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Pinus taeda is a key timber species, and extensive research has been conducted on its wood formation. However, a comprehensive investigation into the biosynthetic pathways of lignin, cellulose, and hemicellulose in P. taeda is lacking, resulting in an incomplete understanding of secondary cell wall (SCW) formation in this species. In this study, we systematically analyzed transcriptomic data from previously published sources and constructed detailed pathways for lignin, cellulose, and hemicellulose biosynthesis. We identified 188 lignin-related genes and 78 genes associated with cellulose and hemicellulose biosynthesis. An RT-qPCR highlighted 15 key lignin biosynthesis genes and 13 crucial genes for cellulose and hemicellulose biosynthesis. A STEM analysis showed that most essential enzyme-coding genes clustered into Profile 14, suggesting their significant role in SCW formation. Additionally, we identified seven NAC and six MYB transcription factors (TFs) from atypical evolutionary clades, with distinct expression patterns from those of the previously characterized NAC and MYB genes, indicating potentially unique functions in SCW formation. This research provides the first comprehensive overview of lignin, cellulose, and hemicellulose biosynthetic genes in P. taeda and underscores the importance of non-canonical NAC and MYB TFs, laying a genetic foundation for future studies on SCW regulatory mechanisms. [ABSTRACT FROM AUTHOR]

Increased tree mortality associated with hotter-drought events has rarely been recorded in mature (>10 years old) commercial plantations. However, we report a recent (2021–2022 warm season) event of this kind that occurred across the Mesopotamian region of Argentina, South America. We aimed to elucidate the mortality timing, rate, and magnitude associated with environmental and stand characteristics at local scale to determine which conditions make these productive systems more vulnerable to extreme climatic events. Using Sentinel-2 satellite images and field-data we estimated the canopy mortality from November 2021 to October 2022, in Pinus spp afforestations (mainly P. taeda). We found that spatio-temporal heterogeneity in canopy mortality was associated with variation in soil and topographic characteristics, but not in stand age and size. We found that canopy mortality occurs at greater extent, earlier and faster in shallow soils (≤ 0.6 m), while the lowest mortality occurred at depressed and waterlogged areas. Intermediate levels of mortality were observed in deep soils (> 1 m), where relatively higher mortality occurred in areas with shallow water table signs, inhibiting deep root development. Our results suggest that sites allowing a deeper rooting system and/or where soil water availability is expected to be higher and long-lasting could represent areas with low-mortality risk for fast-growing pine plantations. [ABSTRACT FROM AUTHOR]

Insectivorous bats in temperate zones have evolved strategies such as migration or hibernation to overcome challenges of reduced resource availability and increased energy demand during winter. In the southeastern United States Coastal Plain, bats are either year‐round residents and remain active during winter or are migrants from colder areas seeking milder temperatures. Southeastern Coastal Plain forests also may represent important areas for remnant populations of species impacted by white‐nose syndrome. Working pine (Pinus spp.) forests comprise a large proportion of southeastern Coastal Plain forests, yet winter bat habitat associations and how forest management affects bat use remain understudied. Hence, we used hierarchical multispecies spatial occupancy models to evaluate factors influencing winter bat occupancy and foraging habitat associations in working forests of the southeastern Coastal Plain. From January to March 2020–2022, we deployed Anabat Swift acoustic detectors and measured site‐ and landscape‐level covariates on six working landscapes. We detected five species of bats and three species groups at 93% (224/240) of sites. We observed higher species richness at sites with high proportions of contiguous forest and low levels of basal area. At the species level, occupancy patterns were influenced by site and landscape covariates, which had varying effects on species with distinct foraging strategies. Temperature was an important predictor of detectability. Our findings offer new insights into the ecology of bats in working forest landscapes during winter, where we highlight positive responses in occupancy with contiguous forests and lower levels of basal area, as in previous summer work. By providing valuable information on winter community composition and foraging habitat associations, we hope to guide management decisions for forest attributes important to these species, thus increasing conservation opportunities within working forests. [ABSTRACT FROM AUTHOR]

Plantation forests were introduced into South Africa to satisfy the regional demand for wood-based products, which are largely found in the Mpumalanga province. To better understand the impacts of climate on the dominant height growth of commercially important plantation species, enumeration data collected from 2012 to 2023 was scrutinised, representing 34740 plots in 2082 plantation compartments. Statistically significant multiple linear regression models were developed to predict dominant heights for Pinus elliottii, Pinus taeda, Pinus patula, and Pinus patulax Pinus tecunumanii hybrids using climate variables as independent factors. Mean annual maximum temperature was statistically significant when modelling dominant height for P. elliottii, while winter maximum temperature was significant for P. taeda, P. patula, and P. patula x P. tecunumanii. Rainfall was found to be significant for P. elliottii and P. taeda, while spring rainfall was found to be more important when modelling dominant height for P. patula. Interestingly, autumn rainfall was found to have a negative impact on dominant height growth of P. taeda and P. patula, while rainfall was not significant in P. patula x P. tecunumanii. The findings imply that the southern pines have water thresholds, while Mexican pines are more temperature limited than water limited. [ABSTRACT FROM AUTHOR]

Loblolly pine (Pinus taeda L.) grown on infertile coastal plain soils typically shows a growth response to N and P applied at mid-rotation. The objectives of this study were to determine whether less soluble poultry litter ash (PLA) provides an adequate supply of P compared to triple superphosphate (TSP), and assess effects on P mineralization and runoff loss. Effects of 56 kg P ha−1 as either PLA or TSP, and no fertilization were compared using an 11-year-old stand of two loblolly pine genotypes on a loamy sand in a completely randomized design. Tree height, diameter and foliar nutrients, soil Mehlich 3 P and phosphatase activity (A and E horizons), and P in surface runoff were monitored. Through more than two years, P fertilization had no effect on tree growth. Similar foliar P with PLA or TSP, together with increasing foliar and soil P over time, suggested that PLA is an adequate source of P for loblolly pine. Neither fertilizer suppressed P mineralization as measured by phosphatase activity. The advantage of PLA compared to TSP is potentially much less runoff P loss. [ABSTRACT FROM AUTHOR]

Ectomycorrhizal fungi and non-ectomycorrhizal fungi are responsive to changes in environmental and nutrient availabilities. Although many species of ectomycorrhizas are known to enhance the uptake of phosphorus and other nutrients for Pinus taeda, it is not understood how to optimize these communities to have tangible effects on plantation silviculture and P use efficiency. The first step of this process is the identification of native fungi present in the system that are associated with P. taeda and influence P uptake efficiency. We used sand-filled mesh bags baited with finely ground apatite to sample ectomycorrhizal and non-ectomycorrhizal fungi associated with the rhizosphere of P-responsive P. taeda under several field conditions. Mesh bags were assessed for biomass accumulation over three years using a single three-month burial period pre-harvest and three six-month burial periods post-planting. Amplicon sequencing assessed ectomycorrhizal and non-ectomycorrhizal communities between phosphorus treatments, sites, mesh bags, and the rhizosphere of actively growing P. taeda in the field. We found biomass accumulation within the mesh bags was inversely related to increasing phosphorus fertilization (carryover) rates from pre-harvest to postplanting. Up to 25% increases in total biomass within the bags were observed for bags baited with P. Taxonomic richness was highest in Alfisol soils treated with phosphorus from the previous rotation and lowest in the Spodosol regardless of phosphorus treatment. [ABSTRACT FROM AUTHOR]

