Search Results (85)

The advance of the soil desertification process and water salinisation hinders reforestation actions in the Brazilian semiarid region due to the negative effects on the initial establishment of seedlings. Knowledge of potential species for overcoming the problems of soil and water salinity is of broad interest. This study evaluated the growth of seedlings of the species Handroanthus impetiginosus and Handroanthus spongiosus subjected to the combined stresses of salinity and water deficit. The species were subjected to three water depths (WDs): WD1—50%, WD2—75% and WD3—100% of reference evapotranspiration, and four salinity levels (SL): SL1—0.27 dS m⁻¹, SL2—2.52 dS m⁻¹, SL3—6.35 dS m⁻¹ and SL4—7.38 dS m⁻¹. Biometric data, including plant height, number of leaves, collar diameter and biomass, was obtained. The results showed that H. impetiginosus was more tolerant of the conditions analysed. The species showed greater sensitivity to salt stress, which reduced growth and dry biomass accumulation by up to 98%. Increased water deficit reduced height, collar diameter, number of leaves, root biomass and total biomass. We propose that the optimal water depth for both species is 100% of the reference evapotranspiration. Full article

The increasing concentration of greenhouse gases is amplifying the global risk of drought on crop productivity. This study sought to investigate the effects of drought on the growth of maize (Zea mays L.) seedlings. A total of 78 maize hybrids were employed in this study to replicate drought conditions through the potting method. The maize seedlings were subjected to a 10-day period of water breakage following a standard watering cycle until they reached the third leaf collar (V3) stage. Parameters including plant height, stem diameter, chlorophyll content, and root number were assessed. The eight phenotypic traits include the fresh and dry weights of both the aboveground and underground parts. Three machine learning methods—random forest (RF), K-nearest neighbor (KNN), and extreme gradient boosting (XGBoost)—were employed to systematically analyze the relevant traits of maize seedlings’ drought tolerance and to assess their predictive performance in this regard. The findings indicated that plant height, aboveground weight, and chlorophyll content constituted the primary indices for phenotyping maize seedlings under drought conditions. The XGBoost model demonstrated optimal performance in the classification (AUC = 0.993) and regression (R² = 0.863) tasks, establishing itself as the most effective prediction model. This study provides a foundation for the feasibility and reliability of screening drought-tolerant maize varieties and refining precision breeding strategies. Full article

Globally, Hibiscus sabdariffa L. (Malvaceae), commonly known as roselle or hibiscus, is a multipurpose vegetable crop. In Malawi, where it is referred to as ‘Chidede’ (Chichewa), it is recognized as an underutilized traditional plant with significant potential. Traditional vegetable production in Malawi is being promoted to enhance nutritional food security and climate change mitigation. Recently, biochar has become increasingly used to improve agricultural productivity through climate-smart technologies. To date, the influence of rice husk biochar (RHB) on H. sabdariffa remains underexplored. This study aims to evaluate the effects of RHB on the vegetative growth, response to water stress, and post-stress recovery of H. sabdariffa using a greenhouse pot experiment. Our findings indicate that biochar-amended soil enhanced plant height, stem thickness, and total leaf area by 16.5%, 12.0%, and 12.9%, respectively. Water stress significantly reduced all assessed growth parameters (p < 0.05) except total leaf area and average leaf area per plant. Under water stress conditions, biochar-treated plants were significantly taller (p < 0.05) and had a higher specific leaf area (p < 0.05), demonstrating a positive effect. A post-stress recovery analysis revealed that H. sabdariffa fully recovered in height and biomass, while partial recovery was observed for root collar diameter and compensatory recovery for total leaf area and average leaf area. Biochar-treated plants exhibited superior post-stress recovery compared to those grown in unamended soil. Overall, plants grown with biochar were taller and had a larger root collar diameter, higher stem and leaf fresh biomass, and greater total leaf area. These findings underscore biochar’s potential as a sustainable soil amendment for enhancing growth and resilience in underutilized crops. Further studies should explore field experiments to access environmental heterogeneity and examine the diverse factors influencing biochar efficiency. Full article

Using beneficial microorganisms as biostimulants is a promising strategy to enhance crop growth and productivity in hydroponic systems. Trichoderma asperellum has demonstrated plant growth-promoting effects in soil cultivation; however, its efficacy in hydroponic Deep-Water Culture (DWC) systems remains underexplored. This research evaluated the effect of T. asperellum strains TaMFP1 and TaMFP2 on the growth, nutrient uptake, and visual quality of hydroponically grown spinach cv. Stella Plus F-1 (Spinacia oleracea L.). A randomized complete design was used, comparing inoculated plants with a control and a commercial Trichoderma harzianum product. After 28 days, the results showed that T. asperellum significantly increased plant height (23.1%), collar diameter (21.8%), root length (39.6%), leaf area (22.0%), number of leaves (18.05), and fresh biomass accumulation (23.5%) compared to non-inoculated plants. Furthermore, inoculation with TaMFP1 improved spinach yield by 34.5%, while nutrient analysis indicated enhanced phosphorus and calcium uptake. No significant changes were observed in photosynthetic pigment concentrations, and the visual quality of the harvested spinach was unaffected. These findings highlight the potential of T. asperellum as a sustainable biostimulant in hydroponic spinach production. These results contribute to developing beneficial microorganism-based strategies to enhance the sustainability of hydroponic agriculture. Full article

