Seedling Establishment Research Articles

Effect of Grasses on Native Tree Seedling Establishment Along a Water Stress Gradient: Results of Forest and Greenhouse Experiments

ABSTRACTAnthropogenic activities such as cattle grazing and forest clearing have led to the establishment of early successional grass layers in some native forests, which may inhibit or entirely prevent native tree regeneration. We hypothesize that increased grass coverage reduces or eliminates the establishment of native tree seedlings by limiting water availability to seeds and seedlings. This study aims to evaluate the impact of grass cover on tree seedling survival under varying levels of soil water stress. We conducted a field experiment using 36 experimental exclosures in two northwest Patagonian valleys, representing a regional gradient in altitude, rainfall, and tree canopy openness. Additionally, a greenhouse experiment was performed with 36 pots, manipulating four levels of grass cover and three levels of water stress. Results from both experiments showed similarities: in the field, the likelihood of finding a live tree seedling was approximately 2.78 times higher in areas without grass compared with grass‐covered sites. In the greenhouse, the presence of grass reduced the final number of established seedlings by an average of 43% across all irrigation levels, indicating significant water competition. These findings suggest that management practices promoting grass invasion could severely hinder tree regeneration in forests not adapted to large herbivore intensive grazing. Such situation may be exacerbated in regions suffering water limitation in the growing season or where the climate change would intensify water stress.

Diaspore Dimorphism, Awn Hygroscopicity and Adaptive Significance in a Winter Annual Bromus tectorum (Poaceae)

Bromus tectorum, a winter annual plant, produces dimorphic diaspores: complex diaspores with multi-awns and simple diaspores with one awn. However, there is no information available about the role of awns and the germination characteristics of dimorphic diaspores. Dispersal germination and awns hygroscopicity of the dimorphic diaspores were assessed. The complex diaspore with multi-awns can easily be dispersed long distances from the mother plant by mammals. The simple diaspores with one awn are tightly attached to the mother plant. Caryopses from the two types of diaspores exhibited non-deep physiological dormancy at maturity, which can be released by dry storage and GA3 treatment. The awns have hygroscopic activity and can move in response to changes in moisture, moving the complex diaspore (the seed) into the soil. The seedling emergence from complex diaspores was significantly higher than those from simple diaspores at all burial depths. Germination of caryopses on the soil surface was poor. The optimal planting depth for both types of diaspores’ emergence is 1–2 cm. The distinct characteristics of dimorphic diaspores and the beneficial influence of hygroscopic awns on dispersal, germination, and seedling establishment have significant ecological implications for B. tectorum’s successful reproduction in unpredictable cold deserts.

Effect of halopriming on seed germination performance and early seedling establishment in okra (Abelmoschus esculentus (L.) Moench) under saline conditions

Effect of halopriming on seed germination performance and early seedling establishment in okra (Abelmoschus esculentus (L.) Moench) under saline conditions

Macro- and micro-geographic genetic variation in early fitness traits in populations of maritime pine (Pinus pinaster Ait.).

Assessing adaptive genetic variation and its spatial distribution is crucial to conserve forest genetic resources and manage species' adaptive potential. Macro-environmental gradients commonly exert divergent selective pressures that enhance adaptive genetic divergence among populations. Steep micro-environmental variation might also result in adaptive divergence at finer spatial scales, even under high gene flow, but it is unclear how often this is the case. Here, we assess genetic variation in early fitness traits among distant and nearby maritime pine (Pinus pinaster Ait.) populations, to investigate climatic factors associated with trait divergence, and to examine trait integration during seedling establishment. Open pollinated seeds were collected from seven population pairs across the European species distribution, with paired populations spatially close (between <1 km up to 21 km) but environmentally divergent. Seeds were sown in semi-natural conditions at three environmentally contrasting sites, where we monitored seedling emergence, growth and survival. At large spatial scales, we found significant genetic divergence among populations in all studied traits, with certain traits exhibiting association with temperature and precipitation gradients. Significant trait divergence was also detected between pairs of nearby populations. Besides, we found consistent trait correlations across experimental sites, notably heavier seeds and earlier seedling emergence were both associated with higher seedling survival and fitness over two years in all experimental conditions. We identified mean annual temperature and precipitation seasonality as potential drivers of P. pinaster population divergence in the studied early-life traits. Populations genetically diverge also at local spatial scales, potentially suggesting that divergent natural selection can override gene flow along local-scale ecological gradients. These results suggest the species exhibits substantial adaptive potential that has allowed it to survive and evolve under contrasting environmental conditions.

