Tree physiology最新文献

{"title":"Uncovering the mechanisms of heartwood formation and wood resistance to fungal degradation in the tropical Lauraceae tree Sextonia rubra (Mez.) van der Werff.","authors":"Marceau Levasseur, Ambre Senelis, Flavien Zannini, Muriel Barbier, Elsa Van Elslande, Nadine Amusant, Yannick Estevez, Véronique Eparvier, Éric Gelhaye, David Touboul, Emeline Houël","doi":"10.1093/treephys/tpaf079","DOIUrl":"https://doi.org/10.1093/treephys/tpaf079","url":null,"abstract":"<p><p>Heartwood formation is a complex process that contributes to ensuring the integrity of trunks and the longevity of trees. We examined this mechanism in the tropical angiosperm Sextonia rubra in relation to the spatial distribution of specialised metabolites and their functional role at the scale of a mature individual. Heartwood formation was analysed starting from the examination of one of its properties, namely the decay resistance, of the different S. rubra wood tissues (sapwood, heartwood, and pith) using soil bed tests. Annotation and identification of the metabolites present in ethyl acetate extracts were carried out by reverse-phase liquid chromatography coupled to a tandem mass spectrometer (RPLC-ESI-MS/MS) and molecular networks. Following the application of supervised statistical analyses and the use of Glutathione S-transferases enzymatic assays, the specialised metabolites of interest were quantified radially and longitudinally in the different tissues using RPLC-ESI-HRMS system. Heartwood and pith were shown to resist degradation after a ten-months exposure to forest soil, with no effect of the heartwood cambial age. Molecular diversity was specific to each tissue type, with flavonoids and butanolides detected in bark and sapwood, while alkaloids and butyrolactones were identified in heartwood and pith. Supervised analyses and enzyme assays suggested that alkaloids and butyrolactones play a role in the resistance of internal tissues to degradation. Butyrolactone concentrations peaked in the middle heartwood but remained homogeneous longitudinally, while alkaloid concentrations were uniform longitudinally and radially in the heartwood. In conclusion, the resistance of heartwood and pith to fungal degradation was correlated with the accumulation of lactones and alkaloids. While butanolide precursors of butyrolactones have been detected in the sapwood, alkaloids appear to be directly biosynthesised in the heartwood. This suggests that the biosynthesis and accumulation of specialised metabolites during heartwood formation is specific to each molecular family.</p>","PeriodicalId":23286,"journal":{"name":"Tree physiology","volume":" ","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144584968","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"PbHDZ35, an HD-ZIP transcription factor, regulates the trade-off between growth and drought stress in Phoebe bournei.","authors":"Yan Liu, Xiao Li, Mingyang Ni, Yuting Zhang, Wenjun Ma, Yandong Song, Zaikang Tong, Junhong Zhang","doi":"10.1093/treephys/tpaf068","DOIUrl":"10.1093/treephys/tpaf068","url":null,"abstract":"<p><p>Phoebe bournei (Hemsl.) Yang, a valuable afforestation species in subtropical China, is highly sensitive to water availability, thus the growth and distribution significantly impacted by recurrent extreme drought events. Previous studies showed that homeodomain-leucine zipper (HD-ZIP) transcription factors play crucial roles in plant development and abiotic stress responses. However, there has been no thorough investigation of the HD-ZIP gene family in P. bournei, and their regulatory roles under drought stress remain unknown. In the present study, we identified and characterized 42 HD-ZIP genes in P. bournei. Weighted gene co-expression network analysis (WGCNA) of PEG-induced transcriptomic data revealed an ABA-associated gene, PbHDZ35 (homologous to AtHB7/12), which displayed strong sensitivity to Polyethylene glycol (PEG) treatment, abscisic acid (ABA) and natural drought stress. Interestingly, there are two opposite phenotypes of PbHDZ35-overexpressing plants between normal and drought condition, showing enhanced growth in transgenic plants under normal condition, but reduced drought tolerance. To illuminate the regulatory mechanism of PbHDZ35, a DAP-seq was conducted to identify the potential downstream genes of PbHDZ35. Based on the quantitative results from transient transformation in P. bournei leaves and stable transformation in hairy roots, PbHDZ35 was identified as a potential regulator of the ABA receptor PbPYL5 and the auxin response factor PbARF8. Yeast one-hybrid and dual-luciferase assays confirmed the involvement of PbHDZ35 in both ABA feedback regulation and auxin signaling pathways. Our findings demonstrate that PbHDZ35 orchestrates the trade-off between growth and drought tolerance in P. bournei by dual regulation of ABA signaling (via PbPYL5) and auxin responses (via PbARF8), highlighting its pivotal role in balancing stress adaptation with developmental plasticity under water-limited environments.