Época de colheita, estádio de maturação de frutos e compostos fenólicos influenciando a qualidade fisiológica de sementes de mamão

• Autor(a) principal: Dias, Maristela Aparecida
• Data de Publicação: 2011
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/1156
• topic: Carica papaya L.; Mamão; Dormência; Fenóis; Raios-X; Germinação; Carica papaya L.; Papaya; Dormancy; Phenols; X-rays; Germination; CNPQ::CIENCIAS AGRARIAS::AGRONOMIA::FITOTECNIA

The papaya tree occupies a prominent place among the major fruit crops in the Brazil. In papaya seeds are detected the presence of dormancy, which can be attributed to the presence of sarcotesta. This structure contains phenolic inhibitors that interfere with the process of seed germination and seedling emergence. Research objectives were: 1) evaluate the effect of the harvest time and fruit maturation stage on the physiological quality of seeds with and without sarcotesta compounds and the occurrence of inhibitors in papaya seeds, 2) detect and quantify phenolic compounds in seeds papaya at various stages of maturation and harvest time and to assess the effect of these compounds on the germination of papaya seeds and lettuce seeds and 3) evaluate the physiological potential of the papaya seeds obtained from different stages of ripeness of the fruit and regions using the test X-rays. Papaya fruits of the Formosa group, hybrid 'Tainung 1', were collected in April and October 2010, at the maturity stage 1 (up to 15% of the peel surface yellow) and stored in laboratory conditions until they reach the 3 stage , 5 and final maturation, corresponding to 50%, 75% and 100% of the outer surface of the yellow peel, respectively. In a first experiment, seeds with and without sarcotesta at various stages of maturation and harvest time were evaluated by standard germination, first count germination, seedling emergence and accelerated aging. We used a completely randomized design in factorial (2x4x2), with four replications. In the second experiment, we determined the content of total phenolics, caffeic acid, ferulic acid and coumaric acid in sarcotesta, esclerotesta and internal part of the papaya seeds. We also conducted germination test with seeds of papaya and lettuce using a paper germination moistened with solutions containing 10 ppm of each compound, a mixture of these solutions and the pure solvent (control). For the determination of phenols, the experiment was conducted in DIC in a factorial (two harvest times x four maturation stages x three seed structures (sarcotesta, esclerotesta and internal part) with three repetitions in duplicate. For the bioassay, we used the DIC with five treatments and four replications. In the third experiment, the fruits of each maturity stage were cut transversely, the seeds are extracted separately and the central part of the extremities. The seeds had the sarcotesta removed and after drying, were subjected to germination, vigor (seedling emergence and accelerated aging) and X-ray. It was also determined the length of individual seedlings using the computer program Seed Vigor Imaging System®. Analyses were conducted in randomized design in factorial (four maturity stages x 2 positions in the fruit seeds) with four replications. Overall, there was beneficial effect of post-harvest storage of fruits on the physiological quality of seeds with improved germination and vigor and reduction of dormancy in seeds extracted from fruits in the fifth and final stage. Analyses were conducted in randomized design in factorial (4 maturity stages x 2 positions in the fruit seeds) with four replications. In general, there was beneficial effect of post-harvest storage of fruits on the physiological quality of seeds with improved germination and vigor and reduction of dormancy in seeds extracted from fruits in the fifth and final stage. Largest concentrations of phenolic compounds and lower germination were observed in seeds extracted from fruits harvested in October/2010. The sarcotesta was the structure seeds with the highest concentration of total phenolic compounds, p-coumaric acid and ferulic acid. There was, in general, better performance of seeds extracted from fruits in the central region of the 5 stages and final maturation. The test permitted differentiation of X-rays empty seeds and seeds with the embryo developed, and a higher proportion of empty seeds and dormant, were observed in the fruit maturity stage 1.