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This study conducted an activation experiment on tap water using a self‐designed dielectric barrier discharge plasma field. Aged pepper seeds and seedlings were chosen as the investigation's subjects to assess plasma‐activated water (PAW's) effects on aged seed germination, seedling growth, and their respective qualities. PAW cultivation led to notable improvements in pepper seeds' germination potential and rate, with increases of 18.0% and 28.3%, respectively. Moreover, the vitality index exhibited a remarkable rise of 250.0%. Concurrently, seedlings treated with PAW exhibited significant growth enhancements, with root length, root number, stem length, and leaf area increasing by 138.6%, 69.2%, 47.9%, and 28.4 cm², respectively. Additionally, PAW treatment induces changes in endogenous substances and enzyme activities in seeds and seedlings. [ABSTRACT FROM AUTHOR]

Management of alien invasive species is an essential action necessary to help reverse biodiversity loss. Here, we measure the effectiveness of brush piles constructed from invasive alien plant material to suppress the growth of invasive plant seedlings. We found invasive seedling recruitment was fully suppressed in brush pile plots compared to control plots due to suboptimal growth light and temperature conditions created by the piles. Further, brush piles supported 2‐fold to +7‐fold more animals than control plots. This method offers a promising solution for restoration practitioners' need for accessible, low‐cost management intervention for the on‐site disposal of removed plant biomass, which we demonstrated can also enhance native wildlife abundance. [ABSTRACT FROM AUTHOR]

The giant sequoia, a serotinous conifer naturally occurring in mixed‐conifer forests of the southern and central Sierra Nevada, California, USA, is the world's largest tree species. Giant sequoia reproduction has been severely lacking over the past century, due to fire exclusion, creating a significant conservation threat. Previous research on postfire sequoia reproduction in high‐severity fire areas, relative to low‐ and moderate‐severity areas, is limited. At 6 years postfire, we investigated giant sequoia reproduction in a high‐severity fire area, and nearby low‐/mixed‐severity fire areas, in the Nelder Grove, which burned in 2017 in the Railroad fire. Postfire giant sequoia reproduction was positively correlated with fire severity in terms of density, height (growth), and proportion (relative to other conifer species), and sequoia seedling/sapling density was positively correlated with percent shrub cover. There was no correlation between distance to live sequoia seed source and density of sequoia reproduction. More research is needed in other mixed‐severity fire areas, with larger high‐severity fire patches, to determine whether a similar postfire response occurs elsewhere. [ABSTRACT FROM AUTHOR]

Due to intense ash dieback, this research tested the bioactivity of Thymus vulgaris, Lavandula angustifolia, and Cupressus sempervirens essential oils (EO) against Hymenoscyphus fraxineus. In vitro testing showed that EOs had a pronounced fungitoxic effect on H. fraxineus. The most effective EO was extracted from T. vulgaris, while EOs obtained from L. angustifolia and C. sempervirens were less effective and showed the same effect. At a concentration of 1%, all tested EOs inhibited mycelial growth, while 0.01% and 0.1% concentrations of EO extracted from T. vulgaris also inhibited the growth of H. fraxineus. The in planta test of EO extracted from T. vulgaris conducted on three‐year‐old Fraxinus angustifolia seedlings showed a reduction in the size of necrotic lesions and a better crown condition compared to untreated seedlings. This research demonstrates, for the first time, the efficiency of EOs in suppressing ash dieback making a path for the development of new biological protection measures against H. fraxineus. [ABSTRACT FROM AUTHOR]

Drought is a major threat to alfalfa (Medicago sativa L.) production. The discovery of important alfalfa genes regulating drought response will facilitate breeding for drought‐resistant alfalfa cultivars. Here, we report a genome‐wide association study of drought resistance in alfalfa. We identified and functionally characterized an MYB‐like transcription factor gene (MsMYBH), which increases the drought resistance in alfalfa. Compared with the wild‐types, the biomass and forage quality were enhanced in MsMYBH overexpressed plants. Combined RNA‐seq, proteomics and chromatin immunoprecipitation analysis showed that MsMYBH can directly bind to the promoters of MsMCP1, MsMCP2, MsPRX1A and MsCARCAB to improve their expression. The outcomes of such interactions include better water balance, high photosynthetic efficiency and scavenge excess H2O2 in response to drought. Furthermore, an E3 ubiquitin ligase (MsWAV3) was found to induce MsMYBH degradation under long‐term drought, via the 26S proteasome pathway. Furthermore, variable‐number tandem repeats in MsMYBH promoter were characterized among a collection of germplasms, and the variation is associated with promoter activity. Collectively, our findings shed light on the functions of MsMYBH and provide a pivotal gene that could be leveraged for breeding drought‐resistant alfalfa. This discovery also offers new insights into the mechanisms of drought resistance in alfalfa. [ABSTRACT FROM AUTHOR]

Nitrogen (N) is an essential element for plant growth and development. The identification and utilization of N use efficiency (NUE) loci are essential for breeding high NUE cultivars. In this study, 15 NUE traits were measured in a recombinant inbred line population containing 121 lines derived from the cross between a cultivated barley (Baudin) and a wild barley (CN4027). The hydroponic culture was conducted with normal N and low N treatments in one‐time frame, and field trials were conducted with N sufficiency and N deficiency treatments in two growing seasons. Twenty‐two quantitative trait loci (QTLs) and four clusters were detected. Of them, the five stable QTLs Qgna.sau‐3H for grain N concentration, Qtna.sau‐3H for total N accumulation per plant, Qnhi.sau‐3H for N harvest index, Qnutegy.sau‐3H for N utilization efficiency for grain yield and Qanutedm.sau‐3H.1 for N utilization efficiency for aboveground dry matter were co‐located on chromosome 3H flanked by the markers bpb6282426 and bpb4786261. These two novel QTL clusters simultaneously controlled NUE traits at the seedling and maturity stages. Some genes related to NUE traits in intervals of the major QTLs were predicted. The significant relationships between NUE traits and agronomic and physiological traits were detected and discussed. In conclusion, this study uncovers the most promising genomic regions for the marker‐assisted selection of NUE traits to improve NUE in barley. [ABSTRACT FROM AUTHOR]

SUMMARY: The development of photosynthetically competent seedlings requires both light and retrograde biogenic signaling pathways. The transcription factor GLK1 functions at the interface between these pathways and receives input from the biogenic signal integrator GUN1. BBX14 was previously identified, together with GLK1, in a core module that mediates the response to high light (HL) levels and biogenic signals, which was studied by using inhibitors of chloroplast development. Our chromatin immunoprecipitation‐Seq experiments revealed that BBX14 is a direct target of GLK1, and RNA‐Seq analysis suggests that BBX14 may function as a regulator of the circadian clock. In addition, BBX14 plays a role in chlorophyll biosynthesis during early onset of light. Knockout of BBX14 results in a long hypocotyl phenotype dependent on a retrograde signal. Furthermore, the expression of BBX14 and BBX15 during biogenic signaling requires GUN1. Investigation of the role of BBX14 and BBX15 in GUN‐type biogenic (gun) signaling showed that the overexpression of BBX14 or BBX15 caused de‐repression of CA1 mRNA levels, when seedlings were grown on norflurazon. Notably, transcripts of the LHCB1.2 marker are not de‐repressed. Furthermore, BBX14 is required to acclimate plants to HL stress. We propose that BBX14 is an integrator of biogenic signals and that BBX14 is a nuclear target of retrograde signals downstream of the GUN1/GLK1 module. However, we do not classify BBX14 or BBX15 overexpressors as gun mutants based on a critical evaluation of our results and those reported in the literature. Finally, we discuss a classification system necessary for the declaration of new gun mutants. Significance Statement: A picture is emerging in which BBX proteins have multifaceted functions in plant development, acting as receivers of chloroplast signals as well as playing a role in responses to acute stress. [ABSTRACT FROM AUTHOR]

