This study investigated the natural variation in lignin content and syringyl/guaiacyl (S/G) ratio of Eucalyptus globulus from native Australian (AU) trees and introduced trees from Argentina (AR), Portugal (PT), and Uruguay (UY). The S/G ratio is a key player for pulping more than lignin content since syringyl type lignin are easier to remove during pulping and less prone to condensation. Even though Klason lignin content (18-24%) and S/G ratio (1.58-2.41) varied considerably between trees, the differences between countries were smaller: AU (20.5%; 1.97), PT (20.2%; 2.02), AR (21.7%; 1.94), and UY (21.7%; 2.16). In terms of lignin content and S/G ratio, AU and PT are quite similar, whereas AR and UY have identical lignin content but differ in the S/G ratio. However, the detailed analysis of the pyrolysis products shows that the lignin composition of AU and AR is both similar and distinct from that of PT or UY. The principal component analysis (PCA) using mean-centered data shows that the main variation is due to the tree-to-tree variation of the most important lignin peak, S4 (syringol, 4-propenyl-trans), which accounts for 14% of the total lignin peaks. Higher percentages of S10 (sinapinaldehyde), S1 (syringol), and S5 (syringaldehyde), which together made up 24% of lignin peaks, are primarily responsible for the differentiation of PT from AU/AR along PC 2 (21%). The age of the trees seems having no effect on the S/G ratio of wood lignin and is likely not responsible for the structural differences in lignin between countries.

Eucalyptus dunnii is one of the most important Eucalyptus species for short-fiber pulp production in regions where other species of the genus are affected by poor soil and climatic conditions. In this context, E. dunnii holds promise as a resource to address and adapt to the challenges of climate change. Despite its rapid growth and favorable wood properties for solid wood products, the advancement of its improvement remains in its early stages. In this work, we evaluated the performance of two single nucleotide polymorphism, (SNP), genotyping methods for population genetics analysis and Genomic Selection in E. dunnii. Double digest restriction-site associated DNA sequencing (ddRADseq) was compared with the EUChip60K array in 308 individuals from a provenance-progeny trial. The compared SNP set included 8,011 and 19,008 informative SNPs distributed along the 11 chromosomes, respectively. Although the two datasets differed in the percentage of missing data, genome coverage, minor allele frequency and estimated genetic diversity parameters, they revealed a similar genetic structure, showing two subpopulations with little differentiation between them, and low linkage disequilibrium. GS analyses were performed for eleven traits using Genomic Best Linear Unbiased Prediction (GBLUP) and a conventional pedigree-based model (ABLUP). Regardless of the SNP dataset, the predictive ability (PA) of GBLUP was better than that of ABLUP for six traits (Cellulose content, Total and Ethanolic extractives, Total and Klason lignin content and Syringyl and Guaiacyl lignin monomer ratio). When contrasting the SNP datasets used to estimate PAs, the GBLUP-EUChip60K model gave higher and significant PA values for six traits, meanwhile, the values estimated using ddRADseq gave higher values for three other traits. The PAs correlated positively with narrow sense heritabilities, with the highest correlations shown by the ABLUP and GBLUP-EUChip60K. The two genotyping methods, ddRADseq and EUChip60K, are generally comparable for population genetics and genomic prediction, demonstrating the utility of the former when subjected to rigorous SNP filtering. The results of this study provide a basis for future whole-genome studies using ddRADseq in non-model forest species for which SNP arrays have not yet been developed.

