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1.
Health Place ; 87: 103235, 2024 May.
Artigo em Inglês | MEDLINE | ID: mdl-38569450

RESUMO

The decline of children's opportunities to play outdoors raises a new concern about the quality of outdoor play environments, and their developmental and well-being benefits for children. This systematic review aims to synthesize the associations between outdoor play features and children's behavior and health. PRISMA guidelines were followed (2021). The inclusion criteria were studies with children aged between 5 and 12 (Population); that addressed presence, absence or disposition of equipment, natural elements, loose parts, resources availability, type of terrain and space modifications (Intervention or Exposure); in pre-post intervention or between groups (Comparison); related to health and behavior in different domains (Outcomes); with an experimental, observational, descriptive or longitudinal design (Study design). Indoor context, adult-led activities and structured activities were excluded. A literature search of five databases (PubMed, Web of Science, ERIC, Scopus, and PsycINFO) was concluded in March 2022. After identifying 28,772 records, duplicates and irrelevant titles were removed, and abstracts and full-text articles were screened in duplicate. The remaining 51 eligible articles (45 primary studies) were assessed for risk of bias with QualSyst. A narrative synthesis of the results was conducted. The most frequent behavioral or health outcome addressed was physical activity. Included studies focused on the following space features: fixed structures, space naturalness, floor markings, loose parts/equipment, area available, and the combination of factors. Although some positive effects were found, the heterogeneity between studies did not allow to draw firm conclusions on the effects of each environmental feature on primary children's health and behavior. Systematic review registration: PROSPERO CRD42020179501.


Assuntos
Comportamento Infantil , Exercício Físico , Jogos e Brinquedos , Humanos , Criança , Comportamento Infantil/psicologia , Planejamento Ambiental , Pré-Escolar , Comportamentos Relacionados com a Saúde
2.
ACS ES T Water ; 4(3): 784-804, 2024 Mar 08.
Artigo em Inglês | MEDLINE | ID: mdl-38482340

RESUMO

Wastewater treatment companies are facing several challenges related to the optimization of energy efficiency, meeting more restricted water quality standards, and resource recovery potential. Over the past decades, computational models have gained recognition as effective tools for addressing some of these challenges, contributing to the economic and operational efficiencies of wastewater treatment plants (WWTPs). To predict the performance of WWTPs, numerous deterministic, stochastic, and time series-based models have been developed. Mechanistic models, incorporating physical and empirical knowledge, are dominant as predictive models. However, these models represent a simplification of reality, resulting in model structure uncertainty and a constant need for calibration. With the increasing amount of available data, data-driven models are becoming more attractive. The implementation of predictive models can revolutionize the way companies manage WWTPs by permitting the development of digital twins for process simulation in (near) real-time. In data-driven models, the structure is not explicitly specified but is instead determined by searching for relationships in the available data. Thus, the main objective of the present review is to discuss the implementation of machine learning models for the prediction of WWTP effluent characteristics and wastewater inflows as well as anomaly detection studies and energy consumption optimization in WWTPs. Furthermore, an overview considering the merging of both mechanistic and machine learning models resulting in hybrid models is presented as a promising approach. A critical assessment of the main gaps and future directions on the implementation of mathematical modeling in wastewater treatment processes is also presented, focusing on topics such as the explainability of data-driven models and the use of Transfer Learning processes.

3.
Children (Basel) ; 10(2)2023 Jan 25.
Artigo em Inglês | MEDLINE | ID: mdl-36832343

RESUMO

This study examined the relationship between the quality of the kindergarten physical and social environment to promote physical activity (PA) and preschoolers' motor and social-emotional competence. Two Portuguese kindergartens (Gondomar city) were selected from a pool of seventeen with an assessment of kindergarten PA best practices (one with high PA practices, the other with low). Thirty-six children (M = 4.42; SD = 1.00 years) without neuromotor disorders participated in this study. Motor and social-emotional competence were assessed with standardized motor skills tasks and parent report of child behaviors. Children from the kindergarten with higher compliance with PA best practices showed significantly better motor competence. No statistically significant differences were found for social-emotional competence scores. These findings emphasize the critical importance of kindergarten in promoting preschoolers' motor competence by assuring a physical and social environment that enhances their PA practice. This is a particularly relevant concern for directors and teachers during the post-pandemic period, given the developmental delays and decreases in physical activity preschool children experienced across the pandemic period.

