844 resultados para Germination success


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Secondary compounds produced by plants are considered an alternative method of weed suppression but can cause negative effects on crops in succession, especially in a no-tillage system, due to the degradation of crop residues with allelopathic potential. The objective of this work was to analyze the influence of foliar aqueous extracts of Brassica napus on the germination and initial development of seedlings of Phaseolus vulgaris. The extract was prepared as a stock 10 % weight/volume solution, and diluted into treatments of relative concentrations of 100 % (i.e. 10 % w/v stock), 75 %, 50 %, 25 % and 0 % (untreated control consisting of distilled water), in a completely randomized design. The seeds of Phaseolus vulgaris were moistened with the differing concentrated extracts and kept in a germination chamber at 25 °C, with a photoperiod of 12 h for nine days. The variables evaluated were: percentage germinating, first count of germination and germination velocity index, as well the root and hypocotyl length, and fresh and dry mass of the seedlings. The aqueous leaf extracts of Brassica napus did not influence the germination of Phaseolus vulgaris seeds, but did induce the growth of abnormal seedlings by inhibition of secondary roots and reduced prominence of the primary root.

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Annona emarginata (Schldtl.) H. Rainer (araticum-de-terra-fria) is used as a rootstock for several species of Annonaceae. It is suggested that these seeds should be sown immediately after extraction and, therefore, they could be intolerant to desiccation. There are several mechanisms involved with desiccation tolerance. Soluble sugars, for example, can accumulate and act as osmoprotectants for the membrane system during desiccation. The aim of this study is to assess desiccation tolerance in A. emarginata seeds. In addition, we examined the soluble sugars involved in desiccation tolerance. Finally, we determined the effect of gibberellic acid (GA4+7) and N-(phenylmethyl)-aminopurine in promoting the germination of seeds with different water contents. The experiment consisted of a randomized 4×5 factorial design (desiccation levels × concentration of growth regulators). After drying, seeds containing 31 (control), 19, 12 and 5% water were incubated in different concentrations of GA4+7 N-(phenylmethyl)-aminopurine (0, 250, 500, 750 and 1000 mg L-1) for 60 hours. The experiment was conducted in a germination chamber with alternating temperature and photoperiod of 20oC for 18 hours of darkness and 30oC for 6 hours of light. We analyzed electrical conductivity, germination rate, mean germination time, germination speed, frequency and uniformity of germination, percentage of dormant seeds and soluble sugar profile in intact seeds through high-performance liquid chromatography (HPLC). The data were subjected to analysis of variance, and the means were compared using Tukey's test at a threshold of p<0.05. The results showed that seeds of A. emarginata appears to be desiccation tolerant and, also, that sucrose increases when seed water content is reduced to values as low as 12%, exogenous GA4+7+N-(phenylmethyl)-aminopurine improves its germinability.

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Tillandsia gardneri is a bromeliad with ornamental value and a wide geographical distribution over Brazil. However, due to habitat loss and illegal overcollection in the wild it is included as a vulnerable species in the official list of endangered plants of the State of Rio Grande do Sul, Brazil. The development of a protocol for T. gardneri seed propagation in vitro may be useful for reintroducing plants in their natural habitats, and for germplasm conservation. A difficult problem encountered during the establishment of an in vitro culture is explants disinfection, especially when working with endangered species, from which explant availability is restricted. Thus, the establishment of a sterilization protocol is crucial for the initiation and success of a micropropagation system for T. gardneri. The objective of this study was to evaluate the effect of sodium hypochlorite concentration and exposure time in seed and seedling surface disinfection, tissue sensitivity and development. Sodium hypochlorite solutions (10 or 20%/5, 10 or 15 min; 25%/5 or 10 min; and 50%/5 min) were effective in eliminating seed superficial contaminants. There was no significant difference among the effective sterilization treatments in relation to seed germination (%), and seedling length and number of leaves, after 120 days in vitro. Also, no damage to seed and seedling tissues were observed. Surface sterilization of seedlings, for initiation of an in vitro culture, required higher concentrations of sodium hypochlorite (25%/15 min; 20 or 50%/5, 10 or 15 min; and 40%/5 and 10 min) for controlling fungal and yeast contamination, compared to seed sterilization. No significant differences among these treatments were found in relation to seedling length and number of leaves, after 60 days in vitro.

