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The short cultivation cycle and high essential oil content of basil plants render them a valuable raw material source for diverse industries. However, large-scale production is hindered by the lack of specific protocols to assess seed vigor; thus, a consistent supply of high-quality seeds that meet consumer demands cannot be ensured. This study investigated the effectiveness of an automated system for seedling analysis as a tool for evaluating basil seed vigor and compared it to traditional tests. For this purpose, seeds from eight commercial lots were evaluated in two separate trials spaced six months apart using the following tests: germination, first germination count, saturated salt accelerated aging, primary root emergence, mean germination time, seedling emergence, seedling emergence speed index, and computerized seedling image analysis. The parameters provided by the system allowed us to clearly and objectively classify the basil seed lots based on vigor, and the results were strongly and significantly correlated with the findings of traditional vigor tests, particularly between the vigor index and seedling length. Digital analysis of four-day-old seedlings proved to be a fast and efficient technique for evaluating basil seed vigor and has the potential for use in automating the data collection and analysis process. [ABSTRACT FROM AUTHOR]

Organic mulching has been suggested as an option for managing spontaneous species in restoration plantings and can promote improvements in soil properties and performance of planted species. The aim of this study was to test the effect of crowning techniques on soil microclimatic and performance of forest seedlings. The experiment was carried out in Goiás state, Brazil. Two study factors were used: crowning techniques (manual weeding, cardboard, wood chipping and control—without weed competition management), and six tree species: Anadenanthera peregrina, Ceiba speciosa, Dipteryx alata, Inga edulis, Genipa americana and Spondias mombin. Soil temperature and moisture assessments were performed within the crowning area (0.25 m2). Seedling survival and growth in height and diameter were evaluated over 219 days. Organic mulching treatments of wood chipping and cardboard provided increase in soil moisture and decrease in temperature, resulting in higher seedling survival rate. The increase in height and diameter differed among species under study, with A. peregrina standing out in height and C. speciosa in diameter. The crowning techniques did not influence the average height of species; however, wood chipping provided greater diameter increase. The findings of this study indicate that mulching treatments, by contributing to increase soil moisture and decrease soil temperature, can be used as crowning techniques to increase the survival rate and diameter growth of tree species in restoration plantings. [ABSTRACT FROM AUTHOR]

Premise of research. Seed ontogeny between fertilization and seed maturity is a neglected life history stage in demographic studies, yet this period may have profound consequences for seed set and seedling vigor. For plant species with multiovulate linear fruits, it is possible to record the relative position of each ovule, thereby allowing investigators to assess whether ovule development occurs at random or whether it exhibits unique discernible patterns within fruits. We studied effects of ovule position on patterns of ovule development, seed mass, and seedling size within linear pods of Cercis canadensis. Methodology. Fruits were collected from multiple trees at each of three sites in southeastern Michigan. Intraovary ovule position and developmental fate (i.e., undeveloped ovule, aborted ovule, insect-damaged seed, and mature seed) and seed mass were determined. Seedling performance from three seed size classes was also monitored. Seedling traits included days to emergence, height, leaf area, and seedling biomass. Pivotal results. Three-fourths or more of all ovules within fruits across the populations reached seed maturity. Patterns of seed maturation and abortion were nonrandom and significantly depended on populations, individuals, and ovule positions within fruits. Probability of seed maturation within individual fruits was lowest at the basal end and highest at either the center or the distal end, suggesting the existence of a fertilization gradient. Conversely, frequencies of undeveloped ovules and aborted seeds were highest at the bases of fruits. Insect-damaged seeds accounted for 1%–3% of all ovules and occurred randomly. Seeds located in basal sections of fruits were also smaller than seeds located in central and distal sections. Seed mass was positively correlated with all measures of seedling performance. Conclusions. Patterns of ovule development and seed maturation were determined to be nonrandom within fruits of C. canadensis. Ovule position influences abortion and maturation of seeds, seed mass, and early seedling vigor and has the potential to affect overall plant fitness. [ABSTRACT FROM AUTHOR]

Understanding the interactive effects of global change drivers on tree demography is fundamental for realistic predictions of future forest dynamics. Multiple studies have shown increasing drought and exotic pathogens to severely threaten forest persistence by increasing mortality and decreasing growth of adult trees. However, much less is known about their effects on regeneration, and how they might affect seedling performance in additive and non‐additive (synergistic or antagonistic) ways.Here we aimed to fill this gap by experimentally exploring the effects of increasing drought and soil‐borne pathogens on tree regeneration in two types of mixed oak forests (Quercus suber‐Q. canariensis and Q. suber‐Olea europaea) invaded by the exotic soil‐borne oomycete Phytophthora cinnamomi, one of the most aggressive plant pathogens on earth. We conducted a seed sowing experiment with oomycete‐specific fungicide taking advantage of rainfall exclusion infrastructures that excluded 30% of the annual rainfall, simulating predictions of climate change models for Mediterranean systems. Seedling emergence, survival and growth of the three tree species were followed during 3 years.We found that neutral or positive drought effects on regeneration dominated over negative effects in the tree community. Moreover, most positive drought effects on the dominant species (Q. suber) were not direct, but indirectly mediated by soil‐borne pathogens. This was shown by the fact that positive drought effects disappeared with fungicide application.Synthesis: Overall, our results suggest that rainfall reductions predicted by climate change models for the Mediterranean region might have minor direct negative effects on early regeneration of tree species, but could play a major indirect role by limiting the negative effects of exotic pathogens on highly susceptible tree species. These findings highlight that antagonisms among global change drivers should be recognized as important forces that might slow down the current loss of tree health. [ABSTRACT FROM AUTHOR]

Understanding the adaptation of plant species will help us develop effective breeding programs, guide the collection of germplasm, and improve the success of population restoration projects for threatened species. Genetic features correlate with species adaptation. Acer yangbiense is a critically endangered plant species with extremely small populations (PSESP). However, no information was available on its seed germination and seedling growth in populations with different genetic characteristics. In this study, we investigated seed germination and compared the performance of 566 seedlings in 10 maternal half-sib families cultivated in Kunming Botanical Garden. The results showed that A. yangbiense seeds required an average of 44 days to start germinating, with a 50% germination rate estimated to take about 47–76 days, indicating slow and irregular germination. There is a trade-off between the growth and survival in A. yangbiense seedlings, with fast growth coming at the cost of low survival. Groups that were able to recover from a recent bottleneck consistently had higher relative growth rates. High genetic diversity and low levels of inbreeding are likely to be responsible for their improved survival during drought conditions and rapid growth under optimal environmental conditions. Our results suggest that maternal genetic traits might be used as indicators for conservation and population restoration. These findings provide us with new information that could be applied to support ex situ conservation and reintroduction of threatened species. [ABSTRACT FROM AUTHOR]

