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Braz. j. biol ; 79(3): 404-409, July-Sept. 2019. tab
Article in English | LILACS | ID: biblio-1001466


Abstract Passion fruits species presents a larger economic importance for in natura consumption and industry. The main way to propagate these species is by seeds; however, the aril presence and environmental conditions may inhibit the seeds germination. In this sense, the objective of this study was to evaluate the effect of aril removal methods and light conditions on P. edulis var. flavicarpa seeds quality and germination. There were used five methods to remove the seeds aril: (1) friction on steel mesh sieve for 5 minutes; (2) friction with coarse sand on steel mesh sieve for 5 minutes; (3) immersion in lime solution at 10% (w/v), for 30 minutes; (4) fermentation in sugar solution at 10% (w/v), during 48 hours; and (5) natural pulp fermentation, during five days. The seeds were submitted to germination test at darkness and lightness, as well as, to length seedlings and emergence test. Regardless the aril removal method, the germination percentage was lower at lightness than darkness highlighting the natural pulp fermentation treatment, which presented 86% of seeds germinated. On the other hand, the aril removal methods did not affect the seedlings emergence, with emergence percentages ranged from 88 to 94%.

Resumo As espécies de maracujá apresentam grande importância econômica, tanto para o consumo in natura, quanto para a indústria. A principal maneira de propagar essas espécies é por sementes; contudo, a presença de arilo e condições ambientais pode inibir a germinação. Nesse sentido, objetivou-se estudar o efeito de métodos de remoção do arilo e luminosidade na qualidade e germinação das sementes de Passiflora edulis var. flavicarpa. Cinco métodos foram empregados para a remoção do arilo: (1) fricção em peneira de malha de aço por cinco minutos; (2) fricção com areia grossa em peneira de malha de aço por cinco minutos; (3) imersão em solução de cal a 10% (m/v), por 30 minutos; (4) fermentação da polpa em solução de açúcar a 10% (m/v), por 48 horas; e (5) fermentação natural da polpa, por cinco dias. As sementes foram submetidas ao teste de germinação no escuro e no claro, teste de comprimento de plântulas e teste de emergência. Independente do método de remoção do arilo, a porcentagem de germinação no claro apresentou-se menor em comparação ao escuro, com destaque para o tratamento de fermentação natural da polpa, o qual apresentou 86% de sementes germinadas. Por outro lado, os métodos de remoção do arilo não afetaram a emergência das plântulas, com porcentagem de emergência variando entre 88 a 94%.

Seeds/physiology , Germination/physiology , Passiflora/physiology , Flowers/physiology , Seeds/growth & development , Seeds/radiation effects , Passiflora/growth & development , Passiflora/radiation effects , Seedlings/physiology , Light
Biol. Res ; 51: 7, 2018. tab, graf
Article in English | LILACS | ID: biblio-888432


Abstract Background: Low phosphorus availability is a major factor restricting rice growth. Dongxiang wild rice (Oryza rufipogon Griff.) has many useful genes lacking in cultivated rice, including stress resistance to phosphorus deficiency, cold, salt and drought, which is considered to be a precious germplasm resource for rice breeding. However, the molecular mechanism of regulation of phosphorus deficiency tolerance is not clear. Results: In this study, cDNA libraries were constructed from the leaf and root tissues of phosphorus stressed and untreated Dongxiang wild rice seedlings, and transcriptome sequencing was performed with the goal of elucidating the molecular mechanisms involved in phosphorus stress response. The results indicated that 1184 transcripts were differentially expressed in the leaves (323 up-regulated and 861 down-regulated) and 986 transcripts were differentially expressed in the roots (756 up-regulated and 230 down-regulated). 43 genes were up-regulated both in leaves and roots, 38 genes were up-regulated in roots but down-regulated in leaves, and only 2 genes were down-regulated in roots but up-regulated in leaves. Among these differentially expressed genes, the detection of many transcription factors and functional genes demonstrated that multiple regulatory pathways were involved in phosphorus deficiency tolerance. Meanwhile, the differentially expressed genes were also annotated with gene ontology terms and key pathways via functional classification and Kyoto Encyclopedia of Gene and Genomes pathway mapping, respectively. A set of the most important candidate genes was then identified by combining the differentially expressed genes found in the present study with previously identified phosphorus deficiency tolerance quantitative trait loci. Conclusion: The present work provides abundant genomic information for functional dissection of the phosphorus deficiency resistance of Dongxiang wild rice, which will be help to understand the biological regulatory mechanisms of phosphorus deficiency tolerance in Dongxiang wild rice.

Phosphorus/deficiency , Oryza/genetics , Stress, Physiological/genetics , Gene Expression Profiling , Seedlings/genetics , Phosphorus/pharmacology , Oryza/drug effects , Oryza/physiology , Stress, Physiological/drug effects , Down-Regulation , Gene Expression Regulation, Plant , Seedlings/drug effects , Seedlings/physiology
Braz. j. biol ; 77(2): 260-266, Apr.-June 2017. tab, graf
Article in English | LILACS | ID: biblio-888733


Abstract Flood events in riparian forests of southern Brazil, can be characterized as unpredictable and of low magnitude with an average duration of less than 15 days. Inga marginata is an evergreen tree which grows in Southeast South America on a wide range of environments, including riparian forests. In this paper, the interactive effects of the light environment and soil flooding on morphological parameters of I. marginata were examined. Seedlings were acclimated in two contrasting light conditions: sun or shade for 30 days. Sun and shade plants were subjected to soil flooding for two periods; five or 15 days. After 5 days, the interaction between flooding and light did not affect growth, chlorophyll content and dry mass or the root-shoot ratio. After 15 days, flooded plants from the sunny treatment had a lower shoot dry mass compared to control sun plants and flooded plants from the shaded treatment. Moreover, the higher dry mass observed for shade plants compared to sun plants, following flooding, can also be directly associated with a higher content of soluble sugars. Shade plants of I. marginata showed a greater acclimation to soil waterlogging. This acclimation appears to be associated with a larger accumulation of soluble sugars compared to non-flooded plants. The responses observed on the shade plants appear to be decisive to indicate the use of I. marginata in degraded areas.

Resumo As inundações em florestas ripárias do Sul do Brasil, podem ser caracterizadas como imprevisíveis e de baixa magnitude com uma duração média de menos de 15 dias. Inga marginata é uma árvore que cresce no sudeste da América do Sul em uma grande variedade de ambientes, incluindo matas ciliares. Neste trabalho, os efeitos combinados da luminosidade e do e alagamento do solo nos parâmetros morfológicos de I. marginata foram examinados. As plântulas foram aclimatadas em duas condições contrastantes de luminosidade: sol e sombra por 30 dias. Plantas de sol e sombra foram submetidas ao alagamento do solo por dois períodos; cinco ou 15 dias. Após 5 dias, a interação entre a inundação e luminosidade não afetou o crescimento, teor de clorofila e massa seca e a razão raiz-parte aérea. Após 15 dias, plantas de sol sob inundação apresentaram menor massa seca na parte aérea em relação as plantas controle de sol e as plantas alagadas de sombra. Além disso, a maior massa seca observada nas plantas de sombra em comparação com plantas de sol, sob inundação, pode ser diretamente associado com um maior teor de açúcares solúveis. Plantas de sombra de I. marginata mostraram uma maior aclimatação ao encharcamento do solo. Esta aclimatação parece estar associada com um maior acúmulo de açúcares solúveis em comparação com as plantas não-inundadas. As respostas observadas nas plantas de sombra parecem ser determinantes para a indicação do uso de I. marginata em áreas degradadas.

