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Seedling Growth (seedling + growth)

Distribution by Scientific Domains

Life Sciences	60%
Earth and Environmental Science	32%
Chemistry	5%

Distribution within Life Sciences

Plant Science	30%
Ecology & Organismal Biology	16%

Kinds of Seedling Growth

early seedling growth

Selected Abstracts

Seedling Growth of Agronomic Crops in Crude Oil Contaminated Soil

JOURNAL OF AGRONOMY AND CROP SCIENCE, Issue 4 2006
I. Issoufi
Abstract Phytoremediation of hydrocarbon-contaminated soil shows promise as a low-cost alternative to most remediation methods. This study evaluated seedling growth of six crop species in crude oil contaminated soils. The experiments were conducted in a greenhouse. Weathered crude oil was added to an Ipava silt loam soil at the rate of 0 (control), 10, 50 and 100 g of crude oil kg,1 of soil, which was then placed into pots. Irrigation was used to maintain soil moisture at approximately field capacity. Five seeds of Zea mays, Meticago sativa, Lolium perenne, Triticum aestivum, Glycine max or Vicia villosa were sown per pot. The experimental design was completely randomized with five replications per treatment. Germination and seedling height data were recorded on day 7, 14, 21 and 28. Plants were harvested on day 28, separated into shoots and roots and dried to measure biomass. Analysis of variance was used to determine treatment significance. Significant treatment mean values were separated using Tukey's Honestly Significant Difference Test. Based upon percent emergence and plant biomass production in contaminated soil, Z. mays and G. max seedlings show the greatest potential to enhance remediation. [source]

Allelopathic Effects of Parthenium hysterophorus Extracts on Seed Germination and Seedling Growth of Eragrostis tef

JOURNAL OF AGRONOMY AND CROP SCIENCE, Issue 5 2002
T. Tefera
The present study was conducted to investigate the allelopathic effects of Parthenium hysterophorus weed on seed germination and seedling growth of tef. Flower, stem, root and leaf aqueous extracts of Parthenium at 0, 1, 5, and 10 % concentrations were applied to determine their effect on tef seed germination and seedling growth under laboratory conditions. Increasing concentrations of aqueous extracts of Parthenium from leaf and flower inhibited seed germination and complete failure of seed germination was recorded when the extract concentration from the leaf part was 10 %. In contrast, aqueous extracts from stem and root had no effect on tef seed germination. Roots appeared more sensitive to allelopathic effect than shoots. Extracts from flower, root and stem had a stimulatory effect on shoot length at all concentration levels, as against an inhibitory effect of leaf extracts. Root extracts at low concentration (1 %) greatly promoted root length but aqueous extracts from leaf and flower inhibited root length. [source]

Comparative Effects of NaCl and Polyethylene Glycol on Germination, Emergence and Seedling Growth of Cowpea

JOURNAL OF AGRONOMY AND CROP SCIENCE, Issue 4 2002
B. Murillo-Amador
Abstract Seeds of Paceño and Cuarenteño cultivars of cowpea (Vigna unguiculata L. Walp.) were tested for salt and drought tolerance at germination, seedling emergence and early seedling growth in NaCl and PEG-8000 solutions of different osmotic potentials (0, ,0.2, ,0.4, ,0.6, and ,0.8 MPa). Daily and final germination and emergence percentage, as well as germination and seedling emergence rate, and seedling growth were recorded under controlled conditions. Results showed that germination and emergence rate were delayed by both solutions in both cultivars, with differences between cultivars among growth stages, given that cultivar Cuarenteño, showed a higher germination rate than Paceño in NaCl, but Paceño was less affected by NaCl and PEG solutions at the emergence stage. Sodium chloride had a lesser effect on both cultivars in terms of germination rate, emergence rate and the final germination and emergence percentage than did PEG-8000. This conclusively proves that the adverse effect of PEG-8000 on germination, emergence and early seedling growth was due to the osmotic effect rather than the specific ion. Seedling growth was reduced by both stresses, but NaCl usually caused less damage than PEG to cowpea seedlings, suggesting that NaCl and PEG acted through different mechanisms. Zusammenfassung Vergleich der Wirkungen von NaCl und Polyethylenglykol auf die Keimung, das Auflaufen und das Sämlingswachstum von Kuhbohne Samen von Paceño- und Cuarenteño-Kultivaren von Kuhbohne (Vigna unguiculata L. Walp.) wurden hinsichtlich Salz- und Dürretoleranz zum Zeitpunkt der Keimung, des Sämlingsauflaufens und des frühen Sämlingswachstums in NaCl- und PEG-8000-Lösungen mit unterschiedlichem osmotischen Potential (0, ,0.2, ,0.4, ,0.6 und ,0.8 MPa) untersucht. Tägliche und abschließende Keimungs- und Auflaufprozente sowie Keimung und Sämlingsauflaufrate und Sämlingswachstum wurden unter kontrollierten Bedingungen bestimmt. Die Ergebnisse zeigen, dass die Keimung und die Auflaufrate durch beide Lösungen verzögert wurden bei beiden Kultivaren, wobei Unterschiede zwischen den Kultivaren hinsichtlich der Wachstumsstadien auftraten; der Kultivar Cuarenteño zeigte eine höhere Keimungsrate als Paceño in NaCl, während Paceño weniger beeinflusst wurde durch NaCl und PEG-Lösungen im Auflaufstadium. Natriumchlorid hatte einen geringeren Einfluss bei beiden Kultivaren hinsichtlich der Keimungsrate, der Auflaufrate und der abschließenden Keimungs- und Auflaufprozente als PEG-8000. Dies bestätigt, dass der ungünstige Einfluss von PEG-8000 auf die Keimung, das Auflaufen und das frühe Sämlingswachstum eine Folge des osmotischen Einflusses und nicht einer spezifischen Ionenwirkung ist. Sämlingswachstum war durch beide Behandlungen beeinträchtigt, aber NaCl zeigte meist eine geringere Schädigung als PEG bei Kuhbohnensämlingen; das lässt vermuten, dass NaCl und PEG durch unterschiedliche Mechanismen einwirken. [source]