A Amazônia está sofrendo consequências por causa do desmatamento, uma vez que está localizada na rota considerada do avanço do Arco do Desmatamento, tornando-se uma das regiões que mais se destaca em áreas desmatadas no Brasil, pois, apresenta vastas alterações em paisagens naturais em decorrência da expansão agropecuária. Este trabalho teve como o objetivo realizar uma revisão bibliográfica de forma sistemática sobre a importância na produção de mudas que fornecem essências florestais para a Amazônia. A pesquisa bibliográfica foi executada nas seguintes bases de dados eletrônicas: Periódicos Capes, SciELO e Google Acadêmico. Foi utilizado como critério de inclusão: artigos originais e artigo de revisão, publicados em periódicos internacionais e nacionais, no período dos últimos 10 anos. Foram encontrados um total de 20 artigos e a partir das análises, os artigos foram categorizados em: Região Amazônica, desmatamento, produção de mudas florestais na Amazônia e reflorestamento da região Amazônica. Além disso, 15 espécies vegetais apresentaram potencial para a produção de mudas de essências florestais. A prática do desmatamento causa grandes impactos ambientais no ecossistema Amazônico e os ecossistemas que sofrem influência direta. Portanto, a região Amazônica tem uma grande importância ecossistêmica, pois apresenta grandes diversidades de espécies. O resultado desta pesquisa irá auxiliar novos trabalhos que possam mitigar os efeitos da prática do desmatamento.

The Amazonia is suffering consequences due to deforestation, since it is located on the considered path of the advance of the Deforestation Arc, becoming one of the regions that most stands out in deforested areas in Brazil, since it presents vast alterations in natural landscapes due to the agricultural expansion. This work aimed to carry out a systematic bibliographical review on the importance in the production of seedlings that provide forest essences for the Amazon. The bibliographic research was carried out in the following electronic databases: Periodicals Capes, SciELO and Academic Google. It was used as inclusion criterion: original articles and review article, published in international and national periodicals, in the period of the last 10 years. The total of 20 articles were found and from the analysis, the articles were categorized into: Amazon Region, deforestation, production of forest seedlings in the Amazon and reforestation in the Amazon region. In addition, 15 plant species showed potential for the production of seedlings of forest essences. The practice of deforestation causes major environmental impacts on the Amazon ecosystem and the ecosystems that are directly influenced by it. Therefore, the Amazon region has great ecosystemic importance, as it presents great diversity of species. The result of this research will help new works that can mitigate the effects of the practice of deforestation.

Near Infrared Spectroscopy (NIR) is often used to perform high throughput phenotyping on thousands of genotypes using prediction models with high variability. A study was therefore undertaken to analyze the potential of multispecies, multisite and multi-age NIR calibration models of seven chemical properties of eucalyptus wood. The models are based on 358 samples selected among more than 5000 samples that belong to five eucalypt species including hybrids. The samples were collected from trees aged 2-35 originating from four different countries. Spectra were measured on non-extracted wood powders using an FT-NIR spectrometer. Models were established in the spectral range of 9090-4040 cm(-1) using the PLS regression method, tested by repeated cross-validation and validated on independent test sets. The results showed that the robust models for total extractives (R-P(2) = 0.91, RMSEP = 1.20%, RPD = 3.3) and KL (R-P(2) = 0.89, RMSEP = 1.21%, RPD = 3.0) provided good predictions. These two properties were the best predicted, followed by the S/G ratio (R-P(2) = 0.84, RMSEP = 0.19, RPD = 2.5) and ASL content (R-P(2) = 0.81, RMSEP of 0.54, RPD = 2.3). For holocellulose, alphacellulose, and hemicelluloses contents, the models provided approximate predictions. The prediction errors were always less than twice of the laboratory errors except for ASL and S/G ratio. For total extractives and ASL, beta-coefficients of models were of approximately the same magnitude throughout the 9000-4000 cm(-1) region while for the five other properties, they were higher in the 7500-4000 cm(-1) region. Models were also established in narrower NIR regions, and the quality of models obtained was about the same as that of the models based in the 9090-4000 cm(-1) wide range. These established robust models can be used to make predictions based on samples of high variability.

Eucalyptus globulus is an important pulpwood source due to favorable wood characteristics, including low extractive content. However, there is significant tree-to-tree variation that can be exploited in breeding. This requires screening a large number of samples, which NIR and PLS-R make possible. Models are typically developed for a specific set of samples prepared in the same way. The question is: how well these models predict samples that are different from the ones used in the model. Models developed to determine the extractive content of Eucalyptus globulus wood from Australia were used to E. globulus wood from Argentina, which differed in age and sample preparation. The main difference between spectra of the two origins was in the OH combination band, despite the fact that samples were dried identically. Due to this difference, models that included the O-H band assigned above 73% of the spectra as outliers regardless of preprocessing, whereas models that did not include the O-H band assigned fewer spectra as outliers. The differences in the OH band were attributed primarily to differences in particle size and extractive content, rather than to differences in humidity content. However, all models predict similar results for all samples, including outliers.

