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Biotic factors in fungal exudates impact plant-fungal symbioses establishment. Mutualistic ectomycorrhizal fungi play various ecological roles in forest soils by interacting with trees. Despite progress in understanding secreted fungal signals, dynamics of signal production in situ before or during direct host root contact remain unclear. We need to better understand how variability in intra-species fungal signaling at these stages impacts symbiosis with host tissues. Using the ECM model Pisolithus microcarpus , we selected two isolates (Si9 and Si14) with different abilities to colonize Eucalyptus grandis roots. Hypothesizing that distinct early signalling and metabolite profiles between these isolates would influence colonization and symbiosis, we used microdialysis to non-destructively collect secreted metabolites from either the fungus, host, or both, capturing the dynamic interplay of pre-symbiotic signalling over 48 hours. Our findings revealed significant differences in metabolite profiles between Si9 and Si14, grown alone or with a host root. Si9, with lower colonization efficiency than Si14, secreted a more diverse range of compounds, including lipids, oligopeptides, and carboxylic acids. In contrast, Si14's secretions, similar to the host's, included more aminoglycosides. This study emphasizes the importance of intra-specific metabolomic diversity in ectomycorrhizal fungi, suggesting that early metabolite secretion is crucial for establishing successful mutualistic relationships. • Microdialysis was used to sample secreted metabolites non-destructively in situ • Two isolates of Pisolithus microcarpus has contrasting host colonization ability • The two isolates had significantly different metabolite profiles under axenic state • The isolate with lower root colonization produced a more diverse array of compounds • Metabolites from the isolate with higher colonization efficiency mirrored the host [ABSTRACT FROM AUTHOR]

Background: As an efficient and high-quality additive in agriculture and forestry production, silicon (Si) plays an important role in alleviating heavy metal stress and improving plant growth. However, the alleviating effect of aluminum (Al) toxicity by Si in Eucalyptus is still incomplete. Results: Here, a study was conducted using two Al concentrations (0 and 4.5 mM) with four Si concentrations (0, 0.5, 1, and 1.5 mM) to investigate plant growth, tolerance and antioxidant defense system in four Eucalyptus species (Eucalyptus tereticornis, Eucalyptus urophylla, Eucalyptus grandis, and Eucalyptus urophylla × Eucalyptus grandis). The results showed that the stress induced by 4.5 mM Al increased oxidative damage, disturbed the balance of enzymatic and non-enzymatic antioxidant systems, and negatively affected plant growth and tolerance quality in the four Eucalyptus species. However, the addition of 0.5 mM and 1 mM Si alleviated the effects of Al toxicity on plant growth and improved plant growth quality by strengthening stress tolerance. Besides, adding Si significantly facilitated the synergistic action of enzymatic and non-enzymatic antioxidant defenses, increased the removal of reactive oxygen species, reduced lipid peroxidation, and oxidative stress, and promoted the phytoremediation rate of the four Eucalyptus species by 18.7 ~ 34.8% compared to that in the absence of Si. Conclusions: Silicon can alleviate the effect of Al toxicity by enhancing the antioxidant capacity and improving plant growth and tolerance quality. Hence, the application of Si is an effective method for the phytoremediation of Eucalyptus plantations in southern China. [ABSTRACT FROM AUTHOR]

Spectral and texture features play important roles in plantation leaf area index (LAI) estimation, and their combination may enhance LAI inversion accuracy. Furthermore, research on the impact of different machine learning (ML) models on their hyperparameter combinations and splitting ratios remains challenging. In our study, experiments based on spectral and textural features of GF-6 WFV data were conducted on Eucalyptus grandis plantation forests in Huangmian Town, Guangxi, China. ML methods such as multiple stepwise regression (MSR), random forest (RF), back-propagation neural network (BPNN), and support vector regression (SVR) were mainly utilized to perform model hyper-parameter tuning and split-ratio analysis in order to estimate the LAI. The results of the study showed that spectral and gray level co-occurrence matrix (GLCM) texture features were very sensitive to changes in Eucalyptus grandis LAI. The accuracy of combining the two was 10% higher than when they were not combined. Furthermore, it was found that the nonlinear methods (RF, BPNN, and SVR) outperformed the linear method (MSR), with the average 2 Rmax of the nonlinear model being 26% higher than that of the linear model, and the RMSE value being 29% lower than that of the linear model. In addition, by analyzing different combinations of features, model hyperparameter fine-tuning, and splitting ratios in the nonlinear model, it was found that the splitting ratios of different combinations of model hyperparameters have a great impact on the accuracy of the model. A total of 12 out of 21 data sets showed high accuracy and stability at a split ratio of 8.5:1.5 (ratio of 0.85), with the best-performing RF model differing from the lowest by 91% for 2 max R and 39% for 2 Rstd. Combining spectral and texture features provides highly accurate inversion data. Model hyper-parameter fine-tuning and segmental scale tuning can facilitate the application of inversion data to fully utilize the optimal performance of the ML model. [ABSTRACT FROM AUTHOR]

Introduction: Boron (B) is critical for plant growth, yet its movement in soil is often hindered by leaching and adsorption, leading to deficiencies. Tackling these issues is essential for boosting agricultural productivity, especially in plants like Eucalyptus with high B needs. This paper aims to address these challenges by evaluating B-doped biochar composites (biochar-B) that enhance B distribution and stability in the soil, focusing on Eucalyptus grandis cultivation in two distinct oxisol types. Materials and methods: Biochar-B composites were created using shrimp carcass (FSC), chicken manure (FCM) and sewage sludge (FSS), combined with boric acid (BA) and borax (BX), and pyrolyzed at 300 °C and 550 °C. The experimental design was a completely randomized design (CRD) with three replicates. Results: Fourier transform infrared spectroscopy (FTIR) analysis confirmed successful B integration and interaction with organic matrices, highlighting functional groups responsible for composite properties. This facilitated the development of highly predictive partial least squares (PLS) regression models (R2pred ~ 0.8). The FSC-BA composite at 300 °C showed notable thermal stability, B retention and availability, enhancing B release kinetics. Discussion: These findings emphasize the importance of considering the soluble B rate in composite applications for Eucalyptus cultivation. The use of these composites provides a sustainable method for gradual B release, potentially outperforming conventional fertilization techniques. This approach may lead to improved plant growth and productivity. Further field investigations are recommended in order to validate these findings and refine sustainable fertilization strategies; thus, benefiting a range of crops. [ABSTRACT FROM AUTHOR]

The NITRATE TRANSPORTER 1/PEPTIDE TRANSPORTER (NRT1/PTR) family (NPF) plays an important role in plant nitrate absorption, distribution, and nitrogen use efficiency. Nevertheless, few reports are available regarding Eucalyptus grandis NPF genes and their expression profiles. This study aims to identify and analyze NPF genes and their expression under various nitrogen (N) conditions. In this study, we successfully screened 64 NPF genes within the E. grandis genome. Subsequently, we conducted an extensive analysis, encompassing investigations into chromosome location, gene structure, phylogenetic relationship, promoter region, conserved motif, and gene expression profile. RNA-seq was conducted to analyze the expression profiles of EgNPF genes under different N conditions. The 64 NPF genes were categorized into eight distinct groups, exhibiting an uneven distribution among the 10 chromosomes of E. grandis, and no member was mapped on chromosome (Chr) 9. The examination of cis-regulatory elements revealed that NPF promoters were closely related to light responsive element, MeJA responsiveness, anaerobic induction, gibberellin responsiveness, low-temperature responsiveness, and auxin responsiveness. We used the comparative transcriptome method to identify the 10 differently expressed EgNPF genes of E. grandis under high-nitrogen (N: 119 mg/L) and low-nitrogen (N: 29.25 mg/L) conditions. Expression pattern analyses revealed that EUGRSUZ_G03119 showed an elevated expression in both leaves and roots under high-nitrogen conditions compared to low-nitrogen conditions, suggesting that EUGRSUZ_G03119 might affect nitrogen transport and redistribution, potentially boosting the stress tolerance of E. grandis in response to nitrogen deficiency. These findings may provide valuable insights into the evolutionary development of the NPF gene family in E. grandis and facilitate the clarification of the molecular mechanism underlying EgNPF-mediated N absorption and distribution in E. grandis. [ABSTRACT FROM AUTHOR]