Floods , Fabaceae/physiology , Light , Solubility , Seedlings/anatomy & histology , Seedlings/growth & development , Seedlings/physiology , Sugars/metabolism , Acclimatization , Fabaceae/anatomy & histology , Fabaceae/growth & development
Rev. biol. trop ; 64(3): 1143-1154, jul.-sep. 2016. tab, ilus
Article in English | LILACS | ID: biblio-958202


Abstract:The determination of favorable light habitat conditions per species and life stage is transcendental, for both ex situ and in situ conservation strategies of endangered forest tree species, and for their utilization as plantation trees. This becomes especially important when planting material is scarce. We studied the multivariate responses in biomass allocation and in gas exchange to light and to CO2 in Cedrela salvadorensis seedlings, grown under similar light conditions as those this species faces in nature. During a period of 135 days, groups of ten seedlings were put under 75, 45, 15 and 3.5 % of full sun exposure obtained with neutral shade cloth, under nursery conditions. A series of biomass allocation variables and detailed gas exchange parameters (photosynthesis response curves to light and to internal carbon concentration) were measured at the end of the growth period in plants of the four treatments. According to the principal component analyses, highest values of gas exchange response were associated with the lower values of biomass allocation traits. These changes can be associated with resource-conservative and resource-acquisitive strategies, where the C. salvadorensis seedlings acclimatize their traits for the exploration and exploitation of light, to high or to dim light environment, respectively. The multivariate analyses also showed that the plants had a high performance at 45 % of light environments. These results suggest that 45 % of light environment was the optimal light habitat of this species at the tested developing stage. Our results have important implications to choose the best natural habitat for a successful establishment of C. salvadorensis. We propose practical considerations for programs of reforestation or reintroduction where this species be involved. Rev. Biol. Trop. 64 (3): 1143-1154. Epub 2016 September 01.

ResumenLa determinación de las condiciones lumínicas favorables por especie y estado de vida es trascendental para las estrategias de conservación ex situ y in situ de especies de árboles en peligro de extinción, y su utilización como plantaciones forestales. Esto se vuelve especialmente importante cuando el material de siembra es escaso. Aquí, nosotros estudiamos las respuestas en asignación de biomasa y en intercambio de gases a luz y CO2 en plántulas de Cedrela salvadorensis crecidas bajo condiciones lumínicas similares a las que esta especie enfrenta en la naturaleza. Durante 135 días, grupos de diez plántulas fueron colocadas bajo condiciones de 75, 45, 15 y 3.5 % de exposición total al sol obtenidas por medio de sarán bajo condiciones de vivero. Una serie de variables de asignación de biomasa y parámetros de intercambio de gases (fotosíntesis según curvas de respuesta a la luz y a la concentración de carbono interno) fueron medidas al final del periodo de crecimiento en las plantas de los cuatro tratamientos. De acuerdo con los análisis de componentes principales, valores altos de respuesta de intercambio de gases están asociados con valores bajos de rasgos de asignación de biomasa. Los cambios observados se encuentran asociados con las estrategias recurso-conservativas y recurso-adquisitivas donde C. salvadorensis aclimata sus rasgos para la exploración y explotación de luz en ambientes con escasa o excesiva radiación lumínica, respectivamente. Los análisis multivariados muestran también que las plantas tienen un alto rendimiento a 45 % de luz ambiental. Estos resultados sugieren que el 45 % de ambiente lumínico es el hábitat lumínico óptimo de esta especie en el estado de desarrollo estudiado. Nuestros resultados tienen importantes implicaciones para escoger el mejor hábitat natural para un exitoso establecimiento de C. salvadorensis. Por esto, proponemos consideraciones prácticas para programas de reforestación y reintroducción donde esta especie estaría involucrada.

Photosynthesis/physiology , Sunlight , Biomass , Cedrela/physiology , Seedlings/physiology , Reference Values , Seasons , Species Specificity , Time Factors , Tropical Climate , Forests , Analysis of Variance , Plant Leaves/physiology
Rev. biol. trop ; 64(1): 305-317, ene.-mar. 2016. tab, ilus
Article in English | LILACS | ID: biblio-843279


AbstractThe initial phase of a plant life cycle is a short and critical period, when individuals are more vulnerable to environmental factors. The morphological and anatomical study of seedlings and saplings leaf type enables the understanding of species strategies of fundamental importance in their establishment and survival. The objective of this study was to analyze the structure of seedlings and saplings leaf types of three mangrove species, Avicennia schaueriana, Laguncularia racemosa, Rhizophora mangle, to understand their early life adaptive strategies to the environment. A total of 30 fully expanded cotyledons (A. schaueriana and L. racemosa), 30 leaves of seedlings, and 30 leaves of saplings of each species were collected from a mangrove area in Guaratuba Bay, Paraná State, Brazil. Following standard methods, samples were prepared for morphological (leaf dry mass, density, thickness) and anatomical analysis (epidermis and sub-epidermal layers, stomata types, density of salt secretion glands, palisade and spongy parenchyma thickness). To compare leaf types among species one-way ANOVA and Principal Component Analysis were used, while Cluster Analysis evaluated differences between the species. We observed significant structural differences among species leaf types. A. schaueriana showed the thickest cotyledons, while L. racemosa presented a dorsiventral structure. Higher values of the specific leaf area were observed for seedlings leaves of A. schaueriana, cotyledons of L. racemosa and saplings leaves of A. schaueriana and R. mangle. Leaf density was similar to cotyledons and seedlings leaves in A. schaueriana and L. racemosa, while R. mangle had seedlings leaves denser than saplings. A. schaueriana and R. mangle showed hypostomatic leaves, while L. racemosa amphistomatic; besides, A. chaueriana showed diacytic stomata, while L. racemosa anomocytic, and R. mangle ciclocytic. Seedling leaves were thicker in R. mangle (535 µm) and L.racemosa (520 µm) than in A. schaueriana (470.3 µm); while saplings leaves were thicker in L. racemosa (568.3 µm) than in A. schaueriana seedlings (512.4 µm) and R. mangle (514.6 µm). Besides, seedlings leaves palisade parenchyma showed increasing thickness in L. racemosa (119.2 µm) <A. schaueriana (155.5 µm) <R. mangle (175.4 µm); while in saplings leaves as follows R. mangle (128.4 µm) <A. schaueriana (183.4 µm) <L. racemosa (193.9 µm). Similarly, seedlings leaves spongy parenchyma thickness values were as follows A. schaueriana (182.6 µm) = R. mangle (192.8 µm) <L. racemosa (354.4 µm); while in saplings were A. schaueriana (182.6 µm) = R. mangle (187.3 µm) <L. racemosa (331.3 µm). The analyzed traits, in different combinations, represent morphological adjustments of leaf types to reduce water loss, eliminate salt excess, increase the absorption of light, allowing a higher efficiency on the maintenance of physiological processes in this initial growth stage. Rev. Biol. Trop. 64 (1): 305-317. Epub 2016 March 01.

