Root Collar Research Articles

Adaptation of Different Bamboo Species in Central Zone of Tigray, Northern Ethiopia

Bamboo is the plant species under the family Poaceae, subfamily Bambusoideae. Bamboo is one of the species with greatest diversity in the world comprising about 1,642 species under 121 genera. However, only two species of bamboo are native to Ethiopia. Therefore, this study is designed to evaluate the performance of 9 introduced bamboo species namely: Dendrocalamus asper, Dendrocalamus fuminensis, Dendrocalamus diananensis, Dendrocalamus membranaceus (CV.grandis), Dendrocalamus barbatus, Dendrocalamus laosensis, Bambusa long internode, Bambusa polymorpha, and Bambusa lapidea in Tahtay-maichew district, central Tigray. The design of the experiment is Randomized Complete Block Design (RCBD) with three replications. The total size of the experimental field is 1,680 m2 and the spacing between each blocks and plots is 3 m and 2 m, respectively. There are 10 plots having an area of 30 m2 for each replication. A total of 180 bamboo seedlings were planted in the experiment. The collected data was analyzed using One-way ANOVA. The overall statistical difference in the survival capability of the species was not significant (P = 0.47) and 100% survival capability was observed by all species. The root collar diameter of the different bamboo species shows significant variation (P = 0.003). The highest root collar diameter (1.12±0.06 cm) was observed in the species D. membrenaceus. The highest diameter at stump height (0.87±0.03 cm) was observed by the species B. long internode, followed by D. membrenaceus (0.73±0.04 cm). The highest culm height was observed in the species Bambusa long internode (128±5.9 cm), followed by D. membrenaceus (102±6.8 cm), and the least culm height (49.7±8.8 cm) was observed in O .abyssinica, followed by B. lapidea (77.9±7.4 cm). In general, all nine species showed a very good adaptability to the site and should be included as part of the natural resource development and utilization process.

Lidar-derived estimates of boreal shrub biomass in Southcentral Alaska

Abstract Despite widespread observations of shrub proliferation and expansion (shrubification), few studies quantify shrub biomass at the regional scale. Here we describe and implement a two-part modeling approach to estimate and map tall shrub (diameter at root collar > 2.5 cm) expected aboveground biomass, or E[SHB], across a 16.6 million ha boreal region where shrubification occurs in wetlands and subalpine ecosystems. Using n = 384 field plots nested within m = 11 study sites across southcentral Alaska, we constructed random forest models of the probability (pSH) that shrub wood volume surpasses tree wood volume, and generalized additive models (GAMs) of aboveground biomass of tall shrubs (SHB) using rasterized aerial lidar variables collected by NASA Goddard’s Lidar, Hyperspectral, and Thermal (G-LiHT) Airborne Imager, together with gridded climate data from a Parameter-elevation Regressions on Independent Slopes Model 30-year normal climatology (PRISM). Applying those models to G-LiHT tiles, then averaging across tiles within n = 843 watersheds covering 9.2 million ha, we estimated that below 1,000 m asl, the area-weighted mean value of E[SHB] = pSH x SHB = 6.6 Mg ha-1 with sd = 4.5 Mg ha-1. This is the first study to estimate current shrub biomass density at the regional scale in southcentral Alaska and serves as a biomass baseline for measuring and modeling aboveground carbon fluxes where plant communities are undergoing climate-driven change.

Effects of Root Pruning and Size on Growth Traits of Hybrid Poplar Seedlings

Selecting seedlings of varying sizes and effectively managing root pruning are key challenges in transplantation. However, the effects of seedling size and root pruning on transplantation outcomes are not fully understood. This study classified one-year-old Populus ‘Beilinxiongzhu-01’ seedlings into three size categories based on height: large (308.75 ± 9.66 cm), medium (238.00 ± 7.71 cm), and small (138.92 ± 7.18 cm). In early March of the subsequent year, root pruning was applied with varying intensities based on root collar diameter: low (15 times), medium (7.5 times), and high (3.75 times). A control group without pruning was also included. Over the year, key phenological and morphological traits were monitored. The results showed that (1) root pruning significantly impacted the phenology of seedlings, accelerating root emergence, delaying early leaf phenology, increasing the dieback rate, and postponing end-of-season defoliation. Mortality and the rapid growth phase were not significantly affected. Larger seedlings exhibited earlier end-of-season defoliation and higher dieback rates early in the growing season, while smaller seedlings advanced in early leaf development. (2) Except under low or no pruning, root pruning reduced seedling height (H), diameter at breast height (DBH), and root collar diameter (RCD). However, across all treatments, these indicators remained higher in larger seedlings compared to smaller ones. Under medium- and high-intensity pruning, smaller seedlings exhibited higher relative growth rates and larger leaf areas than larger seedlings, with the reduction in these variables becoming more pronounced as seedlings increased in size. Notably, only larger seedlings demonstrated a reduction in maximum growth rate, suggesting greater vulnerability to root pruning. In summary, root pruning induced significant phenological and morphological differences across seedling sizes. While smaller seedlings showed some response to pruning, larger seedlings experienced more pronounced phenological disruptions and growth inhibition.