Aotearoa New Zealand's swamp forests have experienced significant habitat loss in fewer than two hundred years. Many of the country's tree species are endemic with sparse to no genetic information available to underpin conservation strategies. Syzygium maire, Aotearoa's only endemic Syzygium species, is a culturally and ecologically important component of swamp forest habitats. Unfortunately, populations of S. maire have been greatly reduced, heavily fragmented and are susceptible to the emergent pathogen Austropuccinia psidii (myrtle rust), posing eminent danger of a further decline of the species. We sought to develop genomic resources to inform conservation management of S. maire. To this end, we used long read, high accuracy sequencing technology to produce a highly complete reference quality genome for S. maire. The genome sequence was named 'Ngā Hua o te Ia Whenua' by the local Māori tribe where the tree used for genome sequencing grows. We assess whether genome-level divergence with other Myrtaceae may have followed geographic isolation of the species. We detect conservation of large scale synteny between three Syzygium species and Eucalyptus grandis, providing support for the stability of Syzygium genomes across evolutionary time. We annotate genes implicated in fungal pathogen defence, identifying several hundred putative NLR genes, including putative homologs of previously identified Austropuccinia psidii resistance genes. Finally, we evaluate the genetic relationships of individuals of a small, isolated population of trees. We find evidence of high levels of kinship and inbreeding within small and isolated S. maire populations, informing local-scale conservation strategies for the species. Our findings enable practical conservation actions and provide resources for larger scale studies of S. maire and other Syzygium species in the future. [ABSTRACT FROM AUTHOR]

The conversion of Eucalyptus biomass to ethanol via fermentation is beset with challenges including efficient sugar utilisation, the presence of inhibitors, expensive nutrients, and low yields. To address some of these challenges, this study evaluated Thermosacc Dry® and GSF335 xylose recombinant yeast in fermentations using acid pretreated Eucalyptus grandis fibre and hydrolysates. These fermentations were supplemented with novel and low-cost nutrients. Contrary to previous reports, the inclusion of trace metals in saccharification and hydrolysis fermentations of whole slurries did not eliminate the inhibitory effects of acetic acid. Elevated levels of xylitol and acetic acid suggested a redirection of carbon flux to redress redox imbalances in both yeast types. Using GSF335 propagated in xylose-enriched liquors, and Nutri-Plex Plus™, diammonium phosphate, or crude dried spent yeast as nitrogen sources, saccharification and hydrolysis fermentations produced ethanol yields ranging from 141.4 to 145.6 kg t−1 dry weight E.grandis. Inclusion of yeast hulls and trace metals in simultaneous saccharification and fermentations yielded 175.6 kg ethanol t−1 dry weight E.grandis, corresponding to a 64.4% conversion efficiency. Results from this study support the use of novel low-cost waste by-products as nutrient supplements in bioethanol production from Eucalyptus biomass. Furthermore, they have implications for the production of bioethanol from other lignocellulosic materials and warrant further investigation. [ABSTRACT FROM AUTHOR]

SQUAMOSA promoter‐binding protein‐like (SPL) gene family, a group of plant‐specific transcription factors, played crucial roles in regulating plant growth, development, signal transduction, and stress response. This study focuses on the SPL gene family in the fast‐growing Eucalyptus grandis, employing bioinformatics approaches to identify and analyze the gene physiochemical characteristics, conserved domains, structural composition, chromosomal distribution, phylogenetic relationships, cis‐acting elements, and their expression patterns in various tissues and stress treatments. Twenty‐three SPL genes were identified in E. grandis, which uneven distributed across seven chromosomes and classified into five groups. Prediction of cis‐acting elements revealed that these genes might be related to light, hormone, and stress responses. Furthermore, EgSPL9 and EgSPL23, mainly expressed in the stem apex and lateral branches, seem to be involved in hormone stress resistance. Our study provides insights into the potential functions of the EgSPL genes in plant growth, stress response, and hormone transduction, offering valuable perspectives for subsequent research into their biological roles. [ABSTRACT FROM AUTHOR]

Summary Monolignol serves as the building blocks to constitute lignin, the second abundant polymer on Earth. Despite two decades of diligent efforts, complete identification of all metabolites in the currently proposed monolignol biosynthesis pathway has proven elusive. This limitation also hampers their potential application. One of the primary obstacles is the challenge of assembling a collection of all molecules, because many are commercially unavailable or prohibitively costly. In this study, we established systematic pipelines to synthesize all 24 molecules through the conversions between functional groups on a core structure followed by the application to other core structures. We successfully identified all of them in Populus trichocarpa and Eucalyptus grandis, two representative species respectively from malpighiales and myrtales in angiosperms. Knowledge about monolignol metabolite chemosynthesis and identification will form the foundation for future studies. [ABSTRACT FROM AUTHOR]

Invasion by invasive alien plants is a global challenge and South Africa has invested billions of Rands to manage invaders through the Working for Water programme. However, regular monitoring after alien plant clearing is hardly done, yet it forms the basis for assessing clearing programme effectiveness, particularly ecosystem recovery trajectories. I monitored both vegetation and soil recovery 6 years after Eucalyptus grandis clearing by Working for Water at Zvakanaka Farm in Limpopo Province of South Africa. Vegetation diversity and soil physical properties were surveyed in 2019 and re‐surveyed in 2022 on fell‐and‐removal and fell‐and‐stackburn cleared treatments and compared to the nearby uninvaded treatment. Results show a significant increase in species richness in 2022 compared to 2019 in the fell‐and‐removal treatment. Cover of both native trees and shrubs as well as forbs was significantly higher in 2022 compared to 2019 in the fell‐and‐removal treatment compared to the fell‐and‐stackburn treatment. Most secondary invaders such as Acacia mearnsii, E. cloeziana, Lantana camara and Rubus rigidus that frequently occurred in 2019 showed decreased occurrence in 2022 on both cleared treatments. Between the two sampling years, soil compaction improved on the fell‐and‐removal treatment only, whereas hydraulic conductivity increased significantly in 2022 compared to 2019 in both the fell‐and‐removal and fell‐and‐stackburn treatments. Soils that were strongly and severely repellent in 2019 in the fell‐and‐stackburn treatment were becoming slightly repellent in 2022. These results show varied vegetation and soil improvements between 2019 and 2022 in both the fell‐and‐removal and fell‐and‐stackburn cleared treatments an indication that recovery is moving towards a positive vegetation and soil recovery trajectory in the direction of the uninvaded treatment. Recommendations for successful passive restoration such as secondary invasion follow‐up clearing are discussed. [ABSTRACT FROM AUTHOR]

Yield data represent a valuable layer for supporting decision-making as they reflect crop management results. Forestry decision-makers often rely on coarse spatial resolution data (e.g., forest inventory plots) despite the availability of modern harvesters that can provide high-resolution forestry yield data. The objectives of this study were to present a method for generating high-resolution Eucalyptus grandis yield data (individual tree-level) and explore their applications, such as correlation analysis with soil attributes to aid nutrient recommendations. Two evaluations were conducted at two sites in Brazil: (a) assessing the positioning accuracy of the global navigation satellite system (GNSS) receiver positioning, and (b) analyzing the yield data and their correlation with the soil attributes. The results indicated that positioning the GNSS receiver at the harvesting head provided higher accuracy than placement at the top of the harvester cabin for individual tree-level data. Reliable yield data were generated despite the GNSS receiver's increased susceptibility to damage when mounted on a harvest head. The linear correlation analysis between the Eucalyptus grandis yield data and soil attributes showed both negative (Clay, B, S, coarse sand, and potential acidity − H + Al) and positive correlations (K, Mg, pH-SMP, Ca, sum of bases, pH, base saturation, fine sand, total sand, and silt content). This study demonstrates the feasibility of obtaining high-resolution yield data at the individual tree-level and their correlation with soil attributes, providing valuable insights for improving forestry decision-making. [ABSTRACT FROM AUTHOR]