Seedling Growth and Heavy Metal Accumulation of Candidate Woody Species for Revegetating Korean Mine Spoils

RESTORATION ECOLOGY, Issue 4 2008
Kyung Won Seo
Abstract Selecting plant species that can overcome harsh soil and microclimatic conditions and speed the recovery of degraded minelands remains a worldwide restoration challenge. This study evaluated the potential of three woody species and various organic and inorganic fertilization treatments for revegetating abandoned metalliferous mines in Korea. We compared survival, growth, and heavy metal uptake of species common to Korean minelands in two spoil types and a reference forest soil. Substrate type and fertilization both influenced seedling growth and metal concentrations substantially, but they had little effect on seedling survival. Fertilization increased the growth of all three species when grown in mine spoils but influenced the growth of seedlings grown in forest soil only marginally. Initial seedling survival and growth indicate that the study species can tolerate the heavy metal concentrations and other soil constraints of metalliferous spoil types. We estimate that plants can stabilize 2,22% of various heavy metals contained in spoil materials into plant biomass during 20 years of plantation growth. Combined with the erosion control and site amelioration benefits of mineland reforestation, stabilization of heavy metals in forest biomass justifies this treatment on abandoned Korean metalliferous mines. [source]

Optimizing Hardwood Reforestation in Old Fields: The Effects of Treeshelters and Environmental Factors on Tree Seedling Growth and Physiology

RESTORATION ECOLOGY, Issue 2 2008
Etienne Laliberté
Abstract Strong competition for water is largely recognized as the main factor explaining the resistance of herbaceous old fields to tree invasion. Therefore, site preparation as well as chemical and mechanical vegetation control are recommended when establishing hardwood tree plantations on such sites, but those methods are sometimes socially or ecologically inappropriate. The main objective of this study was to analyze whether treeshelters could improve early tree growth in herbaceous old fields, when mulching alone is used to partially control herbaceous competition. Our results indicate that treeshelters can facilitate tree growth in those conditions but that this was not caused by an improvement of tree water relations. Rather, it appeared to be related to an optimization of light levels inside the shelter, where light intensity was low enough to lead to a photosynthetic system less costly to maintain due to a greater specific leaf area but high enough to have no adverse effects on photosynthetic rates. Although treeshelters increased tree growth when surrounding herbaceous vegetation was low (either height or standing biomass), allowing high light levels, they reduced growth when surrounding vegetation was high and blocked a substantial quantity of light. Therefore, environmental factors such as light availability need to be considered to optimize the success of hardwood plantations when treeshelters are used in recently abandoned agricultural fields. [source]

Chemical Characterization of New Oxylipins from Cestrum parqui, and Their Effects on Seed Germination and Early Seedling Growth

CHEMISTRY & BIODIVERSITY, Issue 9 2008
Antonio Fiorentino
Abstract Isolation, chemical characterization, and phytotoxicity of five new oxylipins, together with seven already known related compounds, from Cestrum parqui L',Hérl. is reported. All the structures were elucidated on the basis of their spectral data, especially 1D- (1H- and 13C-NMR, DEPT) and 2D-NMR (COSY, TOCSY, HSQC, HMBC, and NOESY). The configurations of the stereogenic C-atoms were determined by the Mosher's method. The compounds have been assayed for their phytotoxicity on Lactuca sativa at concentrations ranging between 10,4 and 10,8,M. The results of the phytotoxicity tests on the germination and growth of the test species, obtained by a cluster analysis, showed interesting relationship between the chemical structures of the compounds and their biological effects. [source]

Pronounced drought tolerance characterizes the early life stages of the epiphytic bromeliad Tillandsia flexuosa

FUNCTIONAL ECOLOGY, Issue 3 2009
Maaike Y. Bader
Summary 1Germination and seedling performance may set the limits for plant distributions, particularly in stressful habitats. Stressful conditions at these early stages may be avoided by opportunistic germination and growth, or may be tolerated. Many epiphytic plants are frequently exposed to severe drought. Adult epiphytes endure such dry periods in various ways, but little is known about strategies employed during germination and early life. 2Epiphyte seedlings could show either opportunistic fast growth to quickly attain the benefits of being larger or inherently slow growth and early drought tolerance. Here we address the question: which of these strategies characterizes the early life stages of the epiphytic bromeliad Tillandsia flexuosa, a species typical for dry tropical habitats? 3We studied growth and drought tolerance of germinating seeds, of the emerging seedlings and of 2-month-old seedlings under controlled conditions. Additionally, we studied drought hardening in 6-month-old seedlings. 4Germination of T. flexuosa was reduced by intermittent dry periods. However, compared to the congeneric T. fasciculata, which typically occurs in wetter habitats, the depression of germination by drought was small. Seedling growth was fastest at intermediate moisture levels: both prolonged drought and continuous moisture depressed growth. Prolonged drought had a less negative effect on drought-hardened seedlings than on previously well-watered seedlings. After a 3-week drought treatment the previously well-watered seedlings had lost their growth advantage entirely. Had drought continued, they would have probably been starved, indicated by the low level of their non-structural carbohydrate pool. 5Tillandsia flexuosa employs a stress-tolerance strategy both during germination and during the seedling stage. In its epiphytic habitat this strategy is clearly adaptive, considering the predictable briefness of moisture availability throughout the year and the low competition pressure that allows the very slow growth typically seen in adults and seedlings. These conditions characterize not only the dry-forest habitat of T. flexuosa, but all exposed epiphytic growing sites, so we expect this early stress-tolerance to be common among epiphytes in general. Still, a lower stress tolerance in species from wetter habitats may at least partly explain why T. flexuosa shares its dry-forest habitat with so few other vascular epiphytes. [source]

Comparative Effects of NaCl and Polyethylene Glycol on Germination, Emergence and Seedling Growth of Cowpea

Effects of experimental canopy gaps on mangrove recruitment: lack of habitat partitioning may explain stand dominance