Impact of Fire Recurrence and Water Stress on the Root Nucleolar Activity of Maritime Pine (Pinus pinaster Ait.) Individuals Whose Seeds Were Harvested in Post-Fire Naturally Regenerated Stands

The main role of the nucleolus is ribosomal biogenesis, but it also responds to stress with changes in number, area, and/or morphology. Nucleoli with transcriptionally active ribosomal RNA genes are selectively stained by silver nitrate. Hypothesising that fire recurrence and/or polyethylene glycol (PEG)-induced water stress would cause nucleolar changes in Pinus pinaster roots, nucleolar parameters were analysed upon the germination of seeds harvested in post-fire naturally regenerated stands with different fire regimes. An unburned stand was used as a control. The nucleoli number varied from 1 to 15 among stands and PEG treatments, but a mode of five or six nucleoli was found. The number of nucleoli per interphase (N) increased (p &lt; 0.001) with fire recurrence (stand effect). Increasing PEG concentration (treatment effect) decreased the nucleoli number, notably in the stand with the highest fire recurrence. The nucleolar area decreased (p &lt; 0.001) with increased nucleoli number, fire recurrence, and/or PEG concentration. Fire recurrence and water scarcity are forecasted for future climate scenarios. As demonstrated earlier, these factors could influence protein synthesis or the cell cycle’s regularity, which are crucial processes for root growth and pine seedling establishment. Furthermore, this work revealed that nucleolar parameters could be suitable biomarkers for pine stress studies.

Sweet corn (Zea mays L.) seed performance enhanced under drought stress by chitosan and minerals coating.

Sweet corn (Zea mays L.) var. Saccharata is a tropical and semitropical annual cereal with low germination, poor vigor, and weak seedling establishment in the soil. In order to enhance the physical properties of sweet corn and examine the effects of seed coating on the morphological, biochemical, and physiological characteristics of sweet corn seedlings under drought stress conditions, we conducted a factorial experiment in greenhouse conditions. Seed coating was carried out using a mixture of vermiculite (V), kaolin (K), and perlite (P) in a ratio of 3:1.5:2. The main factors of the greenhouse experiment comprised three levels of coating treatment (chitosan 0.5% + V10K2.5P5 (gr), NaAlg 1% + V10K2.5P5 (gr), and non-coated seeds as a control) along with drought stress at four levels (0, -0.3, -0.6, and -0.9bar). In greenhouse conditions, the growth indexes of sweet corn seedlings were studied under increasing levels of drought stress. The results showed that as drought stress levels increased, certain growth indicators such as seedling emergence and seedling emergence rate, soluble protein, chlorophyll total content, nitrogen, and phosphorus content decreased. On the other hand, mean emergence, proline, potassium, soluble sugars, malondialdehyde, and hydrogen peroxide were increased. The study found that the highest seedling emergence percentage occurred in the coating treatment of chitosan 0.5% + V10K2.5P5 (gr) at all levels of drought stress. Overall, seed coating with the Chitosan 0.5% + V10K2.5P5 (gr) treatment improved the performance of sweet corn seeds and reduced the negative effects of drought stress by increasing seedling emergence and establishment.

