. The regenerated shoots were cultured on MS medium supplemented with 1.33 mmol l−1 6-BA, 0.16 mmol l−1 NAA and 2% (w/v) adenine, after 2-week shoots were transferred to 1/2 MS medium supplemented with 0.49 mmol l−1 IBA for rooting. Hardened plantlets via acclimatization were transferred to pots and transplanted to the soil finally. To ascertain whether tissue culture had effects on the genetic stability of plantlets regenerated, the genetic diversity was assessed using RAPD marker. A total of 96 bands ranging from 0.5 to 2.2 kb with an average of 6.4 bands per primer, were obtained using 15 primers. Amplified products exhibited few of polymorphic patterns across all the plants of P. occidentalis and the overall frequency of detection of somaclonal polymorphisms was lower than 0.0104%.

Aboveground biomass and nitrogen in four short-rotation woody crop species growing with different water and nutrient availabilities

We quantified the effect of water and nutrient availability on aboveground biomass and nitrogen accumulation and partitioning in four species from the southeastern United States, loblolly pine ( Pinus taeda), slash pine ( Pinus elliottii), sweetgum ( Liquidambar styraciflua), and sycamore ( Platanus occidentalis). The 6-year-old stands received five levels of resource input (control, irrigation with 3.05 cm water week −1, irrigation + 57 kg N ha −1 year −1, irrigation + 85 kg N ha −1 year −1, and irrigation + 114 kg N ha −1 year −1). Irrigation significantly increased foliage, stem, and branch biomass for sweetgum and sycamore, culminating in 103% and 238% increases in total aboveground biomass. Fertilization significantly increased aboveground components for all species resulting in 49, 58, 281, and 132% increases in total aboveground biomass for loblolly pine, slash pine, sweetgum, and sycamore, respectively. Standing total aboveground biomass of the fertilized treatments reached 79, 59, 48, and 54 Mg ha −1 for loblolly pine, slash pine, sweetgum, and sycamore, respectively. Fertilization increased foliar nitrogen concentration for loblolly pine, sweetgum, and sycamore foliage. Irrigation increased total stand nitrogen content by 6, 14, 93, and 161% for loblolly pine, slash pine, sweetgum, and sycamore, respectively. Fertilization increased total nitrogen content by 62, 53, 172, and 69% with maximum nitrogen contents of 267, 212, 237, and 203 kg ha −1 for loblolly pine, slash pine, sweetgum, and sycamore, respectively. Growth efficiency (stem growth per unit of leaf biomass) and nitrogen use efficiency (stem growth per unit of foliar nitrogen content) increased for the sycamore and sweetgum, but not the loblolly or slash pine.

First report of powdery mildew of Platanus orientalis caused by Erysiphe platani in China

Platanus occidentalis L., called American sycamore or American plane, is native to North America. The trees are commonly planted throughout the world on the sides of roads and in parks. In June 201...

Influence of bark pH on the occurrence and distribution of tree canopy myxomycete species

This study compares the occurrence and distribution of myxomycete species in the canopy of living trees and neighboring grapevines. Corticolous myxomycetes of three temperate forests in southeastern USA were studied on six tree species (30 trees) and grapevines (30 vines) to determine distribution and occurrence of myxomycete species relating to geographic location, host species, and bark pH. The double-rope climbing technique was used to access the canopy and sample bark up to 16.5 m. Bark samples were examined in 580 moist chamber cultures and 44 myxomycete species were identified representing 21 genera, averaging 3.0 +/- 2.1 species per sample site. Jaccard's coefficient determined community similarity between five individuals of six tree species, Acer saccharum, Fraxinus americana, Liquidambar styraciflua, Liriodendron tulipifera, Platanus occidentalis and Tsuga canadensis, and neighboring grapevines, Vitis aestivalis and V. vulpina. Vertical variation in species richness was significantly different only for Platanus occidentalis and might be attributable to flaking of bark with increasing height in the canopy. Tsuga canadensis and neighboring grapevines had greatest community similarity. Cribraria violacea was observed on all tree and grapevine species except T. canadensis and neighboring grapevines. Occurrence and species assemblages of myxomycetes were associated with bark pH, not geographic location. Bark of V. aestivalis (pH 4.5) was more acidic than neighboring T. canadensis (pH 4.1), compared to grapevines of the same species neighboring other tree species. Results indicated that most species are not regionally restricted, and although some myxomycetes are associated with a certain pH range, others develop on any substratum. Future research protocols for corticolous myxomycetes should emphasize sampling adequate amounts of substrata in a local region from different host species that have a wide range of bark pH, ensuring a representative sample of species for an entire region.