JOURNAL OF ECOLOGY, Issue 2 2004
Peter J. Clarke
Summary 1Few species of Indo-pacific mangroves co-occur at spatial scales of canopy gaps despite environmental heterogeneity and a flora that has varied physiological and morphological traits, but experiments on why such communities are species poor are uncommon. 2Lack of habitat partitioning, in concert with competitive exclusion, may explain low species richness at canopy gap scales. This study examined whether mangrove recruitment differs among species with respect to the effect of forest gap size, ground disturbance, position along an intertidal gradient and canopy membership. 3The canopy of a tropical mangrove forest in northern Australia was experimentally manipulated to create two gap sizes (50 m2 and 225 m2) in low and high intertidal forests with or without sediment disturbance. Propagules of six species, from three mangrove families, were sown into treatments and their predation, establishment, growth and survival measured for 5 years. 4All species established, and five survived, in canopy gaps in both high and low intertidal positions. Interspecific difference in establishment, growth and survival of seedlings in two intertidal positions were not closely matched to canopy membership and hence this does not explain zonation. 5No seedlings survived under the canopy and there was little evidence for shade-tolerant species. The interactions between canopy treatments and sediment disturbance that would have indicated gap partitioning were not detected. Seedling growth and survival was enhanced in large canopy gaps but there were no growth differences among species that matched canopy membership of plots. 6Most species appear to be able to recruit in canopy gaps if there is no dispersal limitation. Rather, the range of species available to fill gaps is limited because predation of propagules advantages species that are from the adjacent canopy. Lack of partitioning of resources within gaps by species may result in the exclusion of competitors that are not canopy members, further reducing coexistence. [source]

Seedling growth and morphology of three oak species along field resource gradients and seed mass variation: a seedling age-dependent response

JOURNAL OF VEGETATION SCIENCE, Issue 3 2010
Ignacio M. Pérez-Ramos
Abstract Question: What is the relative importance of seed mass and abiotic factors in species-specific seedling growth and morphology during the first and the second growing season? How do oak species respond along gradients of these factors? Location: Mediterranean oak forest in southern Spain. Methods: We analysed seedling growth components and morphology of three co-occurring Quercus species (two deciduous and one evergreen). Oak seeds with a wide variety of sizes were sown along broad gradients of abiotic conditions. Intra- and inter-specific differences were evaluated by calibrating maximum likelihood estimators of seedling growth during the first two years of life. Results: We found multiple resources and conditions affecting seedling morphology and biomass allocation. However, the integrative variables of seedling growth , total aboveground biomass and relative growth rate (RGR) , were affected by two main factors: seed mass and light conditions. The relative contribution of these two factors depended strongly on seedling age. Seed mass explained most of the growth and morphological variables during the first year, while light conditions were the best predictor in the second growing season. In contrast, soil factors did not play an important role in seedling growth. We found some evidence of regeneration niche partitioning between oak species along the light gradient, a reflection of their distribution patterns as adults at the study site. Conclusions: We conclude that inter-specific differences in seedling growth, arising from seed size variability and microsite heterogeneity, could be of paramount importance in oak species niche segregation, driving stand dynamics and composition along environmental gradients. [source]

Effect of Grazing on Restoration of Endemic Dwarf Pine (Pinus culminicola Andresen et Beaman) Populations in Northeastern Mexico

RESTORATION ECOLOGY, Issue 1 2005
J Jiménez
Abstract A pilot experiment designed to test the effect of cattle, small mammals, and elevation on the success of reforestation of an endemic dwarf pine species in northeastern Mexico was implemented. Pinus culminicola (Andresen et Beaman) grows only in four high peaks in the Sierra Madre Oriental and is under pressure from grazing, wildfires, and human activities such as mining, road development for timber extraction, and telecommunication and aerial navigation devices. We planted and monitored 2-year-old seedlings at three elevations within the natural distribution range of this species at Cerro El Potosí in Nuevo León, Mexico. At each elevation three treatments were established: (1) seedlings protected from cattle plus small mammals, (2) seedlings protected from cattle, and (3) seedlings with free access to cattle and small mammals. Seedling survival was approximately 50% in (1) after 4 years, but there were no surviving seedlings with free access to cattle. Elevation in general did not account for variation in survival. Seedling growth was poor during the 4 years, which implies that seedlings remain susceptible to grazing and trampling by cattle and small mammals. The implications for a large-scale restoration program are discussed. [source]

Seedling Mortality and Herbivory Damage in Subtropical and Temperate Populations: Testing the Hypothesis of Higher Herbivore Pressure Toward the Tropics

BIOTROPICA, Issue 2 2010
Ek Del-Val
ABSTRACT Herbivory rates are generally thought to be higher in tropical than in temperate forests. Nevertheless, tests of this biogeographic prediction by comparing a single plant species across a tropical-temperate range are scarce. Here, we compare herbivore damage between subtropical and temperate populations of the evergreen tree Aextoxicon punctatum (Olivillo), distributed between 30° and 43° S along the Pacific margin of Chile. To assess the impact of herbivory on Olivillo seedlings, we set up 29 experimental plots, 1.5 × 3 m: 16 in forests of Fray Jorge National Park (subtropical latitude), and 13 in Guabún, Chiloé Island (temperate latitude). Half of each plot was fenced around with chicken wire, to exclude small mammals, and the other half was left unfenced. In each half of the plots we planted 16 seedlings of Olivillo in December 2003, with a total of 928 plants. Seedling survival, leaf production and herbivory by invertebrates were monitored over the next 16 mo. Small mammal herbivores killed ca 30 percent of seedlings in both sites. Nevertheless, invertebrate herbivory was greater in the temperate forest, thus contradicting the expected trend of increasing herbivore impact toward the tropics. Seedling growth was greater in subtropical forest suggesting better conditions for tree growth or that higher invertebrate herbivory depressed seedling growth in the temperate forest. Invertebrate herbivory increased toward temperate latitudes while small mammal herbivory was similar in both sites. We suggest that comparison of single species can be useful to test generalizations about latitudinal patterns and allow disentangling factors controlling herbivory patterns across communities. Abstract in Spanish is available at http://www.blackwell-synergy.com/loi/btp [source]

Species-specific Seedling Responses to Hurricane Disturbance in a Puerto Rican Rain Forest1