• Ultrasonic waves have the potential to increase cell wall permeability without impairing germination capacity. • Ultrasound technology enriches the chemical composition of soybean seeds. • Supplementation of Zn by ultrasonic waves contributes to the production of seedlings with superior energetic performance. • The seedlings show Fv/Fm values 92.7% higher than the control. Strategies to increase the concentration of essential micronutrients for the plant cycle have made a remarkable contribution to agriculture. Ultrasonic waves have the potential to increase cell wall permeability and enhance the chemical composition of seed tissues. In this context, the aim of this study was to verify if it is possible to increase the zinc (Zn) supplementation of soybean seeds through their controlled exposure to ultrasonic waves with improvements in the photosynthetic efficiency (Fv/Fm) of the resulting seedlings. Initially, we investigated the impact of ultrasonic waves on the physical, physiological and spectral parameters of soybean seeds. Next, the seeds were treated with Zn and analyzed by X-ray fluorescence spectroscopy to better understand the kinetics of Zn uptake. Finally, we evaluated the germination, vigor, pigments and photosynthetic performance of seedlings. The main results showed that ultrasound modifies the structure of the seed coat without interfering with the dynamics of water absorption and the germination capacity of the seeds. The changes promoted by the technology favor Zn supplementation of more than 100 % in the seeds. In addition, the resulting seedlings show Fv/Fm values 92.7 % higher than the control, and an increase in chlorophyll fluorescence, initial fluorescence, and anthocyanin. We show that ultrasonic wave technology combined with Zn treatment improves the performance of soybean seeds, producing seedlings with superior photosynthetic efficiency. [ABSTRACT FROM AUTHOR]

Premise: In many flowering plants, flowers contain more ovules than fruits have seeds. What determines which ovules become seeds? When photosynthates are limited, as may happen when plants lose leaf area to herbivory, fewer fertilized ovules become seeds. Methods: Greenhouse‐grown ramets of distinct individuals of a perennial herbaceous legume were manually defoliated to various levels determined in the field, then self‐ or cross‐pollinated. For each seed produced, we recorded its position in the fruit and its mass. From a subset of seeds from different treatments and positions in the fruits, we grew seedlings and measured their dry mass. Results: Ovules were aborted more frequently in fruits from flowers that were self‐pollinated and from those on plants with higher levels of defoliation. Ovules in the basal portion of the fruits were more likely to be aborted than those at the stigmatic end; this pattern was most pronounced for fruits after self‐pollination with high levels of defoliation. Total number of seeds produced and seed mass per pod were greatest in cross‐pollinated fruits after no or low levels of defoliation. Mean individual seed mass was greater for fruits with fewer seeds, indicating a trade‐off between seed number and seed mass. Seedling dry mass (a measure of vigor) was greatest for seeds in the middle positions of fruit produced by cross‐pollination after severe herbivory; no positional differences were seen for seeds from self‐pollinated fruits. Conclusions: Observed locations of seed abortion may have been selected not only by defoliation, but in part by propensity for dispersal, while positional differences in seedling vigor may be related to seed size and differential maternal allocation based on pollination treatment and leaf area lost. [ABSTRACT FROM AUTHOR]

Understanding the adaptation of plant species will help us develop effective breeding programs, guide the collection of germplasm, and improve the success of population restoration projects for threatened species. Genetic features correlate with species adaptation. Acer yangbiense is a critically endangered plant species with extremely small populations (PSESP). However, no information was available on its seed germination and seedling growth in populations with different genetic characteristics. In this study, we investigated seed germination and compared the performance of 566 seedlings in 10 maternal half-sib families cultivated in Kunming Botanical Garden. The results showed that A. yangbiense seeds required an average of 44 days to start germinating, with a 50% germination rate estimated to take about 47–76 days, indicating slow and irregular germination. There is a trade-off between the growth and survival in A. yangbiense seedlings, with fast growth coming at the cost of low survival. Groups that were able to recover from a recent bottleneck consistently had higher relative growth rates. High genetic diversity and low levels of inbreeding are likely to be responsible for their improved survival during drought conditions and rapid growth under optimal environmental conditions. Our results suggest that maternal genetic traits might be used as indicators for conservation and population restoration. These findings provide us with new information that could be applied to support ex situ conservation and reintroduction of threatened species.

Tree mycorrhizal type plays an important role in promoting plant species diversity and coexistence, via its mediating role in conspecific negative density dependence (CNDD), i.e., the process by which an individual's performance is impaired by the density of conspecific plants. Previous findings suggest that ectomycorrhizal (EM) tree species are generally less susceptible to CNDD than arbuscular mycorrhizal (AM) tree species, due to the chemical and physical protection that EM fungi provide their host with. We examined how CNDD effects on leaf herbivory, seedling growth, and survival differ between AM and EM seedlings of ten tree species collected over 3 years in an old-growth temperate forest in northeastern China. We found that AM and EM seedlings differed in how conspecific density affected their leaf herbivory, seedling growth, and survival. Specifically, AM seedlings leaf herbivory rates significantly increased with increasing conspecific seedling and adult density, and their growth and survival rates decreased with increasing conspecific adult density, these patterns were, however, absent in EM seedlings. Our work suggests that AM seedlings have a performance disadvantage relative to EM seedlings related to the negative effects from conspecific neighbors. We highlight the importance of integrating information on seedling leaf herbivory, seedling growth, to provide further understanding on potential mechanisms driving differences in CNDD between AM and EM tree seedlings. [ABSTRACT FROM AUTHOR]

In Mediterranean climates, drought is recognized as the main abiotic stress negatively affecting plant survival and growth after establishment. However, several factors besides water scarcity interact to affect plant performance, including stocktype, field establishment techniques, environmental variability, and the inherent ecological requirements of the target species. To fully comprehend the extent each of these factors influences plant performance, we analyzed plant survival, growth, and physiological performance of contrasting stocktypes of Nothofagus glauca seedlings, a shade-intolerant tree species from Mediterranean central Chile, established under different environmental conditions characterized by a shrubland versus a forest canopy cover. We hypothesize that nitrogen-loaded plants will have higher survival and growth during establishment, and that higher performance will be observed under the shrubland conditions, despite the presence of water constraints that are usually observed in more open canopies. Our experimental design induced contrasting environmental conditions in which the forest canopy was characterized by lower irradiance and water availability during summer versus the shrubland condition. As expected, bigger and nutrient-loaded N. glauca plants had better field performance in terms of survival and growth. After three years of assessment, we did not observe differences in survival between canopy conditions, but plants established under shrubland canopy presented significantly higher biomass accumulation and better water status. According to our relative importance analysis, we observed that soil water availability was the most relevant factor for plant survival, but plants showed more growth when established under a condition of increased irradiance. Considering that plant performance is explained by the combined response of survival and growth, we suggest that under Mediterranean conditions, each response could be independently affected by separate environmental factors as well as by target species biology (i.e., shade tolerant or shade-intolerant). • Soil water content is the main driver of N. glauca survival in a Mediterranean climate. • Irradiance is determinant for plant growth in the shade-intolerant N. glauca. • Plant field survival and growth are affected by different environmental factors. [ABSTRACT FROM AUTHOR]

Environmental gradients influence plant establishment, survival, and functional traits. Along the Panama Canal Isthmus there is a strong rainfall gradient with an underlying mosaic of soil types ranging in soil nutrient availability. In this region, tree species distribution patterns are correlated with soil phosphorus availability and rainfall patterns, but how understory plant species such as palms relate to these factors is less clear. We hypothesized that due to greater resource use efficiency and optimal biomass allocation, specialist species will have greater seedling performance growing in home soil and sites compared to species not occurring there. To test this hypothesis, we used two specialist species (Chamaedorea tepejilote and Geonoma congesta) and two generalist species (Geonoma cuneata var. cuneata and Chamaedorea pinnatifrons), and for these four species we measured traits on seedlings and assessed their performance in shade house and field transplant experiments using five soils. Soils were sourced from five sites which varied in nutrient availability and rainfall, and were distributed along lowland tropical forests of the Panama Canal Isthmus. In the shadehouse experiment, leaf functional traits were determined by species rather than soil nutrient availability. However, in the shadehouse experiment, seedling biomass allocation, and relative growth rate were determined by interactions between species and soil, with weak support for home-site advantage for one of the species. In the field transplant experiment, seedling survival was strongly related to dry season water availability. However, species tended to have high survival at home sites and other sites with higher dry season rainfall. Together, results from these experiments suggest that understory palm species seedling performance are determined by species-specific responses to the combination of soil nutrient and water availability. This indicates that while soil nutrients influence seedling biomass allocation, dry season water availability determines both specialist and generalist seedling survival and therefore distributions along the soil nutrient and moisture gradient.