ResumenLa fase inicial del ciclo de vida de una planta es un período corto y crítico, cuando los individuos son más vulnerables a factores ambientales. El estudio morfológico y anatómico del tipo de hojas de las plántulas y árboles pequeños, permite la comprensión de las estrategias de las especies, que es de importancia fundamental para su establecimiento y supervivencia. El objetivo de este estudio fue analizar la estructura de los tipos de hojas de las plántulas y árboles pequeños de tres especies de mangle: Avicennia schaueriana, Laguncularia racemosa y Rhizophora mangle, para entender sus estrategias de vida tempranas de adaptación al ambiente. Un total de 30 cotiledones completamente abiertos (A. schaueriana y L. racemosa), 30 hojas de plántulas, y 30 hojas de árboles pequeños de cada especie se recolectaron en una área de manglar en Bahía Guaratuba, Estado de Paraná, Brasil. Siguiendo los métodos estándares, se prepararon muestras para análisis morfológicos (biomasa de hoja seca, densidad y espesor) y anatómicos (epidermis y capas sub-epidérmicas, tipos de estomas, densidad de glándulas secretoras de sal y grosor del parénquima empalizado y del esponjoso). Para comparar los tipos de hojas entre las especies se utilizaron un modelo lineal y Análisis de Componentes Principales, mientras que un análisis de conglomerados evaluó las diferencias entre las especies. Observamos diferencias estructurales significativas entre tipos de hoja en las especies. A.schaueriana mostró cotiledones más gruesos, mientras que L. racemosa presenta una estructura dorsiventral. Se observaron valores más altos del área foliar específica para las hojas de las plántulas de A. schaueriana, cotiledones de L. racemosa y hojas de árboles pequeños de A. schaueriana y R. mangle. La densidad de la hoja fue similar a la de los cotiledones y hojas de plántulas de A. schaueriana y L. racemosa, mientras que R. mangle tenía las hojas de las plántulas más gruesas que los árboles pequeños. A. schaueriana y R. mangle mostraron hojas hipostomáticas; L. racemosa anfiestomáticas; por otro lado A. chaueriana mostró estomas diacíticos, L. racemosa anomocíticos y R. mangle ciclocíticos. Las hojas de las plántulas eran más gruesas en R. mangle (535 micras) y L. racemosa (520 micras) que en A. schaueriana (470.3 m); mientras que las hojas de las plántulas eran más gruesas en L. racemosa (568.3 m) que en A. schaueriana (512.4 micras) y R. mangle (514.6 m). Además el parénquima empalizado de las plántulas mostró un aumento de espesor en L. racemosa (119.2 m) <A. schaueriana (155.5 m) <R. mangle (175.4 m); mientras que en las hojas de los árboles pequeños fue de siguiente manera: R. mangle (128.4 m) <A. schaueriana (183.4 m) <L. racemosa (193.9 m). Del mismo modo, en las hojas de las plántulas los valores del espesor del parénquima esponjoso fueron: A. schaueriana (182.6 m) = R. mangle (192.8 m) <L. racemosa (354.4 m); mientras que en los árboles pequeños: A. schaueriana (182.6 m) = R. mangle (187.3 m) <L. racemosa (331.3 m). Los rasgos analizados, en diferentes combinaciones, representan ajustes morfológicos de tipos de hojas para reducir la pérdida de agua, eliminar el exceso de sal, aumentar la absorción de la luz, lo que permite una mayor eficiencia en el mantenimiento de los procesos fisiológicos en esta etapa de crecimiento inicial.

Plant Leaves/physiology , Combretaceae/physiology , Avicennia/physiology , Seedlings/physiology , Rhizophoraceae/physiology , Brazil , Adaptation, Biological , Microscopy, Electron, Scanning , Combretaceae/classification , Combretaceae/ultrastructure , Avicennia/classification , Avicennia/ultrastructure , Seedlings/ultrastructure , Rhizophoraceae/classification
Braz. j. microbiol ; 45(4): 1145-1151, Oct.-Dec. 2014. graf, tab
Article in English | LILACS | ID: lil-741313


Eucalypts is one of the main species used for commercial reforestation in the state of Rio Grande do Sul, Brazil. This study aimed to evaluate the survival and early growth of eucalyptus trees in an area subject to sandy process after three years of growth. The Eucalyptus grandis seedlings were grown in a greenhouse, innoculated or not with the isolated ectomycorrhizal Pisolithus microcarpus (UFSC-Pt116), produced in peat or Entisol. After 120 days, the seedlings were transplanted to an area subject to the sandy process, in the city of São Francisco de Assis, RS. The plants have been evaluated regarding survival, height, stem diameter, nitrogen, phosphorus and potassium levels and total phosphorus, inorganic phosphorus, organic phosphorus and wood production on different days after planting. The seedlings grown on the Entisol which was inoculated with the isolated UFSC-Pt116 presented higher survival rates, height, stem diameter, nitrogen concentration and wood production compared to the non-inoculated seedlings. Inoculation with ectomycorrhizal fungi enhanced the production of E. grandis seedlings in survival rates, height, stem diameter.

Basidiomycota/growth & development , Eucalyptus/growth & development , Eucalyptus/microbiology , Mycorrhizae/growth & development , Brazil , Eucalyptus/physiology , Plant Development , Seedlings/growth & development , Seedlings/microbiology , Seedlings/physiology
Indian J Biochem Biophys ; 2014 Oct; 51(5): 407-415
Article in English | IMSEAR | ID: sea-154272


The involvement of 1, 1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity and contents of H2O2, malondialdehyde (MDA) and proline was investigated in determining salinity tolerance among seedlings of thirty chickpea (Cicer arietinum L.) genotypes having different pedigrees. Chickpea genotypes, including cultivars and advanced lines were grown for 7 days under control and salt stress (50 mM NaCl) conditions. The genotypes showed differential response to salt stress in terms of growth, DPPH radical scavenging activity and contents of H2O2, MDA and proline in seedlings. On the basis of seedling growth, the genotypes having better performance under stress conditions had reduced levels of H2O2 and MDA contents, but increased levels of proline and DPPH radical scavenging activity. Stress tolerance index for these parameters was also determined. Agglomerative hierarchal clustering by Pearson correlation coefficient grouped the genotypes into two major clusters — MC I and MC II. MC II and A1-1 sub-cluster of MC-I comprised mainly of genotypes that showed higher stress resistance levels for the respective parameters in comparison to genotypes in other sub-clusters. Thus, it is possible to identify salt-tolerant genotypes on the basis of above parameters without a field trial.