BIOTROPICA, Issue 4 2003
Lawrence R. Walker
ABSTRACT Seedling dynamics were followed in a Puerto Rican forest for 20 months following a severe hurricane to study the interactive effects of hurricane debris, nutrients, and light on seedling diversity, density, growth, and mortality. Three treatments (debris removal, an unaltered control with hurricane debris, and chemical fertilization added to hurricane debris) altered levels of forest debris and soil nutrients. Canopy openness was measured twice using hemispherical photographs of the canopy. We examined the demographic responses of six common species to treatments over time. Seedling densities increased for all six species but the only significant treatment effects were increased densities of the pioneer tree Cecropia and the shrub Palicourea in the debris removal treatment. Seedling growth declined with declining light levels for four species but not for the pioneer tree Alchornea or the non-pioneer tree Dacryodes. Only Cecropia and the non-pioneer tree Chionanthus had treatment effects on growth. Mortality also differed among species and tended to be highest in the fertilized plots for all but Cecropia and Dacryodes. We found only some of the expected differences between pioneer and non-pioneer plants, as each species had a unique response to the patchy distributions of organic debris, nutrients, and light following the hurricane. High local species diversity was maintained through the individualistic responses of seedlings after a disturbance. RESUMEN Seguimos la dinámica de plántulas en un bosque en Puerto Rico durante 20 meses después del huracán Hugo para estudiar el efecto de la interacción de hojarasca de huracán, nutrientes, y luz sobre la diversidad de especies, la densidad, el crecimiento, y la mortalidad. Establecimos tres tratamientos (remoción de hojarasca, control con la hojarasca de huracán inalterada, y fertilizante químico añadido a la hojarasca del huracán) para alterar los niveles de hojarasca en el bosque y los nutrientes en el suelo. Medimos luz directa e indirecta dos veces usando fotografias hemisféricas del dosel. La diversidad y la uniformidad en la distribución de especies pero no la riqueza de especies fueron reducidas en presencia de fertilización. Durante el estudio examinamos respuestas demográficas de seis especies communes a los tratamientos. La densidad de plántulas aumentó para todas las seis especies pero el único efecto de tratamiento fue el aumento en la densidad del árbol pionero Cecropia y el arbusto Palicourea en el tratamiento de remoción de hojarasca. El crecimiento de plántulas disminuyó según los niveles de luz disminuyeron para cuatro de las especies pero no para el árbol pionero Alchornea o el árbol nopionero Dacryodes. Sólo el crecimiento de Cecropia y del árbol no-pionero Chionanthus fue affectado por los tratamientos. La mortalidad fue diferente entre las especies y tuvo una tendencia a ser mayor en las parcelas fertilizadas. Sólo encontramos algunas de las diferencias esperadas entre plantas pioneras y no-pioneras. Cada especie respondió de forma única a la distribución en parches de hojarasca, nutrientes, y luz luego del huracán. La aha diversidad local de especies se mantuvo a través de las respuestas individualizadas de las plántulas después de la perturbación. [source]

Threatened Peripheral Populations in Context: Geographical Variation in Population Frequency and Size and Sexual Reproduction in a Clonal Woody Shrub

CONSERVATION BIOLOGY, Issue 3 2007
SARAH B. YAKIMOWSKI
especies en riesgo; límites de distribución; poblaciones periféricas; reproducción sexual; Vaccinium stamineum Abstract:,Geographically peripheral populations of widespread species are often the focus of conservation because they are locally rare within political jurisdictions. Yet the ecology and genetics of these populations are rarely evaluated in a broader geographic context. Most expectations concerning the ecology and evolution of peripheral populations derive from the abundant-center model, which predicts that peripheral populations should be less frequent, smaller, less dense, and have a lower reproductive rate than central populations. We tested these predictions and in doing so evaluated the conservation value of peripheral populations for the clonal shrub Vaccinium stamineum L. (Ericaceae, deerberry), which is listed as threatened in Canada. Based on 51 populations sampled from the center to the northern range limits over 2 years, population frequency and size declined toward the range limit, but ramet density increased. Sexual reproductive output varied widely among populations and between years, with many populations producing very few seeds, but did not decline toward range margins. In fact seed mass increased steadily toward range limit, and this was associated with faster germination and seedling growth, which may be adaptive in seasonal northern environments. Our results did not support the prediction that clonal reproduction is more prevalent in peripheral populations or that it contributed antagonistically to the wide variation in seed production. Peripheral populations of V. stamineum are as productive as central populations and may be locally adapted to northern environments. This emphasizes the importance of a broad geographical perspective for evaluating the ecology, evolution, and conservation of peripheral populations. Resumen:,Las poblaciones geográficamente periféricas de una especie de amplia distribución a menudo son el foco de conservación porque son raras localmente dentro de jurisdicciones políticas. Sin embargo, la ecología y genética de estas poblaciones son evaluadas poco frecuentemente en un contexto geográfico más amplio. La mayoría de las expectaciones relacionadas con la ecología y evolución de las poblaciones periféricas se derivan del modelo centro-abundante, que predice que las poblaciones periféricas son menos frecuentes, más pequeñas, menos densas y menor tasa reproductiva que poblaciones centrales. Probamos estas predicciones y al hacerlo evaluamos el valor de conservación de poblaciones periféricas de una especie de arbusto clonal (Vaccinium stamineum L., Ericaceae), que está enlistada como amenazada en Canadá. Con base en 51 poblaciones muestreadas del centro hacia los límites norteños de su distribución durante 2 años, la frecuencia y tamaño poblacional declinó hacia los límites de su distribución, pero la densidad de rametos aumentó. La reproducción sexual varió ampliamente entre las poblaciones y entre años, con muchas poblaciones produciendo muy pocas semillas, pero no declinó hacia los límites de su distribución. De hecho, la masa de semillas incrementó sostenidamente hacia los límites, y esto se asoció a una acelerada germinación y crecimiento de plántulas, lo cual puede ser adaptativo en ambientes norteños estacionales. Nuestros resultados no sustentaron la predicción de que la reproducción clonal es más prevaleciente en poblaciones periféricas o que contribuye antagónicamente a la amplia variación en la producción de semillas. Las poblaciones periféricas de V. stamineum son tan productivas como las poblaciones centrales y pueden estar adaptadas localmente a ambientes norteños. Esto enfatiza la importancia de una perspectiva geográfica amplia cuando se evalúa la ecología, evolución y conservación de poblaciones periféricas. [source]

Do shade-tolerant tropical tree seedlings depend longer on seed reserves?