Aims: To improve soil phosphorus (P) testing in silvicultural systems, we assess microdialysis to study concentrations and establish a standard methodology to assess soil diffusive P and in-vivo translocated sap flow P under variable rates of P carryover from a previous rotation across various soils. Methods: Soils were collected from each treatment in the field and analyzed in laboratory conditions. Soils were analyzed for diffusive soil P using microdialysis and Mehlich III for comparison. Sap flow P measurements were collected in the field from 16 trees, one tree per treatment and replication over four hours. Results: Spodosol soils had higher diffusive P levels than Alfisol soils. On average, diffusive P increased by 137% in Spodosol and 166% in Alfisol from pre- to post-planting of a new stand. In the Alfisol, diffusive P showed a strong relationship with tree height, while no significant association was observed in the Spodosol. The Mehlich III soil extractions were positively related to the Alfisol but not the Spodosol. Microdialysis samples collected from the trees responded to changes in fertilization rates and were shown to be positively related to tree heights and Mehlich soil P tests. Atmospheric conditions substantially impacted sap flow P, with samples collected in full sunlight showing an average increase of 100% compared to overcast conditions. Conclusions: These findings demonstrate the potential of microdialysis as a valuable tool for soil P testing and its application in addressing complex questions related to P translocation and tree physiology in silvicultural settings. [ABSTRACT FROM AUTHOR]

RESUMO Nesse trabalho avaliou-se a granulometria de partículas de madeira de Pinus taeda em combinação com adesivos comerciais para a fabricação de chapas de madeira aglomerada. Foram produzidas chapas utilizando duas granulometrias - partículas que passaram em peneira com malha de 4,37 mm de diâmetro e ficaram retidas em peneira de 0,61 mm (tipo A); e partículas que passaram em peneira de 2,00 mm de diâmetro e ficaram retidas em peneira de 0,61 mm de diâmetro (tipo B). O conteúdo de adesivo utilizado foi de 8% (base peso seco) tanto para Uréia formaldeído (PL 2080) como para fenol formaldeído (PB 2045). Avaliou-se as propriedades de flexão estática, ligação interna e inchamento em espessura (norma americana ASTM D-1037). As chapas produzidas com partículas de granulometria menor (tipo B) apresentaram maior resitência à tração, enquanto que aquelas produzidas com partículas de maior granulometria (tipo A) apresentaram maior resistência à flexão estática. As chapas produzidas com adesivo fenol formaldeído foram mais resistentes à flexão estática. Em relação ao inchamento em espessura, as chapas feitas a partir de adesivos fenol formaldeído e particulas do tipo A, apresentaram menores valores. Pode-se concluir finalmente que partículas, como as utilizadas neste trabalho, geralmente produzidas a partir de resíduos de madeira, podem gerar chapas com qualidade satisfatória.

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This study aimed to investigate the chemical composition and some biological activities of the essential oils (EOs) from needles of Pinus canariensis, P. jeffreyi, and P. taeda cultivated in Tunisia. The chemical composition of the EOs revealed the presence of 119 components, with monoterpene hydrocarbons (in EOs of P. canariensis and P. taeda) and sesquiterpene hydrocarbons (in P. jeffreyi EO) being the main chemical classes. The EOs showed significant inhibitory effects on the germination and seedling and radical growth of the weeds, Sinapis arvensis, Lolium rigidum, and Trifolium campestre. The EO of P. jeffreyi exhibited the highest phytotoxicity, while T. campestre was the most tolerant seed. The EOs showed antibiofilm activity against Gram-positive (Staphylococcus aureus and Listeria monocytogenes) and Gram-negative (Acinetobacter baumannii, Pseudomonas aeruginosa, and Escherichia coli) pathogenic bacterial strains, depending on the EO, and the concentration tested. Overall, the EOs displayed efficacy against mature biofilms and were effective also against the metabolism of the sessile cells in the biofilm. These findings provide valuable insights into the potential applications of these EOs in phytotoxic and antibiofilm strategies, for agriculture, food and pharmaceutical fields. [ABSTRACT FROM AUTHOR]

Copyright of Environmental & Social Management Journal / Revista de Gestão Social e Ambiental is the property of Environmental & Social Management Journal and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Context: In Uruguay, numerous Pinus taeda plantations are at final-turn age, but they still do not have commercial destination and are exported as green-wood logs. For the development of this sector, it is necessary to strive towards a comprehensive processing of this resource. Method: This work focused on analyzing the use of Pinus taeda wood available in the country to produce brown kraft pulp with a kappa number of 80, which can be used to make packaging paper. As raw materials, we employed by-products from the mechanical wood-transformation industry (wood chips and thinning wood) and final-turn wood. Pulping tests were carried out, varying the alkali charge and the H-factor while aiming for a kappa number of 80. The viscosity, pulping, and rejection yield were measured in the pulps, and the pH and residual alkali content were evaluated in black liquor. Results: Based on the results, the best pulping conditions were an active alkali charge of 14% (Na2O) and an H-factor of 1260 for sawmill chips and thinning wood, as well as an active alkali charge of 14% (Na2O) and an H-factor of 1080 for final-turn wood. The pulp obtained with sawmill chips exhibited the most resistant fibers, and the final-turn wood pulp was the most sensitive to the refining process. Under the aforementioned conditions, the paper properties of laboratory-produced pulp are comparable with those of commercial pulp. Conclusions: This indicates that it is technologically possible to produce brown kraft pulp from Uruguayan Pinus taeda wood, with adequate quality to produce packaging paper

RESUMO O objetivo deste trabalho foi avaliar a aptidão tecnológica de cinco espécies florestais, nativas e exóticas, combinadas com cimento Portland tipo CP II para o emprego na produção de painéis de cimento-madeíra, através do estudo do calor de hidratação desse compósito. A metodologia empregada para mensuração do tempo e temperatura de hidratação do cimento quando combinado ou não com as partículas das espécies foi a coleta, em intervalos de uma hora, da temperatura de hidratação de quatro amostras da mistura cimento, partículas e água, até no momento em que a mesma atingisse o valor máximo. Uma equação matemática foi utilizada para se determinar os índices de inibição para cada espécie. Os dados foram analisados comparando-se a temperatura máxima de hidratação, bem como o tempo necessário para se atingir essa temperatura e, ainda, os índices de inibição. Os resultados indicaram que as espécies com maior e menor aptidão ao uso em chapas minerais foram Eucalyptus citriodora e Leucaena leucocephala, respectivamente.