Eucalyptus branches and bark represent highly abundant and available feedstocks with great potential for obtaining bio-based products. Distinct and integrated pretreatment fractionation strategies for eucalyptus branches and bark were performed for the efficient production of xylooligosaccharides (XOS). By combining pretreatments, a high yield of XOS was obtained from eucalyptus branches and bark. The branches and bark were presoaked in 8% (w/w) sodium hydroxide at 60 °C for 30 min to provide a deacetylation effect. The residues were then hydrothermally treated. The findings revealed that 4.64% of XOS originated from the bark and 6.19% from eucalyptus branches. It has been demonstrated that xylan may be selectively depolymerized during pretreatment by preventing excessive hydrolysis through the use of deacetylation in the first phase of the process. More XOS was produced using hydrothermal treatment, yielding 8.00% (w/w) in the branches and 5.12% in the bark. A significant amount of XOS with DP 2–5 might be obtained in certain experiments, up to 60%, but the most abundant XOS are usually those with DP > 5 (approximately 80% of all XOS). This work provides new insights into the effective generation of XOS under relatively mild conditions by overcoming the recalcitrant structure of eucalyptus branches and bark, representing a noteworthy advancement towards forestry leftover valorization. [ABSTRACT FROM AUTHOR]

Allelopathy is an underlying and controversial mechanism for detrimental environmental effects in the management of Eucalyptus plantations. However, little attention has been paid to the dynamics of allelochemicals and phytotoxicity in soil fauna during litter decomposition. To explore the relationship between the dynamics of phytotoxicity and allelochemicals, a decomposition experiment was conducted using 4-year-old and 8-year-old Eucalyptus grandis litter (0, 10, 20, 30, and 45 days). The acute toxicity of Eisenia fetida was assessed, and a chemical analysis of the eucalyptus leaves was performed. Biochemical markers, including total protein, acetylcholinesterase (AChE) activity, and oxidative stress levels (SOD and MDA) were measured. A comet assay was used to determine DNA damage in E. fetida cells. The results showed that after 20–30 days of decomposition, E. grandis litter exhibited stronger phytotoxic effects on E. fetida in terms of growth and biochemical levels. After 20 days of decomposition, the weight and total protein content of E. fetida first decreased and then increased over time. SOD activity increased after 20 days but decreased after 30 days of decomposition before increasing again. MDA content increased after 20 days, then decreased or was stable. AChE activity was inhibited after 30 days of decomposition and then increased or stabilized with further decomposition. Soluble allelochemicals, such as betaine, chlorogenic acid, and isoquercitrin, significantly decreased or disappeared during the initial decomposition stage, but pipecolic acid significantly increased, along with newly emerging phenolic fractions that were present. More allelochemicals were released from 8-year-old litter than from 4-year-old E. grandis litter, resulting in consistently more severe phytotoxic responses and DNA damage in E. fetida. Scientific management measures, such as the appropriate removal of leaf litter in the early stages of decomposition, might help support greater biodiversity in E. grandis plantations. [ABSTRACT FROM AUTHOR]

Atualmente, devido ao enorme apelo ambiental, estão sendo usados produtos mais sustentáveis e renováveis; um exemplo disso são os compósitos cimento-madeira. Esses compósitos são utilizados na construção civil como isolantes termoacústicos e em usos não estruturais, como forros e revestimento de parede, porém a incidência de defeitos pode limitar sua utilização, principalmente quando produzidos em nível laboratorial. Devido a isso, o objetivo do presente trabalho foi aplicar e analisar ferramentas da qualidade no processo produtivo de compósitos cimentícios com madeira de Eucalyptus grandis. Os corpos de prova foram produzidos conforme a norma NBR 7215 (ABNT, 2019) seguindo o traço de 1: 0,1: 0,6 de cimento, madeira e água, respectivamente. Foram realizados os ensaios de densidade, módulo de elasticidade e resistência à compressão aos sete dias, e a análise foi realizada por meio do software MiniTab; as ferramentas utilizadas foram diagrama de Pareto, diagrama de Ishikawa, gráfico por variáveis e capacidade de processo. Foi possível analisar que os principais defeitos foram a incidência de pequenos poros, rompimento por esmagamento e resistência à compressão aos sete dias inferior a 5 MPa. Os compósitos podem ser utilizados como blocos de vedação em sistemas construtivos leves e o processo produtivo se mostrou aceitável, embora melhorias, como a mecanização da produção, possam ser realizadas no processo produtivo a fim de corrigir esses defeitos.

Abstract Background The GRAS gene family is a class of plant-specific transcription factors with important roles in many biological processes, such as signal transduction, disease resistance and stress tolerance, plant growth and development. So far, no information available describes the functions of the GRAS genes in Eucalyptus grandis. Results A total of 82 GRAS genes were identified with amino acid lengths ranging from 267 to 817 aa, and most EgrGRAS genes had one exon. Members of the GRAS gene family of Eucalyptus grandis are divided into 9 subfamilies with different protein structures, while members of the same subfamily have similar gene structures and conserved motifs. Moreover, these EgrGRAS genes expanded primarily due to segmental duplication. In addition, cis-acting element analysis showed that this family of genes was involved involved in the signal transduction of various plant hormones, growth and development, and stress response. The qRT-PCR data indicated that 18 EgrGRAS genes significantly responded to hormonal and abiotic stresses. Among them, the expression of EgrGRAS13, EgrGRAS68 and EgrGRAS55 genes was significantly up-regulated during the treatment period, and it was hypothesised that members of the EgrGRAS family play an important role in stress tolerance. Conclusions In this study, the phylogenetic relationship, conserved domains, cis-elements and expression patterns of GRAS gene family of Eucalyptus grandis were analyzed, which filled the gap in the identification of GRAS gene family of Eucalyptus grandis and laid the foundation for analyzing the function of EgrGRAS gene in hormone and stress response.

The TRICHOME BIREFRINGENCE-LIKE (TBL) gene encodes a class of proteins related to xylan acetylation, which has been shown to play an important role in plant response to environmental stresses. This gene family has been meticulously investigated in Arabidopsis thaliana, whereas there have been no related reports in Eucalyptus grandis. In this study, we identified 49 TBL genes in E. grandis. A conserved amino acid motif was identified, which plays an important role in the execution of the function of TBL gene family members. The expression of TBL genes was generally upregulated in jasmonic acid-treated experiments, whereas it has been found that jasmonic acid activates the expression of genes involved in the defense functions of the plant body, suggesting that TBL genes play an important function in the response of the plant to stress. The principle of the action of TBL genes is supported by the finding that the xylan acetylation process increases the rigidity of the cell wall of the plant body and thus improves the plant's resistance to stress. The results of this study provide new information about the TBL gene family in E. grandis and will help in the study of the evolution, inheritance, and function of TBL genes in E. grandis, while confirming their functions. [ABSTRACT FROM AUTHOR]

Xylan, one of the most important structures and polysaccharides, plays critical roles in plant development, growth, and defense responses to pathogens. Glucuronic acid substitution of xylan (GUX) functions in xylan sidechain decoration, which is involved in a wide range of physiological processes in plants. However, the specifics of GUXs in trees remain unclear. In this study, the characterization and evolution of the GUX family genes in E. grandis, a fast-growing forest tree belonging to the Myrtaceae family, were performed. A total of 23 EgGUXs were identified from the E. grandis genome, of which all members contained motif 2, 3, 5, and 7. All GUX genes were phylogeneticly clustered into five distinct groups. Among them, EgGUX01~EgGUX05 genes were clustered into group III and IV, which were more closely related to the AtGUX1, AtGUX2, and AtGUX4 members of Arabidopsis thaliana known to possess glucuronyltransferase activity, while most other members were clustered into group I. The light-responsive elements, hormone-responsive elements, growth and development-responsive elements, and stress-responsive elements were found in the promoter cis-acting elements, suggesting the expression of GUX might also be regulated by abiotic factors. RNA-Seq data confirmed that EgGUX02, EgGUX03, and EgGUX10 are highly expressed in xylem, and EgGUX09, EgGUX10, and EgGUX14 were obviously responses to abiotic stresses. The results of this paper will provide a comprehensive determination of the functions of the EgGUX family members, which will further contribute to understanding E. grandis xylan formation. [ABSTRACT FROM AUTHOR]