FUNCTIONAL ECOLOGY, Issue 4 2002
Functional growth analysis of three Bignoniaceae species
Summary 1.,A functional growth analysis was used to determine the duration of strict dependency on seed reserves for energy and nitrogen in three woody Bignoniaceae species (Tabebuia rosea DC., Challichlamys latifolia K. Schum. and Pithecoctenium crucigerum A. Gentry) which differed in cotyledon function (photosynthetic, semi-photosynthetic and storage) and shade tolerance (probability of seedling establishment and survival in the understorey). 2.,Seedlings were raised from seeds in sand culture under combinations of three nitrogen levels (daily supply of nutrient solution containing 100, 10 and 0% of 2·6 mm N) and two irradiances (27 and 1% full sun). Time course of biomass, non-cotyledonous biomass and leaf area for 40 days post-germination were compared to identify when the external availability of nitrogen or light began to affect seedling growth. 3.,Seedlings of all species became dependent on external energy supply earlier than they did on nitrogen supply. In all species seed nitrogen was sufficient to support positive seedling growth for 40 days in shade, but not in sun. 4.,Tabebuia rosea with photosynthetic cotyledons responded to light availability earlier than more shade-tolerant species with storage cotyledons. Challichlamys latifolia, the most shade-tolerant species, had the highest nitrogen concentration in seeds and was the last to respond to external nitrogen availability. Thus seedlings of the most shade-tolerant species depended on seed reserves for the longest period for both energy and nitrogen. 5.,Relative growth rate after seedlings initiated autotrophic growth was in a trade-off relationship with seedling survivorship in the understorey across the three species. Tabebuia rosea, the least shade-tolerant species, had the highest positive net carbon balance in sun and shade. 6.,Functional morphology of cotyledons and concentration of seed nitrogen deserve as much attention as seed size as correlates of contrasting seedling regeneration strategies. [source]

Effect of seed coating on plant growth and soil conditions: A preliminary study for restoration of degraded rangeland in the Qinghai,Tibetan Plateau, China

GRASSLAND SCIENCE, Issue 3 2010
Yingchun Liu
Abstract Rangeland degradation is a significant problem in the Qinghai,Tibetan Plateau, China. Restoration of the degraded rangelands through reseeding is being undermined by poor seedling growth under adverse soil moisture and nutrition conditions. Accordingly, seeds of Italian ryegrass (Lolium multiflorum) and Chinese milk vetch (Astragalus sinicus) were coated with a mixture of hygroscopic and plant-derived polysaccharide gums and alga powder (Phaeocystis sp. necolon-1), and inoculated with spores of microorganisms (Aspergillus sp. and Streptomyces sp.), serving as coating mixture decomposers, in order to improve rhizosphere moisture and nutrition. In a growth chamber simulating spring climate on the Plateau, seedling emergence of the coated seeds was 60,80 and 48,82%, respectively, for the two plant species in comparison to 38 and 24% for the uncoated seeds, which was due to moisture being supplied by the coat. In the outdoor pots with soil texture and moisture conditions similar to those of the degraded rangelands on the Plateau, dry weight of the plants from the coated seeds was 109,184 and 118,156 mg plant,1 for the respective plant species, while that of the plants from uncoated seeds was 18,20 and 10,11 mg plant,1. The number of Rhizobium sp. nodules on Chinese milk vetch plants from the coated seeds was 21,25 plant,1 while 0,2 in plants from uncoated seeds. Enhancement of plant growth was caused by increased activity of soil microbes. Plant growth on the soil after sampling plants from the coated seeds was also enhanced, indicating sustainability of improvement of soil conditions. Thus seed coating with hygroscopic nutrient-source materials and inoculation with microorganism spores as slow decomposers of the coating materials is a promising method for restoring degraded rangelands. [source]

Seedling Growth of Agronomic Crops in Crude Oil Contaminated Soil

Allelopathic Effects of Parthenium hysterophorus Extracts on Seed Germination and Seedling Growth of Eragrostis tef

Comparative Effects of NaCl and Polyethylene Glycol on Germination, Emergence and Seedling Growth of Cowpea

Varietal Differences in Allelopathic Potential of Alfalfa

JOURNAL OF AGRONOMY AND CROP SCIENCE, Issue 1 2002
Tran Dang Xuan
Alfalfa (Medicago sativa L.) plants were found to contain water-soluble substances that inhibited the germination and seedling growth of alfalfa (Chung and Miller 1990, Agron. J. 87, 762,767). Tsuzuki et al. (1999, Rep. Kyushu Branch Crop Sci. Soc. Japan 65, 39,40) discovered allelochemicals in alfalfa plants that could have adverse effects on the growth of some lowland weeds. This study was conducted to investigate varietal differences in allelopathic potential in alfalfa plants. Eight common varieties of Japanese alfalfa (Medicago sativa L.), namely Batasu, Hisawakaba, Kitawakaba, Makiwakaba, Natsuwakaba, Lucerne, Tachiwakaba and Yuba, were grown by conventional methods in the Experimental Field of the Crop Science Laboratory, Faculty of Agriculture, Miyazaki University. Aqueous extracts of both fresh and dried material of alfalfa plants of all varieties significantly inhibited both germination and growth of lettuce (Lactuca sativa L.). Leachates from germinating seeds of almost all alfalfa varieties inhibited elongation of the radicle but produced a negligible increase in germination and only slightly inhibited elongation of the hypocotyl of lettuce plants. Results demonstrated that the degree of inhibition of germination and growth of lettuce varied with the variety of alfalfa. In particular, Lucerne was identified as having the strongest allelopathic potential of the varieties studied. The results suggested that the allelopathic potential of alfalfa might be relating to a gene. Varietätsunterschiede im allelopathischen Potential von Luzerne Luzerne (Medicago sativa L.)-Pflanzen weisen wasserlösliche Substanzen auf, die die Keimung und das Sämlingswachstum von Luzerne inhibieren. Es kann angenommen werden, daß Luzernepflanzen allelopathisch wirkende Verbindungen aufweisen, die das Wachstum von Unkrautpflanzen des Tieflands beeinträchtigen. Die Untersuchung wurde durchgeführt, um das Potential allelopathischer Sortenunterschiede bei Luzerne zu bestimmen. Acht im Anbau verwendete Luzernesorten , Batasu, Hisawakaba, Kitawakaba, Makiwakaba, Natsuwakaba, Lucerne, Tachiwakaba und Yuba , wurden nach konventionellen Verfahren auf dem Versuchsfeld des Pflanzenbauinstitutes der Fakultät der Miyazaki-Universität angebaut. Wässerige Extrakte von frischen und trockenen Luzernepflanzen hemmten bei allen Sorten signifikant die Keimung und das Wachstum von Salat (Lactuca sativa L.). Auszüge keimender Samen der meisten Luzernesorten inhibierten das Längenwachstum der Wurzel, hatten aber kaum Einfluß auf eine Förderung der Keimung und zeigten eine geringe Inhibierung des Längenwachstum des Hypokotyls von Salat. Die Ergebnisse zeigen, daß der Grad der Inhibierung der Keimung des Wachstums von Salat abhängig von den geprüften Luzernesorten ist. Lucerne hat das stärkste allelopathische Potential der Sorten. Die Ergebnisse lassen vermuten, daß das allelopathische Potential genetisch bedingt ist. [source]