Investigating Light and Water Optimization for Early Seedling Establishment in Albizia lebbeck (L.) Benth

Seedling growth, development, and establishment are vulnerable stages for trees, greatly influenced by two important environmental factors: light availability and soil moisture regime. This study investigated the interactive effects of light intensity and water availability on key early vegetative growth parameters of collar diameter, height, and the number of leaves in seedlings of the tropical legume tree Albizia lebbeck. The experiment utilized a 4×3 factorial design with four light intensity levels (L1 (75%), L2 (50%), L3 (25%), and L4 (100% as control)) and three watering frequencies (daily (W1), every three days (W2), weekly (W3)) in a nursery greenhouse. Measurements were recorded biweekly for ten weeks. The results showed that moderate light intensity of 50% coupled with adequate moisture supply by daily watering (L2W1) led to optimal seedling growth. This treatment combination resulted in the greatest mean collar diameter (3.62 mm), plant height (41.88 cm), and number of leaves (11). Growth was restricted under full light (L4) and insufficient light (L3). Limited water availability by watering weekly (W3) also suppressed growth metrics. However, there was no significant difference between daily watering (W1) and moderate watering frequency (W2). Strong intrinsic synchronization was observed between the collar diameter and plant height growth trajectories over time, reflecting coordinated lateral and vertical stem expansion regulated by developmental processes. Leaf proliferation showed partially decoupled dynamics from stem growth, indicating specialized control over leaf traits. Collar diameter, height, and the number of leaves were inherently intercorrelated, highlighting their co-dependence in generating resources and signals needed to sustain growth and development. The findings suggest that 50% light intensity and adequate moisture by watering every 1-3 days are optimal for nursery establishment of A. lebbeck seedlings to maximize early vegetative growth.

Differential impacts of fire and inundation on a wetland plant community after wildfire

Context Understanding fire and inundation impacts on wetland vegetation communities is crucial for effective post-fire wetland management. Aims We aimed to determine the impact of post-fire inundation on plant community structure and seedling germination and establishment after a large wildfire. We asked two questions, namely (1) did fire, drought or inundation affect plant communities the most; and (2) did fire or inundation affect seedling germination and establishment? Methods Using a before–after–control–impact (BACI) design, we monitored vegetation changes in water-couch wetland communities before and after a wildfire. Also, soil samples were collected from burnt and unburnt sites and assessed for impacts of fire and post-fire inundation regimes on seed germination and seedling establishment. Key results Inundation variables had more pronounced and more consistent impacts on vegetation measures than did fire or drought variables. Fire impacts were mainly short-term, with impact thresholds at 72 and 143 days after fire. Low germination levels and zero seedling survival were observed without inundation. Conclusions Fire was a major but short-term contributor to wetland vegetation change, whereas drought had longer-term impacts, and inundation regimes had the greatest impacts. Implications Providing a range of inundation conditions post-fire may enhance wetland vegetation recovery and have modifying effects on invasive species.

Biochar and Deactivated Yeast as Seed Coatings for Restoration: Performance on Alternative Substrates

Seedling establishment is often a critical bottleneck in the revegetation of mine tailings and similar substrates. Biochar and deactivated yeast are potential sustainable materials that could be used in this context as seed coatings to aid in seedling establishment. We conducted a greenhouse study on biochar and deactivated yeast use as seed coatings, assessing germination, establishment, and early growth of white clover (Trifolium repens) and purple prairie clover (Dalea purpurea). Coated seeds were applied to a mine tailing, a coarse granitic sand, and potting soil mix substrates; seedling establishment and growth were monitored over 75 days. Biochar coatings enhanced the seedling establishment of Trifolium, with biochar and biochar plus yeast coatings giving the best results. In some cases, these effects persisted throughout the experiment: biochar coatings resulted in a ~fivefold increase in Trifolium biomass at harvest for plants in the potting soil mix but had neutral effects on sand or tailings. Biochar seed coatings also enhanced Dalea germination in some cases, but the benefits did not persist. Our results indicate that biochar-based seed coatings can have lasting effects on plant growth well beyond germination but also emphasize highly species-specific responses that highlight the need for further study.

Genome‐Wide Association Study Revealed the Genetics of Seed Vigour Traits in Rice (Oryza sativa L.)