The current study assessed the association of eucalyptus-tree spacing with forest growth and yield, as well as with the floristic composition, diversity and yield of natural grassland grown in silvopastoral systems in Pampa biome. Data were collected in six family cattle-ranching area in Bagé County (RS). The effect of two different genetic materials (seminal-origin Eucalyptus dunnii plant and one Eucalyptus grandis clone) on shading features of plants grown in 3 planting-spacing dimensions (625, 312 and 208 trees ha-1) was assessed, as well as their association with herbaceous extract (bare soil; green cover; forage dry matter; floristic composition; species richness; and grass, legumes and winter - and summer-growth species rates) and forestry (litter accumulation, diameter at breast height, total height and volume per hectare) variables. Planting carried out at the highest tree density (625 trees ha-1) has increased forest yield. However, it reduced green cover, herbaceous extract dry-matter yield and species richness, mainly in grasses and legumes with greater forage potential. Conversely, it is possible combining forestry and animal yield to the preservation of native forage species at low tree densities (204 to 312 trees ha-1). [ABSTRACT FROM AUTHOR]

This research aimed to select conilon coffee tree clones (Coffea canephora Pierre ex A. Froehner) for agroforestry and/or intercropping systems. The experiment was carried out at Bananal do Norte Experimental Farm (20º45' S and 41º17' W), Espírito Santo, Brazil. The clones were evaluated in an agroforestry system with "urograndis" hybrid eucalyptus trees (Eucalyptus grandis W.Hill × E. urophylla S.T.Blake) plus prata-type banana herbs (Musa spp.) and an intercropping with 'Folha Murcha' sweet orange trees (Citrus sinensis (L.) Osbeck). An augmented block experiment design, with two plants per plot, four controls, in six blocks in the agroforestry system and four in the intercropping, was adopted. Thirteen morphophysiological characteristics were evaluated. Data analysis was performed using the restricted maximum likelihood method and best linear unbiased prediction and the significance of genetic effects by the likelihood ratio test. To select superior clones the Mulamba-Rank index was performed. Twenty clones were selected for the agroforestry and 20 for the intercropped system. The clones 16, 17, 35, 43, 48, 61, 64, 68 and T3 were the most promising for both systems. There is genetic variability to be explored among the clones, being possible the development of varieties, in the future, for agroforestry and intercropping systems. [ABSTRACT FROM AUTHOR]

Future climatic scenarios forecast increasingly frequent droughts that will pose substantial consequences on tree mortality. In light of this, drought-tolerant eucalypts have been propagated; however, the severity of these conditions will invoke adaptive responses, impacting the commercially valuable wood properties. To determine what mechanisms govern the wood anatomical adaptive response, highly controlled drought experiments were conducted in Eucalyptus grandis W. Hill ex Maiden, with the tree physiology and transcriptome closely monitored. In response to water deficit, E. grandis displays an isohydric stomatal response to conserve water and enable stem growth to continue, albeit at a reduced rate. Maintaining gaseous exchange is likely a critical short-term response that drives the formation of hydraulically safer xylem. For instance, the development of significantly smaller fibers and vessels was found to increase cellular density, thereby promoting drought tolerance through improved functional redundancy, as well as implosion and cavitation resistance. The transcriptome was explored to identify the molecular mechanisms responsible for controlling xylem cell size during prolonged water deficit. Downregulation of genes associated with cell wall remodeling and the biosynthesis of cellulose, hemicellulose and pectin appeared to coincide with a reduction in cellular enlargement during drought. Furthermore, transcript levels of NAC and MYB transcription factors, vital for cell wall component biosynthesis, were reduced, while those linked to lignification increased. The upregulation of EgCAD and various peroxidases under water deficit did not correlate with an increased lignin composition. However, with the elevated cellular density, a higher lignin content per xylem cross-sectional area was observed, potentially enhancing hydraulic safety. These results support the requirement for higher density, drought-adapted wood as a long-term adaptive response in E. grandis , which is largely influenced by the isohydric stomatal response coupled with cellular expansion-related molecular processes. [ABSTRACT FROM AUTHOR]

Soil aggregates are the basic unit of soil structure. The stability of soil aggregates is an important indicator for evaluating soil structure and soil fertility. In order to explore the effects of Acacia mangium on particle size distribution and stability of soil aggregates of Eucalyptus grandis × urophylla plantations, we measured the distribution and stability of aggregates indicators such as mean weight diameter(MWD), geometric mean diameter(GMD), mass fractal dimension(Dm), water stable aggregates(WSA), percentage of aggregates destruction(PAD)and aggregates stability index(ASI)in the 0-10 cm and 10-20 cm soil layers by the dry sieving method and the wet sieving method, and a pure plantation of E. grandis × urophylla(PP)and a mixed plantation containing E. grandis × urophylla and Acacia mangium(nitrogen-fixing tree species)(MP)were selected as the research objects. The results were as follows: (1) Compared with PP, the soil physicochemical properties of MP were improved in varying degrees, especially soil pH, organic carbon(SOC)and total nitrogen(TN). (2)The particle size distribution of soil aggregates in MP was better than that of PP, and the differences mainly in the particle sizes of >2.00 mm and <0.25 mm, but both were dominated by large aggregates(>0.25 mm). Compared with PP, the mechanical stability of aggregates in MP only increased significantly at 0-10 cm soil layer, but the water stability of aggregates in MP increased significantly at 0-10 cm and 10-20 cm soil layer. The mechanical stability and water stability of soil aggregates tended to decrease with the deepening of soil layer. (3)Mantel analysis showed that the stability of aggregates was significantly correlated with pH, SOC, TN, TP, BD and SP, and the stability of aggregates had the strongest correlation with TN. RDA analysis indicated that TN was the most critical factor driving the variation of stability aggregates. Our findings suggest that nitrogen-fixing tree species A. mangium can significantly improve proportion of macroaggregates(>0.25 mm)and the stability of soil aggregates in Eucalyptus plantations. This study can provide a theoretical reference for soil and water conservation, soil nutrient management and sustainable management of Eucalyptus plantations in the South Asian tropics. [ABSTRACT FROM AUTHOR]

Eucalyptus grandis is an important planted hardwood tree worldwide with fast growth and good wood performance. The nitrate transporter (NRT) gene family is a major core involved in nitrogen (N) absorption and utilization in plants, but the comprehensive characterization of NRT genes in E. grandis remains mostly elusive. In this study, a total of 75 EgNRT genes were identified from the genome of E. grandis that were distributed unevenly across ten chromosomes, except Chr9. A phylogenetic analysis showed that the EgNRT proteins could be divided into three classes, namely NRT1, NRT2 and NRT3, which contained 69, 4 and 2 members, respectively. The cis-regulatory elements in the promoter regions of EgNRT genes were mainly involved in phytohormone and stress response. The transcriptome analysis indicated that the differentially expressed genes of leaf and root in E. grandis under different N supply conditions were mainly involved in the metabolic process and plant hormone signal transduction. In addition, the transcriptome-based and RT-qPCR analysis revealed that the expression of 13 EgNRT genes, especially EgNRT1.3, EgNRT1.38, EgNRT1.39 and EgNRT1.52, was significantly upregulated in the root under low-N-supply treatment, suggesting that those genes might play a critical role in root response to nitrate deficiency. Taken together, these results would provide valuable information for characterizing the roles of EgNRTs and facilitate the clarification of the molecular mechanism underlying EgNRT-mediated N absorption and distribution in E. grandis. [ABSTRACT FROM AUTHOR]