Biphenyl Compounds/metabolism , Cicer/physiology , Free Radical Scavengers/metabolism , Hydrogen Peroxide/metabolism , Malondialdehyde/metabolism , Oxidative Stress/physiology , Picrates/metabolism , Proline/metabolism , Reactive Oxygen Species/metabolism , Salinity , Salt Tolerance/physiology , Seedlings/physiology
Indian J Exp Biol ; 2014 Sept; 52(9): 905-911
Article in English | IMSEAR | ID: sea-153775


In vitro seedlings were used as explants for protocorm like bodies (PLBs) production which in turn were used for regeneration purpose. PLBs were induced from the base of seedlings (1.0-1.5 cm in size) in MS + BAP (8.88 µM). After 90 days of inoculation, PLBs production rate started declining and most of the PLBs turned into plantlets. Preculture of seedlings in 1.0 µM thidiazuron (TDZ) for 7 days and transfer to BAP supplemented medium resulted in production of 16 PLBs per seedling within 90 days of culture. Increase of TDZ concentration to 2.5 µM and preculture time 15 days, resulted in induction of highest number of PLBs (19 PLBs per seedling) in the basal medium. The results emphasized the importance of thidiazuron (TDZ) concentration and preculture time for PLBs proliferation from the base of seedlings. The PLBs thus produced were used for regeneration studies. Irrespective of single, segmented or clumps of PLBs, the regeneration response was 100% in 2,4-D (4.52 µM) and KN (4.64 µM) but when KN was replaced by BAP (8.88 µM), response was observed only in clumps of PLBs, whereas in single and segmented ones it was 99 and 97%, respectively. Regenerants developed stout root system in half strength M medium supplemented with 2.84 µM of IAA and transferred to greenhouse with 90% survival. The present study holds tremendous potential as the mother plant is not destroyed and PLBs are produced as a continuous system.

Culture Media , Germination/drug effects , Orchidaceae/drug effects , Orchidaceae/growth & development , Orchidaceae/physiology , Regeneration , Seedlings/drug effects , Seedlings/growth & development , Seedlings/physiology , Tissue Culture Techniques
Braz. j. microbiol ; 45(2): 613-620, Apr.-June 2014. graf, tab
Article in English | LILACS | ID: lil-723125


Less than 0.5% of total water in the world is available for human consumption and agriculture. The major part of the world's water is saline and salinity in soils interferes in germination of seeds and the posterior development of the plant. In order to increase the osmotolerance of tomato, seedlings were associated with Azospirillum brasilense Cd, Azospirillum brasilense Cd transformed bacteria with a plasmid harboring a trehalose biosynthesis gene-fusion or Chlorella vulgaris. Two plant culture media: Hydroponic and Murashige and Skoog were tested. In the first set of studies seedlings were associated to single free cells meanwhile in a second set single and combined free cells were studied. A positive interaction between transformed Azospirillum and Chlorella vulagris and tomato plants was observed. Seedlings showed a salt concentration tolerance, as sodium chloride, up to 200 mM. According to our results, the association of plants with A. brasilense Cd-BIF and C. vulgaris is a viable approach to increase their salt tolerance and biomass, as consequence the possible use of sea water to irrigate horticultural plants.

Azospirillum brasilense/growth & development , Chlorella vulgaris/growth & development , Solanum lycopersicum/microbiology , Osmotic Pressure , Salinity , Seedlings/microbiology , Culture Media/chemistry , Solanum lycopersicum/physiology , Seedlings/physiology
Biol. Res ; 47: 1-8, 2014. graf, tab
Article in English | LILACS | ID: biblio-950767


BACKGROUND: Rootstocks play an essential role to determining orchard performance of fruit trees. Pyrus communisand Cydonia oblonga are widely used rootstocks for European pear cultivars. The lack of rootstocks adapted to different soil conditions and different grafted cultivars is widely acknowledged in pear culture. Cydonia rootstocks (clonal) and Pyrus rootstocks (seedling or clonal) have their advantages and disadvantages. In each case, site-specific environmental characteristics, specific cultivar response and production objectives must be considered before choosing the best rootstock. In this study, the influence of three Quince (BA 29, Quince A = MA, Quince C = MC) and a local European pear seedling rootstocks on the scion yield, some fruit quality characteristics and leaf macro (N, P, K, Ca and Mg) and micro element (Fe, Zn, Cu, Mn and B) content of 'Santa Maria' pear (Pyrus communis L.) were investigated. RESULTS: Trees on seedling rootstock had the highest annual yield, highest cumulative yield (kg tree(-1)), largest trunk cross-sectional area (TCSA), lowest yield efficiency and lowest cumulative yield (ton ha(-1)) in the 10th year after planting. The rootstocks had no significant effect on average fruit weight and fruit volume. Significantly higher fruit firmness was obtained on BA 29 and Quince A. The effect of rootstocks on the mineral element accumulation (N, K, Ca, Mg, Fe, Zn, Cu, Mn and B) was significant. Leaf analysis showed that rootstocks used had different mineral uptake efficiencies throughout the early season. CONCLUSION: The results showed that the rootstocks strongly affected fruit yield, fruit quality and leaf mineral element uptake of 'Santa Maria' pear cultivar. Pear seedling and BA 29 rootstock found to be more prominent in terms of several characteristics for 'Santa Maria' pear cultivar that is grown in highly calcareous soil in semi-arid climate conditions. We determined the highest N, P (although insignificant), K, Ca, Mg, Fe and Cu mineral element concentrations on the pear seedling and BA 29 rootstocks. According to the results, we recommend the seedling rootstock for normal density plantings (400 trees ha(-1)) and BA 29 rootstock for high-density plantings (800 trees ha(-1)) for 'Santa Maria' pear cultivar in semi-arid conditions.

Plant Roots/metabolism , Plant Leaves/chemistry , Pyrus/classification , Pyrus/growth & development , Pyrus/chemistry , Desert Climate , Crop Production/methods , Fruit/metabolism , Phosphorus/analysis , Potassium/analysis , Rain , Soil , Temperature , Turkey , Zinc/analysis , Boron/analysis , Calcium/analysis , Copper/analysis , Rosaceae/physiology , Seedlings/growth & development , Seedlings/physiology , Iron/analysis , Magnesium/analysis , Manganese/analysis , Nitrogen/analysis
Rev. biol. trop ; 61(4): 1859-1868, oct.-dic. 2013. ilus
Article in English | LILACS | ID: lil-703933


The neotropical liana Gnetum leyboldii Gnetaceae is a gymnosperm that resembles angiosperms in wood anatomy, overall morphology, and seed dispersal mechanism. Like other woody lianas, seedlings germinate in the shaded forest understory and start climbing towards the canopy, being eposed to sites with etreme differences in light conditions. However, the etent of physiological and structural adjustment to contrasting light conditions in the early regeneration stages of Gnetum is unknown. To answer this question, we analyzed seedling growth and photosynthetic responses using a common garden eperiment with two light regimes: full sun and low light 20 of full sun at La Selva Biological Station, Costa Rica. We also characterized the germination pattern of this species. We monitored one and half-month old seedlings for four months. Leaf structure finely adapted to light treatments, but gas echange properties were buffered by large seed reserves, which dominated biomass distribution about 50 of the total biomass, followed by stem 27, leaf 16 and root biomass 6 across light conditions. The presence of large seeds and the low photosynthetic rates of seedlings in both environments show that G. leyboldii is specialized to eploit deep shade. More research is needed to determine if the patterns found in G. leyboldii are typical of similar lianas that initially eploit deep-shaded understories in their ascension to the canopy.

