Aspectos morfofisiológicos do desenvolvimento de sementes de Tabebuia serratifolia Vahl nich

Abstract

Tabebuia serratifolia is considered a tree symbol of Brazil, named "yellow Ipê" and it is used in the reforestation of the degraded areas. Although due to its improper exploration it is in extinction, in spite of having protected by law for its permanent preservation in the state of Minas Gerais. The objective of this research was to evaluate the morphophysiological alterations of yellow ipê seeds during the maturation process, aiming to preserve the specie. The fruits were collected at anthesis and during seven development stages in trees located in Lavras, MG. In each harvest, the radiographic and microscopic analysis were made, evaluating the colorations and size; the moisture content and dry matter of fruits and seeds; the germination in MS and WPM medium, and in sand substrate; the index of germination speed (IVG); as well as the sugar level; polyphenols concentration and LEA proteins. During the maturation process the fruits that initially were green changed to brownish and the length altered 7,0 to 18,0cm, presenting rifts in the beginning of seed dispersal. The seed color varied from leaf-green to brownish and the length from 1, 0 to 3,0cm. The initial indicative alterations of physiological maturity of yellow ipê seeds started from 39 days after anthesis, when variations were observed in the coloration and size of fruits and seeds, an increase in the water level, dry matter and percentage of germination of seeds and embryos, besides reduction of the reducing sugars and LEA proteins. The physiological maturity of the seeds of Tabebuia serratifolia was reached at 53 days after anthesis, coinciding with the maximum accumulation of dry matter, germination and index of germination speed, besides the decrease in phenols levels and higher intensity bands of proteins resistant to heating and the onset of fruit opening.