Roadside vegetation in Central Europe is mostly species‐poor and dominated by a few grass species. Hemiparasitic plant species, including Rhinanthus spp., might effectively restrict grass growth, thereby making space for light‐dependent herb species. Despite the significance of abiotic site conditions for plant establishment in general, their effects on Rhinanthus establishment are less well known. We investigated combined effects of water availability, litter amount and seed position within litter on Rhinanthus seedling emergence and growth.Two parallel greenhouse experiments were conducted with R. angustifolius and R. minor. In these, we tested the impact of 200 or 400 g litter·m−2 with seeds sown beneath or on top of a litter layer under constantly humid or intermittently dry conditions on seedling emergence and biomass production of Rhinanthus.Presence of litter positively affected Rhinanthus seedling emergence when sown beneath the litter layer and reduced negative effects of water deficiency. Sowing beneath a litter layer increased seedling emergence by 157%, with similar effects at 200 and 400 g litter·m−2. Water level did not affect biomass production. Compared to R. minor, R. angustifolius had higher mean biomass, and its seedlings emerged earlier and in higher numbers.Our results indicate that Rhinanthus spp. react similarly to litter as non‐hemiparasitic plant species from temperate grasslands. Litter presence positively influenced Rhinanthus seedling emergence and growth under intermittently dry conditions. Its hemiparasitic characteristics might reduce drought impacts on biomass production. To ensure seed contact with the soil surface, seeds should be sown when no litter is present, or mulching should occur post‐sowing. [ABSTRACT FROM AUTHOR]

Ammonium nitrogen (NH4+‐N) is essential for fruit tree growth, but the impact of excess NH4+‐N from fertilizer on evergreen citrus trees is unclear.In a climate chamber, 8‐month‐old citrus plants were exposed to five different hydroponic NH4+‐N concentrations (0, 5, 10, 15 and 20 mm) for 1 month to study effects of NH4+‐N on growth characteristics, N uptake, metabolism, antioxidant enzymes and osmotic regulatory substances.Application of 10 mm NH4+‐N adversely affected root plasma membrane integrity, root physiological functions, and plant biomass. MDA, CAT, POD, APX and SOD content were significantly correlated with leaf N metabolic enzyme activity (GOGAT, GDH, GS and NR). GDH was the primary enzyme involved in NH4+‐N assimilation in leaves, while the primary pathway involved in roots was GS‐GOGAT.Under comparatively high NH4+ addition, roots were the main organs involved in NH4+ utilization in citrus seedlings. Our results demonstrated that variations in NH4+ concentration and enzyme activity in various organs are associated with more effective N metabolism in roots than in leaves to prevent NH4+ toxicity in evergreen woody citrus plants. These results provide insight into the N forms used by citrus plants that are important for N fertilizer management. [ABSTRACT FROM AUTHOR]

Understanding the emergence patterns of agricultural weeds is paramount for effective management practices. This study investigates the emergence dynamics of feral radish (Raphanus sativus L.), a widespread weed in the Americas, unravelling the intricate interplay of seed attributes—low or no dormancy, darkness requirement, and indehiscent siliques—on seedling emergence. To explore this, we (1) buried isolated seeds and intact siliques at six increasing depths (0–16 cm) under controlled conditions, and (2) evaluated seedling emergence from both isolated seeds and intact siliques placed on the soil surface and buried at 10 cm under field conditions over 3 years. Our findings reveal that seedlings emergence was about five‐fold higher from shallow‐buried than from surficial isolated seeds, and from isolated seeds than from seeds inside siliques, suggesting strong effects of burial depth and the pericarp. Even isolated seeds buried at 12 cm depth outperformed surface isolated seeds. The burial depth influenced emergence patterns; isolated seeds exhibited rapid emergence, with rates five times higher at 10 cm deep compared to those on the soil surface, showing no emergence after year 1. Conversely, the pericarp delayed and staggered seedlings emergence, contributing to the formation of a persistent seed bank for at least 3 years in both burial depths. Seedlings emergence from seeds inside siliques buried at 10 cm begins in year 1 and in those placed on the soil surface year 2, with emergence peaks predominantly in autumn. These findings enrich our understanding of feral radish seedling emergence, providing valuable insights for the development of sustainable and efficient management practices. [ABSTRACT FROM AUTHOR]

The highly invasive weed Parthenium hysterophorus flowers during both hot, humid summers and cold, dry winters in Nepal, yet it remains unknown if there are differences in seed germination and seedling growth during these contrasting seasons. We analysed seed germination and seedling growth of summer and winter cohorts of P. hysterophorus in Kathmandu Valley. Seeds were germinated at low (25/15°C) and high (30/20°C) temperatures, 12/12 h photoperiod and complete dark, and at different levels of water stress. Seedlings were grown in a greenhouse to determine biomass allocation and relative growth rate (RGR). Winter seeds had higher seed biomass than summer seeds, and both seed types germinated under complete dark and 12/12 h photoperiod. Summer seeds germinated at significantly lower rates and percentage than winter seeds at the low temperature, but this difference in germination was not present when summer and winter seeds were incubated at the high temperature. Winter seeds had higher germination (percentage and rate) and took a longer time to reach maximum germination than summer seeds at different levels of water stress. Seedling emergence of both seed types declined with increasing soil depth. Seedling RGRs were nearly equal (summer: 73 mg g−1 day−1, winter: 77 mg g−1 day−1). Biomass allocation to stem and leaves were similar in both cohorts but root biomass allocation was higher in the winter than in the summer cohort. Overall, the maternal environmental effect was moderate on seed germination, and weak on seedling growth. Lack of a pronounced difference in the germination and seedling growth of summer and winter cohorts of P. hysterophorus suggests a wide environmental tolerance of the species, and this could be one of the reasons for the species' ability to invade diverse climatic and geographic regions globally. [ABSTRACT FROM AUTHOR]

Maize (Zea mays L.) is a widely cultivated monoecious plant, making it vulnerable to seedling soft rot, a significant disease that results in substantial global losses. During the 2020–2021, various regions of Iran reported a series of symptoms, which included seedling stunting, the browning, and rotting of roots and crowns, and post‐emergence dieback. To identify the causal agent of this disease, a total number of 70 symptomatic samples were collected, yielding 117 bacterial strains. These bacterial isolates exhibited small, circular, raised colonies with a yellow pigment on yeast‐extract peptone glucose agar (YPGA) medium, 48 h post inoculation (hpi). Identification of the putative pathogen as Stenotrophomonas maltophilia (formerly known as Xanthomonas maltophilia) was based on colony morphology, biochemical features, amplification of the species‐specific SmeT gene and nucleotide sequences of the gyrB gene. Koch's postulates were completed by inoculating maize seedlings with bacterial suspensions (107 CFU/mL). Two weeks after inoculation, symptoms including decay in the lower part of the seedling, wilting and yellowing of leaves became apparent. Subsequently, the bacteria with typical colony morphology were re‐isolated from the crowns of the inoculated maize seedlings and identified as S. maltophilia. In addition, various plant species were tested to determine the host range of S. maltopilia. Sugarcane and sorghum exhibited complete collapse, while onion showed no symptoms. Other hosts displayed varying degrees of symptom severity. This study marks the first documented case of maize seedling rot caused by S. maltophilia. These findings offer valuable insights into the pathogenicity of the disease and its management implications. [ABSTRACT FROM AUTHOR]

Questions: Do nitrogen deposition and climate warming affect tree seedlings and plant communities in different habitats? In these habitats, how do microenvironments, including soil properties and, when applicable, edge effects relate to plant performance? Location: The University of British Columbia Malcolm Knapp Research Forest, Maple Ridge, British Columbia, Canada. Methods: We assessed performance of Pseudotsuga menziesii (Mirb.) Franco, Thuja plicata Donn ex D. Don and Tsuga heterophylla (Raf.) Sarg. planted tree seedlings and associated vascular plant communities. Performance of tree seedlings (height) and under vascular plant communities (percent cover) were examined in an experiment with warming (open‐top chambers) and nitrogen deposition (ammonium nitrate applied at 10 kg N ha−1 year−1) treatments applied to subplots in six forest edges and six clear‐cuts (N = 298 total subplots). Results: In clear‐cuts, tree seedling height increased with experimental warming and differed among species, and vascular plant cover increased with warming. In clear‐cuts, species identity, not soil variables, was a strong predictor of height, and plant cover was negatively related to pH. In forest edges, edge position and some soil variables were related to height, but not plant cover. There were no interaction effects found between experimental nitrogen deposition and warming. Conclusions: Our results suggest that moderate warming can enhance tree seedling height and understorey vascular plant cover in clear‐cuts in Pacific Northwest coastal ecosystems, but low nitrogen deposition may not have an effect alone or synergistically with warming. [ABSTRACT FROM AUTHOR]