Enhancement of net primary production (NPP) in forests as atmospheric [CO2] increases is likely limited by the availability of other growth resources. The Duke Free Air CO2 Enrichment (FACE) experiment was located on a moderate‐fertility site in the southeastern US, in a loblolly pine (Pinus taeda L.) plantation with broadleaved species growing mostly in mid‐canopy and understory. Duke FACE ran from 1994 to 2010 and combined elevated [CO2] (eCO2) with nitrogen (N) additions. We assessed the spatial and temporal variation of NPP response using a dataset that includes previously unpublished data from 6 years of the replicated CO2 × N experiment and extends to 2 years beyond the termination of enrichment. Averaged over time (1997–2010), NPP of pine and broadleaved species were 38% and 52% higher under eCO2 compared to ambient conditions. Furthermore, there was no evidence of a decline in enhancement over time in any plot regardless of its native site quality. The relation between spatial variation in the response and native site quality was suggested but inconclusive. Nitrogen amendments under eCO2, in turn, resulted in an additional 11% increase in pine NPP. For pine, the eCO2‐induced increase in NPP was similar above‐ and belowground and was driven by both increased leaf area index (L) and production efficiency (PE = NPP/L). For broadleaved species, coarse‐root biomass production was more than 200% higher under eCO2 and accounted for the entire production response, driven by increased PE. Notably, the fraction of annual NPP retained in total living biomass was higher under eCO2, reflecting a slight shift in allocation fraction to woody mass and a lower mortality rate. Our findings also imply that tree growth may not have been only N‐limited, but perhaps constrained by the availability of other nutrients. The observed sustained NPP enhancement, even without N‐additions, demonstrates no progressive N limitation. [ABSTRACT FROM AUTHOR]

The aim of this research was to evaluate the bond-line strength and chemical changes of pine (Pinus taeda) and itauba (Mezilaurus itauba) joints welded by rotary friction and the use of the internal standard method with Rietveld refinement for the determination of the absolute cellulose crystallinity of wood samples. The specimens were composed of itauba dowels welded in substrates made of pine and itauba wood. The shear engaged by tensile pullout of the dowels was determined by mechanical tensile tests. Furthermore, macrostructural evaluation of the specimens and attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) and X-ray diffraction (XRD) tests were performed. The cellulose crystallinity was determined quantitatively by the internal standard method with Rietveld refinement and compared with the Segal and the deconvolution qualitative methods. The results reveal that itauba dowels welded in itauba substrates produce stronger joints (0.81 MPa) and slighter chemical changes than in pine substrates (0.62 MPa). The welded bond-line of itauba dowel and pine substrate has greater cellulose crystallinity than that of itauba dowel and substrate. The cellulose crystallinity is qualitatively consistent for the three applied methods, however, quantitatively, there are divergences between them. [ABSTRACT FROM AUTHOR]

Ectomycorrhizal fungi and non-ectomycorrhizal fungi are responsive to changes in environmental and nutrient availabilities. Although many species of ectomycorrhizas are known to enhance the uptake of phosphorus and other nutrients for Pinus taeda, it is not understood how to optimize these communities to have tangible effects on plantation silviculture and P use efficiency. The first step of this process is the identification of native fungi present in the system that are associated with P. taeda and influence P uptake efficiency. We used sand-filled mesh bags baited with finely ground apatite to sample ectomycorrhizal and non-ectomycorrhizal fungi associated with the rhizosphere of P-responsive P. taeda under several field conditions. Mesh bags were assessed for biomass accumulation over three years using a single three-month burial period pre-harvest and three six-month burial periods post-planting. Amplicon sequencing assessed ectomycorrhizal and non-ectomycorrhizal communities between phosphorus treatments, sites, mesh bags, and the rhizosphere of actively growing P. taeda in the field. We found biomass accumulation within the mesh bags was inversely related to increasing phosphorus fertilization (carryover) rates from pre-harvest to post-planting. Up to 25% increases in total biomass within the bags were observed for bags baited with P. Taxonomic richness was highest in Alfisol soils treated with phosphorus from the previous rotation and lowest in the Spodosol regardless of phosphorus treatment.

Owing to its physico-mechanical properties, wood is widely used in housing for both outdoor structures and indoors in floors, ceilings and others. However, its vulnerability to fire makes protection necessary for occupant safety and damage prevention. In this study, the fire performance of Pinus taeda (loblolly pine) wood from northeastern Uruguay treated with zinc borate synthetized in our laboratory is tested. The effect of leaching on zinc borate fire retardant properties was also evaluated. The following parameters associated with the thermal degradation process of wood were analyzed: flame spread, carbonized area, carbonization index and mass loss. The wood was radially and tangentially exposed to the flame in a Vandersall tunnel under controlled conditions for three exposure times: 30, 60, and 80 seconds. The micromorphology of the surfaces exposed to the flame at each exposure time was analyzed with a scanning electron microscope in order to evaluate fiber damage, zinc borate distribution within the wood, and the effects of leaching on fire performance. A clear improvement in the fire resistance of the zinc borate -treated wood could be verified for all exposure times; leaching did not affect its fire retardant properties despite the harsh conditions of the test, making the product potentially suitable for outdoor use.

Faced with the need for innovation and waste reduction that the market demands, the high consumption of adhesive in the furniture industry led to the need and interest in studying ways to reduce this consumption, through changes in the bonding process without compromising the mechanical properties of the bonded material. The collage is carried out to form Edge Glued Panels of Pinus taeda (loblolly pine), using PolyVinyl Acetate adhesive with an average weight of 205 g/m². If lower weights are used, using the current application method (roller), mechanical strength problems begin to arise. The objective of this work was to study the feasibility of applying glue by another method (spray) with weights and, consequently, shorter pressing times, to evaluate the conservation of the mechanical properties of the panels through shear and traction tests. For that, samples were made according to the standards with the current situation of bonding (weight of 205 g/m² and pressing time of 80 s), to obtain reference results in the tests, and in the proposed situations (adhesive weights of 125 g/m² and 80 g/m² and pressing times of 70 s and 75 s), in an attempt to reach the established reference values. Regarding the results, it was feasible to conclude that the current method could be replaced by the proposed one, using the spray together with an adhesive weight of 125 g/m² and pressing times of 75 s and 70 s, with no statistically significant difference for the current method