ABSTRACTA crucial phenotypic attribute for breeding rice for direct seeded condition is rapid uniform germination and build‐up of biomass during the initial period of seedling establishment. Seed vigour constitutes such traits that have gained potential to meet the requirements of breeding for direct seeded rice. In the present study, a set of 295 markers, including 215 candidate gene‐derived markers covering all chromosome, was used to discover the casual alleles for eight rice seed vigour‐related traits. Using a mixed linear model, the study identified 99 significant associations for seed vigour traits. Many associated markers originated from diverse candidate genes in rice. Notably, alleles from genes like RSR1, OsSRS3 and OsSWEET15 exhibited pleiotropic effects, influencing multiple seed vigour traits. This discovery underscores the potential of certain genes to impact various facets of seed vigour simultaneously. The new candidate gene markers associated with seed vigour traits may be utilized to incorporate variable alleles for seed vigour traits through marker‐assisted breeding programmes. Markers identified to be closely associated with more than one trait have significant application in the simultaneous improvement of multiple traits.

Transcriptomic Insights into Drought Survival Strategy of Sorghum bicolor (L.) Moench during Early Growth under Polyethylene Glycol-Simulated Conditions

Drought stress during sorghum emergence significantly affects seedling establishment, adversely affecting both emergence and population growth. This study investigates drought tolerance mechanisms during sorghum germination by analyzing physiological changes and transcriptomic data from two lines: W069 (drought tolerant) and W040 (drought sensitive). Under drought conditions, a phenotypic analysis revealed that W069 exhibited longer shoots and roots than W040. Additionally, physiological data indicated higher osmotic substance and lower malondialdehyde levels in W069. Using Kyoto Encyclopedia of Genes and Genome analyses, we identified three key pathways (starch and sucrose metabolism, phenylpropanoid biosynthesis, and phytohormone signaling) as pivotal in the drought response during seed germination in sorghum plants. Expression profiling revealed that most drought tolerance-related genes in the three key pathways were expressed at higher levels in the drought-tolerant cultivar W069, possibly explaining its greater stress tolerance. These findings enhance our understanding of drought-responsive gene networks in sorghum seed germination, offering potential target genes and strategies for enhancing drought tolerance in this crop.

In Situ Seedling Establishment and Performance of Cyperus esculentus Seedlings

Cyperus esculentus seeds are often considered irrelevant for C. esculentus spread as their fragile seedlings would not establish or survive in agricultural soils. However, the ever-increasing spread and upsurge of genetically different clonal populations in NW-Europe raises questions about the establishment of C. esculentus seeds and the reproductive performance of seedlings. Indeed, little is known about the potential of C. esculentus seedlings to grow and propagate under outdoor conditions relative to plants grown from tubers. Seeds from different clonal populations were sown outdoors in various soil types and under different irrigation levels (rainfed, irrigated) to assess seed germination and seedling establishment. Additionally, two pot experiments were conducted with three different plant types (plants originating from mother tubers and from seeds harvested on open- or self-pollinated plants) obtained from eight clonal populations. Plant performance was investigated by measuring vegetative and generative parameters. Germination under outdoor conditions was significantly affected by clonal population and was highest in irrigated sand (5.3%). Germination in sand was 4.1 times higher in irrigated plots than in rainfed plots. In irrigated plots, germination was 3.8 and 4.7 times higher in sand than in sandy loam and clay, respectively. Depending on the year, three out of five to five out of six clonal populations produced more tubers when grown from mother tubers than from seeds. Maximal tuber reproduction factors of 1:965, 1:752, and 1:618 were achieved for plants from mother tubers and seeds from open- and self-pollinated flowers, respectively. Plants originating from open-pollinated seedlings have the potential to equal or exceed the vegetative reproductive capacity of plants originating from mother tubers. As a result of their ability to establish in situ and their substantial vegetative reproductive capacity, C. esculentus seedlings are highly relevant for agriculture and merit appropriate attention in any integrated weed management system targeting C. esculentus.