Aim: Seedling recruitment is a vital process for forest regeneration and is influenced by various factors such as stand composition, climate, and soil disturbance. We conducted a long‐term field experiment (18 years) to study the effects of these factors and their interactions on seedling recruitment. Location: Our study focused on five main species in boreal mixed woods of eastern Canada: trembling aspen (Populus tremuloides), paper birch (Betula papyrifera), white spruce (Picea glauca), balsam fir (Abies balsamea), and white cedar (Thuja occidentalis). Methods: Sixteen 1‐m2 seedling monitoring subplots were set up in each of seven stands originating from different wildfires (fire years ranging from 1760 to 1944), with a soil scarification treatment applied to every other subplot. Annual new seedling counts were related to growing‐season climate (mean temperature, growing degree days and drought code), scarification, and stand effects via a Bayesian generalized linear mixed model. Results: Soil scarification had a large positive effect on seedling recruitment for three species (aspen, birch and spruce). As expected, high mean temperatures during the seed production period (two years prior to seedling emergence) increased seedling recruitment for all species but aspen. Contrary to other studies, we did not find a positive effect of dry conditions during the seed production period. Furthermore, high values of growing degree days suppressed conifer seedling recruitment. Except for white cedar, basal area was weakly correlated with seedling abundance, suggesting a small number of reproductive individuals is sufficient to saturate seedling recruitment. Conclusion: Our findings underscore the importance of considering multiple factors, such as soil disturbance, climate, and stand composition, as well as their effects on different life stages when developing effective forest management strategies to promote regeneration in boreal mixed‐wood ecosystems. [ABSTRACT FROM AUTHOR]

We experimentally examined the influence of grass competition, grass species identity (taxa) and water availability on the seedling growth and survival of two dominant tree species (Vachellia (formerly Acacia) robusta and V. tortilis) of the Serengeti National Park in Tanzania. Despite being widely distributed, the species have an opposing overstorey dominance across a rainfall and productivity gradient, with V. robusta dominating the more productive mesic sites and V. tortilis in the lower productivity, drier sites. We investigated the role of different grass species, which vary in distribution and abundance across the rainfall gradient, in influencing the growth and survival of Vachellia seedlings. We found a significant effect of grass competition but no effect of grass species identity on the growth or survival of seedlings. Seedling survival was highest in the absence of grass competition, intermediate when grasses were defoliated to simulate grazing and lowest when grown with ungrazed grasses. Grass competition had a more negative effect on the stem diameter of V. tortilis than V. robusta. All V. tortilis seedlings grown under a combination of drought conditions and unclipped grasses died by the end of the experiment. However, reduced grass competition by simulated grazing improved V. tortilis seedling survival to comparable levels achieved by V. robusta species. Our study advances our understanding of tree and grass competition across environmental gradients and suggests that the presence of grass and soil moisture have species‐specific effects on tree seedling growth and survival in African savannas. [ABSTRACT FROM AUTHOR]

Droughts are predicted to become more frequent and intense in many tropical regions, which may cause shifts in plant community composition. Especially in diverse tropical communities, understanding how traits mediate demographic responses to drought can help provide insight into the effects of climate change on these ecosystems. To understand tropical tree responses to reduced soil moisture, we grew seedlings of eight species across an experimental soil moisture gradient at the Luquillo Experimental Forest, Puerto Rico. We quantified survival and growth over an 8‐month period and characterized demographic responses in terms of tolerance to low soil moisture—defined as survival and growth rates under low soil moisture conditions—and sensitivity to variation in soil moisture—defined as more pronounced changes in demographic rates across the observed range of soil moisture. We then compared demographic responses with interspecific variation in a suite of 11 (root, stem, and leaf) functional traits, measured on individuals that survived the experiment. Lower soil moisture was associated with reduced survival and growth but traits mediated species‐specific responses. Species with relatively conservative traits (e.g., high leaf mass per area), had higher survival at low soil moisture whereas species with more extensive root systems were more sensitive to soil moisture, in that they exhibited more pronounced changes in growth across the experimental soil moisture gradient. Our results suggest that increasing drought will favor species with more conservative traits that confer greater survival in low soil moisture conditions. [ABSTRACT FROM AUTHOR]

Most trees die as seedlings, with harsh environmental conditions, such as early‐spring frosts and summer heat waves, being important drivers of early mortality. However, it remains unclear whether tolerance to different environmental extremes (e.g. frost vs. heat) trades‐off, or covaries synergistically and how stress tolerances relate to growth rates and life history strategies. Given the likely role of extreme environmental conditions as environmental filters, the ability to tolerate different stressors at the seedling stage could shape the occurrence and composition of present and future forests.We explored the relationships between different leaf‐level stress tolerances, functional traits and geographic distributions across 22 species of temperate European tree seedlings. We measured indicators of tolerance to frost, drought and heat and related these values to growth rates and to important functional traits (e.g. leaf mass per area and stem‐specific density). Finally, we explored the links between measured seedling stress tolerances and climatic niche limits inferred from adult trees' distributions.We found that seedlings of most species were either moderately tolerant to all three stressors, or susceptible to all of them. Moreover, higher stress tolerances were associated with traits describing slower growth and lower competitive ability. However, seedling tolerances to climatic factors were unrelated to the environmental limits of their adult geographic distributions.Synthesis. Our results suggest that temperate tree seedlings might not experience trade‐offs when facing an increase in multiple extreme climate stressors, but may experience trade‐offs related to growth rate and competitive ability in the establishment phase. The lack of correlation between leaf‐level stress tolerances and the environmental limits of adult geographic distributions suggests that predicting species' current or future geographic distributions in Europe will require a more nuanced understanding of how climatic tolerances at juvenile and adult stages influence range limits. A better understanding of the interaction between survival in extreme climate, leaf‐level stress tolerances of seedlings and the factors driving species distributions is needed to understand future forest responses to climate change. [ABSTRACT FROM AUTHOR]

Cost‐effective, large‐scale strategies are needed to restore degraded ecosystems worldwide. Applied nucleation is one technique that can accelerate succession in tropical forests. However, the effectiveness of irrigation and fertilization in the context of large‐scale applied nucleation in tropical dry forests (TDFs) has not yet been tested. To this end, we established a large‐scale experiment in southwestern Colombia on abandoned pastures. We planted 11,382 seedlings of 11 native species coupled with six management treatments that varied in the amounts of fertilizer and water. We monitored survival, height, and resprouting ability seedlings over 2 years. We also estimated the cost of seedling production, planting procedures, management, and monitoring, and assessed their cost‐effectiveness using seedling survival as an indication of effectiveness. After 2 years, 73% (8,266) of seedlings planted survived, and species survival ranged from 5 to 99%. Individuals that received the lowest amount of fertilizer (25 g of Nitrogen, Phosphorus, and Potassium [NPK]) with additional irrigation had the highest survival rates (>76%). Final height ranged from 52 to 330 cm across species. Seedlings that received the highest amount of fertilizer (50 g of NPK) without additional irrigation had the highest mean final height (174 ± 9.0 cm). The control was cheapest ($7313/ha) and the most cost‐effective method in terms of seedling survival. Our findings suggest that the best way to establish cost‐effective, large‐scale restoration projects in TDFs is to plant native species mixtures of locally adapted species without fertilization and irrigation and to invest in long‐term monitoring. [ABSTRACT FROM AUTHOR]

Seagrasses provide various ecosystem functions in coastal areas of the world. In the Mediterranean Sea, Posidonia oceanica is an endemic species threatened by several activities despite being protected by national and international laws. Currently, several transplanting initiatives have been carried out using different methods, among which those including seeds and seedlings are considered the most ecological and low‐cost ones. Beach‐cast fruits and seeds can be found in spring and their appearance can easily be reported, through a citizen science approach, by the community. One of the obstacles in using these methods is identifying the best substrate in which to place P. oceanica seeds to facilitate root adhesion of the seedlings prior to their transplantation into the sea. In the present study, we analyzed, using a 3D surface optical microscope, the roughness of natural rocks to identify the availability of specific roughness ranges suitable for adhesion and root anchoring of P. oceanica seedlings. Conventional roughness parameters and roughness power spectral density were calculated for the inner and outer surfaces of 9 different rock samples. Among the rock samples examined, the calcarenitic ones and in particular marsala calcarenite, due to the presence of the "ideal roughness for seedlings" can be considered one of the best consolidated substrates to be used for the construction of ad hoc devices on which plantlet of P. oceanica can grow for the purpose of restoration. [ABSTRACT FROM AUTHOR]