In gynodioecious systems, female plants must counteract the selective disadvantage of not passing genes via pollen production, as hermaphrodites can. Theory predicts that females must produce more or better‐quality seeds than hermaphrodites in order to be maintained within the same population. This female advantage has been widely measured and reported for seed number, but whether female advantage is gained through the production of better seeds remains relatively under‐studied.Here, a meta‐analysis approach was used to investigate whether females in gynodioecious species produce seeds of better quality than hermaphrodites (measured as seed mass, seed nutrient content, seed germinability and seedling survival and performance) in addition to achieving a larger seed production. In total, 50 studies were included, reporting traits for 34 gynodioecious species in 17 different families.Female advantage was significant for seed number and seed germination, but was not detected for seed mass, seed nutrient content or seedling performance.A female advantage in seed number was corroborated in this meta‐analysis, which together with better seed germination, may explain maintenance of female plants within gynodioecious populations. [ABSTRACT FROM AUTHOR]

Abstract: The use of computational resources to assess the physiological potential of seeds has attracted the attention of researchers and professionals in the seed sector. The aim of this study was to evaluate the vigor of cowpea seeds using the Vigor-S software (Automated Seed Vigor Analysis System), in comparison to the information provided by traditional vigor tests that are recommended for the species. Seven seed lots of the cultivar BRS Guariba were used. They underwent germination and seed vigor assessment by testing first germination count, accelerated aging, electrical conductivity, seedling emergence, speed of seedling emergence and use of Vigor-S, an automated image system for seedling assessment, in two evaluation periods. The data underwent analysis of variance, in a completely randomized design and their means were compared by the Scott-Knott test (p ≤ 0.05). An analysis was made of the correlation between the vigor tests traditionally used and the variables provided by Vigor-S. Using the Vigor-S software for automated image analysis of cowpea seedlings three days after sowing is an efficient alternative to detect differences in vigor between seed lots, similarly to traditional seed vigor evaluations.

Cactus seeds have developed adaptations to survive with high temperatures and low soil moisture in their habitats. We studied the effect of the combination of four water potentials (0, −0.2, −0.4 and −0.6 MPa) and two temperatures (25°C and 35°C) on germination and seedling mass of four endemic Leptocereus species from Cuba. There were two semi‐arid coast species (L. arboreus and L. santamarinae) and two species inhabiting dry inland karstic hills (L. ekmanii and L. scopulophilus). We hypothesized that: (a) a decrease in water potential and an increase in temperature would result in low and slow germination, as well as in low seedling mass, and (b) ungerminated cactus seeds after exposure to combined water and temperature stress would have a high recovery capacity. The minimum time required for the seeds to start germination (Tmin), mean germination time (MGT) and germinability were evaluated. In addition, seed mass, the recovery after treatments of non‐germinated seeds, and the seedling fresh mass obtained under different treatments were compared between species. In general, germination was only obtained at 25°C and germinability and seedling mass were drastically affected by the reduction from 0 MPa to −0.2 MPa. Seeds showed thermoinhibition at 35°C at all water potentials. There was a tendency to increase the MGT with decreasing water potential in three species. Low seed recovery occurred at all combined treatments for three species. If the predictions of increased temperature and decreased rainfall for the Caribbean region occur, a reduction in the germination of the Leptocereus species studied is expected. [ABSTRACT FROM AUTHOR]

The use of computational resources to assess the physiological potential of seeds has attracted the attention of researchers and professionals in the seed sector. The aim of this study was to evaluate the vigor of cowpea seeds using the Vigor-S software (Automated Seed Vigor Analysis System), in comparison to the information provided by traditional vigor tests that are recommended for the species. Seven seed lots of the cultivar BRS Guariba were used. They underwent germination and seed vigor assessment by testing first germination count, accelerated aging, electrical conductivity, seedling emergence, speed of seedling emergence and use of Vigor-S, an automated image system for seedling assessment, in two evaluation periods. The data underwent analysis of variance, in a completely randomized design and their means were compared by the Scott-Knott test (p < 0.05). An analysis was made of the correlation between the vigor tests traditionally used and the variables provided by Vigor-S. Using the Vigor-S software for automated image analysis of cowpea seedlings three days after sowing is an efficient alternative to detect differences in vigor between seed lots, similarly to traditional seed vigor evaluations. [ABSTRACT FROM AUTHOR]

Seed predators sometimes inflict non‐lethal seed damage. We asked whether seed size modulates the location of insect seed damage and examined whether location‐specific damage on the embryo influences early plant development (embryo survival, germination, seedling emergence and performance). We used intact and weevil‐infested seeds of a prevalent California oak tree Quercus agrifolia as study model. We conducted observational and manipulative studies (simulate partial embryo damage). Seed size significantly affected the location of insect damage within the seed and, in turn, the probability of embryo damage, with larger seeds showing lower probability of embryo damage. The location of the larva exit hole was strongly associated with the probability of embryo damage, with 0.9 probability when the exit hole is located <5 mm from the embryo. Partial damage on the embryo was found in ca 11% of the infested seeds (n = 250). Among them, 63% showed damage only on the inner part (plumule) of the embryo. Damage on the plumule (the rudimentary shoot) was more lethal than damage on the radicle, particularly at the emergence phase, when success rate of plumule‐damaged seeds decreased by half as compared to that of radicle‐damaged seeds. Plumule‐damaged seeds also emerged much later and performed more poorly than radicle‐damaged seeds. Furthermore, seedlings that emerged from plumule‐damaged seeds showed poorer physiological parameters (lower chlorophyll and nitrogen content) than those emerged from radicle‐damaged seeds. Overall, intact seeds performed better than both types of damaged seeds. We highlight that seed size and its associated differential location of seed damage determines the occurrence of embryo damage and the region affected within the embryo (e.g. plumule versus radicle) which, in turn, affects important components of plant fitness. Different selective pressures affecting mostly the plumule (insects) versus the radicle (embryo‐clipping rodents) may contribute to elucidate the co‐evolutionary dynamics of seeds and their predators. [ABSTRACT FROM AUTHOR]

This study examined whether the morphological attributes of Austrian pine (Pinus nigra ssp. nigra var. nigra Arnold) seedlings measured in the nursery could be used to forecast subsequent field performance over an extended time frame. Seedlings from three seed sources were produced in two types of containers and in bareroot seedbeds. These seedlings were measured for an array of morphological attributes (height, HT; root collar diameter, RCD; shoot height/diameter ratio, HD; shoot and root dry weight, SDW and RDW, respectively; shoot:root ratio, S:R; number of the first order lateral roots, FOLR; and Dickson quality index, DQI) and then planted at two sample plots with different soil depth. Seedling attributes were tested against field survival and growth in the first three years and growth in the twelfth year for their ability to forecast field performance. Correlations between morphological attributes and field performance were stronger for the plot with shallower soil, having potentially drier conditions. HT, HD, and S:R were the best attributes for forecasting seedling survival. HD was the most reliable attribute to forecast growth during the first three years after planting, defining the largest proportion of variation for growth (r2=0.36 to 0.86). Morphological attributes were better able to forecast field performance in the first three years at the shallow soil site, with FOLR the best single morphological variable. HT, DIA, and RDW were the best attributes to forecast growth during the first three years after planting on both sites. Morphological attributes were not able to forecast growth 12 years after planting.