The residual lignin content of unbleached maritime pine (Pinus pinaster Aiton) Kraft pulps was assessed by analytical pyrolysis (Py-lignin) and the results were compared to the Klason lignin content and kappa number. Thirty samples, each from an individual tree, were delignified under identical conditions. The residual lignin content of the pulps varied widely as assessed by Py-lignin (5.9%–9.2%), Klason (8.2–15.1), and kappa number (59–112). Despite a systematic difference between Py-lignin and Klason, they were strongly correlated (R2 = 0.90). The H/G ratio of the residual pulp lignin ranged from 0.145 to 0.195, with a mean of 0.165, which is more than two times the average H/G ratio of Maritime pine wood lignin (0.064). The results show that Kraft pulping, which selectively degrades lignin with more labile inter-unit links, changed the pattern of pyrolysis products of pulp lignin considerably and, consequently, its structure. This pattern shows an enrichment in H-lignin-derived products, namely phenol, p-cresol, and m-cresol, and in some G-lignin-derived products such as guaiacol and 4-mthylguaiacol, and a decrease in coniferylaldehyde, homovanillin, and eugenol. Principal component analysis (PCA) of the G- and H-lignin-derived pyrolysis products shows that pulps are distributed along PC 1 based on their residual lignin content. The loadings plot shows that this separation is mainly due to a small number of G-lignin products, including 4-methyl guaiacol, 4-vinyl guaiacol, isoeugenol (trans), and guaiacol, which are more abundant in pulps with higher residual lignin content. The obtained results show that analytical pyrolysis is an appropriate method for quantifying the residual lignin content and H/G ratio of unbleached Kraft pulps and provide information regarding how lignin is degraded during the pulping process.

Eucalyptus globulus Labill is an important raw material for pulpwood for which low lignin content and high S/G ratios are important parameters. This work shows a highly significant positive and strong correlation between S/G ratio and acid-soluble lignin (ASL) content among E. globulus trees. Although significant, the negative correlation between the S/G ratio and Klason lignin is weak, and there is no correlation with total lignin content. The Klason residue has a lower S/G ratio than that of the original wood. This suggests that the contribution of the S units to the solubilisation of lignin in acidic conditions is not limited to the S units but also to the G units. This effect becomes more pronounced as the percentage of S units increases.

The objective of this study was the development of a NIRS (Near InfraRed Spectroscopy) and PLSR (Partial Least Square Regression) model for quantitatively determining extractives, in four clones of the Italian cypress Cupressus sempervirens. Extractives were correlated to the fungal resistance of wood samples evaluated with a non-standard procedure based on the mass loss of mini-blocks. PLSR regression models based on NIRS gave good predictions of extractives content with RPD (Residual Prediction Deviation) equal or above 2.7, suggesting that NIRS-PLSR procedure could be used for the characterization of cypress wood. Total extractives were significantly different among heartwood and sapwood but not among clones. Both inner and outer heartwood of the four C. sempervirens clones were resistant to three brown rot fungi. Minimal differences were found among clones in the mass loss of the heartwood samples, while significant inter-clonal differences emerged in the mass loss of sapwood samples. Intra-clonal variation was detected for sapwood samples and only in one of the four tested clones. The correlation between durability and extractives content was significant only if sapwood was added to heartwood in the dataset. Nevertheless, the high durability observed in the examined clones encourages selection of these cypress genotypes for wood production.

Analytical pyrolysis can be used to determine the lignin content (Py-lignin) in eucalypt woods with a precision (0.37%) similar to the wet reference methods. Good correlations were found between the Py-lignin results and Klason (94%) and total lignin contents (95%). Besides apparent species-specific deviations, an average difference of 1.3% compared to the total lignin content was observed, well below the 3.9% difference reported for softwoods (guaiacyl lignin). Since Eucalyptus has more syringyl (S) than guaiacyl (G) units, this suggests that S units are overestimated in comparison to G units by analytical pyrolysis, in line with previous findings for different degradation methods, including pyrolysis.