Type conversion from native shrubland to invasive annual grassland is on the rise due to global change factors such as prolonged drought and increasing fire frequency. Efforts to restore chaparral ecosystems are limited by current understanding of competitive interactions between shrub seedlings and invasive grasses as well as soil moisture requirements of chaparral seedlings. We set up a restoration experiment where we out‐planted Adenostoma fasciculatum seedlings, manipulated invasive grass density, monitored soil moisture at two depths, and tracked seedling survival and biomass. We found that higher invasive grass cover was associated with higher rates of seedling mortality but found no difference in biomass per surviving plant. Soil moisture was higher at 15 cm under the 100% weeded treatment than the 50% weeded and control treatments during January. Lower invasive cover resulted in higher richness of annual native plant species, as plots with 100% invasive removal had higher richness than 50% removal and unplanted control plots. Future restoration efforts in the chaparral will likely be more successful in increasing initial seedling establishment if invasive grass removal is included. [ABSTRACT FROM AUTHOR]

Understanding the phenological stages and thermal requirements of the seedling phase of forest species is crucial for sustainable nursery management. This study proposed an adaptation of a phenological scale based on the basic Biologische Bundesanstalt, Bundessortenamt, and Chemical industry, associated with the thermal requirement to describe the phenological stages during the seedling phase of three forest species: Cybistax antisyphilitica, Libidibia ferrea, and Platycyamus regnellii. The phenological scale of C. antisyphilitica and L. ferrea was defined and described through 22 seedling development stages ranging from dry seed to 20th visible leaf emitted on the main stem (from 00 to 120) and P. regnellii for 12 leaf development stages, from dry seed to 10th visible leaf emitted on the main stem (from 00 to 110). In addition, the duration (days) and thermal time (°C day) were determined for each seedling development stage. C. antisyphilitica needs to accumulate more energy (and days) to finish the seedling phase (1551.9°C day or 261 days) compared to L. ferrea (1127°C day or 175 days) and P. regnellii (1109.7°C day or 193 days). However, the three forest species exhibit similar energy demands throughout most stages of seedling development, except code 09–12 for C. antisyphilitica. This study provides important information for optimizing silvicultural techniques, evaluating the response of temperature on phenological stages, and assessing the impacts of global warming on forest seedling development. [ABSTRACT FROM AUTHOR]

One of the ways in which plants are responding to climate change is by shifting their ranges to higher elevations. Early life‐history stages are major bottlenecks for species' range shifts, and variation in seedling emergence and establishment success can therefore be important determinants of species' ability to establish at higher elevations. Previous studies have found that warming per se tends to not only increase seedling establishment in alpine climates but it also increases plant productivity, which could limit establishment success through increased competition for light. Here we disentangle the relative importance of several climate‐related abiotic and biotic factors on sub‐alpine species' seedling emergence and survival in the alpine. Specifically, we test how temperature, precipitation and competition from neighbouring vegetation impacts establishment, and also whether species' functional traits, or strategies impact their ability to colonise alpine locations. We found that our six sub‐alpine study species were all able to recruit from seed in alpine locations under the extant alpine climate, but their emergence was limited by competition from neighbouring vegetation. This indicates that biotic interactions can hinder the range shifts expected as a result of climate warming. Species with a resource conservative strategy had higher emergence in the extant alpine climate than species with a resource acquisitive strategy, and they were largely unaffected by changes in temperature. The resource acquisitive species, in contrast, had faster emergence under warming, especially when they were released from competition from neighbouring vegetation. Our results indicate that competition from the established vegetation is limiting the spread of lowland species into the alpine, and as the climate continues to warm, species with resource acquisitive traits might gain an advantage. [ABSTRACT FROM AUTHOR]

Caucasian alder (Alnus subcordata) is among the major constituents of the Hyrcanian forests extending all along the southern coast of the Caspian Sea in northern Iran. An angular leaf spot with a yellowish chlorotic halo has attained a widespread occurrence throughout the forest and suburban areas of the northern provinces including Guilan, Mazandaran and Golestan. Strains of a Xanthomonas sp. were consistently isolated from the symptomatic leaves of A. subcordata. Colonies of the isolates were yellow circular, convex and mucoid on nutrient agar containing glucose or sucrose. In multilocus sequence analysis using the genes gyrB, rpoD, dnaK, gltA, fyuA and gapA, the representative isolates occupied a clade shared by the known pathovars of Xanthomonas arboricola. The isolates were relatively heterogeneous phenotypically, but more so in their rep‐PCR fingerprints. Pathogenicity of several isolates was confirmed on seedlings of A. subcordata and Alnus rhombifolia, whereas Alnus cordata, Alnus glutinosa and Alnus crispa appeared not to be susceptible. Based on these characteristics, the isolates causing angular leaf spots of Caucasian alder appear to represent a novel pathovar of X. arboricola. [ABSTRACT FROM AUTHOR]

Amaranthus blitoides S. Watson and A. hybridus L. are common herbaceous annual summer weeds in different regions of Iran, which produce a large number of small seeds per plant. The goal of these experiments was to determine seed germination cardinal temperature and investigate the effect of constant temperature, osmotic and salt stresses, stratification, flooding duration, after‐ripening and seed planting depth on seed germination and seedling emergence. Two‐piece segmented, dent‐like and beta four‐parameter models were used to investigate the relationship between germination rate and constant temperature. The dent‐like model showed the best description of the effect of constant temperature on seed germination rate of both A. blitoides and A. hybridus. Optimal seed germination of A. blitoides occurred at 35°C, but in A. hybridus optimum germination was observed in a range of constant temperatures from 30 to 40°C. Osmotic and salt stresses and flooding adversely affected seed germination of both species. After ripening for 6 months increased germination percentage of both A. blitoides and A. hybridus. Maximum seedling emergence of A. blitoides (42.8%) and A. hybridus (44.9%) occurred at a planting depth of 3.3 cm, whereas further increased planting depth minimized seedling emergence of both weeds. Information obtained from this study will help us to develop effective techniques for management of A. blitoides and A. hybridus. [ABSTRACT FROM AUTHOR]

Soil mulches and conditioners have been shown to improve soil moisture conservation, infiltration, and seed germination and survival, but their interactive effects with sporadic rainfall and the existing vegetation have rarely been considered. In an experimental field study, we assessed the effects of soil additives (sawdust and hydrogel) and mulches (river sand and plant debris) on seedling emergence and survival of Astragalus nigricans Barneby, in the rangelands of Mashhad, northeast Iran. We also assessed any effects on soil moisture and temperature several days after rain in July 2017 and May 2018 and weed composition, density, and diversity. The most successful treatment was hydrogel, associated with earlier seedling emergence for A. nigricans, greater seedling survival, and biomass production. Sawdust and sand treatments were useful for root proliferation and seedling emergence in the spring of the first season, but they led to high seedling mortality under drought. Debris of Artemisia khorasanica shoots was the most efficient and consistent treatment for soil moisture conservation and temperature stability in both years, but its possible allelopathic effects led to high seedling mortality and a long delay (41 days) on seedling emergence. Plant debris also negatively affected the density, richness, and diversity of nontarget plant species. Despite differences among different rainfall events, mulch treatments have an important role in regenerating degraded rangelands. [ABSTRACT FROM AUTHOR]

Root hairs are considered important for rhizosphere formation, which affects root system functioning. Through interactions with soil microorganisms mediated by root exudation, root hairs may affect the phenotypes and growth of young plants. We tested this hypothesis by integrating results from two experiments: (1) a factorial greenhouse seedling experiment with Zea mays B73‐wt and its root‐hairless mutant, B73‐rth3, grown in live and autoclaved soil, quantifying 15 phenotypic traits, seven growth rates, and soil microbiomes and (2) a semi‐hydroponic system quantifying root exudation of maize genotypes. Possibly as compensation for lacking root hairs, B73‐rth3 seedlings allocated more biomass to roots and grew slower than B73‐wt seedlings in live soil, whereas B73‐wt seedlings grew slowest in autoclaved soil, suggesting root hairs can be costly and their benefits were realized with more complete soil microbial assemblages. There were substantial differences in root exudation between genotypes and in rhizosphere versus non‐rhizosphere microbiomes. The microbial taxa enriched in the presence of root hairs generally enhanced growth compared to taxa enriched in their absence. Our findings suggest the root hairs' adaptive value extends to plant‐microbe interactions mediated by root exudates, affecting plant phenotypes, and ultimately, growth. Summary Statement: An experiment with seedlings of Zea mays B73 and its root‐hairless mutant (Z. mays B73‐rth3) with contrasting soil microbiomes showed that root hairs are beneficial towards plant growth but can be costly. Root hairs' adaptive value was partly mediated by plant‐microbe interactions involving exudates, which feedback to plant phenotypes and growth. [ABSTRACT FROM AUTHOR]