La liana neotropical Gnetum leyboldii Gnetaceae es una gimnosperma que se asemeja a las angiospermas en la anatomía de la madera, morfología general de la planta y mecanismo de dispersión de semillas. Al igual que otras lianas leñosas, las plántulas se regeneran en el sotobosque bajo dosel cerrado y eventualmente ascienden hacia el dosel, eplotando sitios con diferencias etremas en condiciones lumínicas. Se desconoce el grado de ajuste fisiológico a condiciones lumínicas contrastantes en las primeras fases de regeneración de Gnetum. Para contestar esta pregunta, analizamos las respuestas de crecimiento de las plántulas a ambientes contrastantes de luz de sol y sombra en un jardín común con condiciones de alta cielo abierto y baja luminosidad 20 del ambiente de sol en la Estación Biológica La Selva, Costa Rica. También caracterizamos su patrón de germinación. Monitoreamos plántulas de 1.5 meses de edad por 4 meses. La estructura foliar mostró una fina adaptación a los tratamientos de luz, pero las propiedades de intercambio gaseoso no cambiaron sino que fueron amortiguadas por las reservas de las semillas grandes, las cuales dominaron la distribución de biomasa aproimadamente 50 de la biomasa total seguidas por el tallo 27, la hoja 16 y raíces 6. El tener semillas grandes y plántulas con bajas tasas fotosintéticas muestra que G. leyboldii en su etapa de plántula está adaptado para eplotar la sombra profunda. Se requiere más investigación para determinar si los patrones encontrados en G. leyboldii son típicos de otras lianas que inicialmente eplotan la sombra profunda en su ascensión al dosel.

Acclimatization/physiology , Gnetum/physiology , Photosynthesis/physiology , Rain , Sunlight , Seedlings/physiology , Biomass , Costa Rica , Gnetum/growth & development , Seedlings/growth & development , Trees , Tropical Climate
Rev. biol. trop ; 61(3): 1433-1444, sep. 2013. ilus, graf, tab
Article in English | LILACS | ID: lil-688487


Environmental heterogeneity mostly dominated by differing light regimes affects the expression of phenotypic plasticity, which is important for plant growth and survival, especially in the forest understory. The knowledge about these responses to this heterogeneity is a key factor for forest restoration initiatives. In this study, we determine several phenotypic responses to contrasting light conditions in five native tree seedling species of La Cangreja National Park, Central Pacific of Costa Rica, four of them with threatened or relict populations. After 14 weeks at a medium gap condition (24% of full sun), seedlings were transferred and acclimated for 11 weeks to three different natural light regimes: large gap (LG), medium gap (MG) and small gap (SG), corresponding to 52%, 24%, 9% of the mean direct and indirect radiation at each site from full sun. Growth, biomass allocation and leaf gas exchange were measured after the acclimation period. Four species strongly reduced relative growth rate (RGR) in the lower light condition. Total biomass (TB) and RGR were different in Hymenaea courbaril and Platymiscium curiense. H. courbaril and Astronium graveolens had significant changes in the maximum assimilation rate, with a mean value in the LG of 11.02 and 7.70µmolCO2/m²s, respectively. P. curuense showed the same trend and significant changes in RGR and biomass allocation. Aspidosperma myristicifolium and Plinia puriscalensis showed no adjustments to the light regimes in any of the measured variables. This study remarks the importance of determining the growth and physiological performance of these tree native species. It also demonstrates that the most threatened species are those with the less plastic responses to the light regimes, which stresses the difficult situation of their natural populations. This study highlights an urgent definition of the conservation and restoration needs of the degraded forests of the Costa Rican Central Pacific area, where these species dwell.

La heterogeneidad ambiental dominada mayormente por diferencias en los regímenes lumínicos afecta la expresión de la plasticidad fenotípica, la cual es importante para el crecimiento y la supervivencia de las plantas, especialmente en el sotobosque. Conocer dichas respuestas ante la heterogeneidad es un factor clave para las iniciativas de restauración forestal. En este estudio, determinamos varias respuestas fenotípicas ante condiciones lumínicas contrastantes de cinco especies de plántulas de árboles nativos del Pacífico Central de Costa Rica, algunos de ellos con poblaciones amenazadas. El crecimiento, la asignación de biomasa y el intercambio gaseoso a nivel foliar se midieron al final de once semanas de aclimatación en tres regímenes con diferente radiación: claro grande (LG), claro mediano (MG) y claro pequeño (SG) que corresponden al 54, 24 y 9% de la media del factor de radiación indirecta e indirecta en cada sitio a pleno sol, respectivamente. Cuatro especies presentan fuertes disminuciones en la tasa de crecimiento relativo (RGR) en la condición de poca luz. La biomasa total, RGR y la relación raíz/tallo fueron diferentes para todas las especies. Hymenaea courbaril y Astronium graveolens respondieron significativamente en la tasa de asimilación máxima, con un valor promedio en el LG de 11.02 y 7.70µmolCO2/m²s¹ respectivamente. Platymiscium curuense mostró tendencias similares y cambios significativos en la RGR y la asignación de biomasa. Aspidosperma myristicifolium y Plinia puriscalensis mostraron una plasticidad muy baja debido que no expresaron ajustes en ninguna de las variables medidas ante los regímenes de luz. Este estudio resalta la importancia de determinar el crecimiento y el rendimiento fisiológico de estas especies de árboles nativos. También demuestra que las especies más amenazadas son aquellas con las respuestas con menor plasticidad ante los regímenes luz, lo que acentúa la difícil situación de sus poblaciones naturales. Este estudio destaca una urgente definición de las necesidades de conservación y restauración de los bosques degradados de zona del Pacífico Central costarricense, donde estas especies habitan.

