-(Germination of newly collected diaspores of Myracrodruon urundeuva Allemão (Anacardiaceae) occurring in the cerrado of Central Brazil). Myracrodruon urundeuva occurs in Northeast, Southeast, and West Center Brazilian regions, being considered as a vulnerable species to extinction. Diaspores collected in the Araguari River valley, MG, were used in three experiments, in a completely randomized design, with five replications of 50 diaspores each one. In the first and second experiments, germination boxes with vermiculite moistened with distilled water, GA 3 and cytokinin at 1, 10, 100 µg mL -1 , and 0.2% KNO 3 were used as treatments. The first experiment was conducted under continuous fluorescent white lamps and the second in darkness. In the third experiment the diaspores were moistened with distilled water and stratified during one to six days at 4-5 °C in darkness. Control treatment was constituted by diaspores moistened with water, without stratification. For the experiments conducted under light conditions, data were collected observing the embryo protrusion every 24 hours; in darkness conditions counting was processed after seven days from the beginning of the experiment. Under continuous light, diaspores treated with 1 µg.mL -1 GA 3 were more homogeneous (CV t = 17.13%) and synchronized (Z = 0.64) in relation to the other treatments. The germinability ranged from 52.8% to 60% and occurred between two and three days. In darkness condition, germinability ranged from 50.4% to 58.8% and under stratification, from 49.6% to 61.2%. For the experiment testing stratification, the lowest mean time, the highest rate and germination uniformity were registered for diaspores stratified during six days. Although the germination process had been fast, low germinability indicates that new investigations are necessary to the sustainable exploration of this species.Key words -germination measurements, growth regulators, stratification RESUMO -(Germinação de diásporos recém-colhidos de Myracrodruon urundeuva Allemão (Anacardiaceae) ocorrente no cerrado do Brasil Central). Myracrodruon urundeuva distribui-se no nordeste, sudeste e centro-oeste brasileiro, sendo considerada uma espécie vulnerável à extinção. Diásporos coletados no vale do Rio Araguari, MG, foram utilizados em três experimentos, em delineamento inteiramente casualizado, cada um deles com cinco repetições de 50 diásporos. No primeiro e segundo experimentos, utilizou-se gerbox com vermiculita umedecida com água destilada, GA 3 e citocinina a 1, 10, e 100 µg.mL -1 e KNO 3 a 0,2%, o primeiro mantido sob luz branca fluorescente contínua e o segundo no escuro. No terceiro experimento, os diásporos foram umedecidos com água e estratificados por um a seis dias a 4-5 °C, no escuro; no controle os diásporos não foram estratificados. A cada 24 horas observou-se a protrusão do embrião nos experimentos mantidos sob luz e, aos sete dias, na ausência de luz. Sob luz contínua, diásporos tratados com GA 3 1 µg.mL -1 foram mais homogêneos (CV t = 17,13%) e sincronizados...
http://dx.doi.org/10.5902/1980509810541A estratégia de germinação dos diásporos é fundamental para a sobrevivência das espécies, sendo um dos fatores que permitem a sua manutenção e regeneração no ambiente. A germinação das sementes e a emergência das plântulas de Anadenanthera colubrina foram estudadas para analisar a eficiência reprodutiva da espécie, oriunda de fragmentos de vegetação do bioma Cerrado. Os frutos foram coletados no Vale do Rio Araguari, MG. O teor de água a 105ºC, a germinação em condições controladas de laboratório e a emergência das plântulas em estufa semiaberta, coberta com sombrite, foram analisados. As sementes apresentaram baixo teor de água, entre 6,7 e 10,7%. A germinabilidade e a porcentagem de emergência foram altas para quase todos os indivíduos estudados, estando entre 68 (indivíduo 2) e 85 - 94% (para os demais indivíduos); 38 (indivíduo 2) e 78 - 91% (para os demais), respectivamente. A velocidade dos processos foi alta, com o término da germinação dentro de 12,8 dias e emergência em 18,8 dias. Os processos foram heterogêneos, com valores do coeficiente de variação do tempo acima de 28,5%; assíncrono, sendo registrados valores acima de 1,5 bits para a incerteza e abaixo de 0,3812 para a sincronia. As sementes desta espécie se mostraram eficientes em ambos os processos e a heterogeneidade e assincronia podem ser indicativos dos efeitos das oscilações ambientais durante a formação das sementes, além da variabilidade genética, intrínseca de cada indivíduo da população. A rapidez e o alto potencial de germinação das sementes desta espécie também podem viabilizar programas de revegetação, com a produção de grande quantidade de plantas jovens em curto tempo.
Hymenaea courbaril L. is an important Neotropical species, with low population density, restricted to fragments of semideciduous forests, with low mortality and low recruitment. Thus, some questions guided the goals of this paper including the capacity of stored seeds to form normal seedlings. Seeds collected from ten mother plants in the Brazilian Cerrado region and stored during three years were mechanically scarified, sown and analyzed during 43 days. Intraspecific variability was observed for water content, seed biometry, and emergence process. The seedling emergence varied from 19 to 92%. Nine phases of development were observed. About 91% of the seedlings reached their complete autotrophy and this represents the success of the sample; the rest of the seedlings presented atypical morphology. This means that it is possible to store the seeds with the purpose of obtaining seedlings for ex situ cultivation. The great consumption of the cotyledon reserves occurred in the period that marks the alignment of cotyledons with hypocotyls (phases 1 to 4). For this species, if the seeds are scarified, the first 40 days after sowing are essential for the seedling establishment. After this time, the cotyledons fall signing a good point of reference for restoration projects because it indicates that the young plant is autonomous.
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