Fire and species range in Mediterranean landscapes: an experimental comparison of seed and seedling performance among Centaurea taxa

JOURNAL OF BIOGEOGRAPHY, Issue 1 2002
Miquel Riba
Aim Fire is a major disturbance event in Mediterranean landscapes. In this paper, we experimentally assess the effects of fire and post-fire conditions on seed germination and establishment of twenty Centaurea taxa to test whether differences among taxa are associated with range size. Methods The taxa (species and subspecies) considered were classified as rare and widespread according to their `area of occupancy' in the Mediterranean coast of Spain and France. In a first experiment, we analyse the effects of heat-shock (particularly, room temperature, 70 and 110 °C) on percentage germination and speed of germination (T50). In a second experiment, we analyse the effects of post-fire conditions (shading and soil type: burned/unburned) on seed germination and establishment ability. Results Temperatures over 120 °C resulted in 100% mortality, while temperatures in the range of those expected to be found in the first centimetres down the soil profile during a wildfire (70,110 °C) had no effect on seed germination. Differences in germination percentage and T50 among taxa were not related to rarity. In the post-fire conditions experiment, decreased radiation (shading) increased percentage germination and T50 in most taxa, while burned soil decreased germination in some of them. The effects of post-fire conditions on seedling growth (number of leaves and leaf size) were also different among taxa, but such differences were not related to rarity. However, rarity was associated with low establishment ability, as rare taxa tended to show smaller seedling size and higher mortality rates under the whole range of conditions tested. Main conclusions The results obtained indicate that fire has a negative effect upon the survival of populations in all the taxa considered, and that rare-common differences in germination and seedling establishment are not directly related to disturbance by fire. As far as interspecific differences in range size are concerned, other factors, either alone or in combination with a low regeneration ability after fire, need to be explored further. [source]

Response of Faidherbia albida (Del.) A. Chev., Acacia nigrescens Oliver. and Acacia nilotica (L.) Willd ex Del. seedlings to simulated cotyledon and shoot herbivory in a semi-arid savanna in Zimbabwe

AFRICAN JOURNAL OF ECOLOGY, Issue 2 2010
Sijabulile Dube
Abstract Woody plant seedling establishment is constrained by herbivory in many semi-arid savannas. We clipped shoots and cotyledons of three woody species 5-day (=,early') or 28-day (= ,late') post-emergence to simulate herbivory. Seedlings had shoot apex, one or two cotyledon(s) removed, or were retained intact. Survival rates were ,80%, ,40% and ,20% for Acacia nilotica, Acacia nigrescens and Faidherbia albida respectively. F. albida mobilized stored cotyledon reserves faster and consequently shed the cotyledons earlier than the two Acacia species. Cotyledons were shed off as late as 70 days post-emergence with 5-day shedding earlier than 28-day and cotyledon life-span decreasing with intensity of defoliation. Shoot apex removal 28-day resulted in higher compensatory growth than 5-day in all three species. Cotyledon removal had no effect on shoot length, while shoot apex removal reduced shoot length. In F. albida root growth was stimulated by shoot apex removal. We conclude that potential tolerance to herbivory in terms of seedling survival was of the order A. nilotica > A. nigrescens > F. albida, timing of shoot apex and cotyledon removal influenced seedling growth in terms of biomass and that shoot apex removal stimulated compensatory growth which is critical to seedling survival. Résumé L'établissement de jeunes plants ligneux est contrarié par l'herbivorie dans de nombreuses savanes semi arides. Nous avons coupé les pousses et les cotylédons de trois espèces ligneuses à 5-j (= tôt) ou à 28 j (= tard) après leur émergence pour simuler l'herbivorie. On coupait l'apex de la tige et un ou deux cotylédons, ou on les laissait intacts. Le taux de survie était , 80%, , 40% et , 20% pour Acacia nilotica, Acacia nigrescensetFaidherbia albida respectivement. F. albida mobilisait plus rapidement les réserves stockées dans les cotylédons et par conséquent perdait les cotylédons plus tôt que les deux espèces d'acacia. Les cotylédons étaient perdus jusqu'à 70 jours après leur apparition, les 5-j les perdant plus tôt que les 28-j, et la durée de vie des cotylédons diminuait avec l'intensité de la défoliation. L'enlèvement des cotylédons n'avait pas d'effet sur la longueur de la pousse, tandis que celui de l'apex la réduisait. Chez F. albida, la croissance des racines était stimulée par l'enlèvement de l'apex. Nous concluons que la tolérance potentielle à l'herbivorie, en termes de survie des jeunes plants, suit cet ordre-ci : A. nilotica > A. nigrescens > F. albida; que le moment de l'enlèvement du bourgeon apical et des cotylédons influence la croissance des jeunes plants en termes de biomasse; et que l'enlèvement du bourgeon apical stimule une croissance compensatoire qui est critique pour la survie du jeune plant. [source]