This study investigates the effect of the spatial distribution of soil water and nutrients on cork oak (Quercus suber) architecture. Fertirrigation is being tested in cork oak plantations to accelerate tree growth up to the production stage. To assess the impact of wet bulb location on tree development, six trees (three subjected to subsurface drip irrigation and three controls) were fully excavated at a sandy soil site, along with a seventh tree subjected to surface drip irrigation at a sandy loam soil site. The aerial parts of the trees were digitized using a Polhemus Fastrak magnetic digitizer and segmented into orders starting from the main trunk. Roots with diameters greater than 0.5 cm were digitized during excavation and segmented by size and order from the root collar. For each segment, length, orientation, and spatial location were calculated. General linear models were then applied to compare total root length across orientation and quadrant classes. Crown architecture was influenced by factors such as light competition. Irrigation treatments did not significantly affect root architecture when wet bulb formation was constrained. However, tree no. 7 had 50% of its total root length located within the wet bulb quadrant. These findings suggest that differences in soil type and irrigation method influence wet bulb formation, potentially reducing the impact of fertirrigation on root architecture. Strategies to minimize tree dependence on wet bulb zones are crucial for enabling future irrigation suppression. Full article

The exploration of the genetic resources of drought-resistant trees is highly significant for improving the ecological environment. Elm trees are widely distributed in the cold and arid regions of the Northern Hemisphere and have a strong tolerance for adverse conditions. This study evaluated the drought tolerance of 20 elm varieties (Ulmus pumila L.) collected from areas subject to varying degrees of drought and cold. By assessing phenotypic and growth indicators, we found that the drought-sensitive varieties ULP-2 and ULP-3 exhibited a significant reduction in height (31 cm and 16 cm) and root collar diameter (0.37 cm and 0.17 cm), whereas the drought-tolerant varieties ULP-19 and ULP-12 maintained favorable growth conditions under drought stress. Moreover, ULP-19 and ULP-12 displayed significantly fewer yellow leaves (12 and 19) and greater root biomass (237.8 g and 221.2 g). Compared with the sensitive varieties, the relative water content in leaves (21.02% and 30.10%) and roots (26.13% and 34.53%) decreased less in the drought-tolerant varieties. Transcriptome sequence analysis showed that the stable drought resistance of the drought-resistant variety ULP-19 is associated with changes in the processes of carbohydrate metabolism and lignin synthesis in the roots, and these processes are governed by an increase in the regulation of transcription in the leaves of protective pathways controlled by calcium ions and phytohormones (abscisic acid). These results will aid in the selection of appropriate elm varieties for afforestation initiatives and the development of sustainable forest ecosystems in arid regions. Full article

The success of reforestation and restoration projects depends on several factors, with proper seedling management and the selection of an appropriate planting area being crucial. In Peru, the populations of Retrophyllum rospigliosii (Pilg.) C.N.Page (Ulcumano) have been decreasing due to intensive logging of one of the most valuable woods in South America’s tropical forests. There are few studies that unify the production of plants through seeds in nurseries and the identification of suitable areas to place the plants produced. Our study has two components. The first aimed to optimize the plant production process through an experiment that evaluated the effects of three doses of controlled-release fertilizer (CRF) (4.2, 8.4, and 12.6 g/L) and two container sizes (115 and 180 cc) on the morphological quality of seedlings in the nursery. The second component involved identifying potential reforestation areas using ecological niche modeling, based on climatic and edaphic variables. The results indicated that the 4.2 g/L CRF treatment for both container sizes had a significant positive effect on seedling growth. The average germination rate was 85% at 120 days. At six months after seedling transplantation, treatments of 4.2 g/L CRF in 115 cc and 180 cc containers were shown to have the best positive effect on morphological variables of seedlings, with a root collar diameter of 3.76 mm and a height of 13.25 cm. Regarding the potential niche models, an area of 6321.97 km² with ideal conditions for reforestation with R. rospigliosii was estimated, with the departments of Huánuco, Pasco, Junín, and Cusco showing the highest potential. Based on this, it is estimated that over three million plants are needed for large-scale reforestation projects. Integrating silvicultural studies with niche models is a valuable tool for supporting reforestation and ecosystem restoration projects. Full article