Monoculture tree plantations have been preferred by farmers and companies because they maximize the production of specific products and are easier to manage, while multispecies plantations can provide multiple ecosystem services but have still been adopted at very limited scales. One potential midway to enhance the ecological contribution of monoculture plantations is to introduce native tree species in the plantation understory. We conducted phylogenetically explicit enrichment planting experiments beneath the monocultures of two tree species native to the Brazilian Atlantic Forest to assess if the evolutionary distance of each seedling species to the overstory tree explained variations in seedling performance. We planted in the understory of two replicate plantations of species Esenbeckia leiocarpa Engl. (Rutaceae; 38 and 25 years old) and Zeyheria tuberculosa (Vell) (Bignoniaceae; both replicates were 30 years old) six native tree species, ranging in their evolutionary distances to these overstory species. We assessed individual seedling survival and height at 1, 7, and 19 months after planting. We found a weak yet significant, positive correlation between seedling performance (growth and survival) and the phylogenetic distance of the planted seedling to the overstory species, which was driven by the poor performance of conspecifics. Seedlings of the same order and class as the overstory trees showed a significantly lower risk of death compared to conspecifics and to the furthest relative, Cryptocarya aschersoniana. These findings highlight that very close relatives to the overstories should be avoided when planting beneath monoculture plantations, but that knowledge on species‐specific requirements is still the most important for a successful planting. [ABSTRACT FROM AUTHOR]

Rodents regularly rely on emerged epicotyls to locate and remove cotyledons still containing valuable nutrients. However, the extent to which acorn characteristics influence tolerance to post‐germination predation has received little attention.Here, we investigated the impact of cotyledon removal following epicotyl emergence on seedling performance and survival of seven oak (Quercus) species. We imitated cotyledon predation at different stages of seedling establishment and development in order to detect effects on seedling height, leaf number and tissue/component mass.Seedling growth and survival were negatively affected by cotyledon loss regardless of oak species. However, these negative effects decreased as the epicotyl length at which cotyledons were removed increased. We also found that there was a threshold epicotyl length above which seedling survival and performance were relatively unaffected in white oak species compared to red oak species.Following cotyledon removal, early germinating white oak (section Quercus) seedlings survived and/or grew better than the late germinating red oak (section Lobatae) seedlings. This was likely caused by a difference in dependence on cotyledon reserves, which ultimately affected the ability of seedlings to tolerate cotyledon removal.Synthesis. From an evolutionary perspective, this is likely to follow from the early germination in white oaks and the ability of seed consumers to locate young seedlings from the emerging epicotyls. Our study has implications for forest regeneration by suggesting additional opportunities for white oak species to establish following epicotyl emergence. Future studies should consider quantifying the rates of post‐germination cotyledon loss. [ABSTRACT FROM AUTHOR]

In Andean Patagonia, Argentina, severe wildfires produce high mortality in Austrocedrus chilensis forests. Owing to its high timber quality, A. chilensis trees are generally salvage logged right after wildfires. Post-logged areas result in open, denuded stands with low herbaceous or shrub cover, which precludes natural A. chilensis regeneration. In severely burned A. chilensis stands, we determined how different site conditions (salvage logging, SL, and without logging, WL), and the combination of different methods of control of above- and belowground competition and micro-environmental factors (incident radiation, soil temperature and soil moisture) affected survival, growth and hydric status of planted A seedlings. Two growing seasons after plantation, seedling survival was lower than 10% at SL sites, whereas it was near 90% at WL sites. Four seasons after establishment, and regardless of competition treatments, no seedlings survived at SL sites, whereas over 75% survived at WL sites. Radiation attenuation by canopy of WL sites benefitted A. chilensis seedling survival, and no additional control of early successional herbaceous species should be necessary to attain high seedling survival 4 years after restoration. Selective logging, by leaving ~50% of burned snags, and active restoration practices, may help reconcile economic needs of society and ecological requirements of A. chilensis for recovering former structure and functions. We determine how post-fire salvage logging (SL) v. without logging (WL) affected Austrocedrus chilensis seedling survival and growth under different aerial and root-competition treatments. High radiation levels at SL sites precluded A. chilensis seedlings survival, whereas aerial or root competition had insignificant effects. Remaining snags at WL sites attenuate radiation, allowing high seedling survival. [ABSTRACT FROM AUTHOR]

Local tree species distributions in tropical forests correlate strongly with soil water availability. However, it is unclear how species distributions are shaped by demographic responses to soil water availability. Specifically, it remains unknown how growth affects species distributions along water availability gradients relative to mortality.We quantified spatial variation in dry season soil water potential (SWP) in the moist tropical forest on Barro Colorado Island, Panama, and used a hierarchical Bayesian approach to evaluate relationships between demographic responses of naturally regenerating seedlings to SWP (RGRs and first‐year mortality) and species distributions along the SWP gradient for 62 species. We also tested whether species that were more abundant at the wet or dry end of the gradient performed better (a) at their "home end" of the gradient ("best at home" hypothesis) and (b) "at home" compared to co‐occurring species ("home advantage" hypothesis).Four and five species responded significantly to SWP in terms of growth or mortality respectively. Growth (but not mortality) responses were positively related to species distributions along the SWP gradient; species with a more positive (negative) growth response to SWP were more abundant at higher (lower) SWP, that is, at wetter (drier) sites. In addition, wet distributed species grew faster on the wet end of the SWP gradient than on the dry end ("best at home") and grew faster on the wet end than dry distributed species ("home advantage"). Mortality rates declined with seedling size for all species. Thus, seedling growth responses to SWP indirectly shaped local species distributions by influencing seedling size and thereby mortality risk.Synthesis. By demonstrating how growth responses to spatial variation in soil water availability affect species distributions, we identified a demographic process underlying niche differentiation on hydrological gradients in tropical forests. Recognizing the role of these growth responses in shaping species distributions should improve the understanding of tropical forest composition and diversity along rainfall gradients and with climate change. This study shows that growth responses to soil moisture play an important role in shaping the distribution of tree seedlings along a local soil moisture gradient. Species that grew well on the wet end of the gradient were more abundant there because they became taller more quickly, reducing their mortality risk, and because they grew faster than dry distributed species. [ABSTRACT FROM AUTHOR]