BACKGROUND: Salt has been identified as an elicitor that can increase the accumulation of phytochemicals in seedlings during the germination process. However, the salinity level required to maximize the yield of phytochemicals, particularly phenolic compounds, needs further investigation for several plant species. To address this issue, we imposed increasing levels of salinity (NaCl solutions) on the sprouting substrate of Triticum durum (var. Platone) grains, at concentrations of 0, 50, 100, 150, 200, 250, and 300 mM (0_S, 50_S, 100_S, 150_S, 200_S, 250_S, and 300_S, respectively). RESULTS: The highest NaCl doses (250_S and 300_S) significantly impacted germination performance and were excluded from further analysis. The seedlings harvested at 8 days after sowing exhibited different growth stages depending on the salinity level: wheatgrass for 0_S, early wheatgrass for 50_S, intermediate between sprout and wheatgrass for 100_S, sprout for 150_S, and very early sprout for 200_S. Furthermore, salinity induced the concentration of phenolic compounds (PhCs) in the seedlings' tissues (i.e., both roots and shoots) in a salinity‐dependent manner. The highest values were observed at 200_S, with an increase of 187% of the total investigated PhCs in comparison with 0_S, averaged over shoots and roots. In particular, in 200_S, the accumulation of phenolic acids was up to fourfold higher in roots, and that of flavonoids was up to twofold higher in shoots. CONCLUSION: Our findings suggest that the use of 200 mM NaCl applied to the sprouting substrate is excessive for producing edible sprouts but may be suitable for phytochemical extraction purposes. © 2023 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Light is an essential environmental signal for plant development called photomorphogenesis. Here, we show that diethyl ether anaesthesia inhibits the de‐etiolation process in barley (Hordeum vulgare) seedlings. Illuminated seedlings exposed to diethyl ether accumulated significantly less chlorophylls and chlorophyll‐binding proteins, and exhibited reduced maximum quantum yield of photosystem II photochemistry (Fv/Fm). Although the direct effect of light necessary for the greening process, i.e. for the photoreduction of protochlorophyllide (Pchlide) to chlorophyllide (Chlide) catalysed by light‐dependent protochlorophyllide oxidoreductase A (PORA), was not inhibited, the RNA‐seq and qPCR analyses showed that light‐induced expression of photosynthesis‐associated nuclear genes (PhANGs) and genes encoding enzymes for chlorophyll biosynthesis were attenuated. On the other hand, transcription of chloroplast‐encoded genes was not negatively affected by diethyl ether treatment during greening. Among the genes negatively regulated by light, PORA and PHYA were only slightly affected by diethyl ether. The effect of diethyl ether was fully reversible and, after its removal, the greening process was fully restored. Our data indicate that diethyl ether had two effects on greening: i) it inhibited the expression of PhANGs and chlorophyll biosynthesis‐related genes irrespective of light conditions, ii) it blocked the light‐induced expression of these genes and greening process of etiolated seedlings. Our study indicates that diethyl ether affects plastid biogenesis, which alters the orchestration of negative and positive regulators affecting phytochrome and/or retrograde signalling and does not allow expression of PhANGs. Thus, the plants are locked in an intermediate skoto‐photomorphogenetic state in the light. [ABSTRACT FROM AUTHOR]

It is hypothesized that 'hydraulic vulnerability segmentation' (the vulnerability of expendable organs is higher compared to the vulnerability of nonexpendable organs) can enhance the drought‐tolerance of trees. However, prediction of positive segmentation (leaf minus branch) did not gain undisputed support in field observations. Further, the main organs of trees (leaf/trunk/root) are vital to test the hypothesis at the individual level. Unfortunately, most verifications of the hypothesis focus on the hydraulic vulnerabilities between leaves and terminal branches of mature trees. In this study, we grew three deciduous oak (Quercus mongolica, Q. variabilis and Q. aliena) seedlings (6 months old), and measured the hydraulic vulnerabilities of leaves (by rehydration method), main stems and main roots (by bench dehydration method). The sensitivity of stomata to water potential was obtained by monitoring the stomata conductance response to drought stress. The xylem anatomy of main stem and main root was also measured. It was found that the leaves of all three oak species exhibited greater vulnerability than the main stems and main roots. The leaf‐stem segmentation was more pronounced than the stem‐root one, and the stem‐root in Q. aliena even showed a reversed segmentation. Further, we found that higher stomatal sensitivity was associated with higher P50,leaf (water potential at 50% loss of leaf hydraulic conductivity), and narrower segmentation between leaf and the most embolism‐resistant organ. Collectively, our results support the 'hydraulic vulnerability segmentation' hypothesis at the individual level, and highlight the importance of stomatal regulation in hydraulic vulnerability segmentation. [ABSTRACT FROM AUTHOR]

Aulonemia aristulata is a tropical bamboo species of mixed rhizome type and monocarpic flowering that can become super‐dominant after anthropogenic disturbances in tropical forests. The synchronized reproductive events of flowering and die‐off of monocarpic bamboo systems provide a rare opportunity to evaluate the temporal effects of bamboo dominance on forest regeneration. To evaluate the effects of bamboo dominance on forest regeneration, we compared the structure (abundance, richness, composition) and dynamics (mortality, recruitment, survival and growth) of tree and shrub seedling communities from two non‐contiguous forests stands (bamboo‐dominated vs. non‐dominated sites) for 2 years, before and after a synchronized reproductive event. Bamboo dominated plots had higher abundance, floristic richness and recruitment of tree and shrub seedlings when compared with bamboo non‐dominated plots. Bamboo die‐off did not represent an opportunity to improve establishment and investment in the vertical growth (height) of seedlings in bamboo‐dominated plots. We postulate that the mode of rhizome extension seen in bamboos might be a consistent trait determining the spatial pattern of occupation and population structure and thereby playing a fundamental role in the pattern of native tree community establishment after bamboo die‐off. The formulation of a management approach is necessary in order to better understand the biological traits of bamboo species and their influence on the spatial pattern of occupation and population structure. Additionally, this influence may differently impact restoration and definition of management practices, including the need for direct intervention by manually controlling bamboo cover following die‐off to promote and maintain seedling establishment and diversity. [ABSTRACT FROM AUTHOR]

Stenotrophomonas rhizophila CFBP13503 is a seedborne commensal bacterial strain, which is efficiently transmitted to seedlings and can outcompete the phytopathogenic bacterium Xanthomonas campestris pv. campestris (Xcc8004). The type VI secretion system (T6SS), an interference contact‐dependent mechanism, is a critical component of interbacterial competition. The involvement of the T6SS of S. rhizophila CFBP13503 in the inhibition of Xcc8004 growth and seed‐to‐seedling transmission was assessed. The T6SS cluster of S. rhizophila CFBP13503 and nine putative effectors were identified. Deletion of two T6SS structural genes, hcp and tssB, abolished the competitive advantage of S. rhizophila against Xcc8004 in vitro. The population sizes of these two bacterial species were monitored in seedlings after inoculation of radish seeds with mixtures of Xcc8004 and either S. rhizophila wild‐type (wt) strain or isogenic hcp mutant. A significant decrease in the population size of Xcc8004 was observed during confrontation with the S. rhizophila wt in comparison with T6SS‐deletion mutants in germinated seeds and seedlings. We found that the T6SS distribution among 835 genomes of the Stenotrophomonas genus is scarce. In contrast, in all available S. rhizophila genomes, T6SS clusters are widespread and mainly belong to the T6SS group i4. In conclusion, the T6SS of S. rhizophila CFBP13503 is involved in the antibiosis against Xcc8004 and reduces seedling transmission of Xcc8004 in radish. The distribution of this T6SS cluster in the S. rhizophila complex could make it possible to exploit these strains as biocontrol agents against X. campestris pv. campestris. [ABSTRACT FROM AUTHOR]