Shoot and root dendroanalysis of Ulmus pumila 10 years after outplanting in the Mongolian semi-arid steppe reveals a short-term developmental pattern enhanced by watering

An accurate investigation is needed to determine if the selected location, the tree species, and the applied treatments can support a successful seedling establishment and outplanting performance to ensure the success of large-scale tree-planting initiatives. To shed light on the growth pattern of the trees used in the Green Belt Project plantations in the Mongolian steppe, we analysed the biomass allocation in the stem and roots of Ulmus pumila in terms of ring width, considering different management techniques involving irrigation and fertilisation. We found that the root and shoot ring width of U. pumila followed a bell-shaped curve and reached maximum values after three or four years from seedling outplanting. Moreover, our data confirm that increasing watering regimes may enhance plant growth, especially the root system, while fertilisation did not show a positive effect independently of the fertilisation type (i.e. NPK and compost). Our data allowed us to develop a predictive regression model that could be used with other species and in different environmental conditions to forecast stem and root tree growth and to simulate afforestation performances in different climatic conditions.

NATIVE MYCORRHIZAE FROM ETHIOPIA IMPROVE TREE GROWTH AND SEEDLINGS SURVIVAL CONTRIBUTING TO THE GREEN LEGACY PROGRAM

&lt;p&gt;&lt;strong&gt;Background&lt;/strong&gt;: A rapid production of tree seedlings in nurseries with a high survival rate after transplanting is important to respond to the current demand for programs of restoration of arid environments by forestation. The low level of seedlings’ survival and establishment, caused by low moisture and nutrient content of soils, has been a bottleneck to reaching the target of the forest national restoration in Ethiopia of last years. It is suggested that, inoculation with root-associated plant growth promoting microorganisms could help to ameliorate this scenario and also respond to the Ethiopia's Green Legacy Program. &lt;strong&gt;Objective&lt;/strong&gt;: To assess the potential of inoculation with arbuscular mycorrhizal fungi (AMF) native to Ethiopia to improve the survival and growth of trees that could be used in afforestation programs in Ethiopia. &lt;strong&gt;Methodology&lt;/strong&gt;: The study was carried out in three stages: (1) soil samples associated with roots of selected acacia species (T&lt;sub&gt;1&lt;/sub&gt;-AMF of&lt;em&gt; A. abyssinica&lt;/em&gt;, T&lt;sub&gt;2&lt;/sub&gt;-AMF of&lt;em&gt; A. seyal&lt;/em&gt;, T&lt;sub&gt;3&lt;/sub&gt;-AMF&lt;em&gt; &lt;/em&gt;of &lt;em&gt;A. tortilis &lt;/em&gt;and&lt;em&gt; &lt;/em&gt;T&lt;sub&gt;4&lt;/sub&gt;-Control) were collected of highland and lowland areas from Ethiopia, (2) Sorghum (&lt;a href="https://www.researchgate.net/publication/342429051_Evaluation_of_sorghum_Sorghum_bicolor_L_Moench_variety_performance_in_the_lowlands_area_of_wag_lasta_north_eastern_Ethiopia"&gt;&lt;em&gt;Sorghum bicolor&lt;/em&gt; (L.), provided by the Melkasa Agricultural Research Center-(MARC) served as a trap plant for &lt;/a&gt;the AMF consortium multiplication and (3) plant growth promotion by AMF was assessed throughout inoculations of seedlings of&lt;em&gt; &lt;/em&gt;&lt;em&gt;Delonix regia&lt;/em&gt; (Hook.) Raf.,&lt;em&gt; Sesbania grandiflora &lt;/em&gt;(L.)&lt;em&gt;, Cassia fistula &lt;/em&gt;L&lt;em&gt;., &lt;/em&gt;and&lt;em&gt; Azadirachta indica &lt;/em&gt;A. Juss., trees&lt;em&gt;. &lt;/em&gt;&lt;strong&gt;Results&lt;/strong&gt;: All inoculated seedlings showed significantly greater responses in all growth and mycorrhizal parameters over the non-inoculated trees. Consortium T&lt;sub&gt;2&lt;/sub&gt;-AMF associated to roots of&lt;em&gt; A. seyal &lt;/em&gt;from lowlands of Batu, showed significantly greater responses in all plant growth and mycorrhizal parameters over the AMF inoculums associated to other tree species evaluated. Significant and positive correlations were found between mycorrhizae and plant-growth parameters&lt;em&gt;. &lt;/em&gt;&lt;strong&gt;Implications:&lt;/strong&gt; Our results suggest that inoculation with native arbuscular mycorrhizal fungi indigenous from Ethiopia has the potential to significantly enhance survival and growth rates of tree seedlings. This could thereby advance national reforestation goals and addressing challenges in seedling establishment in arid environments. &lt;strong&gt;Conclusion&lt;/strong&gt;: The potential for growth promotion and establishment of tree seedlings evidenced, implies that further efforts should be directed towards the in-mass production of AMF-based inoculants, particularly associated with &lt;em&gt;A. seyal&lt;/em&gt; roots.&lt;/p&gt;