4.
Children (Basel) ; 10(2)2023 Jan 29.
Artigo em Inglês | MEDLINE | ID: mdl-36832369

RESUMO

Play has a key role in children psychomotor development, and the quality of play spaces can be a facilitator of the former. The physical properties of the environment, such as equipment or material available, can influence children's behavior. However, it is not clear how the provision of different loose parts impacts children's play patterns. This study aimed to analyze the influence of four types of loose parts on the time, frequency and number of children using them during free play sessions. We recorded the 1st, 5th and 10th sessions delivered by playworkers in a primary school, with 14 children (Mage = 9.96 years). The available loose parts were categorized, and four types of materials were chosen: tarpaulin/fabrics, cardboard boxes, plastic crates and plastic tubes. The influence of these materials on the time spent using them, frequency of use and number and sex of users (dependent variables) was analyzed. Some tendencies emerged, such as the popularity of tarpaulin/fabrics, but results showed no significant differences between materials. This could mean that the specific physical qualities of each loose part were not determiners of the behavioral domains analyzed. These findings suggest that all types of materials studied can be meaningful for children to engage with in diverse play opportunities.

5.
Cluster Comput ; : 1-14, 2022 Sep 07.
Artigo em Inglês | MEDLINE | ID: mdl-36091661

RESUMO

Nowadays, Blockchain has been widely used to store decentralized and secure transactions involving cryptocurrency, e.g., Bitcoin, Ethereum, etc. However, Blockchain can also store other types of information besides monetary transactions. On the other hand, innovative solutions for smart cities are concerned with how services and information can be safely stored and shared. For this reason, smart city systems can benefit from using Blockchain to integrate their data and services. These smart solutions also demand consistency and standardization across the industry. However, this Blockchain integration varies according to its implementation. FIWARE, a framework of an open-source platform for smart solutions, adopts NGSI Standards (Context Information Management (CIM); NGSI-LD API: Tech. Rep., CIM and ETSI Industry Specification Group (ISG), 2020) to enable the integration of components and provides the basis for interoperability and portability among smart solutions. Unfortunately, FIWARE does not support any integration with Blockchain technology. Hence, this paper proposes a set of new components to allow FIWARE to be integrated with Blockchain technology. With these proposed components, it is possible to support Blockchain technology with smart city applications via the FIWARE platform. For instance, we have designed and implemented a FIWARE Blockchain adapter to submit/listen to transactions from/to FIWARE Context Broker to/from any Blockchain implementation without human intervention. In addition, we present a global post-pandemic vaccination case study to evaluate the proposed approach in the Smart City context.

6.
J Phys Act Health ; 19(6): 456-472, 2022 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-35537707

RESUMO

BACKGROUND: The purpose was to synthesize evidence on the association between nature-based Early Childhood Education (ECE) and children's physical activity (PA) and motor competence (MC). METHODS: A literature search of 9 databases was concluded in August 2020. Studies were eligible if (1) children were aged 2-7 years old and attending ECE, (2) ECE settings integrated nature, and (3) assessed physical outcomes. Two reviewers independently screened full-text articles and assessed study quality. Synthesis was conducted using effect direction (quantitative), thematic analysis (qualitative), and combined using a results-based convergent synthesis. RESULTS: 1370 full-text articles were screened and 39 (31 quantitative and 8 qualitative) studies were eligible; 20 quantitative studies assessed PA and 6 assessed MC. Findings indicated inconsistent associations between nature-based ECE and increased moderate to vigorous PA, and improved speed/agility and object control skills. There were positive associations between nature-based ECE and reduced sedentary time and improved balance. From the qualitative analysis, nature-based ECE affords higher intensity PA and risky play, which could improve some MC domains. The quality of 28/31 studies was weak. CONCLUSIONS: More controlled experimental designs that describe the dose and quality of nature are needed to better inform the effectiveness of nature-based ECE on PA and MC.