Aim of study: To assess the effectiveness for improving early seedling performance of the individual and combined application of (i) various doses of an innovative soil conditioner including polyacrylamide-free super-absorbent polymers, fertilizers, root precursors and humic acids; and (ii) innovative mulches based on renewable-biodegradable or recycled raw materials. The assessment was carried out in comparison with reference (commercial) soil conditioners and mulches. Area of study: Upper montane afforestation site located at 1,430 m altitude in the southern Pyrenees (NE Spain). Material and methods: We studied the effect of 15 treatments (various combinations of soil conditioners and mulches) on mountain ash (Fraxinus excelsior L.), testing survival, diameter and height growth and water and nutrient status during two growing seasons (2014-2015). We also assessed mulch durability during 2014-2016. Main results: The innovative soil conditioner improved diameter and height seedling growth (92% and 72% respectively) and water and nutrient status. The 40 g/seedling dosage was more cost-effective than the 20 and 80 g/seedling doses. The new formulation performed better in general than the commercial formulation. Mulches led to slight gains compared to control seedlings, and there were no major differences between the mulch models. The combined application of soil conditioners and mulches was not of particular interest. Research highlights: Soil conditioners consisting of synergic mixtures of water super-absorbent polymers, fertilizers, root growth precursors and humic acids can improve early seedling performance in coarse-textured, stony soils in montane conditions. Small mulches may be only of limited interest as long as weed competitiveness is poor. Keywords: ecotechnology; groundcovers; reforestation; seedling performance; restoration; water super-absorbent polymer; weed. Abbreviations used: GSn, growing season number ‘n’; leaf water potential, LWP; water super-absorbent polymers, SAP; soil conditioner with water super-absorbent polymers, SCwSAP; Soil Plant Analysis Development, SPAD.

This study aimed to evaluate the allelopathic effect of various concentrations of an aqueous extract of eucalyptus leaves on Urochloa decumbens and Panicum maximum seeds. The extract was prepared from Eucalyptus urograndis leaves that were milled and mixed with distilled water in a 1:9 milled leaves: water ratio to obtain an extract with a defined concentration of 100%. In addition, dilutions of 50%, 25% and 12.5% were prepared, and a 0% dilution was used as a control. The experiment followed a completely randomized design, with four replicates, each of 50 seeds of U. decumbens and 50 seeds of P. maximum, arranged on filter paper moistened with each concentration of extract in a Gerbox plastic box. The results demonstrated the allelopathic potential of E. urograndis aqueous extracts applied to the seeds of U. decumbens and P. maximum. The 50% and 100% concentrations of leaf extract most strongly inhibited the germination, vigor and seedling growth of U. decumbens and P. maximum. The germination speed index and the root length were the characteristics that were most affected by the potentially allelopathic substances contained in the eucalyptus extracts at all concentrations.

This work was carried out in the Agricultural Faculty of Süleyman Demirel University in Isparta. As a plant material, MM111 rootstock and "Golden Delicious", "Redchief" and "ScarletSpur" apples varieties were used on this rootstock. The scions belonging to these varieties were grafted on MM111 rootstocks internally in February by "Table-type" grafting machine and "Splice grafting" methods. For each grafting method, 3 replicates and 30 seedlings were used. The grafted seedlings were placed in a cold air store at + 4 ° C and transferred to the nursery in April. In this study, the success rate of grafting, nursery plant length and diameter were monitored monthly until October when the plant developing stopped. According to the results obtained, the "Splice grafting" method has a higher value in terms of grafting success rate than the "Table-type grafting" method. However, in the Redchief and Scarlet Spur varieties, the grafting success rate is higher in "Table-type grafting machine". It can be said that when we compare the grafting with the machine in terms of the success of the grafting, nursery plant width and length by means of hand-made "Splicegrafting" method, it can be preferred especially in terms of nursery plant length. [ABSTRACT FROM AUTHOR]

Early regeneration is a critical life stage that affects the future species composition of forests. Knowledge about regeneration success under different environmental conditions allows better understanding of forest dynamics. We studied the effects of seedbed conditions on the establishment and performance of seedlings of pedunculate oak, beech and red oak. In 50 plots of a tree-diversity oriented research platform in mature forests in northern Belgium (TREEWEB), we installed a field experiment with three treatments (potting soil, mineral soil, mineral soil + forest floor), in which we sowed seeds of each species. We monitored early establishment and survival, height, root and shoot biomass of the seedlings after two growing seasons. Mineral soil negatively affected seedling establishment and performance relative to the potting soil. The negative soil effects did not vary with measured abiotic soil properties. In general, the forest floor did not deteriorate or mitigate the soil effects, and only for root biomass did the forest floor partly compensate the negative soil effects. Forest floor effects did not vary with the measured forest floor properties. In the studied forests, creating bare soil was not enough to promote regeneration; improving soil properties might be important for the success of natural regeneration. [ABSTRACT FROM AUTHOR]

There is growing interest in innovative ways to minimise the environmental footprint of port developments. Herein we present results of a mangrove planting trial along an artificial tidal creek at Port Hedland, Western Australia. A 75 m-long tidal creek with exposed sloping and terraced banks was constructed, creating,1000 m2 of intertidal area in which 800 nursery-raised seedlings of four mangrove species (Avicennia marina, Rhizophora stylosa, Ceriops australis and Aegiceras corniculatum) were transplanted. Planting followed a randomised block design to test seedling performance against tidal elevation, bank design and erosion protection. After 3 years, 142 seedlings (18%) had survived. Another 1171 mangrove seedlings, dominated by A. corniculatum (75%) and Aegitialis annulata (15%), had recruited naturally into the site. Performance and survival of planted and recruited seedlings was significantly affected by tidal elevation (P=0.002), but not by bank design or erosion protection. A. marina showed highest survival (46%), followed by R. stylosa (18%). These results demonstrate that by creating appropriate environmental conditions conducive to mangrove growth, seedlings will recruit and establish naturally. Owing to the slow growth typical of semi-arid mangroves, it may take well over a decade before vegetation at this site is comparable to adjacent natural creeks. [ABSTRACT FROM AUTHOR]

In this study, we determined the competition effects of herbaceous vegetation on survival, growth, and plant water relations of planted lenga ( Nothofagus pumilio) seedlings under field and nursery conditions in western Patagonia, Argentina. In the field, thirty (1.5 × 1.5 m) plots were randomly set in a grazing-free exclosure built in a typical grazing-degraded lenga canopy gap mainly colonized by non-native herbs and grasses ( empastado). Herbaceous aerial and root biomass was removed in half of the plots (non-competition treatment, NCT), while the others (competition treatment, CT), remained undisturbed. Four similarly-sized lenga seedlings were planted per plot. In the nursery, 120 lenga seedlings were planted in individual pots containing soil of the field study site, and set to a factorial experiment including two competition levels (CT and NCT) and two watering regimes: normal (simulating average rains during the growing season, 500 mm, NW), and high (equivalent to 1000 mm, HW). During three growing seasons, we determined seedling survival, growth, and plant and soil water status of both experiments. Higher survival and growth, and better plant water status values were obtained in NCT as compared to CT in both experiments. In the nursery, HW did not improve survival and growth as compared to NW. In restoration trials implying grazing-degraded areas, increases in lenga seedling survival and growth could be achieved by reducing nearby competition of grasses and herbs, while extra watering appears unnecessary. However, limitations in the experimental design (pseudo-replication), limits generalization of results to other forest ecosystems with similar structural and functional characteristics. [ABSTRACT FROM AUTHOR]