Seed passage through frugivorous bats' gastrointestinal tracts is important in seed dispersal, germination and seedling emergence. We investigated the ingestion and effects of Wahlberg's epauletted fruit bats, Epomophorus wahlbergi, on the germination and seedling emergence of four Ficus species in separate laboratory feeding trials in KwaZulu-Natal Province, South Africa. We observed seedling emergence and germination rates for all ingested seeds, whole and de-pulped fruits. Our results showed that ingestion amounts were high and the germination of Ficus seeds was positively influenced by mastication and/or gut passage of E. wahlbergi, underscoring the potential of fruit bats as effective seed dispersers. [ABSTRACT FROM AUTHOR]

Following the control of an invasive tree species, native forest ecosystem restoration can be prevented by a secondary invasion by another invasive species that inhibits the reestablishment of native trees. In this study, we evaluated the effects of the invasive shrub Leucaena leucocephala on the initial growth of planted seedlings of four native tree species (Pandanus boninensis, Rhaphiolepis indica, Schima mertensiana, and Terminalia catappa) after eradication of the invasive tree Casuarina equisetifolia in the Ogasawara Islands in the northwestern Pacific Ocean. In a 24‐month field experiment, we compared the sizes of planted seedlings (diameter at ground level, height, and leaf number) among four treatments in a 2 × 2 design of initial seedling size (large vs. small) × L. leucocephala invasion (sowing L. leucocephala seeds vs. control). More than 75% of the seedlings (excluding S. mertensiana) survived regardless of the treatments. For all four species, initially large seedlings tended to become larger plants at the end of the experiment than initially small seedlings. We detected significant effects of L. leucocephala invasion on one or more plant size parameters in all four species. Seedlings grown in L. leucocephala invasion quadrats were smaller than those in control quadrats at the end of the experiment. We detected significant interactions between initial seedling sizes and L. leucocephala invasion for three species. Together, these results indicate that secondary invasion by L. leucocephala after controlling C. equisetifolia inhibits the initial growth of native tree seedlings, depending on their size at the time of invasion. [ABSTRACT FROM AUTHOR]

Exploring sustainable strategies for improving crop water and nitrogen use efficiency is essential. Silicon (Si) has been reported as a beneficial metalloid for plants since it alleviates several abiotic stresses (including drought) by triggering the plants' antioxidant system. However, its role in mitigating the negative impact of nitrogen (N) deficit alone or when combined with water (W) deficit is not well studied. This study applied 0 or 2 mM of Na₂SiO3 to 3‐week‐old tomato cv. Micro‐Tom seedlings that were grown under the following conditions: control (CTR; 100%N + 100% Field Capacity), N deficit (N; 50% N + 100% Field Capacity), water deficit (W; 100% N + 50% Field Capacity) or combined stress (N + W; 50% N + 50% Field Capacity). The Si effect on tomato plant growth depended on the type of stress. Si could only alleviate stress caused by N + W deficit resulting in a higher root dry weight (by 28%), total dry weight (by 23%) and root length (by 37%). Alongside this, there was an increase in the antioxidant (AOX) system activity with the root activity of ascorbate peroxidase and catalase enzymes being enhanced by 48% and by 263%, respectively. Si application also enhanced AOX enzyme activity when tomato plants were subjected to individual deficits but to a lesser extent. In conclusion, Si‐treated tomato plants could efficiently modulate their AOX networks in a situation of combined N and water limitation, thus mitigating some of the adverse effects of this combined stress. [ABSTRACT FROM AUTHOR]

In mountain forests, tree regeneration is limited by increasingly frequent frosts with increasing elevation. We investigated the effects of exposure to freezing temperature on early life stages of two native trees of different elevational origin in a seasonally dry mountain forest. We hypothesized that the negative effects of freezing exposure on performance of early life stages increases as freezing temperature decreases, and that frost resistance increases in plants of high elevational origin.We collected seeds of two tree species (Kageneckia lanceolata and Lithraea molleoides) from populations located at different elevations and grew seedlings and saplings in a greenhouse. Dry seeds, imbibed seeds and 1‐month‐old seedlings were exposed to seven temperature treatments ranging from 4 °C to −20 °C, while 12‐month‐old saplings were exposed to four temperature treatments from −8 °C to −20 °C. After freezing exposure in a climate chamber, we monitored seed germination and seedling and sapling survival.Germination of K. lanceolata decreased with decreasing temperature only for imbibed seeds from mid‐ and high elevations, whereas germination of L. molleoides slightly increased with decreasing temperature only for imbibed seeds from high elevations. For both species, seedling survival decreased with decreasing temperature. For K. lanceolata, the negative effects of freezing temperatures were weaker as elevational origin of seeds increased, whereas L. molleoides showed the opposite pattern. For both species, saplings only survived at the mildest applied freezing temperature (−8 °C).We conclude that effects of climatic variation associated with elevation depend on the study species and life stage. The observed patterns could be caused by maternal effects, which are absent at the sapling stage. Moreover, temperatures below −8 °C can limit recruitment since partial mortality of seedlings and saplings occurred at such values. [ABSTRACT FROM AUTHOR]

Summary: Isogenic individuals can display seemingly stochastic phenotypic differences, limiting the accuracy of genotype‐to‐phenotype predictions. The extent of this phenotypic variation depends in part on genetic background, raising questions about the genes involved in controlling stochastic phenotypic variation.Focusing on early seedling traits in Arabidopsis thaliana, we found that hypomorphs of the cuticle‐related gene LIPID TRANSFER PROTEIN 2 (LTP2) greatly increased variation in seedling phenotypes, including hypocotyl length, gravitropism and cuticle permeability. Many ltp2 hypocotyls were significantly shorter than wild‐type hypocotyls while others resembled the wild‐type.Differences in epidermal properties and gene expression between ltp2 seedlings with long and short hypocotyls suggest a loss of cuticle integrity as the primary determinant of the observed phenotypic variation. We identified environmental conditions that reveal or mask the increased variation in ltp2 hypomorphs and found that increased expression of its closest paralog LTP1 is necessary for ltp2 phenotypes.Our results illustrate how decreased expression of a single gene can generate starkly increased phenotypic variation in isogenic individuals in response to an environmental challenge. [ABSTRACT FROM AUTHOR]

Summary: Early responses of plants to environmental stress factors prevent damage but can delay growth and development in fluctuating conditions. Optimising these trade‐offs requires tunability of plant responsiveness to environmental signals.We have previously reported that Histone Deacetylase Complex 1 (HDC1), which interacts with multiple proteins in histone deacetylation complexes, regulates the stress responsiveness of Arabidopsis seedlings, but the underlying mechanism remained elusive.Here, we show that HDC1 attenuates transcriptome re‐programming in salt‐treated seedlings, and we identify two genes (LEA and MAF5) that inhibit seedling establishment under salt stress downstream of HDC1. HDC1 attenuates their transcriptional induction by salt via a dual mechanism involving H3K9/14 deacetylation and H3K27 trimethylation. The latter, but not the former, was also abolished in a triple knockout mutant of the linker histone H1, which partially mimics the hypersensitivity of the hdc1‐1 mutant to salt stress. Although stress‐induced H3K27me3 accumulation required both H1 and HDC1, it was not fully recovered by complementing hdc1‐1 with a truncated, H1‐binding competent HDC1 suggesting other players or independent inputs.The combined findings reveal a dual brake function of HDC1 via regulating both active and repressive epigenetic marks on stress‐inducible genes. This natural 'anti‐panic' device offers a molecular leaver to tune stress responsiveness in plants. See also the Commentary on this article by Archacki, 241: 7–9. [ABSTRACT FROM AUTHOR]

Initial difficulties in germinating the PRAIRIE dropseed grass Sporobolus heterolepis (A. Gray) A. Gray and the ways in which they were it was overcome are described. The resulting seedlings are grown in deep plugs before being planted out in the developing prairie. [ABSTRACT FROM AUTHOR]