</p>","PeriodicalId":23286,"journal":{"name":"Tree physiology","volume":" ","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144200097","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Gene expression regulation of the effect of shading on chlorophyll content in Fuding white tea (Camellia sinensis L.).","authors":"Guangzheng Li, Xi Chen, Yichen Zhao, Degang Zhao","doi":"10.1093/treephys/tpae049","DOIUrl":"10.1093/treephys/tpae049","url":null,"abstract":"<p><p>Shading is an important practical method to improve the quality of green tea. Previous research of our group found that because the biosynthesis and distribution of theanine in tea plants were affected by down regulation of gene encoding amino acid permeases, theanine content in tea leaves that grown under shading condition was significantly higher than those under natural light. In this study, our group analyzed the changes of tea leaf area, free amino acid content and photosynthetic parameters under natural light and shading conditions, to ensure that moderate shading did not reduce but improved the quality of tea. Transcriptome sequencing and Kyoto Encyclopedia of Genes and Genomes enrichment analysis were conducted to reveal the expression levels of genes related to chlorophyll content and chlorophyll a/b ratio under natural light and shading conditions. Experimental results revealed the presence of the following differentially expressed genes in the porphyrin and chlorophyll metabolism pathway of tea under natural light and shading conditions: the up regulation of CPOX expression may lead to an increase in the accumulation of raw materials of chlorophyll synthesis, while the down regulation of SGR expression may lead to a decrease in chlorophyll degradation. The combined effect of these two genes may lead to an increase in the total chlorophyll content of tea. The down regulation of NOL expression may lead to the obstruction of chlorophyll b transform to chlorophyll a, that is, the decrease of the chlorophyll a/b ratio. This study investigated the molecular mechanism of chlorophyll content and component alteration in Fuding white tea under natural light and shading conditions, and elucidated the effects of different light intensities on the porphyrin and chlorophyll metabolism pathway of tea. Thus, it provided deep understanding of chlorophyll regulation under shading condition in tea cultivation, which could contribute to high-quality matcha production.</p>","PeriodicalId":23286,"journal":{"name":"Tree physiology","volume":" ","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"140892647","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Genetic and geographic determinants of nitrogen isotope discrimination in black cottonwood (Populus trichocarpa).","authors":"Yi Hu, Robert D Guy, Jaroslav Klápště, Xuyang Lu, Raju Y Soolanayakanahally","doi":"10.1093/treephys/tpaf072","DOIUrl":"10.1093/treephys/tpaf072","url":null,"abstract":"<p><p>Genotypic variation in nitrogen-use traits remains largely unexplored in trees on a range-wide scale, either in field studies or under controlled experiments. Understanding natural variation in nitrogen-related traits and their relationships to climate is essential for studying local adaptation and advancing breeding efforts. In this study, we took advantage of a large collection of black cottonwood genotypes covering a major portion of the species' natural range, to study the genetic variation in nitrogen isotope discrimination (Δ15N). Nearly 350 unrelated wild genotypes were grown under steady-state hydroponic conditions and analyzed for growth and Δ15N-related traits. Differences in biomass, root-to-shoot ratio, whole-plant and organ-level nitrogen percentages, and Δ15N were found between genotypes and populations. Leaf nitrogen percentage and root-to-shoot ratio were significantly correlated to geographic and climatic variables, implying natural selection for lower leaf nitrogen and lower root-to-shoot ratio in regions with longer growing seasons and a lower risk of drought. Root Δ15N and (less so) leaf Δ15N correlated with geographic and climatic variables, and measurements from either tissue provide a reasonable indication of plant nitrogen uptake efficiency. A genome-wide association study was conducted on leaf and root Δ15N, leaf nitrogen percentage and root-to-shoot ratio. The analysis identified a candidate gene encoding glutaminyl-tRNA synthetase linked to root Δ15N, but found no significant associations with genes involved in nitrate transport or assimilation. However, multiple associations were detected for root-to-shoot ratio and leaf nitrogen percentage, both of which affect isotope-based calculations of root nitrogen efflux/influx and leaf nitrogen assimilation activity.