Root Collar Diameter 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.

Indiferentní reakce sazenic borovice lesní a buku lesního ošetřených hydroabsorbenty

Super-absorbents are expected to amend soils as they are capable of retaining water, which turns dry loose powdery substances (also capsule) into hydrogel. These were applied to prevent an artificial regeneration failure due to drought events. Four commercially-available products were mixed with soil from planting holes (the capsule was put to the soil) in order to support bare-root Scots pine and European beech seedlings after a spring planting on eleven clear-cut sites in 2020–2021. The plantations were designed as rows with 4 × 150 plants treated with four hydrogels plus 150 plants without hydrogel as a control. The performance evaluation of new plantations was based on attributes such as mortality/survival and relative height and root-collar diameter increments. The plants, which lost their initial size, due to pine weevil damage, dry tops and damage by game, were excluded from the evaluation. Besides the plant response to the applied super-absorbents, the planting operations were evaluated from economic point of view. The 2020 plantations showed higher mortality than 2021 ones; both years showed an excessive loss. The hydrogels did not help the plants to survive better compared to control and growth data also showed ambiguous results. Therefore, from commercial perspective, the application of all tested super-absorbents just increased the renewal costs.

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.

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.

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.

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.

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.

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.

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.

Overstory and understory resource competition variably influences conversion of introduced conifer plantations to native hardwoods

Restoration of native hardwood forests through tree planting may provide significant ecological and economic benefits, but reforestation in natural forests and afforestation on open field sites is challenging. Conversion of existing plantations of introduced conifers to hardwoods may provide an alternative opportunity for restoration. In the Midwest US, large areas of mature, introduced pine (Pinus spp.) plantations exist that have little economic and ecological value. These stands may provide ideal sites for planting of native hardwood species that have similar site preferences to pine. We sought to determine optimal management strategies for converting pine plantations by manipulating overstory canopy density and understory competition. We underplanted American chestnut (Castanea dentata (Marsh.) Borkh.) and northern red oak (Quercus rubra L.) seedlings in three overstory canopy treatments: control, shelterwood, and clearcut. Understory competition was either controlled or not through two growing seasons. After three growing seasons, oak performed best in the clearcut and chestnut in the shelterwood, reflecting variation in the species’ shade tolerance. Chestnut height and root collar diameter (RCD) were double that of oak, and chestnut leaf N content increased with light availability while oak did not, which can be explained by the species’ different adaptive strategies in biomass allocation. Both species had highest photosynthesis in the clearcut. Chestnut seedlings had significantly higher RCD in weeded clearcut and shelterwood plots, and oak in weeded clearcut plots. Weeding in the uncut control plots was ineffective because shade limited competition. Our results indicate that pine plantations offer suitable habitat for these hardwood species and provide insight regarding their growth strategies. Pine shelterwoods and clearcuts are each viable silvicultural conversion options for chestnut and oak if understory competition is controlled.

Survival and Growth Performance of Calophyllum inophyllum L. Seedlings in Peat Soil and at Different Levels of Groundwater

Selecting proper tree species for revegetation is important for restoring tropical peatland. Tamanu (Calophyllum inophyllum L.) has been suggested one of the promising native species in Indonesia for the revegetation of tropical peatland; however, there is a lack of understanding of its growth in peat soil with different groundwater levels. We investigated the survival rate, plant height, number of leaves, root collar diameter, and dry biomass of tamanu seedlings grown in peat soil with different groundwater levels using a randomized block design in a water tank. The study involved five groundwater level treatments and 12 tree-level replicates each: M0 (non-groundwater level, control); M1 (−15 cm below the soil surface); M2 (−10 cm); M3 (−5 cm); and M4 (0 cm, soil surface level). The results showed that all tamanu seedlings survived in every treatment. However, their plant height, number of leaves, and root collar diameter growth were significantly inhibited in the highest groundwater level condition (M4, 0 cm) at 81 days after sowing, while their growth in −15 cm of groundwater level (M1) was as good as the growth in the fully drained conditions in M0 (control). This result indicates that the groundwater level should not be higher than −15 cm for the growth of tamanu. Considering that peatlands in Indonesia are assessed to be degraded when the groundwater level is lower than −40 cm, this study suggests that maintaining groundwater levels between −40 cm and −15 cm in peatland is the best condition for rapid growth of early tamanu seedlings while protecting peatlands. Further studies are needed to extend the range of water levels and water treatment duration.