Wood is an organic material and its energetic and physical properties are related to its chemical and anatomical constituents. This study evaluated the influence of the chemical constituents on the energetic and physical properties of Parapiptadenia rigida (Benth.) Brenan, Peltophorum dubium (Spreng.) Taub., Eucalyptus grandis W. Hill × Eucalyptus urophylla S.T. Blake (hybrid), and Schizolobium parahyba (Vell.) Blake an agroforestry system. Five trees of each species aged 9 years were sampled. Samples were collected at a diameter at breast height (DBH) of 1.30 m above the ground and were used to analyze the chemical, energetic, and physical properties of the wood. Chemical properties influence the energetic and physical properties of wood. We reported that the higher the lignin content in the wood, the greater the correlation with the fixed carbon content (0.76) and gross calorific value (0.65). High values of fixed carbon content increased the basic density of the wood (0.80). In contrast, the lower the lignin content in the wood, the greater the correlation with the extractive content (-0.76) and volatile material content (-0.74), and the higher the volatile material content, the lower the fixed carbon content (-0.98) and gross calorific value (-0.74). [ABSTRACT FROM AUTHOR]

The impacts of the successive planting of Eucalyptus on soil microbial communities and their underlying mechanisms remain unknown, limiting our understanding of its long-term effects on soil ecosystems. This study examined the 0–20 cm and 20–40 cm soil layers, investigating changes in soil bacterial and fungal communities after multiple plantings of Eucalyptus grandis × urophylla using high-throughput sequencing. Furthermore, we used the structural equation model (SEM) to analyze the relationships among soil active organic carbon (SAOC), enzyme activity, and microbial diversity. The study showed that the multigeneration successive planting of Eucalyptus significantly increased the soil bulk density and decreased the soil physicochemical properties and soil enzyme activities (p < 0.05). The soil's dominant microbial compositions were unchanged in the two soil horizons, but the relative abundances of some dominant phyla (e.g., Crenarchaeota, Basidiomycota and Actinobacteriota) were affected by successive planting. The variability in the microbial community structure was influenced primarily by the soil water content (SWC) and organic carbon (p < 0.05). The microbial community diversity in the 20–40 cm horizon was significantly affected by multigeneration succession (p < 0.05). SWC was the core factor driving microbial community diversity. SEM results showed that multigeneration successive planting obviously limits SAOC fractions and enzyme activities, negatively affecting soil microbial diversity. Our study highlights the impact of the multigeneration successive planting of Eucalyptus on soil microbial community structure and suggests adjustments in forestry practices to mitigate soil degradation. [ABSTRACT FROM AUTHOR]

Soil liming is a crucial strategy to reduce acidity and increase nutrients availability. Lime recommendation for eucalyptus aims to supply the Ca and Mg. Lime might reduce metallic micronutrients content in plants (e.g., Cu, Fe, Mn, and Zn), thereby impairing the nutritional status. Copper and zinc fertilization in eucalyptus plantation is recommended to replace the amount extracted from harvesting plant products. We investigated lime and Cu plus Zn application on (a) biomass production, leaf area, and leaf pigments; and (b) Cu and Zn concentration, accumulation, and distribution in Eucalyptus grandis seedlings. The experiment was conducted with eucalyptus seedlings under Ferralsol in five randomized blocks, in a 3 × 4 factorial scheme, with three lime and four fertilizer rates of Cu and Zn. Plants grown under lime application had increased leaf area and flavonoid content. Lime and Cu plus Zn application improved dry biomass relative to plants grown unlimed and micronutrient supply. Copper plus zinc fertilization improves the nutritional status of eucalyptus, leading to enhance content of Cu, Zn, and chlorophyll, which could prove to be a crucial strategy for increased plant growth and, consequently, boosting biomass production. [ABSTRACT FROM AUTHOR]

Stacked timber is quantified in-store units and then adjusted with a conversion factor for volume estimation in cubic meters, which is important for the wood trade in South America. However, measuring large quantities accurately can be challenging. Digital image processing and artificial intelligence advancements offer promising solutions, making research in this area increasingly attractive. This study aims to estimate conversion factors of stacked Eucalyptus grandis timber using supervised image classification with Artificial Neuronal Network (ANN). Measured data and photographs from an experiment involving thirty stacks of timber were used to achieve this. The conversion factor was determined using photographic methods that involved the applications of equidistant points and ANN and subsequently validated with values observed through the manual method. The ANN method produced more accurate conversion factor estimates than the equidistant points method. Approximately 97% of the ANN estimates were within the ±1% error class, even when using low-resolution digital photographs. [ABSTRACT FROM AUTHOR]

Background: The GRAS gene family is a class of plant-specific transcription factors with important roles in many biological processes, such as signal transduction, disease resistance and stress tolerance, plant growth and development. So far, no information available describes the functions of the GRAS genes in Eucalyptus grandis. Results: A total of 82 GRAS genes were identified with amino acid lengths ranging from 267 to 817 aa, and most EgrGRAS genes had one exon. Members of the GRAS gene family of Eucalyptus grandis are divided into 9 subfamilies with different protein structures, while members of the same subfamily have similar gene structures and conserved motifs. Moreover, these EgrGRAS genes expanded primarily due to segmental duplication. In addition, cis-acting element analysis showed that this family of genes was involved involved in the signal transduction of various plant hormones, growth and development, and stress response. The qRT-PCR data indicated that 18 EgrGRAS genes significantly responded to hormonal and abiotic stresses. Among them, the expression of EgrGRAS13, EgrGRAS68 and EgrGRAS55 genes was significantly up-regulated during the treatment period, and it was hypothesised that members of the EgrGRAS family play an important role in stress tolerance. Conclusions: In this study, the phylogenetic relationship, conserved domains, cis-elements and expression patterns of GRAS gene family of Eucalyptus grandis were analyzed, which filled the gap in the identification of GRAS gene family of Eucalyptus grandis and laid the foundation for analyzing the function of EgrGRAS gene in hormone and stress response. [ABSTRACT FROM AUTHOR]

Eucalyptus roots form symbiotic relationships with arbuscular mycorrhizal (AM) fungi in soil to enhance adaptation in challenging environments. However, the evolution of the AM fungal community along a chronosequence of eucalypt plantations and its relationship with soil properties remain unclear. In this study, we evaluated the tree growth, soil properties, and root AM fungal colonization of Eucalyptus grandis W. Hill ex Maiden plantations at different ages, identified the AM fungal community composition by high-throughput sequencing, and developed a structural equation model among trees, soil, and AM fungi. Key findings include the following: (1) The total phosphorus (P) and total potassium (K) in the soil underwent an initial reduction followed by a rise with different stand ages. (2) The rate of AM colonization decreased first and then increased. (3) The composition of the AM fungal community changed significantly with different stand ages, but there was no significant change in diversity. (4) Paraglomus and Glomus were the dominant genera, accounting for 70.1% and 21.8% of the relative abundance, respectively. (5) The dominant genera were mainly influenced by soil P, the N content, and bulk density, but the main factors were different with stand ages. The results can provide a reference for fertilizer management and microbial formulation manufacture for eucalyptus plantations. [ABSTRACT FROM AUTHOR]

Uganda hosts Africa's largest refugee population, exceeding 1.5 million in early 2023. While commended for its progressive refugee policies, which grant freedom of movement and work opportunities, the influx of displaced people since 2015 has strained shared environmental resources, including slow-growing indigenous trees utilized for construction and fuel. Efforts to preserve indigenous biodiversity have promoted the growth and use of faster-growing exotic tree species. However, local communities often favor indigenous trees as fuel sources, despite limited evidence supporting their superiority. This study assessed fuel properties of selected indigenous and exotic tree species in Lamwo District, Northern Uganda. Laboratory analysis of wood samples revealed no significant differences in moisture content, fixed carbon, volatile matter, or Fuel Value Index (FVI) among the species. The study therefore recommends promoting fast-growing exotic species like Eucalyptus grandis, Caliandra calothyrsus, and Senna siamea, urging international agencies, NGOs, and community-led organizations to leverage the findings for behavior change campaigns. This approach would facilitate species regeneration, alleviate pressure on natural forests, and supplement Uganda's investment strategy in Modern Energy Cooking Services (MECS) such as LPG and solar e-cooking technologies. [ABSTRACT FROM AUTHOR]