</p>","PeriodicalId":23286,"journal":{"name":"Tree physiology","volume":" ","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144512553","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Survival secrets of mistletoes: high drought tolerance in canopy habitats.","authors":"Xian-Yan Huang, Yun-Bing Zhang, Marina Corrêa Scalon, Yan Ke, Wen-Hua Li, Da Yang, Amy N A Aritsara, Yong-Jiang Zhang, Zheng-Lin Wan, Xiao-Li Cheng, Jiao-Lin Zhang","doi":"10.1093/treephys/tpaf071","DOIUrl":"10.1093/treephys/tpaf071","url":null,"abstract":"<p><p>The interaction between mistletoes and hosts impacts tree performance and mortality under climate change. However, little is known about the hydraulic performance and drought resistance of mistletoes, and their potential impacts on hosts. Here, we measured 21 functional traits related to hydraulics and drought resistance of eight mistletoe-host species pairs. We found that mistletoes were more drought tolerant compared with their hosts, characterized by more negative midday leaf water potentials during the dry season, turgor loss point (ranging from -1.81 to -2.48 MPa) and water potential at 12% loss of conductivity (ranging from -0.97 to -2.94 MPa), higher Huber values, sapwood density and vessel density, and lower leaf size, specific leaf area, vein density and stomatal density. Meanwhile, mistletoes were less hydraulically efficient compared with their hosts, demonstrated by lower leaf-specific hydraulic conductivity, sapwood-specific hydraulic conductivity and hydraulically weighted vessel diameter. Paradoxically, mistletoes showed lower water-use efficiency (as indicated by more negative stable carbon isotope values). Notably, trait associations between mistletoes and hosts differed, with mistletoes showing stronger correlations among functional traits, both within leaf traits and between leaf and stem traits. This suggests divergent ecological strategies between mistletoes and their hosts. However, no trade-off between hydraulic efficiency and safety was observed across the mistletoes and hosts examined. High plasticity in hydraulic traits was also found in mistletoes, with water potential at 12, 50 and 88% loss of conductivity varying significantly and intraspecifically across host species. Furthermore, trait correlations in mistletoes were driven by both intraspecific and interspecific variation, with interspecific variation being more important. These findings highlight the response capacity of mistletoes, enabling them to adjust their hydraulic strategies based on host-specific conditions. This study provides insights into mistletoe water use, drought resistance and potential responses to changing environmental conditions.</p>","PeriodicalId":23286,"journal":{"name":"Tree physiology","volume":" ","pages":""},"PeriodicalIF":3.7,"publicationDate":"2025-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144508400","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Unveiling the integration of above- and below-ground tree carbon-hydraulic traits in Amazonian trees across hydrological niches.","authors":"Mauro Brum, Raimundo Cosme Oliveira-Junior, Luciana F Alves, Elizabeth Agee, Luciano Pereira, Deliane Penha, Carina Araujo, Juliana L S Mayer, Victor Hugo Pereira Moutinho, Rafael S Oliveira, Scott Stark, Scott R Saleska","doi":"10.1093/treephys/tpaf063","DOIUrl":"10.1093/treephys/tpaf063","url":null,"abstract":"<p><p>Understanding trait coordination and trade-offs along the root-to-leaf hydraulic pathway is critical for assessing forest functioning, as these traits significantly impact ecosystem carbon allocation and water use. Here, we investigated the relationship between carbon and hydraulic traits in 11 Amazonian tree species distributed across vertically structured hydrological niches. Using a carbon-hydraulic framework, we tested the hypothesis that interspecific differences arise from the optimization of xylem hydraulic efficiency, reflecting how tropical trees balance water transport efficiency with the carbon costs of maintaining transport tissues across vertical canopy positions. Our results show that above-ground traits were largely explained by canopy position (vertical stratification), whereas below-ground carbon-hydraulic traits were predominantly influenced by interspecific differences. Upper canopy trees exhibited lower and less variable specific root length (SRL) than shallow-rooted understory trees, indicating divergent carbon allocation strategies. Thicker terminal roots had higher hydraulic conductivity (Ks) than finer roots, but Ks declined from roots to terminal branches in most species. Additionally, branch and