Allometric estimation models for aboveground and belowground biomass of pre-fire and post-fire vegetation in Scots pine forests

Abstract Wildfires have recently destroyed large areas of forest in Central Europe. After a fire, the post-fire vegetation succession rebuilds previously lost biomass and carbon. Nevertheless, ground vegetation and tree regeneration, as well as belowground biomass, are largely neglected in allometric biomass models. Moreover, most models are calibrated for undisturbed forests, which differ from burned forests in terms of site conditions and species composition. We adapted a model using plant cover and shoot length of herb, graminoid and bryophyte species (PhytoCalc), and a single tree model using shoot length and root collar diameter of juvenile trees to estimate aboveground biomass (AGB) of post-fire species and growth groups, and extended them to estimate belowground biomass. We sampled the most dominant species from the herb and moss layer and the tree regeneration of burned and unburned Scots pine (Pinus sylvestris L.) forests in NE Germany. We successfully calibrated post-fire vegetation models and showed that models for undisturbed forests from the literature mostly underestimate post-fire AGB. Using models from the literature for clear-cuts often improved the estimation of post-fire AGB, but still failed to estimate AGB accurately for some species. Inaccurate estimation of post-fire biomass with these other models can be explained by high irradiance and increased nutrient availability on burned sites, which affect tissue and wood density. We showed that own species- and growth group-specific allometric models calibrated to post-fire vegetation are required to correctly estimate the total (above- and belowground) biomass of post-fire vegetation needed to calculate carbon storage.

Drought effects on growth, biochemical changes and leaf gas exchange in laurel (Laurus nobilis L.)

Abstract Drought is one of the abiotic factors that negatively affect the productivity of laurel (Laurus nobilis L.). Increasing water scarcity in arid and semi-arid regions is pushing the physiological limits of woody species, necessitating strong resistance to drought. Studies should be conducted on the effects of drought stress not only on forest trees but also some medicinal and ornamental species, and ways to increase their resistance should be explored. This study was carried out to determine the effect of drought stress on seedling growth and some physiological and biochemical properties in laurel. The seedlings were subjected to drought stress for about 4 months with three different irrigation regimes: watering once every 2–3 days (control), every 15 days, and every 30 days. Morphological properties (root collar diameter, height, dry weight, stem: root ratio, and number of leaves), physiological properties (midday xylem water potential and photosynthesis properties), and biochemical properties (photosynthetic pigments, total carbohydrate, and proline contents) were determined. Results have shown that drought stress has a negative effect on root collar diameter, seedling height, and dry weight. Likewise, leaf number and midday xylem water potential decreased due to increased drought stress. Furthermore, the net photosynthesis rate, stomatal conductance, and transpiration rate of the least irrigated (30th day) seedlings were quite low compared to those of control seedlings. The differences in chlorophyll a, chlorophyll b, total chlorophyll, and carotenoid contents were also found to be statistically significant. Total carbohydrate and proline contents showed the highest values for the least irrigated seedlings and the lowest values for controlled irrigation seedlings. Our results reflect the improved tolerance capacity of laurel to increased drought stress.

Interactive Effect of Fertilization and Biochar on the Growth of Juniperus scopulorum under Various Shading and Irrigation Conditions