Fungi in the Cryphonectriaceae are important canker pathogens of woody shrubs and trees in the Melastomataceae and Myrtaceae (Myrtales). During 2021 disease surveys in KwaZulu‐Natal (South Africa) plantations, a serious stem canker disease was discovered on species of Eucalyptus and Corymbia. The cankers had structures on their surfaces typical of fungi in the Cryphonectriaceae. The aims of the study were to identify the fungus associated with the disease and to test its pathogenicity. Morphological characteristics of both sexual and asexual structures and phylogenetic analyses based on partial sequences of the conserved nuclear large subunit (LSU) ribosomal DNA, the internal transcribed spacer (ITS) regions including the 5.8S gene of the ribosomal DNA operon, and two β‐tubulin (BT1/BT2) regions were used for identification purposes. Phylogenetic analyses of the sequence data and morphological characteristics supported the establishment of a new genus in the Cryphonectriaceae, for which the name Xanthoporthe myrticola gen. et sp. nov. is provided. Pathogenicity trials showed that isolates were pathogenic on tested Eucalyptus grandis and hybrids as well as Corymbia henryi. The results suggest that this is an emerging pathogen that could influence the sustainability of plantation forestry in South Africa. [ABSTRACT FROM AUTHOR]

Background: Nutritional disorders of phosphorus (P), due to deficiency or toxicity, reduce the development of Eucalyptus spp. seedlings. Phosphorus deficiency often results in stunted growth and reduced vigor, while phosphorus toxicity can lead to nutrient imbalances and decreased physiological function. These sensitivities highlight the need for precise management of P levels in cultivation practices. The use of the beneficial element silicon (Si) has shown promising results under nutritional stress; nevertheless, comprehensive studies on its effects on Eucalyptus spp. seedlings are still emerging. To further elucidate the role of Si under varying P conditions, an experiment was conducted with clonal seedlings of a hybrid Eucalyptus spp. (Eucalyptus grandis × Eucalyptus urophylla, A207) in a soilless cultivation system. Seedlings were propagated using the minicutting method in vermiculite-filled tubes, followed by treatment with a nutrient solution at three P concentrations: a deficient dose (0.1 mM), an adequate dose (1.0 mM) and an excessive dose (10 mM), with and without the addition of Si (2mM). This study assessed P and Si concentration, nutritional efficiency, oxidative metabolism, photosynthetic parameters, and dry matter production. Results: Si supply increased phenolic compounds production and reduced electrolyte leakage in seedlings provided with 0.1 mM of P. On the other hand, Si favored quantum efficiency of photosystem II as well as chlorophyll a content in seedlings supplemented with 10 mM of P. In general, Si attenuates P nutritional disorder by reducing the oxidative stress, favoring the non-enzymatic antioxidant system and photosynthetic parameters in seedlings of Eucalyptus grandis × Eucalyptus urophylla. Conclusion: The results of this study indicate that Eucalyptus grandis × Eucalyptus urophylla seedlings are sensitive to P deficiency and toxicity and Si has shown a beneficial effect, attenuating P nutritional disorder by reducing the oxidative stress, favoring the non-enzymatic antioxidant system and photosynthetic parameters. [ABSTRACT FROM AUTHOR]

Summary: Ectomycorrhizal (ECM) fungi are crucial for tree nitrogen (N) nutrition; however, mechanisms governing N transfer from fungal tissues to the host plant are not well understood. ECM fungal isolates, even from the same species, vary considerably in their ability to support tree N nutrition, resulting in a range of often unpredictable symbiotic outcomes.In this study, we used isotopic labelling to quantify the transfer of N to the plant host by isolates from the ECM genus Pisolithus, known to have significant variability in colonisation and transfer of nutrients to a host.We considered the metabolic fate of N acquired by the fungi and found that the percentage of plant N acquired through symbiosis significantly correlated to the concentration of free amino acids in ECM extra‐radical mycelium. Transcriptomic analyses complemented these findings with isolates having high amino acid content and N transfer showing increased expression of genes related to amino acid transport and catabolic pathways.These results suggest that fungal N metabolism impacts N transfer to the host plant in this interaction and that relative N transfer may be possible to predict through basic biochemical analyses. [ABSTRACT FROM AUTHOR]

Understanding how thinning strategies impact wood quality and quantity for different purposes is of interest, given that plantation management is often based on parameters that require validation under varying growth conditions. Planted forests for solid purposes in the northern region of Urugay, western Argentina and South of Brazil are usually managed in initial stockings ranging from 800 to 1200 trees·ha−1 depending on the use of clones or seeds. Subsequent thinnings are applied (at plantation ages varying from 3 to 11 years) up to final stockings of around 200 trees·ha−1. This study evaluated contrasting thinning regimes applied early in the crop cycle, with an initial tree density of 840 trees·ha−1. Two thinning treatments were applied at 1.5 and 7.3 years, reducing tree densities to 700–400 and 400–100 trees·ha−1, respectively. Growth analyses were conducted from 1.5 to 20.8 years, considering total height, diameter at breast height, individual volume, total and commercial volume per hectare, mean annual increase, and current annual increase. At the final harvest, contrasting tree densities of 100, 250, and 400 trees·ha−1 were sampled to assess wood density and mechanical properties (bending and compression on small-scale clear samples). Individual growth and wood properties were related to a Stand Density Index to understand the effect of competition on these values. The results identified thinning regimes that resulted in the most significant individual and per-hectare growth (both in thinning and clear felling) and the optimal harvest time under specific growth conditions. We assessed the proportions of commercial logs for sawmill and pulp uses, providing valuable inputs for subsequent economic analyses of thinning regimes aiming for the most convenient combination of wood products. Wood's physical and mechanical properties were relatively little affected by contrasting levels of competition between trees; therefore, the choice of silvicultural system will depend on production and economic criteria. [ABSTRACT FROM AUTHOR]

Eucalyptus is a widely planted hardwood tree species due to its fast growth, superior wood properties and adaptability. However, the post‐transcriptional regulatory mechanisms controlling tissue development and stress responses in Eucalyptus remain poorly understood. In this study, we performed a comprehensive analysis of the gene expression profile and the alternative splicing (AS) landscape of E. grandis using strand‐specific RNA‐Seq, which encompassed 201 libraries including different organs, developmental stages, and environmental stresses. We identified 10 416 genes (33.49%) that underwent AS, and numerous differentially expressed and/or differential AS genes involved in critical biological processes, such as primary‐to‐secondary growth transition of stems, adventitious root formation, aging and responses to phosphorus‐ or boron‐deficiency. Co‐expression analysis of AS events and gene expression patterns highlighted the potential upstream regulatory role of AS events in multiple processes. Additionally, we highlighted the lignin biosynthetic pathway to showcase the potential regulatory functions of AS events in the KNAT3 and IRL3 genes within this pathway. Our high‐quality expression atlas and AS landscape serve as valuable resources for unravelling the genetic control of woody plant development, long‐term adaptation, and understanding transcriptional diversity in Eucalyptus. Researchers can conveniently access these resources through the interactive ePlant browser (https://bar.utoronto.ca/eplant_eucalyptus). Summary statement: We provide a dataset on gene expression and alternative splicing in Eucalyptus tissues across various developmental stages, stress conditions, and hormone treatments. It was integrated into the interactive ePlant browser, providing a valuable resource for understanding the transcriptional and post‐transcriptional regulation of woody plants. [ABSTRACT FROM AUTHOR]