Assuntos
Exercício Físico , Comportamento Sedentário , Criança , Pré-Escolar , Humanos
7.
Front Public Health ; 10: 861390, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35570950

RESUMO

Background: Learning to cycle is an important milestone for children, but the popularity of cycling and the environmental factors that promote the development and practice of this foundational movement skill vary among cultures and across time. This present study aimed to investigate if country of residence and the generation in which a person was born influence the age at which people learn to cycle. Methods: Data were collected through an online survey between November 2019 and December 2020. For this study, a total of 9,589 responses were obtained for adults (self-report) and children (parental report) living in 10 countries (Portugal, Italy, Brazil, Finland, Spain, Belgium, United Kingdom, Mexico, Croatia, and the Netherlands). Participants were grouped according to their year of birth with 20-year periods approximately corresponding to 3 generations: 1960-79 (generation X; n = 2,214); 1980-99 (generation Y; n = 3,994); 2000-2019 (generation Z; n = 3,381). Results: A two-way ANOVA showed a significant effect of country, F(9,8628) = 90.17, p < 0.001, ηp2 = 0.086, and generation, F(2,8628) = 47.21, p < 0.001, ηp2 = 0.122, on the age at which individuals learn to cycle. Countries with the lowest learning age were the Netherlands, Finland and Belgium and countries with the highest learning age were Brazil and Mexico. Furthermore, the age at which one learns to cycle has decreased across generations. There was also a significant country x generation interaction effect on learning age, F(18,8628) = 2.90, p < 0.001; however, this effect was negligible ( ηp2 = 0.006). Conclusions: These findings support the socio-ecological perspective that learning to cycle is a process affected by both proximal and distal influences, including individual, environment and time.


Assuntos
Comparação Transcultural , Pais , Adulto , Brasil , Criança , Humanos , Espanha , Inquéritos e Questionários
8.
Artigo em Inglês | MEDLINE | ID: mdl-35627504

RESUMO

This systematic review synthesised evidence on associations between nature-based early childhood education (ECE) and children's social, emotional, and cognitive development. A search of nine databases was concluded in August 2020. Studies were eligible if: (a) children (2-7 years) attended ECE, (b) ECE integrated nature, and (c) assessed child-level outcomes. Two reviewers independently screened full-text articles and assessed study quality. Synthesis included effect direction, thematic analysis, and results-based convergent synthesis. One thousand three hundred and seventy full-text articles were screened, and 36 (26 quantitative; 9 qualitative; 1 mixed-methods) studies were eligible. Quantitative outcomes were cognitive (n = 11), social and emotional (n = 13), nature connectedness (n = 9), and play (n = 10). Studies included controlled (n = 6)/uncontrolled (n = 6) before-after, and cross-sectional (n = 15) designs. Based on very low certainty of the evidence, there were positive associations between nature-based ECE and self-regulation, social skills, social and emotional development, nature relatedness, awareness of nature, and play interaction. Inconsistent associations were found for attention, attachment, initiative, environmentally responsible behaviour, and play disruption/disconnection. Qualitative studies (n = 10) noted that nature-based ECE afforded opportunities for play, socialising, and creativity. Nature-based ECE may improve some childhood development outcomes, however, high-quality experimental designs describing the dose and quality of nature are needed to explore the hypothesised pathways connecting nature-based ECE to childhood development (Systematic Review Registration: CRD42019152582).