Evaluating the suitability of Brazilian native species for riverbank stabilization and protection

In Brazil, soil and water bioengineering techniques have mainly been used for hydraulic stabilization, water course management and to re-establish the vegetation in fluvial environments. In these techniques plants are considered as an important structural component and their use requires adequate selection. The present study aimed to evaluate the root system and shoot development traits of the Allamanda cathartica L., Ludwigia elegans (Camb.) H. Hara and Sesbania virgata (Cav.) Pers species. The experiment was conducted in a greenhouse at the Laboratory of Soil Bioengineering at the Federal University of Santa Maria. The following variables were evaluated after 120 days: the survival rate, average height, average root collar diameter, average number and sum of shoot length per plant, average number of primary roots and the sum of primary root length, length of the largest root and root dry mass per plant. The percentage of fine roots and coarse roots and distribution of root dry mass percentage in soil depth were also evaluated. The results confirm the suitability of the L. elegans, S. virgata and A. cathartica species for riverbank stabilization and protection in soil and water bioengineering works.

Microclimatic effects of tree shelters on the early establishment and resilience of seeded acorns vs. outplanted seedlings

Little is known about the effects of tree shelters on the early response of oak seedlings produced by acorn seeding. In this paper, we explore the effects on holm oak (Quercus ilex L. subsp. ballota (Desf.) Samp.) seedlings of the microenvironment created by the tree shelters and the restoration method (seeding vs. outplanting) in terms of emergence, survival, growth, and resilience after harvesting. For this purpose, seedling height [H], root collar diameter [RCD], number of leaves, and aerial biomass were monitored. We made two sowings of acorns in February 2017 and February 2018, together with a seedling outplanting in February 2018 in a common garden site in semiarid SE Spain. In total, 600 acorns were randomly sowed and 300 nursery-grown seedlings were outplanted and studied until 2022. Mother tree and initial acorn mass were also monitored as additional variables in the analyses. Tree shelters consisted of closed plastic Tubes, Mixed tubes, Cork shelters, Tiles, and a Control with no shelter. Emergence rate was positively influenced by the Tube shelter (86%) as compared to the Control (64%), and especially by the initial acorn mass. By contrast, mother tree or year of sowing seemed to have no effect. The survival rate for the emerged acorns (88%) was statistically similar to that of outplanted seedlings (91%), and was unaffected by mother tree, tree shelter, or acorn mass. In terms of growth, the slenderness ratio (H:RCD) was considerably higher in seedlings from directly seeded acorns than for those that were outplanted. With the exception of Tile, all the shelters showed a higher slenderness ratio than the Control, especially the Tube shelter, which also showed a lower number of leaves and a lower aboveground dry biomass than the Control, Cork, and Tile shelters. Virtually no interactions were observed between the mother tree and the tree shelter. At harvesting, all the growth-related parameters were still strongly dependent on the acorn mass and the initial seedling features recorded after the first growing season. Resprouting rate and growth were also highly dependent on the acorn mass and the plant features at the beginning of the experiment and at harvesting. In summary, we did not find evidence to support tree shelters to improve the microclimate of holm oak seedlings both seeded or outplanted. Direct acorn seeding can be as successful as outplanting of nursery-grown seedlings. Selection of heavy acorns from mothers with a high germination and emergence rate is highly advisable.

First Report of Root Collar Canker Caused by Neoscytalidium dimidiatum on Jacaranda mimosifolia in China.