Magnoliopsida/growth & development , Biomass , Photosynthesis/physiology , Sunlight , Seedlings/physiology , Magnoliopsida/physiology , Costa Rica , Phenotype
Rev. biol. trop ; 61(1): 335-342, Mar. 2013. ilus
Article in Spanish | LILACS | ID: lil-674085


Desiccation tolerance in seeds of Prosopis ferox and Pterogyne nitens (Fabaceae). The high number of endemisms and species diversity together with the accelerated biodiversity loss by deforestation, especially in North Western Argentina, points out the need to work on species conservation combining ex situ and in situ strategies. The aim of this work was to study the desiccation tolerance in seeds of P. ferox and P. nitens for long term ex situ conservation at the Germplasm Bank of Native Species (BGEN) of the National University of Salta (Argentina). The fruits were collected from ten individuals in P. ferox at the National Park Los Cardones and from two sites (Orán and Rivadavia) for P. nitens. Desiccation tolerance was assessed following previous established methodologies. The moisture content (MC) of the seeds was determined by keeping them in oven at 103°C and weighting the samples at different intervals till constant weight. Germination essays were carried out with two treatments (control and scarification), with different seed MC (fresh, 10-12%, 3-5%) and in desiccated seeds (3-5% MC) stored six months at -20ºC. The MC in P. ferox seeds was 14.2% and 10% in P. nitens, for both populations studied. Percentage germination in P. ferox was higher in the scarification treatments (<82%). The difference between treatments increased with the reduction in MC and the storage for six months at -20°C. Fresh seeds of P. nitens do not need scarification treatment, but it is required with the reduction in MC and storage. Mean germination percentage of desiccated seeds stored six months at -20°C was similar in both populations and greater than 82%.We concluded that both species are probably orthodox because seeds tolerated desiccation to 3-5% and storage for six months at -20°C.

La elevada diversidad de especies y endemismos, conjuntamente con la acelerada pérdida de biodiversidad por deforestaciones, destaca la importancia de emprender acciones combinadas de conservación in situ y ex situ. El objetivo de este trabajo fue estudiar la tolerancia a la desecación de las semillas de Prosopis ferox y Pterogyne nitens, para su conservación ex situ a largo plazo en el BGEN. El contenido de humedad (CH) se determinó colocando las semillas de cada población en estufa a 103°C y pesando las muestras a intervalos regulares hasta peso constante. Se realizaron ensayos de germinación en distintos CH: semillas frescas, 10-12%, 3-5%, y en semillas mantenidas seis meses a -20ºC y a 3-5% de CH. El CH de las semillas frescas de P. ferox fue de 14.2% y el de P. nitens de 10% para las dos poblaciones estudiadas. Las semillas de P. ferox llegaron a peso constante a las 17hr y las de P. nitens a las 3hr de secado. La germinación de las semillas de P. ferox fue mayor en los tratamientos con escarificación y la diferencia aumento con la reducción del CH y el almacenamiento. Las semillas de P. nitens con el CH reducido, requieren escarificación. Se concluye que las semillas de ambas especies son probablemente ortodoxas ya que la germinación superó el 80% en las semillas desecadas al 3-5% CH y almacenadas durante seis meses a -20°C.

Desiccation/methods , Fabaceae/physiology , Germination/physiology , Seeds/physiology , Argentina , Conservation of Natural Resources/methods , Fabaceae/classification , Fabaceae/growth & development , Humidity , Seedlings/physiology , Seeds/growth & development , Temperature , Time Factors
Biol. Res ; 46(1): 79-85, 2013. ilus
Article in English | LILACS | ID: lil-676825


The effects of nickel, cobalt, chromium and zinc on the content of vitamins A, E and C, malondialdehyde (MDA), chlorophyll and carotenoids were investigated in bean seedlings (Phaseolus vulgaris L.) grown in Hoagland solution Control and heavy metal-treated plants were grown for ten days in Hoagland solution. Vitamin A, E, and C content were measured in primary leaves by high performance liquid chromatographic (HPLC). MDA, chlorophyll and carotenoids were measured in leaves by spectrophotometer. In heavy metal treated plants, the levels of MDA, vitamins A, E and C and carotenoids significantly increased, while chlorophyll content decreased in leaves of seedlings. The results indicate that heavy metals caused an oxidative stress in bean plants. The strongest effect on vitamins A, E and C, MDA, chlorophyll and carotenoids was found in plants exposed to nickel, followed by the sequence cobalt > chromium> zinc.

Malondialdehyde/analysis , Metals, Heavy/metabolism , Phaseolus/physiology , Pigments, Biological/analysis , Seedlings/physiology , Vitamins/analysis , Ascorbic Acid/analysis , Chromatography, High Pressure Liquid , Carotenoids/analysis , Chlorophyll/analysis , Chromium/metabolism , Cobalt/metabolism , Lipid Peroxidation/physiology , Nickel/metabolism , Oxidative Stress/physiology , Plant Leaves/chemistry , Vitamin A/analysis , Vitamin E/analysis , Zinc/metabolism
Rev. biol. trop ; 59(2): 921-933, jun. 2011. graf, tab
Article in English | LILACS | ID: lil-638130


Life history and recruitment information of tropical trees in natural populations is scarce even for important commercial species. This study focused on a widely exploited Neotropical canopy species, Pachiraquinata (Malvaceae), at the southernmost, wettest limit of its natural distribution, in the Colombian Amazonia. We studied phenological patterns, seed production and natural densities; assessed the importance of seed dispersal and density-dependent effects on recruitment, using field experiments. At this seasonal forest P. quinata was overrepresented by large adult trees and had very low recruitment caused by the combination of low fruit production, high seed predation and very high seedling mortality under continuous canopies mostly due to damping off pathogens. There was no evidence of negative distance or density effects on recruitment, but a clear requirement of canopy gaps for seedling survival and growth, where pathogen incidence was drastically reduced. In spite of the strong dependence on light for survival of seedlings, seeds germinated readily in the dark. At the study site, the population of P. quinata appeared to be declining, likely because recruitment depended on the rare combination of large gap formation with the presence of reproductive trees nearby. The recruitment biology of this species makes it very vulnerable to any type of logging in natural populations. Rev. Biol. Trop. 59 (2): 921-933. Epub 2011 June 01.

Información acerca de la historia de vida y reclutamiento de poblaciones naturales de árboles tropicales es escasa, incluso para especies de alto interés comercial. Este estudio se centró en una especie de dosel altamente explotada, Pachira quinata (Malvaceae), en la zona más húmeda de su distribución geográfica, en la Amazoní a colombiana. Estudiamos sus patrones fenológicos, producción de semillas y densidades naturales, además de la importancia de la dispersión de semillas y efectos denso-dependientes en el reclutamiento natural, todo lo anterior se logró con el uso de experimentos y observaciones en el campo. En este bosque estacional, la población de P. quinata estaba dominada por grandes árboles adultos y el reclutamiento era extremadamente bajo, como consecuencia de la baja producción de frutos, alta depredación de semillas y muy alta mortalidad de plántulas bajo el bosque por infección de patógenos. No encontramos evidencia de efectos de distancia al árbol parental o densidad de semillas en el reclutamiento, pero si hallamos un evidente requerimiento de claros de luz para la supervivencia y el crecimiento de plántulas, donde la mortalidad por patógenos se reduce drásticamente. Sin embargo, a pesar de la dependencia de la luz para la supervivencia, las semillas germinan en la oscuridad. En la zona de estudio, la población de P. quinata parece estar en claro declive, probablemente porque el reclutamiento depende de la coincidencia de la formación de grandes claros con la presencia cercana de árboles reproductivos. Los requerimientos de reclutamiento de esta especie la hacen muy vulnerable a cualquier actividad extractiva de árboles adultos en poblaciones naturales.