Light acts as a complex signal, influencing various plant physiological, phenological and morphogenetic traits. Although previous studies have explored the effects of varying light levels on branch growth and survival, the underlying mechanisms of branch mortality under shade conditions remain poorly understood, hindering our understanding of canopy dynamics. In this study, contrasting shade conditions were imposed on Pinus taeda branches, and the changes in their water relations and carbon dynamics were evaluated. Monthly measurements of the photosynthetic light–response curve (LRC), sap flow and water potential of the branches were conducted. Furthermore, the conditions that led to the deaths of lower branches were investigated, and principal component analysis (PCA) was used to classify branches according to their mortality status. Significant shade treatment effects were observed for all photosynthetic parameters. The assimilation at light saturation (Amax), dark respiration rate (Rd), apparent quantum yield (AQY), light compensation point (LCP) and light saturation point (LSP) all decreased from full light to deepest shade, whereas the opposite was the case for the convexity term (θ). All water relations traits also decreased from full light to deepest shade; however, although significant shade effect was observed in stomatal conductance (gs) and sap flow, the differences in the pre-dawn (Ψpre-dawn) and mid-day (Ψmid-day) water potentials among treatments were not statistically significant. The PCA classification results showed that it could be used as a reliable method to screen for branch mortality as early as four months before mortality becomes evident. Our results shed more light on branch physiology and mortality under shade and have the potential to help improve the prediction of tree crown size, ultimately improving process-based forest growth models. [ABSTRACT FROM AUTHOR]

PremiseAn informatics approach was used for the construction of an Axiom genotyping array from heterogeneous, high-throughput sequence data to assess the complex genome of loblolly pine (Pinus taeda).MethodsHigh-throughput sequence data, sourced from exome capture and whole genome reduced-representation approaches from 2698 trees across five sequence populations, were analyzed with the improved genome assembly and annotation for the loblolly pine. A variant detection, filtering, and probe design pipeline was developed to detect true variants across and within populations. From 8.27 million variants, a total of 642,275 were evaluated and 423,695 of those were screened across a range-wide population.ResultsThe final informatics and screening approach delivered an Axiom array representing 46,439 high-confidence variants to the forest tree breeding and genetics community. Based on the annotated reference genome, 34% were located in or directly upstream or downstream of genic regions.DiscussionThe Pita50K array represents a genome-wide resource developed from sequence data for an economically important conifer, loblolly pine. It uniquely integrates independent projects that assessed trees sampled across the native range. The challenges associated with the large and repetitive genome are addressed in the development of this resource.

Chip size distribution is important in kraft pulping, as it affects chemical use, quality, and yield in pulp production. Pinus taeda logs with two storage periods (0 and 2 weeks) and two log lengths (2.4 and 7.0 m) were processed with a disc chipper. Logs stored for two weeks produced chips with 7% less moisture than logs with no storage period. The storage period significantly influenced the quantities of overthick, accept, pin, and fines classes. Logs stored for two weeks produced 1.7% more overthick, 3.8% more pin, and 1.1% fines than logs with no stocking period. Consequently, the amount of accept produced was 6.2% higher for chips from processing freshly harvested logs. Log length influenced the produced quantities of oversize, overthick, and accept. Logs with a length of 2.4 m produced chips with 1.4% more oversize, 2.5% more overthick, and 4.6% less accept, compared to 7.0 m logs. Thus, it was concluded that Pinus taeda logs with shorter storage periods and longer lengths generate more chips in the “accept" class.

Chip size distribution is important in kraft pulping, as it affects chemical use, quality, and yield in pulp production. Pinus taeda logs with two storage periods (0 and 2 weeks) and two log lengths (2.4 and 7.0 m) were processed with a disc chipper. Logs stored for two weeks produced chips with 7% less moisture than logs with no storage period. The storage period significantly influenced the quantities of overthick, accept, pin, and fines classes. Logs stored for two weeks produced 1.7% more overthick, 3.8% more pin, and 1.1% fines than logs with no stocking period. Consequently, the amount of accept produced was 6.2% higher for chips from processing freshly harvested logs. Log length influenced the produced quantities of oversize, overthick, and accept. Logs with a length of 2.4 m produced chips with 1.4% more oversize, 2.5% more overthick, and 4.6% less accept, compared to 7.0 m logs. Thus, it was concluded that Pinus taeda logs with shorter storage periods and longer lengths generate more chips in the “accept" class. [ABSTRACT FROM AUTHOR]

To facilitate the utility of genetic improvement in loblolly pine, individual-tree volume (productivity) scores estimated from single-tree plot or row-plot progeny test designs were compared with stand-level volume per unit area from block plots. A large number of families representing a wide range of progeny test scores for volume were established in growth and yield trials to generalize the results to families created by the breeding program. Individual-tree volume scores from progeny tests strongly corresponded with stand-level volume from block plots, especially after accounting for site quality and the risk of fusiform rust disease. A ten-point increase in the volume score from progeny test data was estimated to increase stand-level volume by 3.9 m3 ha-1 at age 6 years. A prediction model is presented that includes a new statistic, rust risk index, which is the expected rust incidence for a family at a new site when the hazard of rust for a checklot can be estimated from historical data. The study results through age 6 years corroborate the Performance Rating System as effective in guiding family deployment decisions. The models presented are based on pre-crown closure data at 6 years and will be updated with older measurements as the study matures. Study Implications: The Performance Rating System (PRS™) has been a successful tool for presenting genetic merit of improved loblolly pine families for landowners and forest managers in a more coherent and standardized manner. This system can be easily applied in other forest tree improvement programs, because it makes genetic improvement user-friendly for silviculturists and forest managers. Landowners can use this system to make decisions for selecting improved families suited to their specific forest management objectives. Seed orchard and nursery managers also depend on the PRS to choose the families to produce and as a third-party verification to market their genetic merit to customers. This study demonstrates that higher stand-level volume per unit area can be achieved when forest managers plant fast growing families with low fusiform rust disease risk on productive sites. The combined effect of genetic improvement for productivity and fusiform rust disease resistance is significant on stand-level volume per unit area. [ABSTRACT FROM AUTHOR]

The Nantucket pine tip moth (NPTM) (Rhyacionia frustrana Comstock) is a native, regeneration pest of young loblolly pines (Pinus taeda L.), causing shoot dieback, tree deformity, and growth and volume declines. Soil applications of systemic insecticides may be an effective strategy to suppress NPTM populations. The study objective was to assess the efficacy of four systemic insecticide treatments (chlorantraniliprole, dinotefuran, fipronil, and imidacloprid) for two growing seasons in outplanted bareroot and containerized seedling trials. Response variables included NPTM infestation rates, along with tree height, groundline diameter, volume index, and stem form. Infestation rates significantly decreased for each systemic insecticide treatment during the first year compared to controls, although dinotefuran and imidacloprid provided season-long control in one trial. Chlorantraniliprole reduced NPTM infestation rates for two growing seasons in both trials. While imidacloprid treatments did not alter growth metrics except for one comparison, fipronil and dinotefuran treatments improved several growth metrics. Chlorantraniliprole consistently improved growth metrics throughout the study. [ABSTRACT FROM AUTHOR]