Evaluation of Germination and Early Seedling Growth of Different Grasses Irrigated with Treated Mine Water

Coal mining is known to have negative impacts on the environment, necessitating land rehabilitation after mining activities. Amongst the problems associated with coal mining is the accumulation of acid mine drainage characterized by large amounts of heavy metals and high acidity. The impact of these environmental problems on the ecosystem around mining areas underscores a need to devise strategies that will ensure sustainable restoration of the ecosystem integrity to ensure environmental protection. Of these, treatment of acid mine drainage using calcium sulfate dihydrate, which is subsequently used for irrigation during phytoremediation, holds great promise for restoration of open-cast mines. However, although grasses are used for rehabilitation of coal mined areas, the impacts of treated mine water on the germination, seedling emergence, and plant growth of grasses are not well known. The aim of the study was to evaluate the germination and early seedling growth responses of different forage grasses to treated mine water. Seven forage grass species were selected, with four species represented by two varieties while others were represented by one variety, totaling 11 forage grasses. For each plant entry, 100 seeds were placed in J.R. Petri’s dishes lined with Whatman No. 2 filter paper and watered with distilled and mine water to assess germination. For the seedling establishment experiment, only five species were studied, in which twenty seeds per species were sown in pots containing mine soil and irrigated using distilled and treated mine water. The final germination percentage (FGP), germination rate index (GRI), corrected germination rate index (CGRI), and T50 were determined for the germination trail and total biomass was assessed for the seedling growth trail. The highest FGP for all grasses was attained under controlled conditions, using distilled water, ranging from 38–94%. All grasses germinated when watered using treated mine water and had a FGP ranging from 20–91%. Relative to distilled water, GRI and CGRI were highest only for L. multiflorum cv AgriBoost when seeds were watered using the treated mine water. All grasses watered with treated mine water produced high biomass for the first two weeks, after which biomass production started to decline. Two grasses, Eragrostis curvula cv Ermelo and Lolium multiflorum cv Archie, showed tolerance to treated mine water irrespective of its high electrical conductivity (557 mS∙m−1). Therefore, these grasses could be used in the rehabilitation of coal-mined areas irrigated with treated mine water.

An Excessive K/Na Ratio in Soil Solutions Impairs the Seedling Establishment of Sunflower (Helianthus annuus L.) through Reducing the Leaf Mg Concentration and Photosynthesis

