Trees最新文献

Key message

Falcataria falcata, one of the fastest-growing trees, showed a distinctively high photosynthetic rate and leaf nitrogen content. These traits were linked to seedling relative growth rates among nine populations.

Abstract

The increased demand for lightweight wood products requires genetic improvements in the growth, wood properties, and stress tolerance of fast-growing timber species. Falcataria falcata (Leguminosae) is one of the fastest-growing trees worldwide and an important multipurpose plantation species. This species is distributed across various geological locations in Southeastern Asia and Melanesia; therefore, populations from different regions may show phenotypic variations. Herein, we investigated variations in relative growth rate (RGR) and 17 traits related to growth, photosynthesis, and stress tolerance using current-year seedlings from nine populations grown under common greenhouse conditions. We detected a threefold variation in RGR among populations, with those from North Maluku, Papua, and Solomon showing relatively higher RGR. In total, 10 out of 17 traits varied significantly, with pronounced variation in nitrogen (N)-use traits, such as root nodule fraction (16.8-fold) and leaf nitrogen content per unit area (2.7-fold). F. falcata exhibited remarkably high photosynthetic rate (A_area), leaf nitrogen concentration (N_mass), and specific leaf area, reaching the maxima reported for woody broadleaf species. The RGR was positively associated with A_area, N_mass, and leaf dark respiration rate among populations, but not with biomass allocation. These results suggest that Falcataria falcata contains wide phenotypic variations among geologically different populations and that leaf traits can be used as an index of seedling RGR. This information could aid in designing efficient breeding programs for this species.

Key message

Success of invasive non-native conifers in New Zealand may be in part due to introduced hybrids or unintentional hybridisation post-introduction, resulting in unexpected traits that impact control success.

Abstract

Exotic conifers are amongst the most successful weeds in the Southern Hemisphere, in part due to their frequent introductions for commercial forestry and sustainable land use. Multiple introductions of many species, subspecies, and races can help overcome genetic bottlenecks and shape unique invasive populations. Populations of Pinus contorta, the most vigorously spreading conifer in New Zealand, were believed to be dominated by a single non-serotinous subspecies, largely due to its perceived faster spread rate. However, recent work has identified serotinous cones in P. contorta stands leading to confusion around the identity of populations. Here, we investigated the historical planting literature to determine which P. contorta subspecies were introduced across New Zealand to better understand which traits may be expected in invasive populations. We also consider the effect that cone serotiny, expressed by two of four subspecies, may have on control operations by comparing the viability of serotinous seed banks in treated and untreated areas. We find that all four subspecies of P. contorta were established almost ubiquitously across New Zealand. Therefore, we postulate that invasive populations are unlikely to represent any one subspecies and observed trait shifts could be due to intentionally introduced hybrids or unintentional intermixing between subspecies. Additionally, we note that serotinous cone banks persist within herbicide-treated populations with no effect on seed viability. Despite lessening initial spread rates, cone serotiny may become more common across New Zealand by allowing populations to reinvade after herbicide treatments and confer fitness benefits as wildfires become more common under climate change.

Key Message

Low-concentrations of nanoencapsulated NO donor protect tree seedlings from drought, enhancing photosynthesis, stomatal conductance, root hair growth, and stem water potential, but the effects are species-dependent.

Abstract

Nitric oxide (NO), a critical signaling molecule in plants, plays a protective role against water deficit (WD). However, its application is hindered by its relatively unstable chemical nature. To address this, researchers have explored the nanoencapsulation of NO donor molecules. The study aimed to evaluate the effects of treatments using chitosan nanoparticles (NPs) containing the NO donor S-nitrosoglutathione (GSNO) on neotropical tree seedlings (Cecropia pachystachya and Cariniana estrellensis) exposed to short and long-term WD in a greenhouse. Seedlings under long-term WD received nanoformulations in the substrate three times at ten-day intervals. Under short-term WD, seedlings were treated for three alternate days before initiating the WD. The treatment with NPs containing GSNO (50 µM) increased the stomatal conductance, photosynthetic rate, and plant water potential of C. pachystachya submitted to short and long-term WD, reaching levels similar to those of plants kept at field capacity. The same effects were not induced by free GSNO and NPs without NO. Under long-term WD, GSNO-loaded NPs also increased root and leaf biomass in comparison to other WD treatments and increased the amount and incidence of root hairs. In contrast, Cariniana estrellensis seedlings did not respond to the application of NPs containing GSNO at the tested concentrations (from 25 to 800 µM), in any WD condition. Results suggest that nanoencapsulated GSNO can protect C. pachystachya seedlings in both WD conditions, highlighting the potential for obtaining drought-tolerant tree seedlings in reforestation programs. However, this action is species-dependent, as no effect was induced in C. estrellensis.

Key message

Eremanthus incanus depends on outcrossing for reproduction, and the loss of pollinators can severely compromise the viability of populations of this species.