Bombacaceae/growth & development , Seed Dispersal/physiology , Seedlings/physiology , Bombacaceae/classification , Colombia , Seasons
Rev. biol. trop ; 58(2): 717-732, jun. 2010. ilus, graf, tab
Article in Spanish | LILACS | ID: lil-638036


Seed germination and key to seedling identification for six native tree species of wetlands from Southeast Mexico. Wetland tree species are of importance for economic and restoration purposes. We describe the germination process and seedling morphology of six arboreal native species typical of Southeastern Mexico: Annona glabra, Ceiba pentandra, Pachira aquatica, Haematoxylum campechianum, Coccoloba barbadensis and Crataeva tapia. A total of 300 seeds per species were planted in a mixture of sand, cocoa plant husk and black soil (1: 1: 1), and maintained in a tree nursery with 30% artificial shade, from February to November of 2007. We carried out the morphological characterization, and elaborated a key to seedlings based on: 1) germination type 2) seedling axis and 3) leaf elements. P. aquatica has cryptocotylar hypogeal germination, the others have phanerocotylar epigeal germination. Germination rates were high (>86%), except for C. barbadensis (69%). Rev. Biol. Trop. 58 (2): 717-732. Epub 2010 June 02.

Especies arbóreas de humedales son de importancia económica y para fines de restauración. Nosotros describimos el proceso de germinación y morfología de plántulas de seis especies arbóreas nativas típicas del sureste de México: Annona glabra, Ceiba pentandra, Pachira aquatica, Haematoxylum campechianum, Coccoloba barbadensis y Crataeva tapia. Un total de 300 semillas por especie fueron sembradas en una mezcla de arena, cascarilla de cacao y tierra negra (1: 1: 1), y mantenidas en invernadero a 30% de sombra artificial, de febrero a noviembre de 2007. Se realizó la caracterización morfológica, y elaboró una clave de plántulas con base en: 1) tipo de germinación 2) eje de la plántula y 3) elementos foliares. P. aquatica presenta germinación criptocotilar hipogea, las otras tienen germinación fanerocotilar epigea. Las tasas de germinación fueron altas (>86%), a excepción de C. barbadensis (69%).

Magnoliopsida/physiology , Germination/physiology , Seedlings/physiology , Magnoliopsida/classification , Annonaceae/physiology , Bombacaceae/physiology , Capparaceae/physiology , Fabaceae/physiology , Mexico , Polygonaceae/physiology , Seeds/growth & development , Seeds/physiology , Wetlands
Acta amaz ; 40(1): 165-170, mar. 2010. graf, tab
Article in Portuguese | LILACS, VETINDEX | ID: lil-546971


O presente trabalho teve por objetivo avaliar a emergência de plântulas de Astrocaryum aculeatum a partir de sementes submetidas a diferentes temperaturas e períodos de embebição. O delineamento experimental foi inteiramente casualizado, em esquema fatorial 4 (temperaturas de embebição em água: 25ºC, 30ºC, 35ºC e 40ºC) X 3 (períodos de embebição: 2, 4 e 6 dias), com testemunha (sem embebição) e com quatro repetições. As semeaduras foram realizadas em viveiro. A emergência e o índice de velocidade de emergência só diferiram entre a testemunha e os tratamentos aplicados, independentes do período e da temperatura, com resultados favoráveis para a embebição das sementes. O tempo médio de emergência apresentou efeito de interação significativo, destacando-se a utilização da temperatura de embebição de 40ºC, associada ao período de 4 dias, que proporcionou um menor tempo médio (163 dias). O tempo inicial de emergência foi menor na temperatura de 35ºC (80 dias), enquanto o tempo final de emergência não apresentou diferença entre as médias. Sementes embebidas por 2 dias apresentaram 50 por cento de sementes mortas ao final do experimento, enquanto as embebidas por 4 dias, apenas 38 por cento. A emergência de plântulas de A. aculeatum foi favorecida pela embebição, independente da temperatura e do período utilizados.

This study evaluated the seedling emergence of Astrocaryum aculetum seeds soaked in water for different periods at different temperatures. The experimental design was entirely randomized, in factorial 4 (temperatures of soaking in water: 25ºC, 30ºC, 35ºC e 40ºC) X 3 (period of soaking: 2, 4 and 6 days), additional treatment (control, without soaking), with four replications. Before (control) and after the soaking periods in different temperatures, the seeds were planted in nursery. The emergence and its velocity differed only in the comparison of the control with the applied treatments, with favorable results of all soak treatments, independent of temperature and duration. The mean time of emergence presented a significant interaction effect, with the four day 40ºC soaking temperature period, presenting a lower mean time (163 days). The initial emergence time was lower in 35ºC temperature (80 days), while the final time didn't show differences among means. Seeds soaked for two days had 50 percent dead seeds, while seeds soaked for four days had just 38 percent. Seedling emergence was favored by soaking, independent of temperature and duration.

Germination/physiology , Arecaceae/embryology , Seedlings/physiology , Plant Dormancy
Braz. j. biol ; 70(1): 19-24, Feb. 2010. tab, ilus
Article in English | LILACS | ID: lil-539729


Canopy cover has significant effects on the understory environment, including upon light availability for seedling growth. The aim of the present study was to verify spatial heterogeneity and seasonal changes in the canopy cover of a dense Cerrado area, and their relationship to understory photosynthetic active radiation availability. Leaf area index (LAI) values in the rainy season varied from 0.9 to 4.83, with 40 percent of the values ranging from 4.0 to 5.0, while in the dry season LAI varied from 0.74 to 3.3, with 53 percent of the values oscilating from 2.0 to 3.0. Understory light (Qi ) and the Lambert-Beer ratio (Qi/Qo) were taken around noon on sunny days (between 11:00 AM and 1:00 PM). They were also statistically different (p < 0.01) between the dry and wet seasons, with 72 percent of sampled points in the rainy season presenting photosynthetic photon flux density (PPFD) values lower than 250 μmol.m-2/s around noon, whereas in the dry season, most PPFD values varied from 1500 to 1817 μmol.m-2/s , thus providing high light availability for understory plants. In most of the studied sites, understory plants did not even receive enough light for 50 percent of their photosynthetic capacity in the wet season. In contrast during the dry season, Qi/Qo values of 0.8 to 1.0 were observed in more than 50 percent of the points, thereby allowing for photosynthetic light saturation. Thus, light variability around noon was higher during the dry season than in the wet season, its heterogeneity being related to spatial complexity in the canopy cover.

