1000 resultados para chuva de sementes
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Todos sabemos, por observação ou por própria experiência, que é um mito considerar a infância como um tempo de plena harmonia, como se a felicidade fosse condição obrigatória no cotidiano dos pequenos; todos sabemos quão intensa pode ser a dor no horizonte restrito da dependência. Neste artigo, pretende-se traçar um paralelo entre o modo como duas crianças, diferentes, mas em certo sentido bem próximas, uma menina e um menino, vivenciam e enfrentam a experiência da morte. A análise focará o comportamento dos narradores em “Manuela em dia de chuva”, de Autran Dourado, e “Campo geral”, de Guimarães Rosa, em especial no momento em que se apresenta o confronto com a perda irreparável do irmão, que protegia e orientava. Experiência da dor, fonte de aprendizado, passagem da infância à maturidade.Tristeza e alento, formas de narrar a solidão e o desamparo, mas também de celebrar, no Mutum ou na casa da família, a força da vida, que continua.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
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Pós-graduação em Agronomia (Agricultura) - FCA
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Pós-graduação em Agronomia (Horticultura) - FCA
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Matayba guianensis Aubl . is a shrubby or arborial Sapindaceae quite common in the Brazilian Cerrado with a key role in providing resources for ants and bees. It presents a rapid growth, and is important for the recovery of degraded areas, but little is known about its seedlings production. Therefore, the aim of this study was to describe the morphology of the branch and the seed germination and of seedling Matayba guianensis Aubl . in its post-seminal development and define the type of substrate and container suitable for seedling emergence and seedling production of this species. We evaluated three types of containers: black polyethylene bags, cartridge and polystyrene tray, with 5 kinds of substrates: sand, earth, earth - sand - manure (1:1:1); commercial substrate, and coconut fiber, with 4 replicates of 25 seeds per treatment . The branch, fruit, seed, seedling and their morphological events were described. The branch is cylindrical with paripinnate and alternate leaves, the fruit is dry and dehiscent. The seeds have a large amount of aryl, and the germination is cryptocotylar and hypogeal. The highest percentage of emergence occurred in styrofoam container with 91 % of the seeds germinated in commercial substrate , followed by coconut fiber (88 %). The development of root and stem were higher in tubes and plastic bags , using coconut fiber or commercial substrate.
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Physiological responses like the thermal requirements for germination may be influenced during seed formation by environmental conditions such as water availability and temperature. Here we analyzed germination of embryos of Ingavera subsp. affinis from different sources in response to various temperature regimes, including calculation of degree days and accumulated rainfall during development and maturation. Embryos were taken from ripe fruits collected on trees located in São Paulo and Minas Gerais, and were analyzed as to germination, water content and dry matter content. The results showed that the origin of the embryos was related to variation in response under sub-optimal temperatures. Depending on the origin, I.vera subsp. affinis embryos were able to germinate even at low temperatures (10 to 15 ºC), with better performance attained from 20 to 25 ºC. This variation may be associated, among other factors, to environmental conditions during maturation and to the maturation stage at seed dispersal.
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The aim of this study was to adapt the methodology of electrical conductivity (EC) test and determine the physiological quality of seeds of B. virgilioides. Seeds were separated into three batches according to tegument color (1-yellow, 2-orange, and 3-red/black). The EC test analyzed three quantities of seeds (25, 50 and 100), three volumes of water (25, 50 and 100 mL), and six times of seed imbibition (12, 24, 36, 48, 60 and 72), at 25 °C with 6 replications. Germination test was employed to compare the results. The EC test allowed the differentiation of batches in three levels of vigor - the same was observed in germination test: batch 1 presented the best seed vigor, followed by batches 2 and 3. The use of 25, 50 or 100 seeds imbibed in 50 mL of water for 24 hours is recommended.
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This study aimed to assess the incidence of fungi and nematodes in Brachiaria sp. and Panicum maximum seeds produced in the Brazilian states of Mato Grosso do Sul (MS), Mato Grosso (MT), Goiás (GO), Minas Gerais (MG) and São Paulo (SP). The main fungi found in the seeds were Bipolaris sp., Curvularia sp. and Phoma sp.. The lowest incidence of these fungi was found for seeds of Brachiaria brizantha cultivars BRS Piatã and Xaraés, and Brachiaria decumbens cv. Basilisk, from the states of GO, MG and MS, respectively. The cultivars Marandu and BRS Piatã, from several regions, exhibited high occurrence of Aphelenchoides sp. and Ditylenchus sp.. Seeds of B. humidicola cultivar Humidicola, produced in MS and SP, did not show association with nematodes. The seeds of Panicum maximum cv. Massai and cv. Mombaça showed higher incidence of Bipolaris sp., Cladosporium sp., Curvularia sp., Fusarium sp. and Phoma sp., as well as Aphelenchoides sp. and Ditylenchus sp., especially for seeds produced in MT. Some of the detected pathogens are causative agents of diseases of major importance in forage plants, such as Bipolaris sp., causing leaf spot in Panicum, of high severity in Tanzânia, which provides serious compromising of the pasture sustainability.