Jacaranda mimosifolia is widely cultivated as a garden ornamental tree. In July 2023, an unknown root collar canker of J. mimosifolia was discovered in green belts of Qingxiu District, Nanning, China, with a 8% incidence rate. Crowns of affected trees ranged from reddish brown leaves to deciduous or dead. Root collar tissue became necrotic matched by underbark dark brown lesions with irregular margins, and rotted at last. Six diseased plants distributed within 3000 m2 were choosed, and 24 root collar tissues were surface sterilized and placed on potato dextrose agar (PDA) plates to incubate at 28℃ for 3 to 5 days. Same colonies were consistently isolated from 18 tissues, and three isolates (M3-B1-1, M3-B1-2 and M3-B1-3) were purified for morphological and molecular determination. These isolates formed colonies with lush aerial mycelia rapidly, which covered a 90 mm plate in 72h. The colonies were initially white, then grayish-green to black. Arthrospores were colourless to light brown, short columnar, aseptate, truncate base, averaging 12.1±2.5 µm × 3.4±0.7 µm, sometimes formed arthric chains. Chlamydospores were dark brown, round or oval, aseptate, averaging 8.7±1.6 µm × 5.0±0.9 µm. Mature pycnidia and conidia produced for about 50 days on oatmeal agar medium (OMA), and conidia were colorless, oblong, aseptate, averaging 11.2±1.2 µm × 6.0±1.4 µm. These morphological characteristics were consistent with the description of Neoscytalidium dimidiatum (Penz.) Crous & Slippers (Crous et al. 2006). Genomic DNA was extracted from three isolates. The partial ITS region, TUB2 and TEF1-α genes were amplified (White et al., 1990; Glass and Donaldson 1995; Carbone and Kohn 1999). The sequences were deposited in GenBank (ITS: PP939650-PP939652; TUB2: PP942728-PP942730; TEF1-α: PP942731-PP942733). Blastn analysis revealed that ITS sequences of three isolates showed 99.8%, 100%, 100% identity (506 bp out of 507 bp, 507 bp out of 507 bp, 507 bp out of 507 bp) to N. dimidiatum C21 (KX447539), the TUB2 sequences showed 100% identity (436 bp out of 436 bp, 437 bp out of 437 bp, 437 bp out of 437 bp) to N.dimidiatum LNeo (ON099066), and the TEF1-α sequences showed 99.64% identity (276 bp out of 277 bp) to N.dimidiatum ARM230 (MK495384), respectively. Phylogenetic analysis based on concatenated ITS, TUB2 and TEF1-α sequences showed that three isolates were clustered into the same clade as N. dimidiatum. To fulfill Koch's postulates, pathogenicity of these isolates was tested on healthy two-year-old J. mimosifolia trees. Stem and root collar were wounded and placed mycelial plugs (8mm), and the inoculation sites were wrapped with parafilm or covered with nursery substrate to maintain the humidity. Four plants were inoculated with each isolate. As a control, four plants were inoculated with noncolonized PDA plugs. All treated plants were kept in a greenhouse at 28 ± 3°C and 70% relative humidity. Foliar blight and necrotic lesions around inoculation points were observed about 65 days after inoculation, and 50% of inoculated trees exhibited symptoms, whereas the control trees remained symptomless. Neoscytalidium dimidiatum was successfully reisolated from symptomatic tissue via morphological analysis. To our knowledge, this is the first report of root collar canker caused by N. dimidiatum on J. mimosifolia. Neoscytalidium dimidiatum has a wide range of hosts, including pitaya, pine, mulberry, pear, grape, locust tree (Luo et al. 2024). This finding will help in controlling of the disease epidemic.

Impact of environmental conditions on the early growth of the endangered Korean fir (Abies koreana E.H.Wilson): insights for conservation and restoration strategies

Environmental factors are crucial elements that significantly influence the growth and development of plants. This study investigated the impact of environmental conditions (light, air temperature, air humidity, etc.) on the early growth of juvenile Korean fir (Abies koreana E.H.Wilson). Using random forest models and scatterplot matrix analyses, we examined the complex relationships between juvenile Korean fir early survival and various environmental factors. Specifically, a one-way ANOVA was conducted to assess the impact of light regulation in shading experiments on the growth of Korean fir seedlings. Additionally, a t-test was performed to compare the growth differences of Korean fir seedlings in two restoration sites with different canopy coverages. The results confirmed that light conditions significantly affect the growth of Korean fir seedlings, with better early growth observed in shaded conditions compared to full sunlight. Furthermore, field restoration site surveys indicated that the growth of height and root collar diameter of restored Korean fir seedlings was better in areas where the canopy coverage of the existing forest was between 60% and 75%. These findings suggest that the prerequisite for the restoration of the endangered Korean fir seedlings is the achievement of optimal light conditions during the early establishment phase.