Size-dependence of growth and mortality influence the shade tolerance of trees in a lowland temperate rain forest

JOURNAL OF ECOLOGY, Issue 4 2009
Georges Kunstler
Summary 1A trade-off between growth in high-light and survival in low-light of species is often proposed as a key mechanism underpinning the dynamics of trees in forest communities. Yet, growth and survival are known to depend on plant size and few studies have analysed how this trade-off can vary between juvenile life stages and the potential consequences of the trade-off for the differences in regeneration rate between species in mixed forests. 2We quantified growth and mortality for two different juvenile life stages , seedlings and saplings , of seven tree species common in temperate rain forests in New Zealand using data from field studies. We found strong evidence that the ranking of species for survival in shade and growth in full light was affected by size. There was a trade-off between seedling survival in low light and sapling height growth in high light, but no trade-offs were observed when considering other combinations of life stages (seedling growth vs. seedling survival, seedling growth vs. sapling survival, or sapling growth vs. sapling survival). 3We ran simulations with an individual-based forest dynamics model , SORTIE/NZ , to explore how the trade-off drives the differences in tree species regeneration success in gaps vs. under closed forest conditions. These simulations indicate that because species' ranks in shade tolerance varied with life stage, regeneration success was not predicted from knowledge of tree performance at a single life stage. For instance, high-light sapling growth was a strong determinant of regeneration success in forest gaps, but seedling growth was also influential. Under closed forest, regeneration success was primarily limited by low-light mortality at the seedling stage, but seedling growth and sapling survival were also influential. 4Synthesis. Growth-survival trade-offs can be strongly affected by the size of the individual analysed, resulting in completely different rankings of the shade tolerance of species across different juvenile life stages. Performance of both seedlings and saplings influenced regeneration success, highlighting the need to consider growth-survival trade-offs and the shade-tolerance strategies of tree species over a large range of juvenile sizes. [source]

Differential performance of reciprocal hybrids in multiple environments

JOURNAL OF ECOLOGY, Issue 6 2008
Sarah Kimball
Summary 1Closely related taxa may be maintained as distinct species by a variety of reproductive isolating mechanisms. These include: inability to produce hybrid offspring, endogenous selection against hybrids in the form of genomic incompatibilities, and exogenous selection observable in genotype-by-environment interactions. To understand the relative importance of these three isolating mechanisms, we performed hand-pollination and reciprocal transplant experiments in a natural plant hybrid zone. 2We measured reproductive isolation by making crosses between two parent species of Penstemon and naturally occurring hybrids. Inclusion of reciprocal hybrid crosses allowed us to determine whether fitness components differed depending on the identity of the mother. 3Hybrid performance was evaluated in the greenhouse and in a reciprocal transplant experiment in the field. We measured fruit set, seed set, seed weight, time required for fruits to mature and seedling growth for potted plants. To test for exogenous isolation, we planted pure parents, reciprocal F1 hybrids and later generation hybrids in a reciprocal transplant experiment, and measured survival. 4On average, interspecific crosses produced as many seeds as conspecific crosses. Hybrid performance was also equal to or greater than parents in all environments, including the greenhouse and all field gardens, indicating a lack of endogenous isolation. Parent species and reciprocal F1 hybrids differed in many traits measured. In each field garden, the hybrid with the native cytoplasm had a higher survival rate, suggesting local adaptation to different elevations. 5Synthesis. Exogenous factors that differ along elevational gradients can be more important than intrinsic genetic incompatibilities in determining the fitness of plant hybrids. Our results illustrate the importance of studying hybrid performance in multiple environments and in generating reciprocal hybrids to test for isolating mechanisms in natural hybrid zones. [source]

A test of the indirect facilitation model in a temperate hardwood forest of the northern French Alps

JOURNAL OF ECOLOGY, Issue 6 2003
Jean-Philippe Pages
Summary 1We tested the hypothesis that the more frequent occurrence of tree seedlings below the adult trees than in canopy openings might be explained by indirect facilitation. In a temperate hardwood forest, we compared the performance of five target tree seedlings (Picea abies, Abies alba, Fagus sylvatica, Acer pseudoplatanus and Quercus petraea), transplanted with or without a herbaceous competitor (Molinia caerulea), either within the forest or into experimentally created gaps. 2We quantified changes in understorey biomass, light penetration and available forms of soil nitrogen during three growing seasons. 3Photosynthetic photon flux density and total biomass of Molinia were significantly higher in the gap treatment than within the forest. Total available nitrogen was higher in the gaps in the absence of Molinia, but higher in the forest in the presence of Molinia. 4Quercus survival was very low within the forest because of fungal infection, whereas survival was very high for the four other tree species in all combinations of the two treatments. 5Although the competitive effect of Molinia on the growth of the tree seedlings was much greater in the gap treatment, seedling growth was lower within the forest. We conclude that the tree canopy imposed strong light competition, and that this direct negative influence was much greater than any indirect positive effect of increased availability of nutrients to tree seedlings, due to reduced nutrient uptake by Molinia. 6Target species responses to treatments were similar, despite strong differences in nitrogen requirements between species. This may be due to the overwhelming negative influence of the tree canopy in our experiment. [source]

High hybrid fitness at seed and seedling life history stages in Louisiana irises

JOURNAL OF ECOLOGY, Issue 3 2003
Jill A. Johnston
Summary 1,Relative fitness of hybrid genotypes will determine the role that hybrids can play in the evolution of a plant species complex. To realistically evaluate hybrid fitness and how environmental variation affects fitness in a long-lived species, all life stages must be considered. 2,We evaluated germination, seedling survival and growth of two Louisiana iris species and their early generation hybrids in several experimental environments created by manipulating light and water levels. 3,Species and hybrids all required similar moist conditions for germination. The proportion of germinated seeds was highest in shade and seedling survival highest in sun. 4,Iris brevicaulis exhibited the lowest germination and seedling survival overall, yet those individuals that survived grew vigorously. Iris fulva had high levels of germination and seedling survival, but yielded the smallest plants at the end of one season of growth. 5,Germination rates, seedling survival and seedling growth of hybrids equalled or exceeded one or both parent species, indicating that hybrids in this system have high relative fitness at seed and seedling stages in several environmental conditions. 6,We conclude that Iris fulva and I. brevicaulis share a common regeneration niche and similar early stage relative fitness with their hybrids. Thus, environment-dependent fitness in this system is due primarily to selection at adult stages. [source]