Loblolly pine (Pinus taeda L.) is the most widely planted forest tree species in the United States. Most of the seedlings used to establish these plantations come from seed collected in open-pollinated seed orchards, but an increasing number are coming from controlled crosses, about 15%–20% of the loblolly pine seedling crops in the last five years. To produce this seed, millions of pollination bags are installed each spring in orchards throughout the southeastern United States; over 2.6 million bags were installed in 2022. This study evaluated 13 pollination bag types available for use in the mass production of control-cross seed. Using cone analysis, significant differences were found among bag types for the proportion of ovules resulting in filled seed, empty seed, and first-year aborts. Due to differences in the efficacy of orchard management, study trees varied greatly in their proportion of ovules resulting in filled seed and first-year aborts. Under good orchard management, open-pollinated cones had 72% of their ovules as filled seed and 12% in first-year aborted ovules. The best pollination bag type had 62% of its ovules as filled seed with 22% in first-year aborted ovules. These differences are apparently due to the quality of pollen used in the controlled crosses. Study Implications : Compared with open-pollinated families, full-sibling crosses among elite parents of loblolly pine produce more market value to landowners due to greater productivity, increased disease resistance, and enhanced stem form. Specific crosses of loblolly pine have occupied about 15%–20% of the recent seedling market because the seed are costly and difficult to produce. This study tested pollination bag types to determine their effectiveness in producing control-cross seed. Some bag types were superior in increasing seed yield, but seed yields for open-pollinated cones tended to be higher, suggesting problems in the control-cross process. Cone analysis is a useful tool for seed orchard managers to diagnose problems in seed production. Understanding and correcting these problems will help managers increase their production of full-sibling seed and lead to the establishment of new plantations with increased forest productivity. [ABSTRACT FROM AUTHOR]

This study used non-destructive testing with ultrasonic and stress wave propagation to evaluate bending strength and stiffness of wood-polymer composites. Twelve composite plate products were produced with different formulations of polymer matrix (high- and low-density polyethylene and polypropylene) and type and proportion of flour (coconut shell and wood). Mechanical and acoustic properties were influenced primarily by the type of matrix used in the composite. The greater the proportion of wood and coconut shell flour the higher the wave propagation velocity, stiffness, and strength. We found a correlation between mechanical properties (strength and stiffness) and wave velocity and stiffness coefficient. We also present linear regression equations of the stiffness and strength of the specimen as a function of wave velocity and stiffness coefficient obtained through non-destructive testing. For polypropylene and high-density polyethylene matrix composites, the stiffness coefficient provided a better estimate of stiffness, while for low-density polyethylene the wave velocity provided better results.

Summary: To distinguish among hypotheses on the importance of resource‐exchange ratios in outcomes of mutualisms, we measured resource (carbon (C), nitrogen (N), and phosphorus (P)) transfers and their ratios, between Pinus taeda seedlings and two ectomycorrhizal (EM) fungal species, Rhizopogon roseolus and Pisolithus arhizus in a laboratory experiment.We evaluated how ambient light affected those resource fluxes and ratios over three time periods (10, 20, and 30 wk) and the consequences for plant and fungal biomass accrual, in environmental chambers.Our results suggest that light availability is an important factor driving absolute fluxes of N, P, and C, but not exchange ratios, although its effects vary among EM fungal species. Declines in N : C and P : C exchange ratios over time, as soil nutrient availability likely declined, were consistent with predictions of biological market models. Absolute transfer of P was an important predictor of both plant and fungal biomass, consistent with the excess resource‐exchange hypothesis, and N transfer to plants was positively associated with fungal biomass.Altogether, light effects on resource fluxes indicated mixed support for various theoretical frameworks, while results on biomass accrual better supported the excess resource‐exchange hypothesis, although among‐species variability is in need of further characterization. [ABSTRACT FROM AUTHOR]

As awareness of climate change increases, the need for carbon neutral fuel sources is growing. Lignocellulosic biofuel derived from pine trees has been suggested as one potential energy source; however, it requires more research before its efficacy for climate change mitigation can be determined. Due to the large share of forest carbon held in soils and the extensive area of pine plantations in the southeast U.S., a better understanding of plantation soil carbon dynamics is critical for biofuel carbon accounting. This study evaluated the effects of canopy development and productivity on soil CO2 efflux, a proxy for soil respiration (Rs), in an intensively managed loblolly pine (Pinus taeda) stand over a period from May 2015 to December 2019. We found that leaf area index (LAI) and gross ecosystem production (GEP), as well as meteorological variables, had significant effects on Rs, but that both overall Rs and soil carbon pools did not increase over the course of the study. We thus hypothesize that GEP and LAI had intra-annual effects on Rs, and that the lack of change in Rs is the result of an increase in autotrophic respiration (Ra) that offset a decrease in decomposition of the previous stand's organic matter. [ABSTRACT FROM AUTHOR]

Particleboard can be produced from a mixture of different lignocellulosic materials, which can be chosen depending on the density required for the panel and its applications. The aim of this study was to evaluate the mechanical properties of particleboard with bamboo, pine and mate for a new product of high density for the special applications currently served by HDF. Particles of bamboo (Phyllostachys aurea) finely chopped sticks of mate (Ilex paraguariensis) and commercial particles of southern pine (Pinus taeda) wood were used. These particles used 100 % by weight in the panel or in mixtures of 50 % each (three mixtures) or in a triple mixture of one third each, were glued in a drum-type rotary mixer with melamine-urea-formaldehyde (MUF) resin, and pressed in hydraulic press at 120 °C and 5,88 MPa for 10 minutes, up to 6 mm thickness. The panels were produced with 900 kg/m3 nominal density and, after pressing, were conditioned at 20 °C and 65 % relative humidity. Statistical was performed by means the variance analysis and simplex centroid experimental design, with three replicates. It was found the use of pine particles contributed mainly to increase the panel's strength and stiffness, while the use of mate particles facilitated internal bond strength. The mixtures modeling showed that the water absorption, the strength and stiffness in bending and the internal bond strength are explained by the cubic model, while the thickness swelling and hardness are explained by the quadratic model. The best physical and mechanical properties results were found for the pine, bamboo and mate same ratio mixture. [ABSTRACT FROM AUTHOR]