An important issue in container nurseries is the production of seedlings of appropriate quality. These seedlings must meet specific biometric parameters and possess traits that ensure their suitability for later use in forest cultivation. One such traitis the ease of pulling the seedling out of the container cell, characterized by the pulling resistance. This resistance depends on many factors, including theseedling parameters, substrate, and container. In this work, a prototype measuring station was used to record seedling pull-out resistance as a function of their vertical displacement. Tests were conducted on 30 seedlings of each species: pine, beech, and oak. These were grown in polystyrene containers with cell volumes of 150 cm³ for pine (Pinus sylvestris L.) and 300 cm³ for beech (Fagus sylvatica L.) and oak (Quercus robur L.). Significant differences were observed in seedling extraction resistance between species, as well as between resistances associated with containers of different cell volumes. The maximum pull-out resistance of pine seedlingswas the lowest at 12.4 ± 8.58 N, followed by 22.5 ± 1.87 N for beech, and 33.5 ± 18.08 N for oak (extraction speed of 2.5 cm·s⁻¹).Similarly, the total energy required to extract pine seedlings was 0.358 ± 0.196 J, compared to 0.502 ± 0.316 J for beech and 1.479 ± 0.774 J for oak. The pattern of pull-out resistance regardingvertical displacement was consistent across all species. A correlation was found between the maximum pull-out resistance and the total energy required to extract the seedlings, along with biometric parameters such as root collar diameter, shoot height, dry mass of seedling parts, root volume, the extent of root ball overgrowth, and the volumetric density of the substrate within the cell.These relationships should be considered when designing devices for the automatic extraction of seedlings from polystyrene containers. Full article

Our study, conducted in a controlled greenhouse environment over a single growing season, evaluated the growth of seedlings from 25 open-pollinated families of jack pine (Pinus banksiana Lamb.) under two nutrient levels (20 ppm and 200 ppm) and three water regimes (twice a week, once a week, and once every two weeks). We assessed the effects of seed weight, family, nutrient availability, and water treatments on several growth parameters, including height, root collar diameter, shoot dry biomass, root dry biomass, total dry biomass, growing period length, and shoot-to-root ratio at harvest. We found that seed weight significantly influenced all growth traits, maintaining its effect throughout the growth season, although its impact diminished over time. Jack pine families were more responsive to nutrient treatments than to variation in water availability. Genetic variation was significant for all traits except the shoot-to-root ratio, highlighting the intricate role of genetic makeup in shaping growth responses. The substantial impact of nutrient and water treatments and relatively low heritability estimates suggest that pre-conditioning seedlings through nursery management can optimize shoot-to-root ratios. The minimal family-by-treatment interaction and the consistent performance of families across treatments suggest the potential for selecting high-efficiency genotypes with enhanced nutrient use efficiency and drought tolerance. Full article

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. Full article

Argania spinosa is among the most important species of the Moroccan forest in terms of ecological, environmental, and socio-economic aspects. However, it faces a delicate balance between regeneration and degradation in its natural habitat. Hence, the efforts to preserve and regenerate argan forests are crucial for biodiversity, soil quality, and local livelihoods, yet they face challenges like overgrazing and climate change. Sustainable management practices, including reforestation and community engagement, are vital for mitigating degradation. Similarly, exploiting the argan tree’s rhizosphere can enhance soil quality by leveraging its rich microbial diversity. This approach not only improves crop growth but also maintains ecosystem balance, ultimately benefiting both agriculture and the environment. This enrichment can be achieved by different factors: mycorrhizae, plant extracts, algae extracts, and plant growth-promoting rhizobacteria (PGPR). The benefits provided by PGPR may include increased nutrient availability, phytohormone production, shoot, root development, protection against several plant pathogens, and disease reduction. In this study, the effect of rhizobacteria isolated from the Agran rhizosphere was evaluated on germination percentage and radicle length for Argania spinosa in vitro tests, growth, collar diameter, and branching number under greenhouse conditions. One hundred and twenty (120) bacteria were isolated from the argan rhizosphere and evaluated for their capacity for phosphate solubilization and indole acetic acid production. The results showed that 52 isolates could solubilize phosphorus, with the diameters of the solubilization halos varying from 0.56 ± 0.14 to 2.9 ± 0.08 cm. Among 52 isolates, 25 were found to be positive for indole acetic acid production. These 25 isolates were first tested on maize growth to select the most performant ones. The results showed that 14 isolates from 25 tested stimulated maize growth significantly, and 3 of them by 28% (CN005, CN006, and CN009) compared to the control. Eight isolates (CN005, CN006, CN004, CN007, CN008, CN009, CN010, and CN011) that showed plant growth of more than 19% were selected to evaluate their effect on argan germination rate and radicle length and were subjected to DNA extraction and conventional Sanger sequencing. The 8 selected isolates were identified as: Brevundimonas naejangsanensis sp2, Alcaligenes faecalis, Brevundimonas naejangsanensis sp3, Brevundimonas naejangsanensis sp4, Leucobacter aridicollis sp1, Leucobacter aridicollis sp2, Brevundimonas naejangsanensis sp1, and Staphylococcus saprophyticus. The results showed that Leucobacter aridicollis sp2 significantly increased the germination rate by 95.83%, and the radicle length with a value of 2.71 cm compared to the control (1.60 cm), followed by Brevundimonas naejangsanensis sp3 and Leucobacter aridicollis sp1 (2.42 cm and 2.11 cm, respectively). Under greenhouse conditions, the results showed that the height growth increased significantly for Leucobacter aridicollis sp1 (42.07%) and Leucobacter aridicollis sp2 (39.99%). The isolates Brevundimonas naejangsanensis sp3 and Leucobacter aridicollis sp1 increased the gain of collar diameter by 41.56 and 41.21%, respectively, followed by Leucobacter aridicollis sp2 and Staphyloccocus saprophyticus (38.68 and 22.79%). Leucobacter aridicollis sp1 increased the ramification number per plant to 12 compared to the control, which had 6 ramifications per plant. The use of these isolates represents a viable alternative in sustainable agriculture by improving the germination rate and root development of the argan tree, as well as its development, while increasing the availability of nutrients in the soil and consequently improving fertilization. Full article