Mixed cultivation with legumes may alleviate the nitrogen (N) limitation of monoculture Eucalyptus. However, how leaf functional traits respond to N in mixed cultivation with legumes and how they affect tree growth are unclear. Thus, this study investigated the response of leaf functional traits of Eucalyptus urophylla × Eucalyptus grandis (E. urophylla × E. grandis) and Dalbergia odorifera (D. odorifera) to mixed culture and N application, as well as the regulatory pathways of key traits on seedling growth. In this study, a pot-controlled experiment was set up, and seedling growth indicators, leaf physiology, morphological parameters, and N content were collected and analyzed after 180 days of N application treatment. The results indicated that mixed culture improved the N absorption and photosynthetic rate of E. urophylla × E. grandis, further promoting seedling growth but inhibiting the photosynthetic process of D. odorifera, reducing its growth and biomass. Redundancy analysis and path analysis revealed that leaf nitrogen content, pigment content, and photosynthesis-related physiological indicators were the traits most directly related to seedling growth and biomass accumulation, with the net photosynthetic rate explaining 50.9% and 55.8% of the variation in growth indicators for E. urophylla × E. grandis and D. odorifera, respectively. Additionally, leaf morphological traits are related to the trade-off strategy exhibited by E. urophylla × E. grandis and D. odorifera based on N competition. This study demonstrated that physiological traits related to photosynthesis are reliable predictors of N nutrition and tree growth in mixed stands, while leaf morphological traits reflect the resource trade-off strategies of different tree species. [ABSTRACT FROM AUTHOR]

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A serious new disease of Eucalyptus was detected in South African plantations of these trees during the summer of 2021/2022. The first symptoms are minute dark spots on young leaves, petioles and shoots, becoming scab-like as the spots age. On highly susceptible Eucalyptus genotypes, leaves and shoots can become malformed leading to a 'feathering' appearance in the tree canopies and in the case of heavy infections, leaf and shoot death occur. Isolations made directly from developing scabs resulted in slow-growing cultures. These were identified, based on phylogenetic analyses of DNA sequence data for the ITS, LSU, TEF1 and RPB2 regions, as a novel species of Elsinoe (Elsinoaceae, Myriangiales), described here as E. masingae. Inoculations of an Eucalyptus grandis  ×  Eucalyptus nitens hybrid variety produced the same symptoms as those observed under natural conditions and the pathogen could be re-isolated from the emerging lesions. Elsinoe masingae is closely related to, but clearly distinct from, the recently described Elsinoe necatrix that causes a serious scab and shoot malformation disease on Eucalyptus in Indonesia. Field surveys revealed significant variation in the susceptibility of different Eucalyptus genotypes, with the most severely affected genotypes including an E. grandis  ×  nitens and an E. grandis  ×  urophylla hybrid variety and E. grandis. The disease has also been observed on Eucalyptus amplifolia and on Eucalyptus dunnii , which had mild infections. The observed variation in susceptibility of Eucalyptus planting stock should provide opportunities to avoid serious damage because of scab caused by E. masingae in the future. [ABSTRACT FROM AUTHOR]

Soil quality (SQ) pertains to the intricate and ongoing capacity of soil to function as a thriving ecosystem that supports the growth of plants and animals. However, there is a limited understanding of SQ assessment in mixed forest plantations. Therefore, we formulated and tested the hypothesis that the inclusion of a nitrogen-fixing tree species (such as Acacia mangium) improves SQ indicators in mixed treatments involving Eucalyptus trees. To evaluate the changes in SQ, we conducted a field experiment that employed the Soil Management Assessment Framework (SMAF) tool to analyze pure and mixed plantations of Eucalyptus grandis and A. mangium. Soil samples were collected at a depth of 0–20 cm from different treatments, including pure E. grandis without nitrogen fertilization (E), pure A. mangium (A), pure E. grandis with nitrogen fertilization (E + N), and mixed E. grandis and A. mangium (E + A). Sampling took place at 27 and 39 months after planting. We selected seven indicators of SQ: two biological indicators (soil microbial biomass carbon and β-glucosidase enzyme activity), four chemical indicators (soil organic carbon, pH, available phosphorus, and potassium), and one physical indicator (bulk density). By applying the SMAF tool, we determined the SQ scores for each indicator. The results revealed that E + A stands exhibited higher SMAF scores than pure stands, particularly in terms of pH (0.49 and 0.52 at 27 and 39 months, respectively) and phosphorus levels (0.84 and 0.82, at 27 and 39 months), respectively. Forest management practices and the sampling period had the most pronounced impact on biological and chemical indicators. Notably, significant positive correlations were observed between SMAF scores and pH, available phosphorus content, enzymes, soil organic carbon, and microbial biomass in both sampling periods. This study effectively provided novel information that introducing a nitrogen-fixing tree species in combination with eucalyptus trees enhances SQ, as indicated by the SMAF tool, which could reduce the need for external inputs (e.g., mineral fertilizers) by the farmers. Future studies should analyze the effects of A. mangium not only with other E. grandis varieties but also with other forestry essences. [ABSTRACT FROM AUTHOR]

This study aimed to improve the sustainability of the kraft pulp production process by recovering Pinus radiata and Eucalyptus grandis wastewater generated during the bleaching process. The effluents were obtained from the first alkaline extraction stage (E0) of the ECF bleaching sequence used to produce white Kraft cellulose, considering that this stage is where the highest contamination by phenolic compounds occurs and the effluent exhibits an intense color. A photochemical oxidation system, utilizing TiO2/S2O8 2-/UV, was implemented to generate in situ two highly oxidizing radical species, with high redox potential, a hydroxyl radical (HO• 2.8 eV ) and a sulfate radical (SO4 •- 2.5-3.1 eV), which promote rapid degradation of contaminants. To obtain the optimal response, we employed the 2n model to construct a matrix of 15 experiments, utilizing the Box-Behnken design. According to the experimental variables studied, phenolic compounds were completely removed from the Eucalyptus effluent (0.0312 min-1) and 80% of them were removed from the pine effluent (0.0102 min-1), at pH 5.0 with 0.6 gL-1 of persulfate and 1.0 gL-1 of titanium dioxide. Under these conditions, the bioavailability of effluents from Pinus radiata and Eucalyptus grandis increases from 0.16 and 0.26 to 0.90, after the treatment. The excellent bioavailability of the effluents obtained after the treatment demonstrates that the process used is efficient in recovering wastewater from the pulp industry and that the treated water could be reused in the same process or returned to the ecosystem, without harming the environment. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Northwest A & F University - Natural Science Edition is the property of Editorial Department of Journal of Northwest A&F University (Natural Science Edition) 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.)

Abstract Eucalyptus was one of the most cultivated hardwood species worldwide, with rapid growth, good wood properties and a wide range of adaptability. Eucalyptus stem undergoes primary growth (longitudinal growth) followed by secondary growth (radial growth), which produces biomass that is an important source of energy worldwide. In order to better understand the genetic regulation of secondary growth in Eucalyptus grandis, Transcriptome analyses in stem segments along a developmental gradient from the third internode to the eleventh internode of E. grandis that spanned primary to secondary growth were carried out. 5,149 genes that were differentially expressed during stem development were identified. Combining the trend analysis by the Mfuzz method and the module-trait correlation analysis by the Weighted Gene Co-expression Network Analysis method, a total of 70 differentially expressed genes (DEGs) selected from 868 DEGs with high connectivity were found to be closely correlated with secondary growth. Results revealed that the differential expression of these DEGs suggests that they may involve in the primary growth or secondary growth. AP1, YAB2 TFs and EXP genes are highly expressed in the IN3, whereas NAC, MYB TFs are likely to be important for secondary growth. These results will expand our understanding of the complex molecular and cellular events of secondary growth and provide a foundation for future studies on wood formation in Eucalyptus.