Key message The wood of Pinus nigra populations planted in Portugal, comparatively to Pinus pinaster , has higher total extractive content, lower Klason lignin and H/G ratio, and similar mechanical properties, presenting advantages for industrial purposes. Context P. nigra was used in the reforestation of mountainous areas in Portugal, but its wood chemical and mechanical properties were never studied. Aims This work intends to evaluate the chemical and mechanical wood properties of the P. nigra populations planted in Portugal, to relate these properties with previously characterised physical features and to compare these data with other European P. nigra stands and species, namely, P. pinaster. Methods Wood chemical and mechanical properties were analysed in 90 trees from six Portuguese sites, using near-infrared (NIR) spectrometry and the three-point bending test. Results The wood of the P. nigra populations planted in Portugal presented average values of total extractive content = 9.4%, Klason lignin = 26.69%, MOR Rad = 14.93 MPa and MOE Rad = 1200.98 MPa. Ring density showed no significant correlation with ring width. Conclusion The P. nigra populations planted in Portugal presented qualitative and quantitative properties similar to P. pinaster wood, the main resinous species in Portugal. Facing the lack of raw material for wood industry due to frequent forest fires in the Mediterranean region, P. nigra could be used to reforest mountainous areas of those regions.

Mediterranean ecosystems, such as the savannah-type cork oak (Quercus suber) woodlands, are hotspots for climate change, as the highest impacts are forecasted for the Mediterranean region, mainly by more frequent and intense severe droughts. These ecosystems are also threatened by shrub encroachment, which might further decrease tree water availability and affect ecosystem functioning and resilience. Nevertheless, the combined effects of drought and shrub encroachment on ecosystems have seldom been investigated. A precipitation manipulation and shrub removal experiment was established in a cork oak woodland located in SE Portugal and invaded by the native shrub gum rockrose (Cistus ladanifer). Here we present and discuss the combined effects of drought and shrub encroachment on litterfall production of cork oak trees, an evergreen species, over two contrasting years, a wet year (2018) and a dry year (2019) and assess the nitrogen and phosphorus resorption efficiencies from senescent to green leaves.A previous study reported significant increases in cork oak’s nitrogen resorption efficiency in response to drought. Our preliminary results also indicate changes in nitrogen and phosphorus resorption efficiencies. An increase in nutrient resorption efficiency is likely to mitigate the limitation in nutrient uptake by the roots during drought, improving tree fitness in the short-term. However, it will probably exert a negative feedback on the nitrogen and phosphorus cycles in the long-term which might affect the ecosystem functioning under the forecasted droughts.

Wheat is one of the most important cereals for food and feed, and it is, therefore, necessary to determine the effects of short-term high temperature events (heatwaves) during grain filling. These heatwave events are increasingly common, especially in Portugal. In this work, seven commercial varieties recommended for production in Portugal were submitted to one-week high temperature (HT) treatment ten days after anthesis to evaluate heat effects on grain yield and quality. Grain yield parameters, such as grain number and weight, were evaluated as well as grain composition through attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy. Variation in HT response between varieties was detected. Grain number and weight tended to decrease in most varieties analyzed. However, two varieties proved to be more resilient since grain number and weight remain unaltered in the Bancal variety, which is the one with better yield results, and even increased in the Pata Negra variety. Regarding grain composition, the comparison between ATR-FTIR spectra of milled grains from control and HT plants revealed alterations in peaks assigned to polysaccharides and proteins. Additionally, a model was built based on nitrogen elemental analysis to predict protein content in flour samples through spectral data that corroborated the differences identified by spectra profile comparison. Moreover, both analyses showed that the intervarietal diversity observed in control conditions was significantly reduced in HT treated plants. The results obtained highlight the intervarietal diversity of wheat response to HT, regarding grain yield parameters, grain composition, and particularly, protein content.