Feeding by short-snouted weevils on seedlings of seven tree species planted beneath Norway spruce at differing stand densities

AGRICULTURAL AND FOREST ENTOMOLOGY, Issue 1 2009
M. Löf
Abstract 1,Short-snouted weevils, including Strophosoma spp. and related species, may damage tree seedlings. We investigated the damage caused by these weevils feeding on seedlings of seven tree species planted in clear-cuts and under shelterwoods with three densities (control, dense, and sparse). 2,There were no pronounced differences in damage caused by short-snouted weevils in the various shelterwood densities. Most feeding occurred in the clear-cuts during the first year, whereas more seedlings were damaged in the shelterwoods of all densities in the second year. In the third year, virtually no feeding occurred in either the clear-cuts or shelterwoods. We cannot explain this pattern of damage, but a fallow period of 2 years seems to prevent short-snouted weevil damage. 3,We determined the general feeding preferences for short-snouted weevils to be cherry, lime > beech, oak, spruce > maple, ash. However, although Strophosoma mellanogrammum [Correction added after online publication 8 December 2008: Strophosoma melanogrammum corrected to Strophosoma mellanogrammum] was observed feeding on seedlings, no full short-snouted weevil inventory was conducted, so caution must be exercised when drawing conclusions from this study regarding weevil damage patterns and feeding preferences. 4,Short-snouted weevils can sometimes occur in large numbers and may destroy entire reforestation projects, but in our study their influence on seedling growth and survival was minor. [source]

Expression of a High Mobility Group Protein Isolated from Cucumis sativus Affects the Germination of Arabidopsis thaliana under Abiotic Stress Conditions

JOURNAL OF INTEGRATIVE PLANT BIOLOGY, Issue 5 2008
Ji Young Jang
Abstract Although high mobility group B (HMGB) proteins have been identified from a variety of plant species, their importance and functional roles in plant responses to changing environmental conditions are largely unknown. Here, we investigated the functional roles of a CsHMGB isolated from cucumber (Cucumis sativus L.) in plant responses to environmental stimuli. Under normal growth conditions or when subjected to cold stress, no differences in plant growth were found between the wild-type and transgenic Arabidopsis thaliana overexpressing CsHMGB. By contrast, the transgenic Arabidopsis plants displayed retarded germination compared with the wild-type plants when grown under high salt or dehydration stress conditions. Germination of the transgenic plants was delayed by the addition of abscisic acid (ABA), implying that CsHMGB affects germination through an ABA-dependent way. The expression of CsHMGB had affected only the germination stage, and CsHMGB did not affect the seedling growth of the transgenic plants under the stress conditions. The transcript levels of several germination-responsive genes were modulated by the expression of CsHMGB in Arabidopsis. Taken together, these results suggest that ectopic expression of a CsHMGB in Arabidopsis modulates the expression of several germination-responsive genes, and thereby affects the germination of Arabidopsis plants under different stress conditions. [source]

Fluctuation of Vegetative Storage Proteins in the Seedlings of Swietenia macrophylla, Analogous to the Seasonal Changes of Those in the Shoot of the Adult Tree

JOURNAL OF INTEGRATIVE PLANT BIOLOGY, Issue 3 2007
Ya-Qin Han
Abstract In order to identify appropriate plant materials for studying the gene expression and biological function of vegetative storage proteins (VSPs) in woody plants, the VSPs in the seedlings of Swietenia macrophylla King were investigated by using light microscopy, sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and Western-blotting. The seed of S. macrophylla was rich in storage proteins that accumulated in the vacuoles of cotyledon parenchyma cells in appearance of compact spherical grains. The growth and development of S. macrophylla seedlings were characterized by an obvious growth rhythm. The storage proteins in seeds disappeared during seedling growth while VSPs appeared in the stem 2 weeks after seedling leaves matured. Thereafter, the VSPs in the seedling stem almost exhausted during new shoot growth, and when the leaves of new shoot just matured, both the stem beneath the new shoot of seedlings and the stem of new shoot started to accumulate VSPs. Nitrogen application dramatically increased the level of VSPs, but had little influence on the dynamics of VSP consumption and accumulation in seedling stem. Together with these data, the fluctuation of VSPs in seedlings was very similar to that in the branches of the adult trees. In addition, seedlings are easy to be treated due to their small size. Our results suggested that S. macrophylla seedlings were suitable for investigating the biological roles of VSPs and the mechanism of nitrogen storage in trees. [source]

Effects of nitric oxide and nitrogen on seedling emergence, ion accumulation, and seedling growth under salinity in the euhalophyte Suaeda salsa

JOURNAL OF PLANT NUTRITION AND SOIL SCIENCE, Issue 4 2009
Jie Song
Abstract Recently nitric oxide (NO) has emerged as a key signal molecule in plants. However, little is known about the role of NO in the salt tolerance of halophytes. Effects of the NO donors sodium nitroprusside (SNP) and nitrate (NO) on growth and ion accumulation in the euhalophyte Suaeda salsa under salinity were investigated in the present study. The results showed that higher SNP supply increased seedling emergence, but SNP had no effect on shoot growth and the concentrations of Na+, K+, Cl,, and NO. Higher NO had no effect on seedling emergence of the species. Shoot Cl, decreased, but NO3, increased markedly, with a higher NO supply. The decrease in the estimated contribution of Cl, to the osmotic potential was compensated for by an increase in that of NO. It appears that NO plays an important osmotic role in S. salsa under high salinity with a higher NO supply, and this trait may increase salt tolerance of the species under high salinity. [source]