Qualidade fisiológica de sementes de pinhão manso (Jatropha curcas L.) em função do estádio de maturação dos frutos

• Autor(a) principal: Silva, Laércio Junio da
• Data de Publicação: 2010
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/4532
• topic: Jatropha curcas L.; Germinação; Vigor; Maturidade fisiológica; Jatropha curcas L.; Germination; Vigor; Physiological maturity; CNPQ::CIENCIAS AGRARIAS::AGRONOMIA::FITOTECNIA

Physic nut (J.curcas L.) has been listed as promising species for use in biodiesel production, due mainly to its high content and quality of oil for biodiesel. For these species, there is little information about seed maturation process, which is crucial to obtaining seeds with high physiological quality. Thus, the research aimed to evaluate the main changes during maturation of physic nut seeds in order to characterize the physiological maturity and to define the adequate harvest time of the seeds based on the external color of the fruits. Two experiments were carried out in an area of commercial production in Viçosa, MG. At the flowering, female flowers were tagged at anthesis. In the first experiment, from 35 days after anthesis (DAA), every five days, until 80 DAA fruits were collected. These were taken to the laboratory and, after seed extraction and drying, the following parameters were determined: moisture content, dry matter, longitudinal and transversal diameters of the seeds, germination, first count, speed germination index (IVG), seedling growth and weight, dry matter and the transversal and longitudinal diameters of the fruits. The completely randomized design was adopted with 20 replications for the determination of diameters of fruits and seeds and fruit mass, and four replications for seed quality tests. Data were subjected to variance and regression analysis. In the second experiment, fruits were collected at different stages of maturity based on external color: green, yellow-green, yellow, yellow-brown and brown. The seeds, after natural drying, were subjected to the following tests and determinations: moisture content and dry matter, germination, first count, seedling emergence, seedling growth, accelerated aging, electrical conductivity, thousand seed weight and oil content. The completely randomized design was adopted with four replications. The means were compared by Tukey test at the 5% level of significance. It was concluded that physiological maturity of physic nut seeds, represented by the maximum germination and vigor, occurs at 65 DAA. This time coincides with the maximum accumulation of dry mass of the seeds, which have high moisture content, about 52%, and the external color of the fruits is yellow-brown. The seeds obtained of yellow and yellow-brown fruits have high physiological quality. The seeds obtained from green fruits have a lower content of dry matter, oil and physiological quality lower than the others stages of maturation. The seeds obtained from brown fruits have a high germination potential, but they have low vigor in relation to stages yellow and yellow-brown.