Wood density is one of the most important physical properties of the wood, used in improvement programs for wood quality of major timber species. Traditional core sampling of standing trees has been widely used to assess wood density profiles at high spatial resolution by X-ray microdensitometry methods, but alternative methods to predict wood properties quality are also needed. Near-infrared (NIR) spectroscopy, a non-destructive technique, is being increasingly used for wood property assessment and has already been demonstrated to be able to predict wood density. However, the estimation of wood density profiles by NIR has not yet been extensively studied, and improved models using spectra information (NIR) and X-ray data need to be developed. To this end, partial least square regression (PLS-R) models for predicting wood density were developed at a 1.4 mm spatial resolution on Pinus pinaster wood cores, with an improved spatial synchronization along the tangential and radial directions of the strip, between X-ray data and NIR spectra. The validation of the best model showed a high coefficient of determination (0.95), low error (0.026) and no outlier. Compression wood samples were not detected as outliers and were correctly predicted by the model. However, pith spectra were detected as outliers and its predicted values were overestimated by 33% due to unusual spectra suggesting a diverse chemical composition. The results suggest that NIR-PLS models obtained can be used for screening maritime pine wood density profiles along the radii at 1.4 mm spatial resolution.

Wheat is a dietary staple consumed worldwide strongly responsible for proteins and carbohydrate population intake. However, wheat production and quality will scarcely fulfill forward demands, which are compounded by high-temperature (HT) events as heatwaves, increasingly common in Portugal. Thus, landraces assume crucial importance as potential reservoirs of useful traits for wheat breeding and may be pre-adapted to extreme environmental conditions. This work evaluates four Portuguese landrace yield and grain composition through attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy, particularly protein content, and their responses to HT treatment mimicking a heatwave. Landraces showed distinct yield traits, especially plant height and first spike grain number, and a similar pattern in FTIR spectra, although revealing differences in grain components’ proportions. Comparison between spectra band intensity indicates that Ardito has the highest protein-related peaks, contrary to Magueija, which appears to be the landrace with higher lipid content. In plants submitted to 1 week of HT treatment 10 days after anthesis, the first spike grain size and weight were markedly reduced in all landraces. Additionally, it was observed that a general increase in grain protein content in the four landraces, being the increment observed in Ardito and Grécia, is statistically significant. The comparative assessment of control and HT average FTIR spectra denoted also the occurrence of alterations in grain polysaccharide composition. An integrated assessment of the evaluations performed revealed that Ardito and Magueija landraces presented diverse yield-related characteristics and distinct responses to cope with HT. In fact, the former landrace revealed considerable grain yield diminution along with an increase in grain protein proportion after HT, while the latter showed a significant increase in spikes and grain number, with grain quality detriment. These results reinforce the relevance of scrutinizing old genotype diversity seeking for useful characteristics, particularly considering HT impact on grain production and quality.

Abstract Softwood lignin consists mainly of guaiacyl (G) units and low amounts of hydroxyphenyl (H) units. Even in a small percentage, the ratio of H to G (H/G) and the intraspecific variation are crucial wood lignin properties. Analytical pyrolysis (Py) was already successfully used as a reference method to develop a model based on near-infrared (NIR) spectroscopy for the determination of the H/G ratio on Pinus pinaster (Pnb) wood samples. The predicted values of the Pinus sylvestris (Psyl) samples by this model were well correlated (R = 0.91) with the reference data (Py), but with a bias that increased with increasing H/G ratio. Partial least squares regression (PLS-R) models were developed for the prediction of the H/G ratio, dedicated models for Psyl wood samples and common models based on both species (Pnb and Psyl). All the calibration models showed a high coefficient of determination and low errors. The coefficient of determination of the external validation of the dedicated models ranged from 0.92 to 0.96 and for the common models ranged from 0.83 to 0.93. However, the comparison of the predictive ability of the dedicated and common models using the Psyl external validation set showed almost identical predicted values.