Aims Worldwide, evidence suggests that exotic pollinators can disrupt plant mating patterns. However, few studies have determined if pollination by the honeybee Apis mellifera (the world’s most widely introduced pollinator) reduces offspring quality when compared with pollination by native birds. The Australian Proteaceae provides an excellent opportunity to test the impact of honeybees in pollination systems that are adapted to birds and non-flying mammals. Methods We compared the frequency of flower visitation and foraging behaviour of birds and insects within seven populations of Banksia ericifolia. Banksia ericifolia is hermaphroditic and has large nectar-rich, orange inflorescences typical of bird and mammal pollinated species. For a subset of the study populations, we compared the quality of seed produced via an exclusion treatment (that only allowed invertebrates to access flowers) with an open-pollination treatment (potentially visited by mammals, birds and invertebrates), by measuring seed weight, germination rates (T50), percent germination, seedling height after 14 days since the emergence of the cotyledon and time to emergence of the cotyledon. Important Findings Apis mellifera was the only apparent insect pollinator and the most frequent flower visitor, while the open treatment inflorescences were also frequently visited by avian pollinators, primarily honeyeater species. The foraging behaviour of honeybees and honeyeaters showed striking differences that potentially affect patterns of pollen transfer. Honeybees made significantly greater proportions of within cf. among plant movements and only 30% (n = 48) of honeybees foraged for pollen (nectar foragers carried no pollen) whilst all birds were observed to contact both stigmas and anthers when foraging for nectar. Despite these fundamental differences in behaviour, there was little effect of treatment on seed set or quality. Our data show that while honeybees appear to alter patterns of pollen transfer within B. ericifolia populations, they do not impact reproductive rates or performance of early life-stages. [ABSTRACT FROM AUTHOR]

Factors that cause differential establishment among naturalized, invasive, and native species are inadequately documented, much less often quantified among different communities. We evaluated the effects of seed addition and disturbance (i.e., understory canopy removal) on the establishment and seedling biomass among two naturalized, two invasive, and two native species (1 forb, 1 grass in each group) within steppe and low elevation forest communities in eastern Washington, USA. Establishment within each plant immigrant class was enhanced by seed addition: naturalized species showed the greatest difference in establishment between seed addition and no seed addition plots, native and invasive species establishment also increased following seed addition but not to the same magnitude as naturalized species. Within seed addition plots, understory canopy disturbance resulted in significant increases in plant establishment (regardless of plant immigration class) relative to undisturbed plots and the magnitude of this effect was comparable between steppe and adjacent forest. However, regardless of disturbance treatment fewer invasive plants established in the forest than in the steppe, whereas native and naturalized plant establishment did not differ between the habitats. Individual biomass of naturalized species were consistently greater in disturbed (canopy removed) versus undisturbed control plots and naturalized species were also larger in the steppe than in the forest at the time of harvest. Similar trends in plant size were observed for the native and invasive species, but the differences in biomass for these two immigration classes between disturbance treatments and between habitats were not significant. We found that strong limitations of non-native species is correlated with intact canopy cover within the forest understory, likely driven by the direct or indirect consequences of low light transmittance through the arboreal and understory canopy. Considered collectively, our results demonstrate how seed limitation and intact plant ground cover can limit the abundance and performance of naturalized species in Pacific Northwest steppe and low elevation forest, suggesting that local disturbance in both habitats creates microsites for these species to establish and survive. Future studies evaluating interactions between multiple barriers to establishment using more representatives from each immigration class will further reveal how biotic interactions ultimately influence the demography and distribution of non-native plants within these communities. [ABSTRACT FROM AUTHOR]

In order to develop a method for extensive pomiculture on marginal soils in semiarid Brazil, a field experiment was conducted to study the impacts of the soil conditioners biochar, clay substrate and goat manure on soil physical parameters of a sandy soil and on seedling performance ofSpondias tuberosaArruda. Manure significantly increased total porosity, soil water content and reduced bulk density of the sandy soil. Water content at field capacity (θfc) and at permanent wilting point (θpwp) were increased due to manure application. Neither biochar nor clay substrate had a significant impact on the soil physical parameters. Biochar combined with clay substrate led to lower soil water content and significantly reduced the period of retaining atmospheric water. Due to a strong correlation (R2 = 0.75) betweenθfcandθpwp, the available water capacity within all treatments remained unchanged. Amelioration and initial nutrient supplies had no effect on seedling survival and stem growth ofS. tuberosaduring the 23-month experiment. This underlines the nondomesticated character of the available plant material ofS. tuberosa. The independence of the seedling performance of soil management makesS. tuberosaan interesting species for low-input orchards and for reforestation within the Caatinga. [ABSTRACT FROM PUBLISHER]

High seed cost accompanied by poor germination and seedling performance renders cabbage nursery and field production enterprises unsustainable to many small-scale growers in tropical and sub-tropical countries. In most nurseries, adverse ecological conditions and pest damage are among the major factors responsible for poor seedling performance. The objective of this study was to test the potential use of eco-friendly net (EFN) covers as a low cost technology for sustainable cabbage seedling production. The study was a two-season experiment conducted using a randomized complete block design with five replications and two treatments. Treatments were: the standard open field transplant production (control) and transplant production under 0.4 mm mesh polyethylene net covering. EFN covering increased both temperature and relative humidity, enhanced seedling growth and reduced insect pest damage. Seed germination and seedling emergence were under the net covering earlier. Higher seed germination and seedling survival were recorded under the EFN treatment, indicating a potential for reducing the seed requirement per unit area of cabbage production. Seedlings grown under the nets had higher stomatal conductance and leaf chlorophyll content; furthermore, they grew taller, with more leaves within a shorter period of time compared to the control seedlings. The use of EFN in cabbage nurseries offers a sustainable technology for enhancing seedling performance by reducing pest infestation, thereby lowering production cost and improving the grower’s income.

[Display omitted] Plant recruitment is limited by seed predation. However, seeds that are only partially consumed can still contribute to regeneration provided the embryo remains viable. Seed size and shape are important traits that influence the relative location of the embryo, as well as its survival and further development. Yet, it is unclear whether the interaction of seed size and shape affects seed tolerance to partial damage and initial seedling performance. We evaluated the effects of simulated partial damage in three different acorn shapes (flattened, triangular and typical) on early seedling establishment in the threatened Quercus insignis , the largest-seeded oak species worldwide. We also distinguished between lateral acorn damage (pericarp damage only) and cotyledon damage (1/3 of the reserves), using acorn size as a covariate. For this, we recorded the germination, emergence and performance (total height, basal diameter, specific leaf area, total leaf area, above and belowground dry biomass) of each seedling after 110 days of growth. Seed shape influenced the rate and percentage of acorn germination, seedling emergence and performance. Typical-shaped acorns germinated at higher rates and produced more seedlings with higher performance. Simulated damage increased the rate and percentages of germination and emergence, but did not affect performance (except for specific leaf area). Seed size favored performance but not germination or emergence, and no significant interaction was found between acorn shape and seed size with respect to germination, emergence or performance, depending on each damage treatment. Our results suggest that acorn size allows tolerance to partial seed predation, since low to moderate acorn damage (<1/3 of cotyledon lost) had no negative effect on germination or emergence. Larger seed size could therefore not only support seedling performance, but also help to meet the nutritional requirements of small and mid-size predators without risking the integrity or development of the embryo. Acorn shape should therefore be considered in basic and applied oak ecology since seed morphology seems to influence not only germination and emergence, but also seedling performance. These results may have important eco-evolutionary implications in the context of seed-predator interactions, since certain shapes tolerate damage better than others and may thus benefit from the selection pressures exerted by seed foragers, both predators and dispersers. In addition to acorn size, managers should consider acorn shape and its relationship to early seedling establishment, as well as the potential for using partially damaged acorns in oak forest restoration projects. [ABSTRACT FROM AUTHOR]