Assuntos
Desenvolvimento Infantil , Emoções , Pré-Escolar , Cognição , Estudos Transversais , Humanos , Habilidades Sociais
9.
Artigo em Inglês | MEDLINE | ID: mdl-35162834

RESUMO

BACKGROUND: Learning to cycle is an important milestone in a child's life, so it is important to allow them to explore cycling as soon as possible. The use of a bicycle with training wheels (BTW) for learning to cycling is an old approach practiced worldwide. Most recently, a new approach using the balance bike (BB) has received increased attention, and several entities believe that this could be most efficient. Drawing on the work of Bronfenbrenner (1995) and Newel (1986), this study aimed to analyse the effect of BB's use on the learning process of cycling independently. METHODS: Data were collected in Portugal from an online structured survey between November 2019 and June 2020. RESULTS: A total of 2005 responses were obtained for adults and children (parental response). Results revealed that when the BB's approach was used, learning age (LA) occurred earlier (M = 4.16 ± 1.34 years) than with the BTW's approach (M = 5.97 ± 2.16 years) (p < 0.001); or than when there was only the single use of the traditional bicycle (M =7.27 ± 3.74 years) (p < 0.001). CONCLUSIONS: Children who used the BB as the first bike had a significantly lower LA than children who did not use it (p < 0.001). To maximize its effects, the BB should be used in the beginning of the learning process.


Assuntos
Ciclismo , Aprendizagem , Adulto , Criança , Pré-Escolar , Humanos , Portugal , Inquéritos e Questionários
10.
Children (Basel) ; 8(6)2021 Jun 08.
Artigo em Inglês | MEDLINE | ID: mdl-34200996

RESUMO

The present article aimed to verify whether the age at which children learn to ride a bicycle is related to their physical activity or birth order. Data were collected from an online structured survey between November 2019 and June 2020. A total of 8614 responses were obtained from 22 countries. The results reveal significant differences in learning age depending on the frequency of physical activity (F(5, 7235) = 35.12, p < 0.001, ηp2 = 0.24). People who engaged in physical activity less than twice a month learned to cycle later (M = 7.5 ± 5.3 years) than people who engaged in physical activity on a daily basis (M = 5.7 ± 2.2 years) (p < 0.001). There were also significant differences in learning age according to birth order (F(2, 3008) = 7.31, p = 0.00, ηp2 = 0.005). Only children had the highest learning age (M = 5.5 ± 2.4 years), whereas those who were born last had the lowest, (M = 5.1 ± 1.9 years) (p = 0.013). Creating opportunities for children to be engaged in play and physical activity and social modulation through their older siblings seem to be key conditions to encourage children to learn how to ride a bicycle from a young age and to foster their motor development.

11.
Syst Rev ; 9(1): 226, 2020 10 02.
Artigo em Inglês | MEDLINE | ID: mdl-33008489

RESUMO

BACKGROUND: Several systematic reviews have reviewed the evidence relating to nature on aspects of children and adolescent's health and wellbeing; however, none have looked at the associations or effectiveness of attending nature-based early childhood education (ECE). The main objective is to systematically review and synthesise the evidence to determine if nature-based ECE enhances children's health, wellbeing and development. METHODS: We will search the following electronic databases (from inception onwards): MEDLINE, Scopus, PsycINFO, ERIC, SportDiscus, Australian Education Index, British Education Index, Child Development and Adolescent studies, and Applied Social Sciences Index and Abstracts. Grey literature will be identified searching dissertations and reports (e.g. Open Grey, Dissertations Theses Database [ProQuest], and Google Scholar). All types of studies (quantitative and qualitative) conducted in children (aged 2-7 years old) attending ECE who had not started education at primary or elementary school will be included. The exposure of interest will be nature-based ECE settings that integrate nature into their philosophy and/or curriculum and environment. The outcomes of interest will be all aspects of the child's physical, cognitive, social and emotional health wellbeing and development. Two reviewers will independently screen full-text articles. The study methodological quality (or bias) will be appraised using appropriate tools. If feasible, a meta-analysis will be conducted using a random-effect model for studies similar in exposure and outcome. Where studies cannot be included in a meta-analysis, findings will be summarised based on the effect directions and a thematic analysis will be conducted for qualitative studies. DISCUSSION: This systematic review will capture the state of the current literature on nature-based ECE for child health, wellbeing and development. The results of this study will be of interest to multiple audiences (including researchers and policy makers). Results will be published in a peer-reviewed journal. Gaps for future research will be identified and discussed. SYSTEMATIC REVIEW REGISTRATION: PROSPERO CRD42019152582.