RESUMO Foi estudada a flutuação populacional de espécies da ordem Coleoptera em plantios de Eucalyptus grandis na região de Nova Era, estado de Minas Gerais, Brasil. Foram utilizadas cinco armadilhas luminosas Intral, modelo AL 012 providas de luz negra, com baterias de 12 volts. Os insetos coletados foram identificados de acordo com a literatura e coleções entomológicas por espécie ou por família. O levantamento ocorreu a cada quinze dias no período de agosto de 1994 a julho de 1995. Foram coletados 2449 indivíduos, sendo Epicauta sp. (Meloidae), Colaspis sp.2 (Chrysomelidae) e Oxycheila tristes (Cicindelidae) as espécies mais coletadas, representando, respectivamente, 10,75%, 9,95% e 5,38% dos indivíduos coletados por espécie. As famílias com maiores números de indivíduos e de espécies foram Melolonthidae, Carabidae e Chrysomelidae com 37,02%, 36,46% e 5,68%, respectivamente dos indivíduos identificados por família. Foram coletados coleópteros em todo o período de amostragem, mas os maiores picos populacionais para esses insetos foram registrados entre setembro e janeiro.

RESUMO Utilizando-se de um experimento, envolvendo famílias de meios-irmãos de Eucalipytus grandis, conduzido pela Celulose Nipo Brasileira S.A. (CENIBRA), onde foram anotados dados de circunferência à altura do peito (CAP) e altura de plantas (ALT), foram comparadas as metodologias de seleção entre e dentro com a seleção combinada, sob diferentes intensidades de seleção. O processo de seleção combinada mostrou-se superior ao de seleção entre e dentro devido às maiores estimativas de ganhos genéticos esperados e, também, pelo fato de selecionar um número maior de famílias para recombinação.

Eucalyptus was one of the most cultivated hardwood species worldwide, with rapid growth, good wood properties and a wide range of adaptability. Eucalyptus stem undergoes primary growth (longitudinal growth) followed by secondary growth (radial growth), which produces biomass that is an important source of energy worldwide. In order to better understand the genetic regulation of secondary growth in Eucalyptus grandis, Transcriptome analyses in stem segments along a developmental gradient from the third internode to the eleventh internode of E. grandis that spanned primary to secondary growth were carried out. 5,149 genes that were differentially expressed during stem development were identified. Combining the trend analysis by the Mfuzz method and the module-trait correlation analysis by the Weighted Gene Co-expression Network Analysis method, a total of 70 differentially expressed genes (DEGs) selected from 868 DEGs with high connectivity were found to be closely correlated with secondary growth. Results revealed that the differential expression of these DEGs suggests that they may involve in the primary growth or secondary growth. AP1, YAB2 TFs and EXP genes are highly expressed in the IN3, whereas NAC, MYB TFs are likely to be important for secondary growth. These results will expand our understanding of the complex molecular and cellular events of secondary growth and provide a foundation for future studies on wood formation in Eucalyptus. [ABSTRACT FROM AUTHOR]

Some plant species can bioaccumulate copper in their tissues and can be used for phytoremediation in contaminated soils. This work aimed to determine the bioconcentration and bioaccumulation of copper in eucalyptus species and how they affect the physiology of plants. The experimental design was completely randomized in a factorial arrangement (4 × 6), with four species of eucalyptus (Eucalyptus grandis W. Hill ex. Maiden, Corymbia citriodora (Hook.) K.D. Hill and L.A.S. Johnson, Eucalyptus saligna Smith and Eucalyptus dunnii Maiden), six doses of copper (zero, 80, 160, 240, 320, 400 mg kg−1), with twelve repetitions, carried out for 120 days in a greenhouse condition. The exotic species showed a high potential for growing in soils with high copper concentrations and also a potential for copper bioremediation. The highest copper concentration accumulation was shown mainly in the root system of the seedlings of Eucalyptus grandis, Eucalyptus saligna, Eucalyptus dunnii and Corymbia citriodora. E. saligna the copper toxicity was less pronounced, and the plants showed better physiologic effects. Cu levels increased with the doses, with greater intensity for species E. grandis and E. saligna with values of 21.1 and 15.5 mg kg−1, respectively. Also, the species showed a high capacity for copper bioaccumulation in the root system and showed high characteristics for phytoaccumulation and phytoextraction. So, these plants have great characteristics to grow in copper-contaminated sites being useful to reduce free copper in the environment. [ABSTRACT FROM AUTHOR]

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The aim of this work was to evaluate the physical and mechanical properties of cement-wood composites with the addition of biomass ashes at different levels (0, 5, 10, 15, 20, and 25%). The composites were produced using Portland cement CPII, Eucalyptus grandis particles, and ashes from eucalyptus wood. The tests followed the NBR 7215 (2019) and ASTM E1876 (2022) standards, density, 24-hour thickness swelling, 24-hour water absorption, dynamic modulus of elasticity from non-destructive testing, static modulus of elasticity, and compressive strength at 28 days tests were carried out. After the tests, statistical analysis was performed to verify if there were statistically differences between the means at a 5% level of significance. The partial replacement of cement with ashes shows potential, especially with a 5% replacement, due to better physical and mechanical properties. [ABSTRACT FROM AUTHOR]

We measured the tree transpiration of 9-year-old, Eucalyptus grandis x Eucalyptus urophylla clonal hybrid (GU) trees in the commercial forestry area of northern KwaZulu-Natal, South Africa. Transpiration was measured using the heat ratio method over two consecutive hydrological years (2019/20 and 2020/21) and up-scaled to a stand level. Leaf area index (LAI), quadratic mean diameter, and soil water content (SWC) were measured over the same period using an LAI 2200 plant canopy analyser, manual dendrometers and CS616 sensors, respectively. The depth to groundwater was estimated to be approx. 28 m, using a borehole next to our study site. Results showed that transpiration followed a seasonal pattern, with daily mean of 2.3 mm-tree-1·day-1 (range: 0.18 to 4.55 mm·tree-1·day-1) and 3.3 mm·tree-1·day-1 (range: 0.06 to 6.6 mm·tree-1·day-1) for 2019/20 and 2020/21, respectively. Annual GU transpiration was higher than that found by international studies under similar conditions, but was within the same transpiration range as Eucalyptus genotypes in the KwaMbonambi area. Plantation water productivity, calculated as a ratio of stand volume to transpiration, was higher than for other published studies, which was attributed to a very high productive potential of the study site. Multiple regression using the random forests predictive model indicated that solar radiation, SWC and air temperature highly influence transpiration. There is a high possibility that our GU tree rooting system extracted water in the unsaturated zone during the dry season. Due to the use of short-term results in this study, the impact of GU on water resources could not be quantified; however, previous long-term paired catchment studies in South Africa concluded that Eucalyptus has a negative impact on water resources. Further research is suggested with long-term measurements of transpiration and total evaporation and an isotope study to confirm the use of water by GU trees in the unsaturated zone. [ABSTRACT FROM AUTHOR]

Background: The WUSCHEL-related Homeobox (WOX) genes, which encode plant-specific homeobox (HB) transcription factors, play crucial roles in regulating plant growth and development. However, the functions of WOX genes are little known in Eucalyptus, one of the fastest-growing tree resources with considerable widespread cultivation worldwide. Results: A total of nine WOX genes named EgWOX1-EgWOX9 were retrieved and designated from Eucalyptus grandis. From the three divided clades marked as Modern/WUS, Intermediate and Ancient, the largest group Modern/WUS (6 EgWOXs) contains a specific domain with 8 amino acids: TLQLFPLR. The collinearity, cis-regulatory elements, protein-protein interaction network and gene expression analysis reveal that the WUS proteins in E. grandis involve in regulating meristems development and regeneration. Furthermore, by externally adding of truncated peptides isolated from WUS specific domain, the transformation efficiency in E. urophylla × E. grandis DH32-29 was significant enhanced. The transcriptomics data further reveals that the use of small peptides activates metabolism pathways such as starch and sucrose metabolism, phenylpropanoid biosynthesis and flavonoid biosynthesis. Conclusions: Peptides isolated from WUS protein can be utilized to enhance the transformation efficiency in Eucalyptus, thereby contributing to the high-efficiency breeding of Eucalyptus. [ABSTRACT FROM AUTHOR]