The global demand for landscape trees has been amplified with the increasing anthropogenic activity. South Korea has also witnessed a surge in demand for landscape plants, among others, Juniperus scopulorum gaining popularity for its ecological, economic, adaptability, and management attributes. However, the optimum management practice for high-quality Juniperus seedling production in South Korea remains unknown. This research was conducted on the one-to-two-years-old two cultivars of J. scopulorum, namely Blue Angel and Blue Heaven seedlings, to investigate the combined impacts of varying fertilizer concentrations (0 ppm, 150 ppm, 300 ppm) and biochar content (0% and 20%) under contrasting shading intensities (0%, 35%, 55%) and irrigation levels (200 ml, 400 ml, 800 ml). The study revealed that biochar and fertilizer amendment significantly (p < 0.01 and p < 0.05) enhanced the height and root collar diameter growth in Blue Angel and Blue Heaven in light shade intensity (0–35%) and higher irrigation (400–800 ml) conditions. Similarly, seedlings planted in 20% biochar and 300 ppm fertilizer yielded higher foliar, stem, and root biomass in low shade and higher irrigation conditions. The amount of shade and irrigation and their interactions significantly affected the morphological growth of seedlings for both cultivars, causing positive interaction with soil amendment (biochar and fertilizer application). These findings suggest that efficient seedling production of J. scopulorum management should focus primarily on light shading and moderate irrigation under biochar and higher fertilizer application. The research contributes valuable insights toward optimizing management practices and reducing costs associated with J. scopulorum seedling production in the region. Keywords: biochar, fertilizer, irrigation, Juniperus scopulorum, shading

Comparative Analysis of Impact of Soil Mixture and Fertilization on Growth and Seedling Quality of Selected Agroforestry Tree Species

The study was conducted to determine the most suitable soil amendment for germination and early seedling growth of selected indigenous multipurpose agroforestry tree species, viz., Cordia africana, Fiadherbia albida, Millettia ferruginea, and Moringa stenopetala at Haramaya University, Ethiopia. Seedlings were raised in polythene tubes having 10 cm diameter and 15 cm height and the experimental plots were laid out with eight treatments (i.e., potting soil mixture of, A = agricultural soil, M = manure, S = sand, D = DAP, and U = Urea) and three replications. The morphological attributes of seedlings such as shoot and root height, root collar diameter, leaf area were measured to assess tree seedlings vigor and robustness. Analysis of variance indicated that the shoot height of C. africana, F. albida, and M. ferruginea were significantly different (P<0.05) whereas shoot height of M. stenopetala was highly significant (P<0.01). Actual leaf area (cm2) of F. albida and M. stenopetala were significantly different (P<0.05) and estimated leaf area (cm2) of the four species were highly significant at (P<0.01). Treatment 8 (3A: 2M: 1S) for C. africana, treatment 5 (3A: 2M: 1S: 23U) for F. albida and treatment 2 (2A: 2M: 2S: 25D) for both M. stenopetala and M. ferruginea exhibited the lowest sturdiness quotient, which indicates that they are good-quality seedling for plantation. The shoot-to-height ratio indicated positive correlation with most seedling growth parameters whereas root collar diameter and sturdiness quotient showed negative correlation for all species. Treatment 3 (3A: 2M: 1S: 75D) is recommended as the best pot soil mix and fertilization compared to all other treatments, though it needs further study.

Short-term responses of growth and leaf physiology of the sclerophyllous Cryptocarya alba (Molina) seed sources to water restriction

ABSTRACT There are concerns about the vulnerability of some dominant sclerophyllous species in Mediterranean zones to water restriction, especially at outplanting, and much of the efforts for active restoration are on identifying proper seed sources. This study aimed to determine the short-term responses of growth, biomass partitioning, and leaf-physiological traits of Cryptocarya alba provenances to water restriction in nursery conditions. Three seed sources from xeric sites (northern distribution) and one from a more mesic site (southern distribution) were subjected to water restriction for three months and then evaluated in increments in root collar diameter and height, biomass components (leaves, shoots, roots), gas-exchange and fluorescence parameters, and carbon (Δ13) and oxygen (δ18O) isotopic ratios. Water restriction decreased growth and leaf biomass as a short-term response, but this effect was not expressed in stem and root biomass. Similarly, water restriction decreased the photosynthetic rate (Asat), stomatal conductance (gs), and maximum efficiency of PSII. Moreover, water restriction also increased the intrinsic water use efficiency (WUEint), but it had no effect on Δ13 or δ18O. Seed sources did not differ in any traits except in stem and total biomass. The results did not confirm a better performance of seed sources from xeric than mesic origin sites to water restriction.