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The effectiveness of seed dispersal by vertebrates has been analysed by examining both quantitative and qualitative components (Jordano & Schupp 2000, Schupp et al. 2010). While the quantitative component is relatively easily assessed in the field (e.g. visitation rate, number of fruits eaten per visit), the qualitative component (e.g. fate of dispersed seeds, seed treatment in the digestive system of the disperser) is rarely studied under natural conditions, because it is difficult to measure the effects on seeds once ingested by the dispersers (Cortes et al. 2009). © Cambridge University Press 2012.

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Tests on spatial aptitude, in particular Visualization, have been shown to be efficient predictors of the academic performance of Technical Drawing stu-dents. It has recently been found that Spatial Working Memory (a construct defined as the ability to perform tasks with a figurative content that require si-multaneous storage and transformation of information) is strongly associated with Visualization. In the present study we analyze the predictive efficiency of a bat-tery of tests that included tests on Visualization, SpatialWorking Memory, Spatial Short-term Memory and Executive Function on a sample of first year engineering students. The results show that Spatial Working Memory (SWM) is the most important predictor of academic success in Technical Drawing. In our view, SWM tests can be useful for detecting as early as possible those students who will require more attention and support in the teaching-learning process.

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Basic research is fundamental for discovering potential diagnostic and therapeutic tools, including drugs, vaccines and new diagnostic techniques. On this basis, diagnosis and treatment methods for many diseases have been developed. Presently, discovering new candidate molecules and testing them in animals are relatively easy tasks that require modest resources and responsibility. However, crossing the animal-to-human barrier is still a great challenge that most researchers tend to avoid. Thus, bridging this current gap between clinical and basic research must be encouraged and elucidated in training programmes for health professionals. This project clearly shows the challenges faced by a group of Brazilian researchers who, after discovering a new fibrin sealant through 20 years of painstaking basic work, insisted on having the product applied clinically. The Brazilian government has recently become aware of this challenge and has accordingly defined the product as strategic to the public health of the country. Thus, in addition to financing research and development laboratories, resources were invested in clinical trials and in the development of a virtual platform termed the Virtual System to Support Clinical Research (SAVPC); this platform imparts speed, reliability and visibility to advances in product development, fostering interactions among sponsors, physicians, students and, ultimately, the research subjects themselves. This pioneering project may become a future model for other public institutions in Brazil, principally in overcoming neglected diseases, which unfortunately continue to afflict this tropical country. © 2013 Elsevier Ltd.

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Background: Dental implants, indicated for re-establishing both mastigatory and aesthetic functions, can be placed in the sockets immediately after tooth extraction. Most studies investigate the anterior and upper regions of the dental arch, whereas few examine longitudinal appraisal of immediate implant installation in the mandibular molar region. Objective: The aim of this retrospective study was to evaluate the success rate of immediate dental implants placement in mandibular molars within a follow-up period as long as 8 years. Materials and methods: Seventy-four mandibular molar implants after non-traumatic tooth extraction between 2002 and 2008 were examined in the study. All implants were evaluated radiographically immediately after prosthesis placement, 1 year after implantation, and by the end of the experimental period, in 2010. Clinical evaluation was done according to [Albrektsson et al. (1986) The International Journal of Oral & Maxillofacial Implants, 1, 11-25] success criteria for marginal bone loss. The mean bone losses, calculated as the difference between the final evaluation measures and those taken by the end of the first year of implant, were compared using Kruskal-Wallis test with a significance level of 5%. Results: All implants presented clinical and radiographic stable conditions, that is, 100% success rate. Significant bone loss was not found between final evaluation and that of the first functional year (P > 0.05). Conclusion: Immediate implant placement of mandibular molars proved to be a viable surgical treatment given the high success rate up to 8 years after implantation. © 2012 John Wiley & Sons A/S.

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Dictyosperma album, commonly known as Princess Palm, due to its graceful appearance and its ability to withstand strong hurricane force winds is largely used in landscaping areas. The aim of this work was to describe the diaspores (seeds with the stuck endocarp) morphology and the stages of the D. album germination process. Therefore we concluded that the species germination is of the tubular remote type and begins with the opening of a circular operculum in the fruit endocarp, through which emerges a bulbous and hollow structure, named cotyledonal petiole or embryophore. With the embryo growth, the endosperm is being gradually consumed. The embryo grows approximately up to 10 cm, when the dilation begins in its extremity. Starting from this extensive area, it begins the growth of the primary root and the opening of a longitudinal rift, through which emerges the aerial part that is composed by two sheaths that cover the first juvenile leaf. In this phase, the emergence of secondary roots is observed. The first leaves are simple and lance-shaped.