Understanding the mechanisms generating species distributions remains a challenge, especially in hyperdiverse tropical forests. We evaluated the role of rainfall variation, soil gradients and herbivory on seedling mortality, and how variation in seedling performance along these gradients contributes to habitat specialisation. In a 4-year experiment, replicated at the two extremes of the Amazon basin, we reciprocally transplanted 4638 tree seedlings of 41 habitat-specialist species from seven phylogenetic lineages among the three most important forest habitats of lowland Amazonia. Rainfall variation, flooding and soil gradients strongly influenced seedling mortality, whereas herbivory had negligible impact. Seedling mortality varied strongly among habitats, consistent with predictions for habitat specialists in most lineages. This suggests that seedling performance is a primary determinant of the habitat associations of adult trees across Amazonia. It further suggests that tree diversity, currently mostly harboured in terra firme forests, may be strongly impacted by the predicted climate changes in Amazonia. [ABSTRACT FROM AUTHOR]

Summary: Success of establishing native trees in cool temperate environments depends on the ability of seedlings to withstand subzero temperatures and recurrent frosts. This study compared the survival and growth of five tree and shrub species with two guard types at three landscape positions in an upland pasture. Seedlings were planted between December 2013 and March 2014. Half of the seedlings were planted in tall Corflute® guards (60 cm high), and the remaining seedlings were interplanted in milk cartons (30 cm). Seedling survival and height were measured in November 2014. Hourly temperature readings were recorded between March and November 2014. Seedling height for all species was greater in tall guards than milk cartons at all landscape positions, possibly at least partly due to etiolation. However, seedlings in tall guards survived better than seedlings in milk cartons at mid‐ and upper‐slope positions. Higher temperatures may have benefited seedling performance by prolonging the growing season as average maximum temperature was significantly higher inside tall guards than milk cartons and ambient conditions at all landscape positions. Average daily temperature was significantly higher in tall guards compared to milk cartons and ambient conditions at the upper‐slope site only. There were no significant differences in average minimum temperature between guard types at all landscape positions. [ABSTRACT FROM AUTHOR]

Feedbacks between vegetation spatial pattern and resource redistribution from bare areas (sources) to vegetation patches (sinks) are considered critical to the functioning of dryland ecosystems. However, experimental fieldworks testing the underlying assumptions and quantifying the feedbacks involved are very scarce. We hypothesized that the size and surface conditions of the upslope runoff-source areas control the transfer of resources to the downslope vegetation patch, and thereby vegetation performance. In a restored semiarid woodland in Alicante, SE Spain, we investigated the performance of planted shrubs ( Olea europaea and Pistacia lentiscus) in response to the size, upslope length, internal connectivity and soil surface properties of their respective upslope runoff-source areas (drainage microcatchments). Growth of O. europaea seedlings increased with drainage microcatchments size, whilst their water-stress level decreased with the upslope hillslope length. Lower plant density and higher bare-soil connectivity within the respective microcatchments improved the performance of O. europaea seedlings. Seedling survival was much lower for P. lentiscus than for O. europaea, and growth and water-stress of alive P. lentiscus seedlings showed no significant relationships with any of the microcatchment properties assessed. Survival of P. lentiscus seedlings increased with hillslope length upslope the seedling location. Overall, results point to the interplay between the size and connectivity of the bare-soil upslope interpatch and the relative location on the hillslope as the most relevant control factors for seedling performance. Observed linkages between source-sink dynamics and plant performance provide valuable information for improving the design of conservation and restoration actions in semiarid lands. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Ricinus communis is becoming an important crop for oil production, and studying the physiological and biochemical aspects of seedling development may aid in the improvement of crop quality and yield. The objective of this study was to assess the effect of temperature on biomass allocation in two R. communis genotypes. Biomass allocation was assessed by measuring dry weight of roots, stems, and cotyledons of seedlings grown at three different temperatures. Root length of each seedling was measured. Biomass allocation was strongly affected by temperature. Seedlings grown at 25 °C and 35 °C showed greater biomass than seedlings grown at 20 °C. Cotyledon and stem dry weight increased for both genotypes with increasing temperature, whereas root biomass allocation showed a genotype-dependent behavior. Genotype MPA11 showed a continuous increase in root dry weight with increasing temperature, while genotype IAC80 was not able to sustain further root growth at higher temperatures. Based on metabolite and gene expression profiles, genotype MPA11 increases its level of osmoprotectant molecules and transcripts of genes encoding for antioxidant enzymes and heat shock proteins to a higher extent than genotype IAC80. This might be causal for the ability to maintain homeostasis and support root growth at elevated temperatures in genotype MPA11. [ABSTRACT FROM AUTHOR]

The sand medium experiment was conducted in the laboratory with the aim of evaluating the suitability of municipal wastewater (treated and untreated) at different concentrations (0, 2.5, 5, 10, 25, 50, and 100%) for irrigation purposes on seed germination, seedling performance, nutrient uptake, and chlorophyll content of rice (MR220). The utilization of municipal wastewater for irrigation purposes has developed an important way to exploit the nutrients it contains. The study indicated a significant ( P < 0.05) difference between untreated and treated municipal wastewater for seedling length (SL), root volume (RV), root surface area (RSA), seedling vigor index (SVI), and root: shoot ratio (R : S) while no significant different was observed between untreated and treated municipal wastewater for germination percentage (GP) and percentage phytotoxicity (PPT). The municipal wastewaters had stimulatory effect on the rice seeds at lower wastewater concentrations (< 25%) while inhibitory effect was observed at higher wastewater concentrations (> 50%). N, P, K, Ca, Mg, Zn, Fe, Cu, and Mn were high in the untreated municipal wastewater compare to treated municipal wastewater. Seedlings irrigated with untreated municipal wastewater have high seed germination, seedling performance with high nutrient uptake compare to treated municipal wastewater. The municipal wastewaters showed inhibitory effect on chlorophyll content. The inhibition effect was observed at > 50% concentration of both untreated and treated municipal wastewater while promoting effects were observed at lower (< 25%) concentration. The rice MR220 variety showed better growth resistance, tolerance, and adaptability to wastewater. This can be due to its excellent genetic makeup and capacity to sustain the toxicity. Conclusively, municipal wastewater could be recommended as a good source of water and nutrient for seed germination and seedling performance. [ABSTRACT FROM AUTHOR]