Abstract

Pollination biology is crucial for understanding the processes underlying the sexual reproduction of plants and the long-term sustainability of populations, especially in the face of increasing anthropogenic pressures. In this context, we aimed to investigate the reproductive and pollination system of Eremanthus incanus, an endemic species from Brazil, predominantly distributed in the Campos Rupestres of the Espinhaço Range and subjected to intense exploitation pressure. We selected 15 mother trees, on which we applied three pollination treatments: open pollination, non-pollination, and manual cross-pollination. When the fruits reached maturation, we collected the material to evaluate fecundity (number of seeds formed). Subsequently, we conducted experiments that included germination under laboratory conditions, seedling emergence, and initial sapling growth under nursery conditions. All pollination treatments resulted in high fecundity. However, the non-pollination treatment was unsuccessful in germination and seedling emergence, inferring the existence of a self-incompatibility mechanism in E. incanus. Open pollination and manual cross-pollination methods were not statistically different regarding sapling survival and initial growth. Although survival rate decreased over time, it remained consistently high, and the increase in sapling height and diameter was modest at each assessment, reflecting a slow growth strategy. We concluded that E. incanus is dependent on pollinators and does not face pollen limitation in the studied area. Furthermore, the observed variability among mother trees highlights the complexity of the species’ reproductive ecology, emphasizing the importance of considering intraspecific diversity in conservation strategies.

Key message

The power-law equation provides marginally better accuracy than the Montgomery–Koyama–Smith equation for estimating total tepal area, with flexible definitions of maximum tepal length maintaining prediction reliability.

Abstract

Montgomery–Koyama–Smith equation (MKSE) and power law equation (PLE) were evaluated for estimating the total tepal area (A_T) of Magnolia × soulangeana flowers using 3231 tepals from 359 flowers. MKSE assumes an isometric relationship between the A_T and the product of summed tepal widths (L_KS) and maximum tepal length (W_KS), while PLE incorporates an allometric scaling exponent (α). Results showed α = 0.9561 (95% CI 0.9481–0.9641), confirming allometry. PLE exhibited slightly lower root-mean-square error (RMSE: 0.0149 vs. 0.0172) and mean absolute percentage error (MAPE: 1.18% vs. 1.35%) than MKSE. Redefining W_KS as a random selection from the largest 9, 6, or 3 tepal lengths per flower minimally affected model performance, with MAPE consistently below 5% even when sampling the entire length range. This flexibility simplifies field measurements without compromising accuracy. Variability in geometric series common ratios across flowers likely drives the observed allometric scaling. This study validates that A_T can be reliably estimated using summed widths and a flexibly defined maximum length, emphasizing PLE’s marginally superior fit. These findings advance methods for non-destructive floral trait quantification in species with fixed organ counts.

Key message

GSS is a rapid and cost-effective technique for identifying de novo SSRs in non-model plant species for their genetic analysis.

Abstract

Rhododendron campanulatum is a tree line tree species occurring in the greater Himalayas at an altitude of 3000‒3600 m. The present study aims to generate novel genomic simple sequence repeats (SSRs) markers through a genome survey sequencing approach and investigate population-level genetic processes. A total of 91.18 million reads were generated through the Illumina protocol, and high-quality reads were assembled into 257,413 contigs with 39.60% GC content and contig N50 value 3596 bp. After scanning of genomic assembly, a total of 223,850 perfect SSRs, 10,026 cSSRs, 963,958 iSSRs and 67,332 VNTRs were identified. In perfect SSRs, di-nucleotide repeats were most abundant (43.80%), followed by mono-, tri-, tetra-, penta-, and hexa-nucleotide repeats, respectively. Afterwards, 30,715 primer pairs were designed, and a subset of 50 primers was tested for their amplification through polymerase chain reaction. As a result, 35 SSR loci were successfully amplified and 13 showed polymorphism, which were further utilized to characterize the seven natural populations of R. campanulatum of Uttarakhand Himalayas. Under this study, low genetic diversity (expected heterozygosity, He = 0.28; Allelic richness, Ar = 1.91) was recorded in the analysed populations, which primarily dominated by heterozygotic individuals (F_IS = −0.268). Further, AMOVA revealed 83% variation within the populations and the remaining 17% between the populations, indicating a great genetic differentiation (F_ST = 0.173). Due to high genetic divergence, STRUCTURE and cluster analysis revealed two prominent groups. The marker genetic information generated herein is novel and important for understanding the genetic processes and guiding its conservation programme.