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The species of Tabebuia are propagated sexually, and the use of high-quality seeds is crucial to achieving success in restoration of degraded areas, timber and medicinal production. Thus, the use of rapid tests in programs to control seed quality is an essential tool for the assessment of their physiological quality. The objectives of the present study were to establish the methodology for conducting the tetrazolium test in seeds of T. roseoalba and verify seed viability as a function of storage time, evaluating germination parameters and comparing them with the results of the tetrazolium test. The fruits were manually harvested at the opening, and fresh seeds and seeds stored up to 24 months were evaluated by tetrazolium test, germination, emergence, length and dry weight of seedlings. The tetrazolium at a concentration of 0.05% at 36 ° C for 24 hours is indicated to assess the viability of T. roseoalba, and during storage germination, length and dry weight of the seedlings are reduced and the germination in nursery is sharply reduced with seed storage in 24 months.
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The previous knowledge of the infection process and pathogens behavior, for evaluating the physiological potential of maize seeds, is essential for decision making on the final destination of lots that can endanger sowing. This research was carried out in order to study the minimum period required for maize seeds contamination by Fusarium graminearum Schwabe and Fusarium verticillioides (Sacc.) Nirenberg, as well as these pathogens influence on seed germination and vigor, by using the cold test. Three maize seeds hybrids, kept in contact with the pathogens for different periods, were evaluated with and without surface disinfection. After determining the most suitable period, new samples were contaminated by F. graminearum and F. verticillioides, under different infection levels, and subjected to germination tests in sand. The cold test was conducted with healthy and contaminated seeds, at different periods, in a cold chamber. The contact of maize seeds with F. graminearum and F. verticillioides for 16 hours was enough to cause infection. F. graminearum and F. verticillioides did not affect the maize seeds germination, however, F. graminearum reduced the vigor of seeds lots.
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Populations of carrot seeds with superior physiological quality and storage potential are of interest to seed companies and growers. Thus, we verified the efficiency of some tests for the selection of carrot populations with greater vigor and longevity of seeds. Seeds of 50 carrots progenies of different half-brothers from Brasilia cultivar were evaluated for the mass of one hundred seeds, the first count, germination, dormancy, accelerated aging with water and saturated NaCl solution. The seeds were stored at moisture contents of 6.1±0.3% in hermetic packaging at temperatures of 15 and 25°C for 12 months and germination was evaluated quarterly. The experimental data were evaluated for variance and phenotypic, genotypic and environmental heritability, coefficient of variation and genetic gain from selection. Selection based on the mass should not be used because it would increase the occurrence of dormancy in seeds of the next generation. The test of the first count, germination and accelerated aging in water or saline solution saturated may be used to select populations of carrot seeds of higher vigor and longevity. The estimated gain genetic selection for germination after 12 months storage at 25°C was 14%.
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O objetivo deste trabalho foi avaliar os efeitos da adubação com fósforo e potássio na produção e na qualidade de sementes de soja. Foram realizados experimentos em dois anos agrícolas, em delineamento de blocos ao acaso, em arranjo fatorial 5x3, com cinco doses de fósforo (0, 40, 80, 120 e 160 kg ha‑1 de P2O5 como superfosfato triplo), três de potássio (0, 50 e 100 kg ha‑1 de K2O como cloreto de potássio) e quatro repetições. Foram avaliados: produtividade, número de sementes por planta, número de vagens por planta, peso de mil sementes, germinação, vigor (envelhecimento acelerado, condutividade elétrica e lixiviação de potássio), e teores de P e K na folha e na semente. A produtividade, o peso de mil sementes e a produção de vagens e de grãos por planta aumentaram linearmente com a adubação fosfatada. O aumento na produtividade foi de 17,6%, no primeiro ano, e de 39,7% no segundo. As doses de P, no entanto, não interferiram na germinação e no vigor das sementes. A adubação potássica não altera a produtividade nem a concentração de K nas sementes, mas pode melhorar a germinação, sem interferir no vigor.
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Sweet maize seeds present lower physiologic quality, when compared to regular maize seeds, due to the influence of several features, such as the seed size and shape. Thus, this study aimed at evaluating the seed physiologic quality of two sweet maize cultivars (BR-401 and BR-402), separately classified according to thickness, by using slotted screen sieves (8/64 x 3/4, 9/64 x 3/4, 10/64 x 3/4, 11/64 x 3/4, 12/64 x 3/4 and 13/64 x 3/4), and width, with round screen sieves (17/64, 18/64, 19/64, 20/64, 21/64 and 22/64). For each cultivar, sorted lots were compared with the unrated batch, following a completely randomized design, in a 2x7 factorial scheme, with four replications. The biometric parameters evaluated were sieve retention, 100 seeds weight and water content. The physiologic quality was determined according to the first counting, germination, cold test, accelerated aging, electric conductivity and seedling emergence in the field. The classification with sieves improved the physiologic quality of sweet maize seeds. Seeds with intermediate thickness, for both cultivars, generally presented greater vigor. Concerning width, larger seeds, for the BR-401 cultivar, and intermediate seeds, for the BR-402 cultivar, showed better physiologic quality.
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Pós-graduação em Agronomia - FEIS
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Pós-graduação em Agronomia (Genética e Melhoramento de Plantas) - FCAV