leaf Ks increase with tree size, indicating greater hydraulic efficiency in larger canopy species. Below-ground, we presented evidence that an increase in SRL is linked to decreased hydraulic conductivity and is influenced by root diameter. Above-ground, branch and leaf hydraulic conductivity tend to be higher in species with higher wood density, which are also more prevalent in upper canopy layers. Together, our findings reveal a coordinated above- and below-ground carbon-hydraulic trait framework across Amazonian trees. Species that occupy different vertical above-ground hydrological niches in lowland Amazon forests exhibit different carbon allocation strategies, which helps explain variation in species dominance and resource use throughout the vertical forest profile.</p>","PeriodicalId":23286,"journal":{"name":"Tree physiology","volume":" ","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144209521","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"High-resolution isotopic assessment at the cambium-xylem continuum in black spruce reveals sustained seasonal supply from current photoassimilation.","authors":"Darián Díaz-Muñoz, Carolina Morales, Frida I Piper","doi":"10.1093/treephys/tpaf076","DOIUrl":"10.1093/treephys/tpaf076","url":null,"abstract":"","PeriodicalId":23286,"journal":{"name":"Tree physiology","volume":" ","pages":""},"PeriodicalIF":3.7,"publicationDate":"2025-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144576342","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Infection of Norway spruce by Chrysomyxa rhododendri: ultrastructural insights into plant-pathogen interactions reveal differences between resistant and susceptible trees.","authors":"Andrea Ganthaler, Carlos Trujillo-Moya, Stefanie Burger, Juraj Hlavaty, Stefan Kummer, Waltraud Tschulenk, Ingrid Walter","doi":"10.1093/treephys/tpaf066","DOIUrl":"10.1093/treephys/tpaf066","url":null,"abstract":"<p><p>Infection of Norway spruce (Picea abies L.) by the rust Chrysomyxa rhododendri is a major problem in European subalpine forests, causing severe defoliation and reduced growth. However, as with most pathogens from high-elevation environments, little is known about the host-pathogen interaction, the associated plant cellular damage and responses, and their differential expression in susceptible and resistant host trees. Here we report on the development of the biotrophic pathogen in the host tissues, from infection by basidiospores to release of aeciospores, by analysing needles at different time points after infection by histology and transmission electron microscopy. Ultrastructural changes in the host cells, ranging from cell reorganization and degradation to the accumulation of secondary compounds, were localized and characterized in both susceptible and a resistant genotype. Chrysomyxa rhododendri formed a dense mycelium in the intercellular spaces of the needle mesophyll of susceptible trees, followed by the formation of subepidermal spermogonia and aecia. Symptomatic needle yellowing corresponded to the spatial expansion of the mycelium and was caused by degradation, but not collapse, of the mesophyll cells with chloroplasts. In needles of the enhanced resistant genotype, only few fungal hyphae appeared, but distinct modifications of the cell walls and an accumulation of electron dense material in the intercellular space appeared. In addition, large tannin droplets were observed around fungal structures, indicating an increased accumulation of polyphenols. The findings are consistent with observations on other heterocyclic rusts and with known physiological and molecular responses of infected trees, including a reduced photosynthetic activity, changes in the needle phenolic profile and a local hypersensitive response. Highly resistant trees may be able to limit fungal growth and associated damage by rapidly enhancing structural and chemical barriers in the needle mesophyll.</p>","PeriodicalId":23286,"journal":{"name":"Tree physiology","volume":" ","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12229092/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144209520","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Co-expression of SfGPX and SfGST in Nicotiana benthamiana and two Spiraea species further regulates their low-temperature tolerance mechanism.","authors":"Feng Qian, Bingbing Lu, Hao Sun, Hui Zhang, Ziyin Cheng, Zili Jin, Feifan Xu, Huimin Liu","doi":"10.1093/treephys/tpaf069","DOIUrl":"10.1093/treephys/tpaf069","url":null,"abstract":"<p><p>Spiraea fritschiana (S. fritschiana) is widely cultivated in horticulture and exhibits strong cold tolerance. We identified both glutathione peroxidases (GPXs) and glutathione S-transferases (GSTs) as key proteins involved in the low-temperature response of S. fritschiana. Both enzymes are known