Although eucalypts are the most planted hardwood trees worldwide, the majority of them are frost sensitive. The recent creation of frost-tolerant hybrids such as Eucalyptus gundal plants (E. gunnii × E. dalrympleana hybrids), now enables the development of industrial plantations in northern countries. Our objective was to evaluate the impact of cold on the wood structure and composition of these hybrids, and on the biosynthetic and regulatory processes controlling their secondary cell-wall (SCW) formation. We used an integrated approach combining histology, biochemical characterization and transcriptomic profiling as well as gene co-expression analyses to investigate xylem tissues from Eucalyptus hybrids exposed to cold conditions. Chilling temperatures triggered the deposition of thicker and more lignified xylem cell walls as well as regulation at the transcriptional level of SCW genes. Most genes involved in lignin biosynthesis, except those specifically dedicated to syringyl unit biosynthesis, were up-regulated. The construction of a co-expression network enabled the identification of both known and potential new SCW transcription factors, induced by cold stress. These regulators at the crossroads between cold signalling and SCW formation are promising candidates for functional studies since they may contribute to the tolerance of E. gunnii × E. dalrympleana hybrids to cold.

Breeding programs in Africa are generally based on growth criteria and rarely on wood chemical properties. Indeed, chemical analysis are often expensive, time-consuming and require several replicates. Then, using NIRS to predict these properties is a relevant solution. The research question focuses on the possibility of using multispecies models to predict properties of different species. This study considers 7 chemical properties (extractives, Klason lignin, acidosoluble lignin ASL, SG ratio, holocellulose, alphacellulose, hemicelluloses) based on 367 samples from 4 countries, belonging to 5 eucalypt species with hybrids (E. robusta, camaldulensis, urophylla, uropellita, urograndis). Established models were validated by cross- and test-set validation. Results shows that all R2CV are greater than 0.73, and all %RMSECV are less than 8.3% except for extractives and ASL. Prediction errors (%RMSEP) are always less than 9.5% except for these 2 properties, with respectively 23.6% and 18.1%. Prediction errors are always less than the double of the error of laboratory (%SEL). This study shows that multispecies NIRS models can be used to predict chemical properties, there is no significant difference between measurement error obtained with standardized method and %RMSEP. This method is particularly well-suited for a rapid wood phenotyping of multiple samples belonging to different species.

Abstract Quantitative determination of cellulose content by means of diglyme [bis(2-methoxyethyl) ether] isolation is useful for rapid screening experiments. However, diglyme isolation from softwoods results in a certain amount of residual lignin in the cellulose. In this paper, the lignin content (L) in diglyme cellulose of three pine species (Pinus halepensis Miller, Pinus sylvestris L. and Pinus pinaster Aiton) was analysed by ATR-FTIR spectroscopy and analytical pyrolysis (Py). Py allowed lignin quantification. The influence of wood milling on cellulose yield was also analyzed and it was shown that a particle size between 10 and 60 mesh did not noticeably influence the cellulose yield or L; however, ball-milling to powder did cause a cellulose loss of around 37%. The diglyme method is only reproducible if the experimental parameters are standardized and meticulously followed.

The wood of Pine trees can have significant amounts of diterpenic (resin) acids, 14 particularly when the trees are stressed or injured. Resin acids are an important industrial raw 15 material used in a myriad of applications. The analysis of complex resin acid mixtures have been 16 done more commonly by GC-MS but also by NMR. Here we analyzed a resin acid sample from a P. 17 sylvestris wood with an abnormally high resin acid content of 30%, both by GC-MS and NMR to 18 compare the results. The GC-MS analysis showed a mixture of dominantly abietane-type resin acids, 19 namely dehydroabietic acid (50%) and their hydroxylated forms (35%), and much smaller quantities 20 of pimarane type resin acids (8%). The NMR analysis showed a higher proportion of abietic acid 21 (42% to 3%) and pimarane type acids (95% to 15%) relative to dehydroabietic acid, comparatively 22 to the GC-MS analysis. It is hypothesized that the conversion of abietadienoic acids (e.g. abietic) to 23 dehydroabietic acid can be significant in high-temperature GC-MS and that pimarane (pimaric and 24 isopimaric) acids are under-evaluated in GC-MS analysis relative to abietane acids comparatively 25 to NMR analysis. It is concluded that the later can give more accurate results, minimizing resin acids 26 degradation and avoiding GC-MS quantitation bias. 27