Understanding the mechanisms that promote the coexistence of hundreds of species over small areas in tropical forest remains a challenge. Many tropical tree species are presumed to be functionally equivalent shade tolerant species but exist on a continuum of performance trade‐offs between survival in shade and the ability to quickly grow in sunlight. These trade‐offs can promote coexistence by reducing fitness differences.Variation in plant functional traits related to resource acquisition is thought to predict variation in performance among species, perhaps explaining community assembly across habitats with gradients in resource availability. Many studies have found low predictive power, however, when linking trait measurements to species demographic rates.Seedlings face different challenges recruiting on the forest floor and may exhibit different traits and/or performance trade‐offs than older individuals face in the eventual adult niche. Seed mass is the typical proxy for seedling success, but species also differ in cotyledon strategy (reserve vs. photosynthetic) or other leaf, stem and root traits. These can cause species with the same average seed mass to have divergent performance in the same habitat.We combined long‐term studies of seedling dynamics with functional trait data collected at a standard life‐history stage in three diverse neotropical forests to ask whether variation in coordinated suites of traits predicts variation among species in demographic performance.Across hundreds of species in Ecuador, Panama and Puerto Rico, we found seedlings displayed correlated suites of leaf, stem, and root traits, which strongly correlated with seed mass and cotyledon strategy. Variation among species in seedling functional traits, seed mass, and cotyledon strategy were strong predictors of trade‐offs in seedling growth and survival. These results underscore the importance of matching the ontogenetic stage of the trait measurement to the stage of demographic dynamics.Our findings highlight the importance of cotyledon strategy in addition to seed mass as a key component of seed and seedling biology in tropical forests because of the contribution of carbon reserves in storage cotyledons to reducing mortality rates and explaining the growth‐survival trade‐off among species.Synthesis: With strikingly consistent patterns across three tropical forests, we find strong evidence for the promise of functional traits to provide mechanistic links between seedling form and demographic performance. [ABSTRACT FROM AUTHOR]

Shorea robusta Gaertn. (sal) forests are rapidly decreasing across India owing to the low survival rate and establishment of their seedlings. Because of this, the present study identified ectomycorrhizal (ECM) associates of S. robusta and the role they play in increasing the growth and efficiency of nutrient uptake by the mycorrhizal roots of this plant. During the field survey we identified, collected, cultured and systematically investigated three dominant ECM associates of S. robusta: Russula kanadii Dutta & Acharya, R. cyanoxantha (Schaeff.) Fr. and Lactarius shiwalikensis Kumar and Atri, organically connected to the host plant roots. Pure cultures of each of these mycorrhizal fungal associates were grown using tissue culture techniques. We prepared spawn via purified mycelium using boiled wheat grains for mass inoculation and used the prepared inoculums for inoculating the germinating sal seeds for establishing the mycorrhizal association. To evaluate the effects of mycorrhizal colonization on various growth parameters, we observed the inoculated and control plants every three months for one year. The growth parameters in the sal seedlings grown in ECM‐inoculated soil exhibited significantly higher values over the un‐inoculated control soil owing to the increased uptake of both macro‐ and micronutrients. The overall results indicate that S. robusta seedlings inoculated with ECM fungal partners exhibited better establishment and enhanced growth and development, essential for the regeneration and survival of this plant. This technique will accelerate and assure successful reforestation programs and contribute toward appropriate functioning of sal forest ecosystems. [ABSTRACT FROM AUTHOR]

Bryophytes, which include mosses, liverworts and hornworts, indeed play a significant role in the natural dynamics of native forests. They contribute to fundamental ecological processes such as tree regeneration. In this context, the objective was to analyse the association of bryophytes with Nothofagus seedlings, as well as whether the substrates where bryophytes grew influenced bryophyte‐tree seedling association, in sub‐Antarctic forests at two contrasting landscapes (coastal and mountain) of Tierra del Fuego (Argentina), to better understand their impacts on the natural regeneration processes. We hypothesized that bryophytes act as a substrate for seed germination and initial regeneration growth in pure and mixed forests of N. pumilio and N. betuloides, resulting in widespread tree seedlings–bryophyte associations in all landscapes. In each forest and landscape location, 60 transects were established (10 m in length) to evaluate bryophyte cover (by point intercept method) and substrate type (bare soil, decaying wood and litter cover) where they were growing. An adaptation of the relative interaction index (RII) based on tree seedling cover associated with bryophyte species (%) and tree seedling cover in the absence of bryophytes (%) was calculated and analysed to assess competition or facilitation between bryophytes and tree seedlings. Nothofagus pumilio seedlings were less abundant in bryophytes compared to other substrates, suggesting an inhibitory effect on the germination and/or survival of N. pumilio. In contrast, the seedlings of N. betuloides, in both pure and mixed forests, exhibited higher abundance on bryophyte substrates, particularly in mosses at mountain landscape (RII = 0.83 ± 0.08 in litter and 0.62 ± 0.11 in decaying wood). These findings suggest that bryophytes play a facilitating role for N. betuloides seedlings during germination and initial phases of growth, mainly in the mountain. Therefore, their conservation promotes N. betuloides forest continuity, both in pure and mixed structures. [ABSTRACT FROM AUTHOR]

Plant–ungulate interactions are critical in shaping the structure of Mediterranean plant communities. Nevertheless, there is a dearth of knowledge on how plant intrinsic and extrinsic factors mediate the sign and strength of plant–ungulate interactions. This is most relevant when addressing natural or assisted restoration of plant communities in human‐disturbed areas.We conducted field‐clipping experiments simulating how different intensities of ungulate herbivory may affect the natural regeneration and establishment of the Mediterranean dwarf palm (Chamaerops humilis), a keystone species in Mediterranean ecosystems. We quantified seedling survival and size in two human‐disturbed sites (SW Spain) where wild and domestic ungulates exert high herbivory pressure on vegetation.Severe clipping and seedling aging reduced rates of seedling survival. In contrast, moderate clipping did not affect seedling survival, suggesting a certain degree of C. humilis tolerance to herbivory. Severe clipping reduced seedling height strongly but not seedling diameter, and these effects seem to have decreased seedling survival. Nurse shrubs increased seedling size, which likely improved seedling survival. We also found seedling compensatory growth which varied between study sites.Field‐clipping experiments can help disentangle effects of plant extrinsic and intrinsic factors on the sign and strength of plant–ungulate interactions and their ecological consequences on the dynamics of human‐disturbed ecosystems. We call attention to the importance of appropriately managing scenarios of severe herbivory and summer droughts, particularly frequent in Mediterranean ecosystems, as synergic effects of such key drivers can negatively affect the structure and dynamics of plant communities and endanger their conservation. [ABSTRACT FROM AUTHOR]

Restoration of high‐value timber trees in logged tropical forests is indispensable as a conservation strategy and for the enhancement of ecosystem services. Khaya anthotheca is a mahogany tree species of major restoration importance in Uganda. However, the factors affecting the natural regeneration success of this species are poorly understood. We determined the effect of selected site conditions on the abundance of K. anthotheca regeneration in the Budongo Forest Reserve. Two hundred and four 1,000 m2 inventory plots, each nested with four 4 m2 subplots, were systematically established in logged and unlogged sites within the study area. All trees greater than or equal to 10 cm DBH and natural regeneration (<10 cm DBH) were identified and recorded in the plots and subplots, respectively. We characterized plots by the density of conspecifics, light availability, ground cover of undergrowth, litter depth, soil pH, and basal area. Regression models were used to evaluate the variables that influenced regeneration abundance and occurrence. The density of adult conspecifics and soil pH were important. Regeneration abundance and occurrence increased with increasing density of adult conspecifics and decreased with increasing soil pH. Our results highlight that in addition to seed availability, soil pH was important for successful regeneration. This is one of the first K. anthotheca‐specific studies to evaluate more than a few environmental factors influencing the density of its naturally established seedlings in tropical African forests. The abundance and distribution of adult conspecifics in the canopy and soil pH should be considered in K. anthotheca restoration plans. [ABSTRACT FROM AUTHOR]

Plant species produce far more seedlings than those surviving to adulthood. It would seem reasonable to take advantage of that excess production, by relocating seedlings to desired restoration sites. There is, however, little information available on this issue. In the present study, we collected naturally regenerated seedlings of two native species, Calophyllum brasiliense ("barí") and Vochysia guatemalensis ("corpo"), in old‐growth forest patches, and transplanted them for the enrichment of a secondary tropical forest in Veracruz, Mexico. For transplanted C. brasiliense seedlings, overall survival was 32% after 20 months, and for V. guatemalensis seedlings it was 66% after 26 months. The mean height (±standard error) of all C. brasiliense and V. guatemalensis seedlings that survived until the end of the study, was 33 ± 2 cm (from initially 12.9 ± 0.2 cm) and 52 ± 5 cm (from 4.6 ± 0.1 cm), respectively. We applied a cost–benefit model to assess the trade‐off between initial‐investment costs and the resulting survival of transplanting naturally regenerated seedlings in the current study, in comparison with direct seeding (with and without the protection of seeds and emerged seedlings) reported in a previous study for the same area and species. For C. brasiliense, the success of transplanting naturally regenerated seedlings was always inferior to direct seeding without protection, whereas for V. guatemalensis it was always superior. Comparing the transplantation of naturally regenerated seedlings with direct seeding with protection, the best propagation strategy depended on the (monetary) value that a treelet is expected to be worth after 2 years. [ABSTRACT FROM AUTHOR]