Assessment of root foraging behaviour in Aralia elata subjected to drought stress under different light spectra

Drought may be more frequent in foreseen decades that will threat non-wood forest products (NWFP) in temperate forests. Plants cope with drought by increasing root foraging ability, which may be also impacted by exposure to light spectra (components of wavelengths in three colours of monochronic lights). In this study, three hybrid light spectra were provided by light-emitting diode (LED) in red (wavelength: 13.6% blue, 60.0% green, 26.4% red), green (2.9% blue, 84.6% green, 2.5% red), and blue (5.4% blue, 77.8% green, 16.9% red) lights for culturing potted Aralia elata seedlings in homogeneous (67.5 mg nitrogen [N] to both halves of pot) and heterogeneous (135 mg N to left half of pot) under drought and well-watered conditions. The red light spectrum was the unique illumination environment where height growth was promoted under well-watered condition and root biomass in fertilized patch was enhanced under drought. Compared to blue light spectrum, red light spectrum increased root foraging scale and precision and placement ratio. Red light spectrum also promoted aboveground biomass, but reduced root collar diameter. No interaction was detected between any pairs of factors among drought, light, and soil nutrient pattern. The heterogeneous pattern increased root to shoot biomass ratio with decreased shoot biomass and increased root foraging sensitivity and precision and fine root placement ratio. Drought enlarged the overall foraging scale with no effects on foraging sensitivity or precision. Overall, exposure to red light spectrum had the potential to promote fine root foraging behaviour under drought, but more trails deserve being tested in the future on a wider range of wavelengths.

Seedling Growth and Nutritional Status of Elaeagnus angustifolia and Robinia pseudoacacia as Response to Arbuscular Mycorrhizal Fungi and K-Humate

ABSTRACT This study aimed to reveal the effects of arbuscular mycorrhizae and K-humate on some of the morphological characteristics and growth of Russian olive (RO; Elaeagnus angustifolia L.) and black locust (BL; Robinia pseudoacacia L.). The indigenous mycorrhizal spores (Claroideoglomus claroideum, Claroideoglomus etunicatum, Claroideoglomus luteum, and Funneliformis mosseae) collected from rhizospheres of RO and BL trees in afforestation sites located in Central Anatolia. In addition, commercial mycorrhizal mixture and K-humate were used as treatments. Five treatments (1—indigenous mycorrhizal fungi, 2—K-humate, 3—indigenous mycorrhizal fungi + K-humate, 4—commercial mycorrhizal fungi, and 5—control) were assigned in a completely randomized design for both tree species. Four months after the treatments, inoculation rate, above-ground seedling height, fresh and dry weight, root collar diameter, length, fresh, and dry weight, leaf area index, shot-to-root dry weight ratio, seedling height to root collar diameter ratio, and Dickson quality index were determined. Plant and soil analyses were carried out to determine the effects of treatments on plant and soil nutrition. Indigenous arbuscular mycorrhizal fungi and K-humate combinations had positive effects on the morphological characteristics and nutritional status of the seedlings. The indigenous mycorrhizal and K-humate interaction showed the most pronounced effects on RO growth and nutrition.

Introduction and Evaluation of <i>Moringa oleifera</i> (Lam) Growth in Two Districts of Bale Zone, Oromia Region, Southeast Ethiopia

Moringa oleifera is one of the most important plants which has to be introduced, conserved and promoted for its social, economic and environmental benefits. Study was conducted aimed to introduce M. oleifera through evaluating its growth performance under the field condition of mid-altitude areas of Bale, Ethiopia. The experiment was laid-out using randomized complete block design with three replications on two locations. In the study the necessary plant growth traits namely survival rate, plant height and diameters (at breast height and root collar) were collected and analyzed by Genstat software. As to results except survival rate other growth performance traits of the studied species were statistically influenced by location in the subsequent years of monitoring period. With this, the mean value of survival rate recorded at Dello-menna was > 80% whereas at Goro it was < 80% throughout the years of study period. For plant height the recorded mean values were found between 65 cm to 370.30 cm and 58.30 to 296.70 cm range in the respective Dello-menna and Goro sites. Breast height diameter ranged from 0.747 cm to 6.533cm at Goro site and from 1.00 cm to 8.983cm at Dello-menna. In terms of root collar diameter, the values ranged from 1.933 cm to 9.867 cm and from 1.410 cm to 4.592 cm at Dello-menna and Goro sites, respectively. The values pointed that M. oleifera had showed a promising growth and development over both locations with relatively the higher performance at Dello-menna site than Goro. Therefore, the species could be demonstrated, promoted and scaled-up to the farming community of Dello-menna, Goro and other areas with similar agro-ecology. However, the nutritive value of the species in response to the studied locations has remained the focus of future research area.