Assuntos
Saúde da Criança , Atenção à Saúde , Adolescente , Austrália , Criança , Pré-Escolar , Humanos , Metanálise como Assunto , Pesquisa Qualitativa , Revisões Sistemáticas como Assunto
12.
Percept Mot Skills ; 126(3): 366-388, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30773999

RESUMO

Through development, a child's varied movement contexts provide different opportunities or affordances for action that are fundamental to promoting motor competence. Although home is the primary environment for infants, as children age, school and sport environments gain importance. Studies focusing on affordances for motor behavior in children have mainly addressed the home microsystem, providing an incomplete picture of affordances across different settings, particularly later in development. Here, we undertook a narrative literature review of various affordances for children's motor development. This review revealed that prior studies of school and sports contexts have not specifically focused on those environmental properties that promote or hinder motor learning opportunities, meaning that future research should assess these relationships through manipulations of environmental features in these different microsystems.


Assuntos
Comportamento Infantil/fisiologia , Desenvolvimento Infantil/fisiologia , Atividade Motora/fisiologia , Destreza Motora/fisiologia , Criança , Humanos , Lactente , Instituições Acadêmicas , Esportes
13.
Front Psychol ; 9: 2198, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30483200

RESUMO

Meaning of place is usually approached as slow social cognitive construction. However, grounded on the theory of affordances, it may also stem from direct perception-action processes, which enable the formation of immediate perceived functional, social or symbolic meaning of place (Raymond et al., 2017b). In the present study, affordances of places, which are perceived by a specific perceiver in a specific place, were mapped using a web-map survey. Each place offers opportunities for interaction, behavior, use, feeling or meaning, which is directly perceived and actualized there. This paper aims at identifying the degree of youth-friendliness of urban neighborhoods using the hypothetical intertwined model of independent mobility and actualized affordances (Kyttä, 2004) combined with place use and meaning (Broberg et al., 2013a). SoftGISchildren methodology (Broberg et al., 2013a) was adopted to carry out a cross-sectional research, involving 145 sixth to ninth graders of the Great Lisbon area. SoftGIS integrates Public Participation Geographic Information Systems (PPGIS), enabling collection and place mapping of daily subjective environmental experiences in the physical environment, consequently allowing for individuals to be actively engaged in public processes of participation (Brown and Kyttä, 2014). A place based web survey called "Ideal City: a game of graphic imagination" was adopted. Participants were asked to map their home place, select and mark social, functional, leisure and emotional place transactions, and report actual and ideal mobility to these places. Findings on mobility showed that shorter distances to meaningful affordances of places promote active and independent travel; ideally, youths would like to be more frequently active and more frequently autonomous. As for meaningful places, a total of 1632 affordances were localized, with a higher number on social category. Neighborhood area (500 m around home place) was assessed as youth-friendly, where active and independent travel occurred more frequently, and social affordances were the most expressive type. Relational and affectional experience in the neighborhood places was meaningful for youth. Municipalities should consider these features when planning, designing and managing residential areas aiming for the well-being and health of young citizens; and include youths as specialists of space (spatialists) in planning participatory processes (PPGIS).