Abstract

The sustainable use of palm trees requires studies on various aspects of seed physiology, as seeds often serve as the primary means of natural propagation. This study aimed to evaluate the effects of desiccation and storage at different temperatures on the physiological quality of seeds and zygotic embryos of Euterpe precatoria. Seeds were artificially desiccated for seven periods (0, 24, 48, 96, 120, 168 and 216 h) and, after each period, were subjected to germination tests using both whole seeds and zygotic embryos. For conservation, pre-desiccated seeds and embryos with different water contents were stored under different conditions: − 196 ºC (liquid nitrogen), - 20 °C, 6 ºC, and 25 ºC for 30 days. Additionally, morphoanatomical and histochemical analyses of zygotic embryos from dried seeds were performed. E. precatoria seeds exhibited high sensitivity to desiccation, with critical germination and vigor thresholds observed at a water content of 16.9%. Water contents of 12.0 and 8.9% had lethal effects on germination, regardless of the germination method. The presence of phenolic compounds and vacuolated cells, identified through anatomical analysis, confirmed the species’ recalcitrant behavior and revealed physical damage in zygotic embryos with water contents below 8.9%. These findings indicate that E. precatoria seeds are desiccation-sensitive, and none of the tested storage temperatures effectively preserved their physiological quality.

Key message

Euterpe precatoria seeds are highly sensitive to desiccation, with critical germination and vigor thresholds observed at a water content of 16.9%.

Populus euphratica Oliv. is a poplar with heteromorphic leaves. Leaves in the upper part of the crown are mostly dentate oval, whereas those in the lower part of the crown or on saplings are mostly lanceolate. To further explore the reasons of P. euphratica at different heights exhibit different leaf shapes, here, the morphology and the anatomy of the upper and the lower branches and leaves were observed based on optical microscopy in the first. In addition, we have established a detection method for branch xylem based on micro-computed tomography (MicroCT) and we found that mean vessel diameter, mean vessel wall thickness, hydraulic diameter, and mean vessel density showed significant differences between upper and lower branches based on this method. Furthermore, hydraulic conductivity of upper branches was higher than that of lower branches so that water can be transported to the top of the canopy, and the photosynthesis rate of the upper leaves was higher than that of the lower leaves. Finally, we investigated there was a significant positive correlation between water use efficiency (WUE) of the upper leaves, the xylem vessel diameter, and the hydraulic diameter, whereas there was a significant negative correlation between the WUE and the vessel wall thickness. These results indicated that the water status of the branches and the leaves of P. euphratica may be one of the physiological mechanisms causing morphological differences in leaves, and this research provided a new method and insights into the further study of heterophylly in plants.

Key message

N addition positively affected the growth of C. pachystachya (shade-intolerant) in the sun but not in the shade, while the growth of C. estrellensis (shade-tolerant) wasn’t affected.

Abstract

The Brazilian Atlantic Forest is a highly biodiverse and threatened ecosystem, subjected to intense deforestation and N deposition levels that may exceed the critical N load supported by this ecosystem. The objective of this study was to evaluate in green house conditions how 10 weekly applications of N (28 kg N ha⁻) affects the gas exchange, the amino acid and protein concentrations in the tissues, and the growth of seedlings two tree species: Cecropia pachystachya (Urticaceae; shade-intolerant) and Cariniana estrellensis (Lecythidaceae; shade-tolerant). Plant responses to N addition were compared on sun and on shade. While Cecropia pachystachya improved the total plant dry mass and the relative growth rate with N addition in the sun, but not in the shade, C. estrellensis increased the stomatal conductance, net photosynthesis, and instantaneous carboxylation efficiency in the shade, although without any change on the plant total biomass. The results of the study indicate that the deposition of n can have differential effects on different species.

Key message

Experimentally elevated CO₂ does not significantly alter the overall leaf reflectance of mature Quercus robur L., but increases Plant Senescence Reflectance Index (PSRI) suggesting a change in the ratio of chlorophyll to carotene content.

Rising atmospheric CO₂ concentrations, driven by anthropogenic emissions, are projected to reach 550 ppm by 2050. Elevated CO₂ (eCO₂) is expected to have a fertilisation effect on forests, influencing productivity, water relations, and phenology. However, the impact of eCO₂ on leaf reflectance in mature forests remains poorly understood, despite its critical role in radiative transfer processes and remote sensing of forest health. Utilising the Birmingham Institute of Forest Research (BIFoR) Free-Air CO₂ Enrichment (FACE) experiment, we investigated the hyperspectral leaf reflectance of 180-year-old Quercus robur L. trees exposed to eCO₂ for 7 years. Our results demonstrate that overall leaf reflectance under eCO₂ is similar to that of leaves exposed to ambient CO₂, but the Plant Senescence Reflectance Index (PSRI) is significantly higher under eCO₂. This index relates to the ratio of foliar chlorophyll and carotene pigments. These findings suggest that Q. robur reflectance will not significantly shift under future CO₂ conditions, but the relative content of pigments will change, altering the reflectance of specific wavelengths and providing insights into the leaf level physiological and phenological responses of mature trees to eCO₂.