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. Full article

In Hokkaido, northern Japan, bareroot Sakhalin fir seedlings are conventionally planted in spring and fall, following strip site preparation that alternates managed and unmanaged strips. However, this method requires seven years of weeding due to encroachment of evergreen dwarf bamboo. Given diminishing forest labor availability, a shortage of workers for planting and weeding operations has become a problem in reforestation following clearcutting. We examined whether comprehensive mechanical site preparation (MSP) could reduce weeding frequency by preventing regrowth of dwarf bamboo and whether container seedlings could extend the planting season into summer. Over eight years, the survival and growth of summer-planted bareroot and container seedlings were examined on a fully MSP-treated site with only one weeding operation in the fifth year. Full-site MSP resulted in a shift of the vegetation from dwarf bamboo to deciduous plants, leading to high survival and growth rates of Sakhalin fir seedlings despite minimal weeding. Container seedlings exhibited superior establishment and maintained higher survival rates over eight years than bareroot seedlings. However, planting on the forwarder trail decreased seedling growth, and ultimately decreased survival under rare summer drought. Our findings indicate that container seedling summer planting and full-site MSP may represent an alternative approach to reforestation of Sakhalin fir, potentially reducing the need for weeding and extending the planting season. Full article

The negative impact of drought on plant growth may be modified by the different availability of mineral nutrients and by their adaptation to different local habitat conditions. In this study, we examine the impact of drought, fertilization with phosphorus and provenance, as well as their interactions, on the growth and allometric growth relationships between the belowground and aboveground organs of common beech (Fagus sylvatica L.) and sessile oak (Quercus petraea (Matt.) Liebl.). The research was conducted on saplings originating from two mature mixed stands (dry and wet provenances) dominated by these species. In the common garden experiment, saplings were exposed to regular watering and drought in interaction with moderate and high phosphorus concentrations in the growing substrate (achieved by phosphorus fertilization). The obtained results indicate the negative impact of drought and phosphorus fertilization on the growth of both species. In common beech, a negative impact of phosphorus fertilization on the adaptive capacity to drought was demonstrated by unfavorable ratios between fine root mass and the mass of other organs. The sessile oak provenances under the impact of drought showed a different root collar diameter/stem height increment ratio, which indicates their different phenotypic plasticity as a consequence of adaptation to different frequencies of dry periods in their natural habitats. Full article

The increased frequency of climate change-induced droughts poses a survival challenge for forest trees, particularly for the common beech (Fagus sylvatica L.). Drought conditions adversely affect water supply and nutrient uptake, yet there is limited understanding of the intricate interplay between nutrient availability and drought stress on the physiology, growth, and biomass accumulation in young trees. We aimed to address this knowledge gap by examining the effects of irrigation and fertilisation and their interaction with various parameters in common beech saplings, including foliar and root N, P, and K concentrations; height and diameter increments; and aboveground and belowground biomass production. Our findings revealed that a higher fertilisation dose increased nutrient availability, also partially mitigating immediate drought impacts on foliar N concentrations. Also, higher fertilisation supported the post-drought recovery of foliar phosphorus levels in saplings. Prolonged drought affected nitrogen and potassium foliar concentrations, illustrating the lasting physiological impact of drought on beech trees. While drought-stressed beech saplings exhibited reduced height increment and biomass production, increased nutrient availability positively impacted root collar diameters. These insights have potential implications for forest management practices, afforestation strategies, and our broader understanding of the ecological consequences of climate change on forests. Full article