A cobertura do dossel tem efeitos significativos no ambiente do sub-bosque incluindo a disponibilidade de luz para o crescimento das plântulas. O objetivo do presente estudo foi verificar a heterogeneidade espacial e as mudanças sazonais da cobertura do dossel em uma area de Cerrado denso e sua relação com a radiação fotossintetica ativa diponivel no sub-bosque. Os valores do índice de área foliar (IAF) na estação chuvosa variaram de 0,9 a 4,83 com 40 por cento dos valores dentro de 4,0 a 5,0, enquanto na estação seca o IAF variou de 0,74 a 3,3 com 53 por cento dos valores dentro de 2,0 a 3,0. A luz abaixo do dossel (Qi) e razão de Lambert-Beer (Qi/Qo) foi obtida entre as 11:00 e 13:00 horas em dias ensolarados. Os valores também foram estatisticamente diferentes (p < 0.01) entre a estação seca e a chuvosa, com 72 por cento dos pontos amostrados na estação chuvosa apresentando valores de densidade de fluxo de fotons fotossinteticamente ativos (DFFA) menores de 250 μmol.m-2/s por volta do meio dia, enquanto na estação seca a maioria dos valores de DFFA variou entre 1500 a 1817 μmol.m-2/s propiciando alta disponibilidade de luz para o sub-bosque. Na maior parte dos pontos amostrados, as plantas de sub-bosque não receberam quantidade de luz suficiente para 50 por cento de sua capacidade fotossintetica na estação chuvosa. Em contraste durante a estação seca foram observados valores de of Qi/Qo de 0.8 a 1.0 em mais de 50 por cento dos pontos amostrados, permitindo a saturação de luz da fotossíntese. A variabilidade de luz por volta do meio dia no sub-bosque foi maior durante a estação seca do que na estação chuvosa, e a heterogeneidade foi relacionada com a complexidade espacial da cobertura do dossel.

Photosynthesis/physiology , Sunlight , Seedlings/growth & development , Trees/growth & development , Brazil , Plant Leaves/growth & development , Seasons , Seedlings/physiology , Trees/physiology
Rev. biol. trop ; 57(3): 771-780, sep. 2009. graf
Article in English | LILACS | ID: lil-637908


Basic aspects of the reproductive biology are largely unknown for most tropical tree species, although they are important elements to understand the impacts of anthropogenic activities as logging and forest fragmentation on these populations. In this study, data are presented on leaf and reproductive phenology, fruit production and seedling demography of a population of an endemic tree species of Southern Central America, Caryocar costaricense. This species has been affected by selective logging and forest fragmentation of its habitat. Phenology was studied by observation of 15-22 tree crowns during two reproductive periods (2003 and 2005). Circular plots were established around 11 adult trees to count the number of fallen fruits and seedlings during three years (2003, 2004, 2005). Although reproductive phenology is restricted to the short dry season in this species, seed germination occurred year-round. Fruit and seedling production shows a strong inter-individual variation within the study populations, with two large trees producing nearly 50%-70% of the fruits and seedlings during two years. Most of the seeds that fall beneath the tree crown are covered by litterfall or removed by fauna. We found evidence that many of these seeds become part of a seed bank in the forest floor. Because of the observed reproductive dominance of few large trees in these populations, we propose that selective logging on reproductive trees can severely impact the recruitment of this species. Rev. Biol. Trop. 57 (3): 771-780. Epub 2009 September 30.

Los aspectos básicos de la biología reproductiva de árboles tropicales son en su mayoría desconocidos, aunque son conocimientos esenciales para entender el impacto de actividades antropogénicas como la tala selectiva y la fragmentación de bosques. En este estudio se presentan datos sobre la fenología foliar y reproductiva, la producción de frutos, y la demografía de plántulas de una población de Caryocar costaricense, una especie endémica del sur de América Central, afectada por tala selectiva y fragmentación de su hábitat original. La fenología fue estudiada por medio de la observación de las copas de 15 a 22 árboles adultos durante dos períodos reproductivos (años 2003 y 2005). Para estudiar la caída de frutos y la dinámica de germinación y supervivencia de plántulas, se establecieron parcelas circulares alrededor de 11 individuos adultos, donde se realizaron observaciones durante tres años (2003, 2004, 2005). Aunque la fenología reproductiva está limitada a la corta estación seca local, la germinación de semillas se da todo el año. La producción de frutos y plántulas mostró una alta variación inter-individual, con dos árboles produciendo 50-70% de todos los frutos y plántulas durante dos años. La mayoría de las semillas que caen bajo la copa son cubiertas por mantillo o removidas por la fauna. Muchas de estas semillas se vuelven parte de un banco de semillas latente en el piso del bosque. Debido a la dominancia reproductiva de unos pocos grandes árboles en estas poblaciones, se propone que la tala selectiva sobre individuos reproductivos puede provocar un impacto severo sobre el reclutamiento de nuevos individuos en estas poblaciones.

Seedlings/physiology , Trees/physiology , Costa Rica , Flowers/growth & development , Fruit/growth & development , Reproduction/physiology , Seasons , Trees/classification
Braz. j. biol ; 69(3): 813-818, Aug. 2009. graf
Article in English | LILACS | ID: lil-527149


Since cerrado fires may impede the growth of seedlings into trees, they may shape the population of woody species. In this study, we assessed the effects of a severe fire on the population structure and spatial distribution of Zanthoxylum rhoifolium, a widespread cerrado tree. We were interested to know the importance of the resprouting and sexual reproduction in regenerating the population. The study area had been for about six years protected from fire, before a severe fire at the end of the dry season in 2006. We sampled and measured all individuals of Z. rhoifolium found in 80 plots of 25 m². We found 149 individuals before the fire and 112 after the fire, of which 77 were resprouts from burned seedlings and saplings. We did not find significant differences between the population structure before and after the fire. The spatial distribution of the population remained clumped after the fire. Thus, the Z. rhoifolium population was very resilient to a severe fire. We did not find any new seedlings. As a consequence, resprouting seems to be more important than sexual reproduction in promptly regenerating the Z. rhoifolium populations.

Uma vez que as queimadas no cerrado podem impedir o crescimento de plântulas, elas podem moldar a população de espécies arbóreas. Neste estudo, avaliamos os efeitos de uma queimada severa na estrutura e na distribuição espacial da população de Zanthoxylum rhoifolium, uma espécie de árvore comum no cerrado. O objetivo era saber a importância relativa do rebrotamento e da reprodução sexuada na regeneração da população. A área de estudo, há aproximadamente seis anos sem queimar, sofreu uma queimada severa no final da estação seca de 2006. Amostramos todos os indivíduos de Z. rhoifolium encontrados em 80 parcelas de 25 m². Encontramos 149 indivíduos antes do fogo e 112 depois dele, dos quais 77 eram rebrotas de plântulas e jovens queimados. Não encontramos diferenças significativas entre a estrutura da população antes e após o fogo. A distribuição espacial da população permaneceu agregada após a queimada. Portanto, a população de Z. rhoifolium foi resiliente ao fogo. Não foi encontrada nenhuma nova plântula. Consequentemente, o rebrotamento parece ser mais importante que a reprodução sexuada na regeneração imediata das populações de Z. rhoifolium.

Fires , Seedlings/physiology , Zanthoxylum/physiology , Adaptation, Physiological , Brazil , Population Density , Seedlings/growth & development , Zanthoxylum/growth & development