In saline conditions, establishing healthy seedlings is crucial for the productivity of sunflowers (Helianthus annuus L.). Excessive potassium (K+) from irrigation water or overfertilization, similar to sodium (Na+), could adversely affect sunflower growth. However, the effects of salt stress caused by varying K/Na ratios on the establishment of sunflower seedlings have not been widely studied. We conducted a pot experiment in a greenhouse, altering the K/Na ratio of a soil solution to grow sunflower seedlings. We tested three saline solutions with K/Na ratios of 0:1 (P0S1), 1:1 (P1S1), and 1:0 (P1S0) at a constant concentration of 4 dS m−1, along with a control (CK, no salt added), with five replicates. The solutions were applied to the pots via capillary rise through small holes at the bottom. The results indicate that different K/Na ratios significantly influenced ion-selective uptake and transport in crop organs. With an increasing K/Na ratio, the K+ concentration in the roots, stems, and leaves increased, while the Na+ concentration decreased in the roots and stems, with no significant differences in the leaves. Furthermore, an excessive K/Na ratio (P1S0) suppressed the absorption and transportation of Mg2+, significantly reducing the Mg2+ concentration in the stems and leaves. A lower leaf Mg2+ concentration reduced chlorophyll concentration, impairing photosynthetic performance. The lowest plant height, leaf area, dry matter, and shoot/root ratio were observed in P1S0, with reductions of 27%, 48%, 48%, and 13% compared to CK, respectively. Compared with CK, light use efficiency and CO2 use efficiency in P1S0 were significantly reduced by 13% and 10%, respectively, while water use efficiency was significantly increased by 9%. Additionally, improved crop morphological and photosynthetic performance was observed in P1S1 and P0S1 compared with P1S0. These findings underscore the critical role of optimizing ion composition in soil solutions, especially during the sensitive seedling stage, to enhance photosynthesis and ultimately to improve the plant’s establishment. We recommend that agricultural practices in saline regions incorporate tailored irrigation and fertilization strategies that prioritize optimal K/Na ratios to maximize crop performance and sustainability.

Bacterial seed endophytes promote barley growth and inhibits Fusarium graminearum in vitro

ObjectivesSeeds host microbes that function in plant growth and phytopathogen resistance. The aim of the work was to investigate total bacterial community in malting barley seeds and whether their bacterial seed endophytes have dual functional roles in plant growth-promotion and inhibition of Fusarium graminearum, the causative agent of Fusarium head blight (FHB) in barley. We used culture dependent and culture independent methods.ResultsPhylogenetic classification of seed endophytic bacteria based on sequencing data identified B. subtilis, B. licheniformis and B. pumilis as predominant subgroups. Location driven divergence in bacterial endophytic communities was evident based on a clear separation of the samples from Crookston and other location samples. The bio-primed seeds using one hundred and seventy bacterial isolates showed that 3.5% (6/170) of the bacterial isolates conferred greater than 10% increase in both root length (RL) and shoot length (SL), while 19.4% (33/170) and 26.5% (45/170) showed RL and SL specific growth effects, respectively, relative to controls. Among the six bacterial isolates that increased RL and SL, five (#29, #63, #109, #124 and #126) also significantly inhibit the growth of F. graminearum based on in vitro assays. This study identified novel seed bacterial endophytes that could be further exploited for promoting growth during seedling establishment and as biocontrol for combating the devastating scab disease.

Mycorrhizal fungi as critical biotic filters for tree seedling establishment during species range expansions

AbstractGlobal warming has been shifting climatic envelopes of many tree species to higher latitudes and elevations across the globe; however, unsuitable soil biota may inhibit tree migrations into these areas of suitable climate. Specifically, the role of mycorrhizal fungi in facilitating tree seedling establishment beyond natural species range limits has not been fully explored within forest ecosystems. We used three experiments to isolate and quantify the effects of mycorrhizal colonization and common mycorrhizal networks (CMN) on tree seedling survival and growth across (within and beyond) the elevational ranges of two dominant tree species in northeastern North America, which were associated with either arbuscular mycorrhiza (AMF, Acer saccharum) or ectomycorrhiza (EMF, Fagus grandifolia). In order to quantify the influence of mycorrhiza on seedling establishment independent of soil chemistry and climate, we grew seedlings in soils from within and beyond our study species ranges in a greenhouse experiment (GE) as well as in the field using a soil translocation experiment (STE) and another field experiment manipulating seedling connections to potential CMNs (CMNE). Root length colonized, seedling survival and growth, foliar nutrients, and the presence of potential root pathogens were examined as metrics influencing plant performance across species' ranges. Mycorrhizal inoculum from within species ranges, but not from outside, increased seedling survival and growth in a greenhouse setting; however, only seedling survival, and not growth, was significantly improved in field studies. Sustained potential connectivity to AMF networks increased seedling survival across the entire elevational range of A. saccharum. Although seedlings disconnected from a potential CMN did not suffer decreased foliar nutrient levels compared with connected seedlings, disconnected AM seedlings, but not EM seedlings, had significantly higher aluminum concentrations and more potential pathogens present. Our results indicate that mycorrhizal fungi may facilitate tree seedling establishment beyond species range boundaries in this forested ecosystem and that the magnitude of this effect is modulated by the dominant mycorrhizal type present (i.e., AM vs. EM). Thus, despite changing climate conditions beyond species ranges, a lack of suitable mutualists can still limit successful seedling establishment and stall adaptive climate‐induced shifts in tree species distributions.