Cultivation of important woody species with the goal of conserving them is hampered by little, or no, information on how such species can be propagated or their seedlings established. We investigated propagation and seedling establishment of 14 important multipurpose species much valued for traditional medicine in Uganda. The experiments included sexual and vegetative propagation, as well as a seedling growth experiment. The multipurpose speciesPsidium guajava, Markamia lutea, Maesopsis eminiiandSpathodea campanulatapropagated easily from seed, andFicus natalensisfrom cuttings. The medicinal speciesZanthoxylum leprieurii, Warburgia ugandensisandFicus saussureanadid not germinate at all.Toddalia asiaticaandCanarium schweinfurthiihad high dormancy and low synchrony of seed emergence.Markamia luteaseedlings established readily with addition of fertilizer (NPK) and moderate watering (three times a week). We conclude that whereas the multipurpose use species appear to propagate easily, the medicinal plants are difficult to propagate sexually or asexually. [ABSTRACT FROM AUTHOR]

Recent studies have provided evidence that trade-offs in biomass allocation, resource-use efficiency, and anti-herbivore defense influence seedling performance and distribution across soil types. Our previous research suggested that soil nutrient availability acted as a filter for understory palm community assembly and species coexistence in a lower montane forest in western Panama. Here, we experimentally tested three potential mechanisms that could be driving this filtering of palm communities along a soil nutrient gradient. We examined seedling performance of 13 understory palm taxa with differing distribution patterns transplanted to five sites, where they were both exposed to and protected from herbivores. We found the strongest evidence for habitat filtering at the lowest-nutrient site, where seedlings of locally occurring species had significant performance advantages over those of locally absent species, regardless of protection from herbivores. When transplanted to the lowest-nutrient site, seedlings of naturally occurring species maintained high above- to belowground biomass ratios, maximized photosynthetic nitrogen-use efficiency, and minimized leaf area loss to herbivores and pathogens. Species from low-fertility sites were therefore able to maintain higher survival and relative growth rates (RGR) at the lowest-nutrient site than species from more fertile sites. Similar patterns were found for a high-nutrient site, where naturally occurring species had higher RGR compared to species from lower-fertility sites. However, the functional traits associated with the differences in performance at high-nutrient sites were less clear, perhaps due to increased light limitation in the understory of these sites. At higher-nutrient sites, protection from herbivores significantly reduced leaf area damage and mortality rates in seedlings, particularly for naturally occurring species. Overall, morphological and physiological traits were more strongly coupled with soil nutrient availability than were leaf damage or seedling performance across the sites. Nonetheless, the coordination of all three trade-offs was related to the strongest performance advantage and, therefore, ecological filtering along the soil nutrient gradient in this lower montane forest. [ABSTRACT FROM AUTHOR]

One of the most commonly cited hypotheses explaining invasion success is the enemy release hypothesis (ERH), which maintains that populations are regulated by coevolved natural enemies where they are native but are relieved of this pressure in the new range. However, the role of resident enemies in plant invasion remains unresolved. We conducted a field experiment to test predictions of the ERH empirically using a system of native, introduced invasive, and introduced non-invasive Eugenia congeners in south Florida. Such experiments are rarely undertaken but are particularly informative in tests of the ERH, as they simultaneously identify factors allowing invasive species to replace natives and traits determining why most introduced species are unsuccessful invaders. We excluded insect herbivores from seedlings of Eugenia congeners where the native and invasive Eugenia co-occur, and compared how herbivore exclusion affected foliar damage, growth, and survival. We found no evidence to support the ERH in this system, instead finding that the invasive E. uniflora sustained significantly more damage than the native and introduced species. Interestingly, E. uniflora performed better than, or as well as, its congeners in terms of growth and survival, in spite of higher damage incidence. Further, although herbivore exclusion positively influenced Eugenia seedling survival, there were few differences among species and no patterns in regard to invasion status or origin. We conclude that the ability of E. uniflora to outperform its native and introduced non-invasive congeners, and not release from insect herbivores, contributes to its success as an invader in Florida. [ABSTRACT FROM AUTHOR]

The framework species method of reforestation, developed by FORRU (Forest Restoration Research Unit) has been used successfully to restore evergreen forest on degraded former agricultural sites in Doi Suthep-Pui National Park, Chiang Mai province, Thailand. This paper reports 3 year results of an attempt to duplicate the FORRU reforestation techniques at Ban Toong Yah, Mae Chaem district, at a similar elevation as FORRU’s original plots at Ban Mae Sa Mai, Mae Rim district. Twenty species of framework tree seedlings were planted in June 2002. The 2 year results indicate that the seedlings achieved lower survival rates than at the FORRU’s original site. Height growth, root collar diameter, and crown width were also lower. Some seedlings died because they were trampled by cows, which also ate some of the seedlings. However, several sapling species, such as Ficus fistulosa and Phyllanthus emblica, were able to produce new shoots from their axillary buds, after having been browsed by cows. In 2004, 5 well-performed species: Castanopsis tribuloides, Ficus fistulosa, Hovenia dulcis, Ostodes paniculata and Prunus cerasoides, were selected along with 12 never-planted species to be planted in June. The results indicate that the seedlings achieved lower survival rates than at the FORRU’s original site. The seedlings achieved an average survival rate of about 50 % after the first growing season. The exposed, windy environment of the planting site might also account for lower than expected growth and survival rates. The FORRU’s recommended methods of site preparation using herbicide and weed suppression using cardboard mulch may be employed to improve seedling survival and growth on this site.

The sowing depth can influence the seedling emergence and its initial establishment. The aim of this study was to evaluate the influence of sowing depth on the expression of vigor and initial performance of bean seedlings. The cultivars used were IPR-Gralha and IPR-Tiziu and the treatments consisted of different sowing depths 15, 30, 45 and 60 mm. The parameters evaluated were emergence, seedling length (root and shoot), seedling dry weight (root and shoot), leaf area, shoot/root ratio and leaf area ratio. The emergence and seedling dry weight were reduced with the sowing depth. The leaf area ratio increased in the cultivar IPR-Tiziu until depth of 30 mm and in the cultivar IPR-Gralha increased with the depth of sowing. Increased sowing depth decreased the vigor expression and initial performance of bean seedlings. [ABSTRACT FROM AUTHOR]

One particularly compelling explanation for the success of invasive species is the ability to outperform other species in characteristics affecting fitness. Past studies have compared native or introduced non-invasive species to their invasive counterparts, while a system incorporating both native and introduced non-invasive congeners provides an opportunity for multiple controls. We used such a system of Eugenia congeners in Florida to compare seedling performance. In order to determine if invasive Eugenia uniflora seedlings outperform those of its congeners, we sowed seeds in the field and a common garden and quantified seedling emergence, growth, and survival, as well as foliar damage by insect herbivores. We obtained similar results in the field and garden experiments. Although there were no differences in seedling emergence for E. uniflora seedlings when compared to some of its introduced congeners in certain years, emergence of E. uniflora seedlings was consistently high across years. However, emergence, growth, and survival rates of native species were consistently low. In addition, E. uniflora outperformed its introduced and native congeners in growth and survival traits in most comparisons, even when sustaining higher levels of herbivore damage by an introduced weevil, Myllocerus undatus Marshall. Our results support our predictions, indicating that invasive E. uniflora may possess a competitive advantage because its seedlings perform better than or equivalently to its congeners in all of the attributes quantified. Our study further suggests that measurements of such traits may be useful in determining the likelihood of invasion by newly introduced woody plant species. [ABSTRACT FROM AUTHOR]