14.
Braz. J. Psychiatry (São Paulo, 1999, Impr.) ; 37(2): 162-167, 12/05/2015. tab, graf
Artigo em Inglês | LILACS | ID: lil-748977

RESUMO

Objective: To identify, by means of a systematic review, the frequency with which comorbid personality disorders (PDs) have been assessed in studies of euthymic bipolar patients. Methods: PubMed, ciELO and PsychINFO databases were searched for eligible articles published between 1997 and 2013. After screening 1,249 empirical papers, two independent reviewers identified three articles evaluating the frequency of PDs in patients with bipolar disorders assessed in a state of euthymia. Results: The total sample comprised 376 euthymic bipolar patients, of whom 155 (41.2%) had at least one comorbid PD. Among them, we found 87 (23.1%) in cluster B, 55 (14.6%) in cluster C, and 25 (6.6%) in cluster A. The frequencies of PD subtypes were: borderline, 38 (10.1%); histrionic, 29 (7.7%); obsessive-compulsive, 28 (7.4%); dependent, 19 (5%); narcissistic, 17 (4.5%); schizoid, schizotypal, and avoidant, 11 patients each (2.95%); paranoid, five (1.3%); and antisocial, three (0.79%). Conclusion: The frequency of comorbid PD was high across the spectrum of euthymic bipolar patients. In this population, the most common PDs were those in cluster B, and the most frequent PD subtype was borderline, followed by histrionic and obsessive-compulsive. .


Assuntos
Humanos , Transtorno Obsessivo-Compulsivo/epidemiologia , Transtornos da Personalidade/epidemiologia , Comorbidade , Transtorno Obsessivo-Compulsivo/diagnóstico , Transtorno Obsessivo-Compulsivo/psicologia , Transtornos da Personalidade/classificação , Transtornos da Personalidade/diagnóstico , Transtornos da Personalidade/psicologia
15.
Braz J Psychiatry ; 37(2): 162-7, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25946399

RESUMO

OBJECTIVE: To identify, by means of a systematic review, the frequency with which comorbid personality disorders (PDs) have been assessed in studies of euthymic bipolar patients. METHODS: PubMed, ciELO and PsychINFO databases were searched for eligible articles published between 1997 and 2013. After screening 1,249 empirical papers, two independent reviewers identified three articles evaluating the frequency of PDs in patients with bipolar disorders assessed in a state of euthymia. RESULTS: The total sample comprised 376 euthymic bipolar patients, of whom 155 (41.2%) had at least one comorbid PD. Among them, we found 87 (23.1%) in cluster B, 55 (14.6%) in cluster C, and 25 (6.6%) in cluster A. The frequencies of PD subtypes were: borderline, 38 (10.1%); histrionic, 29 (7.7%); obsessive-compulsive, 28 (7.4%); dependent, 19 (5%); narcissistic, 17 (4.5%); schizoid, schizotypal, and avoidant, 11 patients each (2.95%); paranoid, five (1.3%); and antisocial, three (0.79%). CONCLUSION: The frequency of comorbid PD was high across the spectrum of euthymic bipolar patients. In this population, the most common PDs were those in cluster B, and the most frequent PD subtype was borderline, followed by histrionic and obsessive-compulsive.


Assuntos
Transtorno Obsessivo-Compulsivo/epidemiologia , Transtornos da Personalidade/epidemiologia , Comorbidade , Humanos , Transtorno Obsessivo-Compulsivo/diagnóstico , Transtorno Obsessivo-Compulsivo/psicologia , Transtornos da Personalidade/classificação , Transtornos da Personalidade/diagnóstico , Transtornos da Personalidade/psicologia
16.
Rev. biol. trop ; 53(3/4): 369-376, sept.-dic. 2005. graf
Artigo em Inglês | LILACS | ID: lil-451267