Arbor Day (World Tree Planting Day) is an action to help replace dwindling tree cover globally. However, millions of the seedlings planted do not survive because of low regard for best planting practices and post‐planting maintenance activities. This study focused on the planting practices of Arbor Day participants at the Muni‐Pomadze Ramsar Site in Ghana and how that influenced their perception about seedling survival rate and their stewardship intention. The study used electronic questionnaire to solicit information from 229 participants (university students) at a 2021 Arbor Day planting event organized by the Forestry Commission and the Department of Geography Education, University of Education, Winneba. The study found four components of planting practices influenced perceptions including assessment of seedling quality, soil characteristics, surrounding environmental characteristics and planting operation. A multivariate analysis of variance showed that the academic year of participants influenced planting practices specifically planting operations with a post hoc test indicating respondents in academic year 1 observed better planting operations than third year students. A generalized linear model showed that respondents who planted seedlings within areas with good surrounding characteristics (enough spacing between successive seedlings and trees) perceived seedlings survival rate to be higher. Respondents who planted more seedlings were likely to provide time and money for post‐Arbor Day tree monitoring and maintenance. The findings also suggest that organizers of Arbor Day tree planting exercises should educate participants on proper planting practices and organize days for monitoring and maintenance of planted trees to improve participant perceptions and on‐going involvement. [ABSTRACT FROM AUTHOR]

One of the most devastating foliar diseases of wheat worldwide is Septoria leaf blotch (STB), caused by Mycosphaerella graminicola (asexual stage/Anamorph: Septoria tritici) which has been recently intensified in some regions in Iran. In this study, 49 wheat genotypes and 20 wheat differential genotypes were evaluated for their reaction to infection by six isolates of M. graminicola collected from infected fields during 2016–2017 at seedling stage under greenhouse conditions. According to the analysis of variance (ANOVA) of leaf pycnidia coverage percentage, a significant difference (p <.01) was observed between M. graminicola isolates and wheat cultivars. The interaction between genotypes and isolates was also significant (p <.01) and the results indicated a specific interaction between genotypes and isolates. The results presented Dezful and West Azerbaijan isolates that were the most virulent with more pathogenesis on differential genotypes. Although 47 of the wheat genotypes were susceptible to all isolates, some genotypes, including Wc‐46,224 (Austria), Wc‐45,425 (Portugal), Wc‐45,565 (Turkey), P.S.No4 (Italy), Dehdasht, M3 Synthetic, KavKaz‐k4500, Arina, Flame, and Riband were resistant to all isolates. In addition, the isolates exhibited different virulence patterns on wheat genotypes. The results of this study revealed high virulence of M. graminicola isolates, and Iranian and foreign wheat genotypes, commonly used in the region, presented high susceptibility, and the resistance sources had been identified among genotypes that can be applied in the wheat breeding programs. [ABSTRACT FROM AUTHOR]

Plant–soil feedbacks (PSFs) are a key driver of species diversity and composition in plant communities worldwide; however, the factors that may cause feedbacks to vary within species are rarely examined. In dioecious species, the strength of feedbacks may differ near female plants that produce seed versus near male plants (which do not) because repeated inputs of seeds and high seedling densities near females may cause accumulation of host‐specific soil microbes that influence seedling performance. To test whether conspecific seedling performance is reduced near seed‐producing female trees relative to male or heterospecific trees, we conducted shadehouse and field experiments with a dioecious tropical tree species, Virola surinamensis (Myristicaceae), on Barro Colorado Island, Panama. The shadehouse experiment isolated the effect of soil microbial communities on seedling growth and allowed us to quantify colonization by mutualistic arbuscular mycorrhizal (AM) fungi, while the field experiment allowed us to assess seedling survival and growth in the presence of nearby conspecific adults and seedlings. In both experiments, seedling performance was similar between seedlings grown in the soil microbial communities and field environments underneath female conspecific, male conspecific, and heterospecific trees. However, contrary to expectation, seedling colonization by AM fungi was higher in male conspecific soil microbial communities than in female or heterospecific soil microbial communities at the end of the shadehouse experiment. Together, our experiments show that while differences among female and male plants in dioecious species may influence the association of conspecific seedlings with AM fungi in their soils, this variation does not necessarily translate directly to differences in seedling performance, at least over the time frame of our experiments. Studies of additional dioecious species are needed to help determine differences in soil microbial communities beneath male and female plants and to assess the role of seed input versus adult root systems in driving PSFs. [ABSTRACT FROM AUTHOR]

SUMMARY: Seed protein localization in seed storage protein bodies (SSPB) and their significance in germination are well recognized. SSPB are spherical and contain an assembly of water‐soluble and salt‐soluble proteins. Although the native structures of some SSPB proteins are explored, their structural arrangement to the functional correlation in SSPB remains unknown. SSPB are morphologically analogous to electron‐dense amyloid‐containing structures reported in other organisms. Here, we show that wheat, mungbean, barley, and chickpea SSPB exhibit a speckled pattern of amyloids interspersed in an amyloid‐like matrix along with native structures, suggesting the composite nature of SSPB. This is confirmed by multispectral imaging methods, electron microscopy, infrared, and X‐ray diffraction analysis, using in situ tissue sections, ex vivo protoplasts, and in vitro SSPB. Laser capture microdissection coupled with peptide fingerprinting has shown that globulin 1 and 3 in wheat, and 8S globulin and conglycinin in mungbean are the major amyloidogenic proteins. The amyloid composites undergo a sustained degradation during germination and seedling growth, facilitated by an intricate interplay of plant hormones and proteases. These results would lay down the foundation for understanding the amyloid composite structure during SSPB biogenesis and its evolution across the plant kingdom and have implications in both basic and applied plant biology. [ABSTRACT FROM AUTHOR]

Aims: Restoration practitioners often face a tradeoff between low cost but risky seeding vs expensive but more reliable seedling planting to meet revegetation goals. Knowing under what environmental and management conditions direct seeding vs seedling planting benefit different species could improve restoration practice. Methods: We compared seed emergence to planted‐seedling survival among perennial herbaceous species commonly used in restoration across eight experimental restoration sites on the Colorado Plateau, USA. We used linear models to assess relationships between emergence and survival among species, and to assess the effects of site climate and seeding pre‐treatments on those relationships. Results: We found that among species, emergence was positively correlated with survival in the cooler sites, meaning that species with high emergence also had high survival and vice versa, but had no relationship in the hottest sites. Furthermore, pre‐treatments to enhance soil moisture in seeded plots, specifically microtopography (pits) and mulch, also resulted in positive relationships between emergence and survival among species, while seeding without additional soil pre‐treatments did not. Seedling planting cost 14 times as much as direct seeding alone, dropping to nine times as much when pre‐treatments were combined with seeding. Conclusions: Taken together, these results suggest that investments in seedling planting at hotter dryland sites, or in creating microtopography or mulching prior to seeding across sites, are likely to promote establishment success compared to simple seeding methods in degraded dryland ecosystems. These findings also identify opportunities for hybrid seeding and planting approaches that balance tradeoffs between risk and cost, respectively. [ABSTRACT FROM AUTHOR]

Scots pine (Pinus sylvestris) and Stone pine (Pinus pinea) are two important species used in re‐forestation that are subject to damage by damping‐off fungi in forest nurseries. Twenty‐two isolates of Fusarium oxysporum and F. verticillioides from diseased seedlings of eight different hosts were tested for aggressiveness on seeds and seedlings of both pine species, including the effects on seedling emergence and mortality. Scots pine was more susceptible to damping‐off than Stone pine, as indicated both by reduced seedling emergence and elevated seedling mortality. The impact of F. oxysporum and F. verticillioides on seeds and seedlings did not differ significantly for either pine species. Our findings support previous studies that found that these are damping‐off pathogens on the studied pines. Whereas most isolates proved to be pathogenic, some isolates of both Fusarium species showed to be non‐pathogenic. [ABSTRACT FROM AUTHOR]