Factors Affecting Seedling Growth Performance and Quality of Two A<i>cacia Species and Shinus Molle </i>on Nursery Stage, Southern Oromia, Ethiopia

The study was carried out within the Nursery of the Department of Forestry, at Sinana Agricultural Research Center, on the effects of different soils media and varying pot sizes on the early growth of <i>Acacia abyssinica, Acacia saligna and Shinus molle </i>were investigated. Four different soils media used were forest soil (FS), compost (Co), sand soil (SS) and local soil (LS) in different pots size (PS1=8 cm=control, PS2=10 cm and PS3=12 cm lay flats) 15 cm in length and five growing media (GM) or soil mix proportion based on volume GM1= (2 part local/Top soil:2 part forest soil:1 part sand; GM2=2 part local soil:2 compost: 1 part sand; GM3=1 part local soil:2 part forest soil:2 part sand; GM4=3 part local soil:2 part compost:1 sand soil and GM5=3 local soil:2 forest soil:1 sand=control) were filled up of different types of soil named above, and quantified using weighing balance. The experiment was laid out in Randomized Complete Block Design (RCBD) at the Forestry nursery in the study area. The study involved the use of five (5) planting media and three different plastic pots in three (3) replicates. The parameters measured are plant height (cm), seedling root collar diameter (mm) and dry matter (shoot, root and root to shoot ratio). The data collected at the end of twenty weeks were subjected to Analysis of Variance (ANOVA) and means were separated using Duncan test showed that <i>Schinus molle, A.abyssinica </i>and<i> A.saligina</i> tree species plant and grown in large pot size (PS2) and growing media (GM3) had the highest performance with mean value of plant height 19.83cm, 7.833cm and 13.167cm and seedling root collar diameter in GM5PS3 (4.09mm), GM4PS3 (3.35mm) and GM4PS1 (3.97mm) respectively were high significantly (P< 0.05). It is therefore recommended that large pot size (PS3) and GM2 and GM3growing media be used for optimal production of all <i>Schinus molle, A.abyssinica </i>and<i> A.saligina </i>tree species seedling production at nursery stage and their plantation success. This study revealed that optimum ratio of compost and forest soil in growing media and relatively big container/pot size have favorable good quality of seedling growth for all studied tree species for all growth parameters. This is may be due to nutrient variation in the growing media which is farther needs investigation on growing media nutrients contents.

Genome-wide analysis of DNA methylation and transcriptional changes associated with overwintering memory in Brassica rapa L. grown in the field

BackgroundWinter rapeseed, the sole overwintering oilseed crop in northern China, emphasizes winter resilience, yet epigenetic regulatory mechanisms governing overwintering memory remain poorly understood.ResultsIn this study, the root collar tissues from the robust cold-resistant variety Longyou-7 were sampled during the pre-winter period (S1), overwintering periods (S2–S5), and re-greening period (S6), to analyze overall genomic DNA methylation levels using high-performance liquid chromatography (HPLC). The result showed that DNA methylation level exceeded 80% in the S1 stage. Throughout the overwintering periods, methylation levels displayed a decreasing trend in S3, followed by an increase in S5, and a pronounced decrease in S6. Consequently, S1, S3, S5, and S6 periods were chosen for whole-genome bisulfite sequencing analyses to elucidate the overwintering memory mechanisms of Longyou-7. The result revealed that DNA methylation primarily occurs in the CG context in Longyou-7. However, methylation of mC sites is most prevalent in the CHH type, gradually decreasing during overwintering periods. Analysis of methylation patterns in specific genomic regions of Longyou-7 showed that the highest methylation levels in the intergenic region. Moreover, mC sites in repeats and transposon elements are distributed differently across the three contexts. Subsequently, differentially methylated regions and promoters of Longyou-7 were identified during various periods compared to the S1 stage, followed by joint analysis with transcriptome sequencing. Functional enrichment analysis highlighted the involvement of most overlapping genes in the MAPK signaling pathway, plant hormone signal transduction, and starch and sucrose metabolism pathways. Changes in candidate gene expression within these three pathways correlated closely with DNA methylation levels.ConclusionsOur findings underscored the critical role of DNA methylation in regulating the expression of overwintering memory genes in winter rapeseed. These results offer a comprehensive insights into the epigenetic regulatory mechanisms governing winter rapeseed's overwintering memory, while identified overwintering memory genes served as crucial genetic resources for multifaceted breeding of winter-resistant varieties.Graphical

Armillaria Species Causing Kiwifruit Vine Decline and Root Rot in Northeastern Türkiye: A Growing Concern for Kiwifruit Health