Biological ageing is connected to life history variation across ecological scales and informs a basic understanding of age‐related declines in organismal function. Altered DNA methylation dynamics are a conserved aspect of biological ageing and have recently been modelled to predict chronological age among vertebrate species. In addition to their utility in estimating individual age, differences between chronological and predicted ages arise due to acceleration or deceleration of epigenetic ageing, and these discrepancies are linked to disease risk and multiple life history traits. Although evidence suggests that patterns of DNA methylation can describe ageing in plants, predictions with epigenetic clocks have yet to be performed. Here, we resolve the DNA methylome across CpG, CHG, and CHH‐methylation contexts in the loblolly pine tree (Pinus taeda) and construct epigenetic clocks capable of predicting ages in this species within 6% of its maximum lifespan. Although patterns of CHH‐methylation showed little association with age, both CpG and CHG‐methylation contexts were strongly associated with ageing, largely becoming hypomethylated with age. Among age‐associated loci were those in close proximity to malate dehydrogenase, NADH dehydrogenase, and 18S and 26S ribosomal RNA genes. This study reports one of the first epigenetic clocks in plants and demonstrates the universality of age‐associated DNA methylation dynamics which can inform conservation and management practices, as well as our ecological and evolutionary understanding of biological ageing in plants. [ABSTRACT FROM AUTHOR]

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Loblolly pine (LP; Pinus taeda L.) is an economically and ecologically important tree in the southeastern U.S. To advance understanding of the loblolly pine (LP; Pinus taeda L.) genome, we sequenced and analyzed 100 BAC clones and performed a Cot analysis. The Cot analysis indicates that the genome is composed of 57, 24, and 10% highly-repetitive, moderately-repetitive, and single/low-copy sequences, respectively (the remaining 9% of the genome is a combination of fold back and damaged DNA). Although single/low-copy DNA only accounts for 10% of the LP genome, the amount of single/low-copy DNA in LP is still 14 times the size of the Arabidopsis genome. Since gene numbers in LP are similar to those in Arabidopsis, much of the single/low-copy DNA of LP would appear to be composed of DNA that is both gene- and repeat-poor. Macroarrays prepared from a LP bacterial artificial chromosome (BAC) library were hybridized with probes designed from cell wall synthesis/wood development cDNAs, and 50 of the "targeted" clones were selected for further analysis. An additional 25 clones were selected because they contained few repeats, while 25 more clones were selected at random. The 100 BAC clones were Sanger sequenced and assembled. Of the targeted BACs, 80% contained all or part of the cDNA used to target them. One targeted BAC was found to contain fungal DNA and was eliminated from further analysis. Combinations of similarity-based and ab initio gene prediction approaches were utilized to identify and characterize potential coding regions in the 99 BACs containing LP DNA. From this analysis, we identified 154 gene models (GMs) representing both putative protein-coding genes and likely pseudogenes. Ten of the GMs (all of which were specifically targeted) had enough support to be classified as intact genes. Interestingly, the 154 GMs had statistically indistinguishable (α = 0.05) distributions in the targeted and random BAC clones (15.18 and 12.61 GM/Mb, respectively), whereas the low-repeat BACs contained significantly fewer GMs (7.08 GM/Mb). However, when GM length was considered, the targeted BACs had a significantly greater percentage of their length in GMs (3.26%) when compared to random (1.63%) and low-repeat (0.62%) BACs. The results of our study provide insight into LP evolution and inform ongoing efforts to produce a reference genome sequence for LP, while characterization of genes involved in cell wall production highlights carbon metabolism pathways that can be leveraged for increasing wood production.

Neste trabalho são apresentadas as características e a resistência ao cisalhamento das interfaces soldadas por fricção rotativa (SFR) de cavilhas de madeira de itaúba em substratos de madeira de pinus. Os corpos de prova são compostos por cavilhas de itaúba e substratos de pinus, nos quais foram usinados pré-furos usando duas relações de diâmetro cavilha/pré-furo: 1,25 e 1,11. Após a SFR, as uniões soldadas foram submetidas a ensaios mecânicos de extração das cavilhas, a fim de se determinar a tensão de cisalhamento na ruptura. A macro e a microestrutura da interface soldada foram avaliadas visualmente e por microscopia eletrônica de varredura (MEV). Os resultados mostram que: a tensão de cisalhamento média na ruptura, para as relações diâmetro cavilha/pré-furo de 1,25 e 1,11, são de 2,41 e 1,77 MPa, respectivamente, indicando que, para as madeiras estudadas, a relação diâmetro cavilha/pré-furo de 1,25 apresenta ligações soldadas mais resistentes; a SFR ocasiona o escurecimento da interface de soldagem; o pré-furo e a cavilha, originalmente cilíndricos, assumem um formato cônico, durante o processo de SFR; a interface entre as madeiras de pinus e de itaúba é homogênea e bem soldada.

Rotary friction welding technique is a promising alternative of joining dowel-laminated timber (DLT) and dowelled cross-laminated timber (DCLT), without any adhesive. Studies on the welding of Brazilian woods are few and recent, mainly when determining the optimal welding parameters. Therefore, an exploratory study was carried out to evaluate the influence of pre-drilling hole and dowel feed rate on the welded surface strength of pine (Pinus taeda) and itauba (Mezilaurus itauba) joints, determining optimal welding parameters for these woods. The study was complemented with a macrostructural analysis of welded specimens and the determination of the taper rate of itauba dowels, to comprehend the mechanical performance of these welded joints. The specimens comprised itauba dowels, 10 mm in diameter, welded at a rotation of 1000 rpm and feed rates of 100, 300, 400 and 500 mm/min, into single-stage (8 mm in diameter) and two-stage (8 and 7 mm in diameter) pre-drilled holes, made in pine substrates. They were subjected to tensile tests and to macrostructure analysis. The results revealed that two-stage pre-drilled holes contributed to improving the mechanical strength of these welded joints. Feed rates higher than 100 mm/min avoid excessive wear and charring of the dowels, while feed rates lower than 500 mm/min prevent dowel splintering. The optimal welding parameters for pine joints welded with itauba dowels are two-stage pre-drilled holes and a feed rate of 400 mm/min.

Harvesting is a complex and expensive step within forestry operations. In mountainous terrain timber harvesting is complex due to the risks and limitations that the terrain imposes on traditional forms of wood extraction. The objective of this study was to evaluate the effective time of work cycle, productivity, operational costs, and production costs of tree extraction by means of a farm tractor with winch, in two work crew compositions: Crew A: one tractor operator and a choker setter; and Crew B: one tractor operator and two choker setters. The study was implemented in the Vale do Ribeira region of south-eastern Brazil, using a full tree-harvesting system through a time and motion study under different conditions of extraction distance (6–135 m), log yard (5–241 m), and ground slope (7–37°). To evaluate the cycles, a regression analysis was conducted for each treatment, and subsequently compared using the Graybill F-test. Next, a regression with a dummy variable was performed. Crew B showed an average productivity of 13.54 m3; per productive machine hour (PMH), which was higher than the 9.50 m3; PMH−1 of Crew A. The operational costs were US$33.52 PMH−1 for Crew A, and US$44.24 PMH−1 for Crew B. Despite the higher operational cost with Crew B, the increase in productivity resulted in a lower production cost up until the scenario of 120 m of winching distance. [ABSTRACT FROM AUTHOR]