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Copernicia prunifera, known as carnauba, is native to Brazil and presents great potential to be used in gardens and cultivation in pot. Palms species, with relatively few exceptions, can only be propagated by seeds; even so, there are no reports in the literature about the germination of this palm seeds. Several species of the Arecaceae family present seed physical dormancy in varying degrees, demanding treatments to improve germination. The objective of this work was to study the effects of temperature and mechanical scarification on seed germination of C. prunifera. The experimental design was entirely randomized in a factorial arrangement 6 x 2 (six conditions of temperature with or without mechanical scarification) with 4 replications and 25 seeds each. In accordance with the treatment, lateral scarifications were made on the seeds until appearance of the endosperm. Seeds were sown in moist fine vermiculite. Germination (%) and germination rate (GR) were evaluated. Germination data were arcsine (x/100)1/2 transformed before analysis of variance and germination rate data were not transformed. The means of the resulting values were then compared by the Scott-Knott test at 1% confidence level. It was concluded that the biggest germination percentage were obtained at alternated temperature of 25-35°C (92%) and at constant temperature of 25°C (87%). Seeds germinated faster at alternated temperature of 25- 35°C. Germination percentage was similar for the scarified and non-scarified seeds; however, scarified seeds germinated faster.

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Palm species native to Brazil such as Syagrus picrophylla and S. schizophylla have great ornamental value and for this reason are much demanded for use in landscape. Its propagation is by seeds and often presents considerable problems to nursery managers because their seed has a hard and impermeable shell. Temperature is one of the factors that influence the seed germination process; however, the information for these species is scarce. Thus, this work aimed to study the effects of temperature regimes on the germination of S. picrophylla and S. schizophylla seeds and develop some recommendations in which temperature will obtain high rates of seed germination. The experimental design was entirely randomized with six temperatures and four replications of 25 seeds for each species. Germination and germination rate were evaluated. Higher and faster germination of S. picrophylla and S. schizophylla seeds were verified at constant temperature of 30°C and 35°C; and alternated temperature at 25-35°C.

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Antirrhinum majus L. and Senecio douglasii DC. are herbaceous perennial ornamental plants used in landscaping. The multiplication of these plants is by seed; however, there are still doubts about the temperature that can provide higher rates and speed of germination. Thus the aim was to study the effect of temperature on seed germination of A. majus and S. douglasii. The study was conducted separately for each species. The experimental design was entirely randomized with six temperature conditions (temperature controlled constant of 20, 25, 30, 35°C and alternating temperatures of 20-30 and 25-35°C with a photoperiod of 12 hours) with four replications of 100 seeds each. Total germination percentage and germination rate were determined. The means were compared by Tukey test at 5%. For A majus the highest germination percentage was observed at 20°C that did not differ statistically from other temperatures. The highest germination rate was obtained at the temperature of 20 and 25°C. For S. douglasii seeds it was observed that the highest germination percentage and germination rate occurred at 20°C. The lower temperature showed the better percentage and germination rate for these species.

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The invasive behavior of melaleuca (Melaleuca quinquenervia) plants in wetlands is due to its aggressive regeneration strategy, which is based on its seeds germination performance. Understanding of the eco-physiological aspects of the seed germination in melaleuca plants may significantly contribute for the development of management strategies. The objective of this research was to learn how the germination of M. quinquenervia seeds are affected by light and temperature. Melaleuca seeds were placed on filter paper moistened with 12 ml of distilled water at temperatures between 10 and 45°C. Germination was evaluated in dark and light conditions. Seed germination, first count of seed germination (seven days), germination speed index and germination mean time were determined up to 40 days after seeding, when germination had ceased in most of the treatments. After that period, the seeds were transferred to conditions of 30°C and light, which was found to be ideal in the previous phase. Seed germination was daily evaluated up to 63 days when it was again observed no longer to occur. The treatment repetitions were distributed in the growth-chamber according to a completely randomized design in a factorial scheme (eight temperatures x two light conditions) and four repetitions. The data were submitted to analysis of variance with the F test and the means were adjusted to polynomial and non linear regression models. The highest seed germination performance was observed to take place under conditions of 27.3°C with light. The temperatures of 35 and 40°C in the dark induced thermal inhibition of seed germination. The temperature of 45°C was lethal to the seeds.