ABSTRACTKiwifruit (Actinidia deliciosa) production in northeastern Türkiye is facing an emerging threat from Armillaria root rot. Surveys conducted in August 2021 and 2022 revealed that 10.5%–17.5% of the 200–500 vines within each of 35 kiwifruit orchards in the Perşembe, Gülyalı and Altınordu districts of Ordu province exhibited symptoms of Armillaria root rot, including complete defoliation. Diseased plants exhibited diagnostic signs on their root collars and woody roots, including white mycelial fans, extensive wood rot and rhizomorphs. A single Armillaria isolate was obtained from each of the 35 symptomatic orchards. Molecular identification, employing DNA sequencing of the large subunit (LSU) region of rDNA, the translation elongation factor subunit 1‐alpha (TEF1) gene and the second largest RNA polymerase II B‐subunit (RPB2) gene, identified 20 isolates as Armillaria gallica and 15 as A. mellea. Phylogenetic analyses, based on TEF1 alignments, further supported the species identification with a 100% bootstrap value. To examine genetic diversity, start codon targeted (SCoT) marker 13 was used, successfully differentiating the two Armillaria species and revealing three distinct clades. Clades I and II comprised 15 and 5 isolates of A. gallica, respectively, while Clade III contained all 15 A. mellea isolates. Pathogenicity testing on kiwifruit seedlings (cv. Hayward) revealed the ability of both A. gallica and A. mellea isolates to induce disease. Rhizomorph‐producing isolates in kiwifruit seedlings displayed high virulence, inducing severe leaf necrosis and seedling mortality, while isolates lacking these structures were non‐pathogenic. This study identifies the first global instance of A. gallica causing kiwifruit root rot. This finding, along with the identification of A. mellea as a causal agent in the country, highlights the emerging threat of Armillaria root rot to kiwifruit production in the region.

Korištenje morfoloških značajki sadnica obične bukve (Fagus sylvatica L.) za selekciju reprodukcijskog materijala iz provenijencija vjerojatno zahvaćenih klimatskim promjenama

Global climate change causes the reduction of tree growth and spread of European beech (Fagus sylvatica L.) forests, thus indicating the need to preserve tree abundance due to the changes that have occurred. The comparison of beech seedlings from various provenances in southeast and central Europe was carried out based on the dimensions of root collar diameter and height to select the proper starting material that would reduce the negative consequences of the climate. There have been statistically significant differences in root collar diameter and height between various seedlings tested in European provenances. Clear differentiation was recorded between European countries in the growth performances of one-year-old and two-year-old seedlings of F. sylvatica based on the nursery test. The study's results indicate the potential for producing adaptable beech reproductive material from various European provenances. This finding lays the groundwork for future precise analyses that aim to select provenances tolerant to changing climate conditions.

INCIDENCE AND SEVERITY OF DAMAGE AGENTS ON ESTABLISHED TREES IN URBAN GREEN AREAS

Trees in urban green areas (UGAs) face various stress-inducing factors that, together with the incidence and severity of damage agents, reduce their growth and health condition. The objective of this study was to characterize the incidence and severity of damage to trees located in 21 UGAs in the city of Texcoco, Mexico, as well as the relationship between their health, green area typology, and urban infrastructure. Using tree damage indicators, the incidence of two damage agents per tree was determined, and seven damage groups were identified: biotic agents, parasitic and epiphytic plants, insects, animals, abiotic agents, and anthropogenic factors. A damage severity index (DSI) was estimated at species level and by green area. Chlorophyll fluorescence was used to assess stress as an indirect measure of tree health condition in UGAs, and surrounding urban infrastructure was classified. A total of 1543 trees were assessed, and 23 damage agents were identified, affecting 9.95 % of the foliage, 10.24 % of the branches, 4.47 % of the trunk, and 0.45 % of the root collar and roots. As for incidence, 60.01 % showed no damage at all, 29.49 % showed only one agent, and 10.5 % showed two agents. Most of the trees at the UGAs were found to be under stress (≤ 0.78) and uncorrelated with DSI; however, the index was different by species and UGA (p ≤ 0.05). Insect damage and poor management practices were associated with the presence of buildings, busy roads, and people congregation areas inside UGAs.