Exogenously applied double-stranded RNA (dsRNA) can induce potent host specific gene knockdown and mortality in insects. The deployment of RNA-interference (RNAi) technologies for pest suppression is gaining traction in both agriculture and horticulture, but its implementation in forest systems is lagging. While numerous forest pests have demonstrated susceptibility to RNAi mediated gene silencing, including the southern pine beetle (SPB), Dendroctonus frontalis, multiple barriers stand between laboratory screening and real-world deployment. One such barrier is dsRNA delivery. One possible delivery method is through host plants, but an understanding of exogenous dsRNA movement through plant tissues is essential. Therefore, we sought to understand the translocation and persistence of dsRNAs designed for SPB throughout woody plant tissues after hydroponic exposure. Loblolly pine, Pinus taeda, seedlings were exposed to dsRNAs as a root soak, followed by destructive sampling. Total RNA was extracted from different tissue types including root, stem, crown, needle, and meristem, after which gel electrophoresis confirmed the recovery of the exogenous dsRNAs, which were further verified using Sanger sequencing. Both techniques confirmed the presence of the exogenously applied target dsRNAs in each tissue type after 1, 3, 5, and 7 d of dsRNA exposure. These findings suggest that root drench applications of exogenous dsRNAs could provide a viable delivery route for RNAi technology designed to combat tree feeding pests. [ABSTRACT FROM AUTHOR]

Climate change and harsh environmental conditions present significant barriers to the reforestation of surface-mined sites in Appalachia. An experimental site was established on a reclaimed surface mine in eastern Kentucky to investigate the impacts of soil amendments (fertilizer additions and mycorrhizal inoculations) on the growth and survival of northern red oak and loblolly pine, and the effects of amendments and species planted on soil development. While early effects of soil fertility and mycorrhizae treatments were apparent, these did not affect the growth or survival of either species after 10 growing seasons. Overall, loblolly pine exhibited greater growth (7.6 m) and survival (58%) than northern red oak (1.8 m height growth and 39% survival). While the poor growth and survival of northern red oak were attributed to heavy vegetative competition from nonnative species, loblolly pine rapidly achieved canopy closure and shaded out competitive understory vegetation. This study documents that non-native loblolly pine may serve as an important pioneering tree species in reforestation of reclaimed mine sites by potentially outcompeting invasive exotic understory plant species. We speculate that, by suppressing invasive species, loblolly pine may have the potential to serve as a "nurse tree" for more economically and ecologically desirable hardwood species. [ABSTRACT FROM AUTHOR]

Pine wilt disease (PWD) is one of the most devastating diseases of Pinus spp. and is caused by the pine wood nematode (PWN), Bursaphelenchus xylophilus (Steiner & Buhrer) Nickle. To study adaptation of PWN to survive in hosts that differ in resistance, we examined the self-regulatory characteristics of PWN at the biological and molecular levels early in the interaction. Two-year-old susceptible Pinus thunbergii and resistant Pinus taeda were selected for this experiment, and changes in PWNs after inoculation were assessed. qRT-PCR was used to detect changes in genes related to PWN pathogenicity and detoxification. The results showed that the migration and reproductive abilities of PWNs in P. thunbergii were stronger than those of PWNs in P. taeda. After 7 d, the number of nematodes in P. thunbergii was approximately 3.2-fold higher than in P. taeda. After 15 d, the number of nematodes in P. thunbergii was approximately twofold higher than that in P. taeda. Because PWN can adjust its sex ratio after infection, we compared the sex ratio of uninoculated PWNs, to that in the two pine species. In P. thunbergii, the female to male ratio first decreased and then stabilized over time; in P. taeda first decreased and then increased. Relative fat accumulation in PWNs increased significantly after the PWNs entered the tree body; the accumulation rate in P. thunbergii was higher than in P. taeda at 7 d, but lower after 15 d. Scanning electron microscopy (SEM) showed significantly more bacteria on the surface of PWNs in P. taeda compared with PWNs in susceptible P. thunbergii. At 12 h after inoculation, the expression of genes related to cell-wall degradation (BxBeta1-4 and Bxpel1), effectors (BxCDP1, BxSapB1), and active oxygen metabolism (Bxy-ctl-1 and BxGST3) was 2–6 × higher in the resistant pine than in the susceptible one. In contrast, in PWNs, the expression of autophagy-related genes BxATG1 and BxATG16 was 1.5–2 times higher in P. thunbergii than in P. taeda. These results indicate that the interaction between PWNs and pine trees with different resistance levels elicits a series of physiological and molecular adaptations that affect nematode reproduction and virulence. This study will help elucidate the adaptive mechanisms of PWN in different pine trees. [ABSTRACT FROM AUTHOR]

Plywood is widely used in civil construction. Due to the importance of preservation and gluing in bio-composites, this study compares the influence of a chemical treatment with CCA (chromated-copper-arsenate) on Pinus taeda L. wood veneers to produce two plywood types using phenol-formaldehyde (PF) and castor oil-based polyurethane (PU). Four different treatments were performed to analyze both varieties' physical and mechanical properties. As a result, an improvement in the properties of the treated panels was observed. Lower moisture contents and better interactions caused by less thickness swelling and water absorption were identified in the PU-based plywoods. The treatment with CCA was efficient, improving these properties when they were compared to the reference panels. Most treatments evidenced increases in the modulus of elasticity and modulus of rupture for both adhesives when the CCA treatment was applied to the veneers. Comparing the resins, the PF showed the best values of modulus of elasticity. All treatments met the requirements defined by the Brazilian standard document for the glue line shear. [ABSTRACT FROM AUTHOR]

The 22-gigabase genome of loblolly pine (Pinus taeda) is one of the largest ever sequenced. The draft assembly published in 2014 was built entirely from short Illumina reads, with lengths ranging from 100 to 250 base pairs (bp). The assembly was quite fragmented, containing over 11 million contigs whose weighted average (N50) size was 8206 bp. To improve this result, we generated approximately 12-fold coverage in long reads using the Single Molecule Real Time sequencing technology developed at Pacific Biosciences. We assembled the long and short reads together using the MaSuRCA mega-reads assembly algorithm, which produced a substantially better assembly, P. taeda version 2.0. The new assembly has an N50 contig size of 25 361, more than three times as large as achieved in the original assembly, and an N50 scaffold size of 107 821, 61% larger than the previous assembly.