RESUMO

Pistia stratiotes is an aquatic macrophyte that grows in temporary-ponds in the southern Pantanal, Brazil. It reproduces both sexually and asexually and is usually observed forming dense mats on the water surface, a condition favored by the plant’s vegetative reproduction coupled with an ability for rapid growth. In this study we examined the effect of densely crowded conditions on the production of reproductive and vegetative structures. In addition, we verified whether there is a trade-off between clonal growth and investment in sexual reproductive structures, and whether there is an allocation pattern with plant size. Individual plant biomass and the number of the rosettes producing sexual reproductive structures and vegetative growth structures both increased with density. Increase in plant size resulted in increased proportional allocation to sexual reproductive structures and vegetative growth structures. Allocation of biomass to reproduction did not occur at the expense of clonal growth. Thus, the density response appears as a increase of rosettes producing sexual reproductive structures and vegetative growth structures. Therefore, long leaves and stolons may be adaptive under densely crowded conditions where competition for light is intense. An important aspect in the study of trade-offs is the size-dependency of the allocation patterns .Usually, larger plants produce more biomass. Therefore, larger plants can allocate more biomass to both vegetative and sexual reproduction than smaller plants and thus show a positive correlation between both traits rather than the expected negative one


Pistias strariotes es una macrófita acuática que crece en charcas estacionales en el Pantanal sureño de Brasil. Se reproduce tanto sexual como asexualmente y se obsrva generalmente que forma densas parches sobre la superficie del agua, una condicion que favorecida por la reproduccion vegetativa de la planta junto con una habilidad para el rapido crecimiento. En este estudio se examinó el efecto de las condiciones densamente aglomeradas sobre las estructuras reproducctivas y vegetativas. En adicion, se verificó hasta donde hay un intercambio entre el crecimiento clonal y la inversión en estructuras reproductivas, y hasta donde hay un patrón de tranlocación con el crecimiento de la planta. La biomasa individual de las plantas y el número de rosetas productoras de estructuras reproductivas y estructuras de crecimiento vegetativo se incrementan con la densidad. El incremento en el tamaño de las plantas resultó en un incremento proporcional de la asignación hacia estructuras reproductivas y estructuras de crecimiento vegetativo. La asignación de biomasa hacia reproducción no ocurrió a expensas del crecimiento clonal. Así, la respuesta a la densidad parece como un incremento en la producción de rosetas que producen estructuras reproductivas y de crecimiento vegetativo. Por lo tanto, las hojas largas y estolones pueden ser adaptativas bajo condiciones de densamente aglomeradas dond la competencia por la luz es intensa. Un aspecto importante en el estudio de intercambio son los patrones asignación dependientes de la densidad. Usualmente, las plantas más grandes producen más biomasa. por lo tanto, las plantas más grandes pueden asignar más biomasa hacia la reproducción vegetativa y sexual que las plantas pequeñas y así mostraron una correlación positiva entre ambos caracteres


Assuntos
Araceae/fisiologia , Biomassa , Densidade Demográfica , Reprodução/fisiologia
17.
Rev Biol Trop ; 53(3-4): 369-76, 2005.
Artigo em Inglês | MEDLINE | ID: mdl-17354448

RESUMO

Pistia stratiotes is an aquatic macrophyte that grows in temporary-ponds in the southern Pantanal, Brazil. It reproduces both sexually and asexually and is usually observed forming dense mats on the water surface, a condition favored by the plant's vegetative reproduction coupled with an ability for rapid growth. In this study we examined the effect of densely crowded conditions on the production of reproductive and vegetative structures. In addition, we verified whether there is a trade-off between clonal growth and investment in sexual reproductive structures, and whether there is an allocation pattern with plant size. Individual plant biomass and the number of the rosettes producing sexual reproductive structures and vegetative growth structures both increased with density. Increase in plant size resulted in increased proportional allocation to sexual reproductive structures and vegetative growth structures. Allocation of biomass to reproduction did not occur at the expense of clonal growth. Thus, the density response appears as a increase of rosettes producing sexual reproductive structures and vegetative growth structures. Therefore, long leaves and stolons may be adaptive under densely crowded conditions where competition for light is intense. An important aspect in the study of trade-offs is the size-dependency of the allocation patterns .Usually, larger plants produce more biomass. Therefore, larger plants can allocate more biomass to both vegetative and sexual reproduction than smaller plants and thus show a positive correlation between both traits rather than the expected negative one.


Assuntos
Araceae/fisiologia , Biomassa , Densidade Demográfica , Reprodução/fisiologia
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