Survival and plasticity in Acacia saligna growth across Contrasting management practices and growing niches

Reforestation and afforestation either through natural regeneration, tree planting or both methods have been globally promoted to motivate ecological restoration of degraded lands and to improve livelihoods. However, moisture stress and infertile soils limit the survival and growth of trees planted for restoration in drier areas. Hence, understanding the factors that determine the restoration success of drylands through tree planting is critical. We conducted a factorial experiment in Tigray, Ethiopia to evaluate the survival, growth performance and biomass of planted seedlings of the multipurpose agroforestry tree species Acacia saligna over 24 months. The treatments were application of watering (W), mulching (M) and compost (C) separately and in combinations (WM, WMC). We established experimental plots on farmland and on a nearby hillside-exclosure to examine the role of planting niches on seedling performance. Seedlings treated with watering, mulching, and compost (WMC) revealed significantly greater height, root collar diameter (RCD), and dry biomass compared to the other treatments. Seedlings planted in farmland showed significantly greater height, RCD, and total dry biomass compared to those planted at the hillside-exclosure. Although the survival rate was slightly higher in farmland, we also found sufficient survival rates in the hillside-exclosures. Therefore, post-planting care and activities including mulching, watering and fertilization are crucial to enhance the survival and growth performance of A. saligna or other tree species so that efforts in reversing land degradation and restoration of drylands will be successful.

A genome-guided strategy for climate resilience in American chestnut restoration populations

American chestnut (Castanea dentata) is a deciduous tree species of eastern North America that was decimated by the introduction of the chestnut blight fungus (Cryphonectria parasitica) in the early 20th century. Although millions of American chestnuts survive as root collar sprouts, these trees rarely reproduce. Thus, the species is considered functionally extinct. American chestnuts with improved blight resistance have been developed through interspecific hybridization followed by conspecific backcrossing, and by genetic engineering. Incorporating adaptive genomic diversity into these backcross families and transgenic lines is important for restoring the species across broad climatic gradients. To develop sampling recommendations for ex situ conservation of wild adaptive genetic variation, we coupled whole-genome resequencing of 384 stump sprouts with genotype-environment association analyses and found that the species range can be subdivided into three seed zones characterized by relatively homogeneous adaptive allele frequencies. We estimated that 21 to 29 trees per seed zone will need to be conserved to capture most extant adaptive diversity. We also resequenced the genomes of 269 backcross trees to understand the extent to which the breeding program has already captured wild adaptive diversity, and to estimate optimal reintroduction sites for specific families on the basis of their adaptive portfolio and future climate projections. Taken together, these results inform the development of an ex situ germplasm conservation and breeding plan to target blight-resistant breeding populations to specific environments and provides a blueprint for developing restoration plans for other imperiled tree species.

Phytophthora pseudocryptogea Is Associated with Root and Crown Rot of Nursery-Grown Common Sage in Hungary.

In October 2009, necrotic bark lesions at the root collar and lower stem associated with root rot, reduced growth, and wilting were observed on container-grown 2-year-old common sage (Salvia officinalis L. 'Icterina') in two ornamental nurseries in Somogy and Zala counties in Hungary. The disease occurred at a frequency of 15-20% (100 to 150 symptomatic plants in each nursery). A P. cryptogea-like species was isolated consistently from necrotic root collars of many plants on carrot (CA) PARPB agar. Six isolates from the nursery in Zala county and three isolates from the nursery in Somogy county were deposited in the culture collection of Plant Protection Institute (Budapest, Hungary). All developed slightly petaloid colonies on CA agar. Chlamydospores and gametangia were not present in single and dual culture combinations of isolates. Radial colony growth was the fastest at 25°C (6.8 to 7.4 mm/day) and no growth occurred above 34°C. On mycelial discs floating in nonsterile stream water, persistent, nonpapillate, mostly ovoid to obpyriform sporangia (37.4±3.5 to 47.8±4.6 μm long and 22.3±2.6 to 29.2±3.7 μm wide) and hyphal swellings were produced abundantly. Pathogenicity of one selected isolate from each nursery was tested on 3-month-old seedlings of S. officinalis 'Icterina' in 2010. Isolates were grown for 4 weeks at 20°C on autoclaved millet grains moistened with CA broth. Infested and uninfested grains were mixed with autoclaved soil (30 cm3 grain/liter), and the mixes were used as potting media for transplanting five treated and five control plants per isolate, respectively. Plants were kept in a growth room (20-25°C, 16/8 h dark/light). Pots were flooded for 24 hours on the 1st day and every 2 weeks. All and only treated plants showed symptoms of wilt associated with basal stem and root necrosis within three weeks. The trial was repeated with the same result. The pathogen could be reisolated only from the treated plants. Identity of isolates from nurseries and inoculated plants was confirmed recently by amplification and sequence analysis of the rDNA internal transcribed spacers (ITS) and gene regions of cytochrome c oxidase subunit I (coxI) and β-tubulin (tub) according to Jung et al. (2017). BLASTn searches showed 100% identity and only 97.3-99.0% similarity to the corresponding sequences of authenthic P. pseudocryptogea and P. cryptogea strains, respectively (e.g., GenBank accession nos. KP288336-KP288342, KP288370-KP288372, KP288386-KP288392, MN872725, MN872776). Sequences of the 9 field isolates were deposited in GenBank under accession nos. OR771701-OR771709 (ITS), OR787508-OR787516 (coxI) and OR787517-OR787525 (tub). P. pseudocryptogea was delineated from P. cryptogea sensu lato (Safaiefarahani et al. 2015), which has been reported from S. officinalis in the United States (Koike 1997), and S. leucantha (Cacciola et al. 2002) and S. officinalis (Garibaldi et al. 2015) in Italy. The known natural hosts of P. pseudocryptogea includes plant species in families other than Lamiaceae (cf. Aloi et al. 2023), but it was pathogenic on the lamiaceous Plectranthus scutellarioides in artificial inoculations (Christova 2020). The pathogen is present in European nurseries (Antonelli et al. 2023). This is the first report of P. pseudocryptogea on S. officinalis in Hungary. The causal agent threatens the production of sages and other ornamentals, and its spread in Hungary should be prevented by proper disease management and phytosanitary actions.