Pinus taeda plantations depend directly on the supply of resources (light, water, and nutrients) available to the stand. However, studies quantifying edaphic and climatic factors in P. taeda stands are scarce. This study aimed to identify the main edaphic, climatic and stand factors that influence the productivity and growth pattern of P. taeda plantations in southern Brazil. A total of 24 stands, ranging between 8 and 10 years old were evaluated. Biometric variables such as height, diameter at breast height (DBH), stem analysis, growth rings, specific gravity, and soil chemical and physical variables were evaluated. Site index (SI), stem biomass, mean annual increment without bark (MAI) and correlations between variables were calculated. We observed that by nine years after planting, none of the plots had reached their maximum growth; and MAI, standing stem biomass and SI ranged from 15 to 35 m³ ha−1 year−1, 56–131 Mg ha−1, and 12–19 m, respectively, with higher values in Três Barras site. Stem biomass were positively related with SI (r = 0.89), and stem production was related with higher available water content (r = 0.41), warm temperatures (r = 0.61), and higher relative air humidity (r = 0.58). The study corroborates the role of nutrients, well-drained soils, mild climatic conditions, and low water deficit to explain the high yields of P. taeda in Brazil compared to other locations around the world. Based on these results, studies on fertilization, genetic material, and more frequent use of stem analysis, associated with X-ray densitometry, are recommended for P. taeda. • MAI and stem biomass of P. taeda were positively related with SI. • Stem production was highly related to available water content in P. taeda plantation. • Potential to increase P. taeda productivity in southern Brazil by fertilization. [ABSTRACT FROM AUTHOR]

Emissions of Biogenic Volatile Organic Compounds (BVOCs) observed during 2007 from an experimental Pinus taeda plantation in Central North Carolina are compared with model estimates from the Model of Emissions of Gases and Aerosols from Nature (MEGAN) version 2.1. Relaxed eddy accumulation (REA) estimates of 2-methyl-3-buten-2-ol (MBO) fluxes are a factor of 3-4 higher than MEGAN estimates. MEGAN monoterpene emission estimates were a factor of approximately two higher than REA flux measurements. MEGAN β-caryophyllene emission estimates were within 60% of growing season REA flux estimates but were several times higher than REA fluxes during cooler, dormant season periods. The sum of other sesquiterpene emissions estimated by MEGAN was several times higher than REA estimates throughout the year. Model components are examined to understand these discrepancies. Measured summertime leaf area index (LAI) (and therefore foliar biomass) is a factor of two higher than assumed in MEGAN for the P. taeda default. Increasing the canopy mean MBO emission factor from 0.35 to 1.0mgm(-2)h(-1) also reduces MEGAN vs. REA flux differences. This increase is within current MBO emission factor uncertainties. The algorithm within MEGAN which adjusts isoprene emission estimates as a function of the temperature and light of the previous 24h seems also to improve the seasonal MEGAN MBO correlation with REA fluxes. Including the effects of the previous 240h, however, seems to degrade temporal model correlation with fluxes. Monoterpene and sesquiterpene composition data from the REA are compared with MEGAN2.1 estimates and also branch enclosure and needle extract data collected at this site. To our knowledge, the flux data presented here are the first reported for MBO and sesquiterpenes from a P. taeda ecosystem.

Resistance to fusiform rust disease in loblolly pine (Pinus taeda) is a classic gene-for-gene system. Early resistance gene mapping in the P. taeda family 10-5 identified RAPD markers for a major fusiform rust resistance gene, Fr1. More recently, single nucleotide polymorphism (SNP) markers associated with resistance were mapped to a full-length gene model in the loblolly pine genome encoding for a nucleotidebinding site leucine-rich repeat (NLR) protein. NLR genes are one of the most abundant gene families in plant genomes and are involved in effector-triggered immunity. Inter- and intraspecies studies of NLR gene diversity and expression have resulted in improved disease resistance. To characterize NLR gene diversity and discover potential resistance genes, we assembled de novo transcriptomes from 92 loblolly genotypes from across the natural range of the species. In these transcriptomes, we identified novel NLR transcripts that are not present in the loblolly pine reference genome and found significant geographic diversity of NLR genes providing evidence of gene family evolution. We designed capture probes for these NLRs to identify and map SNPs that stably cosegregate with resistance to the SC20-21 isolate of Cronartium quercuum f.sp. fusiforme (Cqf) in half-sib progeny of the 10-5 family. We identified 10 SNPs and 2 quantitative trait loci associated with resistance to SC20-21 Cqf. The geographic diversity of NLR genes provides evidence of NLR gene family evolution in loblolly pine. The SNPs associated with rust resistance provide a resource to enhance breeding and deployment of resistant pine seedlings. [ABSTRACT FROM AUTHOR]

Successful colonization and growth of trees within herbaceous communities may result from different interactions with the herbaceous community. First, colonizing trees compete against larger, established herbs, while subsequent growth occurs among similarly sized or smaller herbs. This shift from colonization to growth may lead three drivers of community dynamics—nutrients, consumers, and herbaceous diversity—to differentially affect tree colonization and, later, tree performance. Initially, these drivers should favor larger, established herbs, reducing tree colonization. Later, when established trees can better compete with herbs, these drivers should benefit trees and increase their performance. In a 4-year study in a southeastern US old field, we added nutrients to, excluded aboveground consumers from, and manipulated initial richness of, the herbaceous community, and then allowed trees to naturally colonize these communities (from intact seedbanks or as seed rain) and grow. Nutrients and consumers had opposing effects on tree colonization and performance: adding nutrients and excluding consumers reduced tree colonization rate, but later increased the size of established trees (height, basal diameter). Adding nutrients and excluding consumers also restricted tree colonization to earlier years of study, which partially explained the effect of nutrient addition on plant size. Together, this shows differing impacts of nutrients and consumers: factors that initially limited tree colonization also resulted in larger established trees. This suggests that succession of grasslands that are either eutrophied or have diminished consumer pressure may experience lags and pulses in woody encroachment, leading to an extended period of herbaceous dominance followed by accelerated woody growth. [ABSTRACT FROM AUTHOR]

Previous studies have reported that phosphorus transporters are involved in glyphosate uptake by plants, so phosphorus fertilization might act as an attenuator of glyphosate effects on a possible drift. The objective of this study was to evaluate the influence of phosphorus fertilization on the initial growth of Pinus taeda genotypes submitted to glyphosate subdoses applied during two growing seasons, warm and cold. Four experiments were conducted in an open area using 10-L pots, two in the warm season (during 180 days after application on Genotypes 1 and 2) and two in the cold season (during 81 days after application on Genotypes 3 and 4). The treatments consisted of a 2 × 4 factorial scheme, with presence or absence of phosphorus fertilization (25.2 kg ha−1 P2O5) and four subdoses of glyphosate (0, 72, 144 and 288 g ha−1 acid equivalente), using five replicates. For warm season, glyphosate subdoses provided a stimulatory effect on the plant growth of both P. taeda genotypes independently of the fertilization condition. The supplementary phosphorus fertilization increased plant growth characteristic in both warm and cold season, regardless of the exposure to glyphosate subdoses. However, the plant response is dependent on the genotype. Glyphosate subdoses did not negatively affect P. taeda genotypes growth at both experimental seasons, regardless of phosphorus fertilization. [ABSTRACT FROM AUTHOR]