to participate in reactive oxygen species (ROS) scavenging through the ascorbate-glutathione cycle. Previous experiments have demonstrated that both SfGPX and SfGST are localized in the cytoplasm and exhibit responsiveness to low-temperature induction. In this context, we hypothesize a potential functional interplay between these two genes in mediating Spiraea's cold tolerance. To elucidate the functional interplay between SfGPX and SfGST in cold stress adaptation, this study employed yeast two-hybrid (Y2H) and luciferase complementation assays (LCA) to validate their protein-protein interactions, providing a foundation for further mechanistic studies. Meanwhile, we constructed SfGPX, SfGST overexpressing and SfGPX/SfGST co-overexpressing lines of Nicotiana benthamiana (N. benthamiana). We monitored phenotypic alterations and quantified key physiological parameters related to cold tolerance, photosynthetic performance and Ca2+ signaling in all transgenic lines under low-temperature conditions. Transient overexpression of SfGPX, SfGST and SfGPX/SfGST in Spiraea japonica 'Gold Mound' (S. japonica 'Gold Mound'), and transient editing of these genes in S. fritschiana were performed. The relative electrical conductivity (REC) was detected in each line under low temperature. The results showed that both Y2H and LCA detected no direct SfGPX-SfGST interaction under our experimental conditions. Under low-temperature stress conditions, SfGPX/SfGST co-overexpressing N. benthamiana lines exhibited significantly improved cold tolerance compared with single-gene overexpression lines. Co-overexpression of SfGPX/SfGST in S. japonica 'Gold Mound' reduced REC under cold stress versus single-gene lines, while co-edited S. fritschiana showed increased REC. This result suggests that while SfGPX and SfGST do not exhibit a reciprocal relationship in regulating low-temperature tolerance in tobacco and the two Spiraea species, their co-expression demonstrates a synergistic effect.</p>","PeriodicalId":23286,"journal":{"name":"Tree physiology","volume":" ","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144226840","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Calibration of a new transient thermal dissipation-based Internet of Things (IoT)-sensor for xylem sap flow density measurements for three different temperate tree species.","authors":"David Dluhosch, Shahla Asgharinia, Francesco Renzi, Benjamin D Hesse, Lasse Löffelbein, Riccardo Valentini, Thorsten E E Grams, Timo Gebhardt","doi":"10.1093/treephys/tpaf047","DOIUrl":"10.1093/treephys/tpaf047","url":null,"abstract":"<p><p>Measuring xylem sap flow is crucial for calculating water use in trees and forests, but remote measurements are challenging, especially regarding power supply. The transient thermal dissipation (TTD) system addresses these challenges by being power-efficient and robust. This study assesses the TreeTalker© system (version TT+), a newly developed battery-powered, Internet of Things (IoT)-based measurement system with new probes in terms of structure and material compared with previous versions. To calibrate the system, different flow indices (Ki) were derived for various heating/cooling cycles at several sap flow densities (SFD) using an artificial hydraulic column made of sawdust. To provide a calibration equation for different species, freshly cut stem segments with three distinct xylem structures of temperate trees were used under controlled conditions: Quercus robur L. (oak, ring-porous), Abies alba Mill. (fir, coniferous) and Fagus sylvatica L. (beech, diffuse-porous). A linear model best described the relationship between Ki and SFD for sawdust and oak, while a power function suited fir and beech. Compared with the literature, the regression steepness increased with the conduit size. Using the sawdust equation for oak resulted in a 55 ± 3% underestimation of SFD. For fir and beech, using the sawdust equation overestimated daily water use by 149 ± 116% and 71 ± 41%, respectively. A multi-media equation across all tested media reduced the underestimation in oak to 19 ± 3% but increase the overestimation for fir and beech compared with the sawdust equation to 352 ± 210% and 209 ± 75%, respectively. For more accurate estimation of absolute values, species-specific calibration equations are recommended assess SFD using the TTD method. However, there appears to be a dependency when comparing different linear calibration equations with the corresponding conduit sizes of the tree species.</p>","PeriodicalId":23286,"journal":{"name":"Tree physiology","volume":" ","pages":""},"PeriodicalIF":3.5,"publicationDate":"2025-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12129067/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144028461","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}