Proline Priming Enhances Seed Vigour and Biochemical Attributes of Rice (Oryza sativa L.) during Germination.

Seed vigour is a desirable trait especially for direct seeded rice (DSR) cultivation. Seeds with high vigour could improve seed germination, support seedlings in competing with weeds for water and nutrients, and improving seedling establishment throughout the early stages of crop growth. The success of DSR system which account for more 25% of world cultivation areas is highly dependent on the seed vigour and seedling establishment. Seed priming is a promising technique to improve seed vigour. Proline is an amino acid that has been well studied for its roles in plants under different environmental stress conditions. Nevertheless, the effect of proline as a seed priming agent in improving seed vigour in rice remain elusive. In this research, the effect of 24 h of proline priming at various concentrations (0 mM, 1 mM, 2 mM, 10 mM and 20 mM) on rice seed vigour, amylase activity, and total soluble sugar (TSS) content of a Malaysia indica rice variety, MR269 was investigated. Results showed that seeds primed with lower concentration of proline (0 mM, 1 mM and 2 mM) had better germination responses while priming at high concentrations (10 mM and 20 mM) reduced seed germination. Among the concentration tested, priming with 1 mM proline enhanced seed vigour with significantly higher germination percentage (GP), germination rate index (GRI) and seedling vigour index (SVI). In addition, proline primed seeds also exhibited increased amylase activity and TSS content as compared to unprimed seeds. However, priming seed with 20 mM proline was detrimental to the seed vigour and seedling growth whereby lower GP, GRI and SVI and higher mean germination time (MGT) were observed. In short, this study shows that proline could be a potential seed priming agent to improve seed vigour in rice.

From Waste to Plant Production: Cattle Dung Compost as an Alternative Nursery Substrate to Commercial Peat for Producing Lettuce Plants

The limited availability of peat-based substrates, a nonrenewable resource, and the negative environmental impacts associated with their extraction require the conservation of this resource. We assessed the use of cattle dung compost as a stand-alone nursery substrate, replacing peat substrate for the production of lettuce (Lactuca sativa L.) seedlings. A completely randomized design was employed, using cattle dung compost (C) and commercial peat (P, control treatment) in various combinations (100% P; 25% C/75% P; 50% C/50% P; 75% C/25% P; 100% C) to assess their effects on different growth parameters of lettuce. Twenty-eight parameters (e.g., seed germination, seedling survival, diameter, height, biomass growth) were assessed, corresponding to the time when the seedlings are transplanted. All treatments achieved 100% seed germination and seedling survival; indicating the successful establishment of lettuce seedlings across all tested substrates. However, seedling growth was found to be significantly influenced by substrate type. Seedling diameter was significantly increased by 10.8% in the 50% C/50% P substrate, while seedling height was significantly increased by 7.7, 6.8, and nearly 10%, respectively, within the 25% C/75% P, 50% C/50% P and 100% C substrates, relative to the control. Other substrate treatments were not significant. Similar or significantly higher values than the control were also observed for biomass growth under the tested substrates, indicating the beneficial effect of cattle dung on the initial growth of plants during the nursery phase. Cattle dung compost, used as a growing substrate, demonstrated similar or superior results to commercial peat, suggesting its potential as a viable alternative potting medium for sustainable horticulture.