The role of near‐surface vegetation in modulating overland flow resistance in grasslands of the Chinese Loess Plateau

AbstractVegetation restoration significantly increases overland flow resistance and decreases soil erosion. The cause of soil erosion is unknown, though grain resistance and form resistance are frequently confused with the overall overland flow resistance. The zonal specie of Bothriochloa ischcemum (Linn.). Keng (BI) and the dominant specie of Artemisia vestita Wall. ex Bess (AG) were selected to investigate the effect of vegetation near soil surface characteristics derived by vegetation restoration on overland flow resistance of grain resistance and form resistance. In total, 24 steel tanks were planted at six planting densities of 5, 10, 15, 20, 25, and 30 plants m−2, and two tanks were used as bare soil controls. Their hydraulic characteristics were tested under a constant rainfall intensity (60 mm h−1) on a 26.2% slope. The results showed that the grain resistance (fg) and form resistance (ff) ranged from 0.06 to 0.35 and 18.01 to 95.77 under six planting densities. Vegetation increased overland flow resistance by more than 90%, which was mainly attributed to ff. Vegetation near soil surface factors of the aboveground part, biological soil crusts, and root collar increased ff by 18.71 to 82.13, 0.74 to 11.50, and 1.61 to 3.40, respectively. Compared with BI, the mean value of fg in AG was 48.87% lower, whereas the mean value of ff was 1.36 times greater. The fg decreased with soil organic matter as a power function. The ff decreased with the Reynolds number, Froude number, and flow velocity and increased with vegetation coverage, aboveground biomass, and root collar area as power functions. Soil properties explained the majority of the variation in fg, and near the vegetation soil surface factors explained the majority of the variation in ff. Finally, ff was simulated using the Reynolds number, vegetation coverage, and root collar area. In addition, a simulation equation for the total flow resistance was established by distinguishing the grain resistance and the form resistance, and the performance of the model developed in this study was satisfactory (NSE = 0.97).

The use of Pisolithus albus found in saline areas to improve the growth of Eucalyptus seedlings under high salinity conditions

ABSTRACT Salinity is an abiotic factor limiting plant fitness and therefore forest crop productivity, and salt-affected areas have been expanding throughout the world. Ectomycorrhizal (ECM) fungi can improve the salt tolerance of woody plants, including Eucalyptus species To screen for salt-resistant Pisolithus albus (PA) isolates, 16 PA isolates were cultivated on modified Melin-Norkrans agar containing NaCl at concentrations of 0, 10, 20, and 30 dS m−1. The P. albus isolate PA33 had the greatest salt resistance under 10 and 20 dS m−1 NaCl, which are soil salinity levels in salt-affected areas of Thailand. We studied the effect of PA33 on Eucalyptus camaldulensis × E. pellita cuttings under salt stress (0 and 16 dS m−1) for 1 month. PA enhanced the growth of the Eucalyptus seedlings, as indicated by higher relative growth rates in height and root collar diameter of inoculated seedlings compared with non-inoculated seedlings. Moreover, the inoculated seedlings had less cell damage from NaCl, as indicated by significantly lesser leaf thickness and electrolyte leakage than the controls. These findings could lead to practices conferring socioeconomic and environmental benefits, as abandoned salt-affected areas could be reclaimed using such Eucalyptus seedlings inoculated with salt-tolerant ECM fungi.