995 resultados para Fruit


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To investigate the movement of seeds transported by fruit-eating birds in an agricultural, fragmented landscape of the Atlantic forest of southeast Brazil, I asked which bird species are the main seed dispersers in such environment, and how they use the available habitats (small forest fragments, forest thickets, live fences, isolated trees, and active pastures) where they are most likely to drop the seeds they swallow the relative importance of fruit-eating birds as seed vectors was evaluated based on the number of fruit species eaten, the number of visits, and visitation rate to fruiting plants. Habitat use was accessed by recording the habitats where birds were seen or heard during walks conducted throughout the study area. Sixteen plant species were observed during 308.3 plant-hours. Forty-one bird species were observed eating fruits in a total of 830 visits to fruiting plants. Sayaca Tanagers (Thraupis sayaca) and Pale-breasted Thrushes (Turdus leucomelas) ate the greatest number of fruit species, were the most frequent plant visitors in terms of number and rate of visits, and had a broad range of habitat use. These two species and the Rusty-margined Guan (Penelope superciliaris), which is able to swallow large fruits with large seeds that smaller bird species cannot cat, likely have a great contribution to the movement of seeds throughout this highly degraded landscape.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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We investigated effects of fruit colour (red, black or white), habitat (anthropogenic edges and forest interior) and fragment size on the removal of artificial fruits in semideciduous forests in south-east Brazil. Eight forest fragments ranging from 251 to 36,000 ha were used. We used artificial fruits, which were placed on shrubs between I and 2 m in height and checked after 48 and 96 h for peck marks in the fruits. All three variables affected the probability of consumption of our fruit models. Red and black fruits were statistically more pecked than the white fruits. The probability of fruit consumption was lower in the interior than at the edge and less in small than in large fragments. However, the decrease fruit consumption in small compared with large fragments was more accentuated for red and black fruits than for white fruits. Our results show that habitat reduction and edges affect the chances of a fruit being eaten by birds, which may ultimately affect plant fitness in forest fragments. (C) 2003 Elsevier B.V. Ltd. All rights reserved.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Fruit traits evolve in response to an evolutionary triad between plants, seed dispersers, and antagonists that consume fruits but do not disperse seeds. The defense trade-off hypothesis predicts that the composition of nutrients and of secondary compounds in fruit pulp is shaped by a trade-off between defense against antagonists and attraction to seed dispersers. The removal rate model of this hypothesis predicts a negative relationship between nutrients and secondary compounds, whereas the toxin-titration model predicts a positive relationship. To test these alternative models, we evaluated whether the contents of nutrients and secondary compounds can be used to predict fruit removal by mutualists and pathogens in 14 bird-dispersed plants on a subtropical island in São Paulo state, southeastern Brazil. We selected eight to ten individuals of each species and prevented fruit removal by covering four branches with a net and left fruits on four other branches available to both, vertebrate fruit consumers and pathogens. The persistence of ripe fruits was drastically different among species for bagged and open fruits, and all fruit species persisted longer when protected against seed dispersers. We found that those fruits that are quickly removed by vertebrates are nutrient-rich, but although the attack rate of pathogens is also high, these fruits have low contents of quantitative defenses such as tannins and phenols. Thus, we suggest that the fruit removal rate by seed dispersers is the primary factor selecting the levels of fruit defense. Likewise, nutrient-poor fruits have low removal of seed dispersers and low probability of attack by pathogens. These species retain ripe fruits in an intact condition for a prolonged period because they are highly defended by secondary compounds, which reduce overall attractiveness. However, this strategy might be advantageous for plants that depend on rare or unreliable dispersers.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Background and aims Late-acting self-incompatibility (LSI). in which selfed flowers fail to form fruits despite apparently successful growth of the pollen tubes to the ovules, is a contentious and still poorly understood phenomenon. Some studies have indicated pollen tube-pistil interactions, and major gene control. Others favour an early acting inbreeding depression explanation.Methods Experimental pollinations, including selfs (in a subsample of which the style was cut before pollen tubes reached the ovary), chase self/cross-pollinations, crosses, and mixed self/cross-pollinations were used to study floral/pistil longevity and effect on fruit set and seed yield in two Ceiba species known to have LSI.Results Self-pollinations, including those with a cut style, had extended floral longevity compared with unpollinated flowers. Chase pollinations in which cross-pollen was applied up to 3 h after selfing set fruits, but with reduced seed set compared with crosses. Those with cross-pollen applied at 4 and 8 h after self-pollination all failed to set fruits. Flowers subjected to 1 : 1 and 2 : 1 self/cross-pollinations all produced fruits but again with a significantly lower seed set compared with crosses.Conclusions Extended floral longevity initiated with self-pollen tubes growing in the style indicates some kind of pollen tube-pistil interaction. Fruit set only in chase pollinations up to 3 h implies that self-pollen tubes either grow more slowly in the style or penetrate ovules more slowly on arrival at the ovary compared with cross-tubes. This agrees with previous observations indicating that the incidence of penetrated ovules is initially lower in selfed compared with crossed pistils. However, the low seed yield from mixed pollinations indicates that self- and cross-pollen tubes arrive at the ovary and penetrate ovules more or less simultaneously. Possible explanations for these discordant results are discussed. (C) 2004 Annals of Botany Company.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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No presente trabalho, avaliou-se a influência de doze porta-enxertos sobre a qualidade dos frutos da lima-ácida 'Tahiti' (Citrus latifolia Tanaka), clone 'IAC-5', amostrados em duas posições nas plantas, em experimento conduzido na Estação de Citricultura de Bebedouro, em um pomar de três anos. O espaçamento utilizado foi de 8.0 x 5.0m. Os porta-enxertos utilizados foram: citrangeiro 'Carrizo' (C. sinensis (L.) Osbeck x Poncirus trifoliata (L.) Raf.); os híbridos 'Cravo' x 'Swingle' (C. limonia Osbeck x P. trifoliata (L.) Raf. x C. paradisi Macf.) e 'Changsha' x 'English Small' (C. sunki Hort. ex Tan. x P. trifoliata Raf.); as tangerineiras 'Sun Chu Sha Kat' (C. reticulata Blanco) e 'Sunki' (C. sunki Hort. ex Tanaka); os limoeiros 'Cravo Limeira' e 'Cravo FCAV' (C. limonia Osbeck); o citrumeleiro 'Swingle' (P. trifoliata Raf. x C. paradisi Macf.), o tangeleiro 'Orlando' (C. reticulata Blanco x C. paradisi Macf.) e os trifoliateiros 'Rubidoux', 'FCAV' e 'Flying Dragon' (Poncirus trifoliata Raf.). Foi utilizado um delineamento em blocos casualizados, com doze tratamentos e seis repetições. Os distintos porta-enxertos induziram diferenças na qualidade dos frutos, entretanto todas as características de qualidade foram consideradas aceitáveis para a variedade, sendo bons substitutos para o limão 'Cravo'.