Maturação de sementes de tabebuia caraiba (Mart.) bureau oriundas de árvores matrizes do cariri paraibano

Abstract

The Tabebuia caraiba (Mart.) Bureau is a forest species widely used for reforestation, timber and medicinal use, occurring mainly in the Caatinga. Because it has dehiscent fruits, finding the ideal point for harvesting through the study of maturation is essential for obtaining quality seeds, before they start the process of natural deterioration in the field. The objective was to study the maturation process of the seeds of the craibeira, to define the harvest stage of the fruits and the physiological maturity point of its seeds. For this, 30 mother trees from the city of São João do Cariri - PB were previously selected, after the verification of the anthesis period, the inflorescences were marked, for later fruit collection, starting at 7 days after anthesis (DAA) and finishing at 49 DAA. The work was conducted in the Seed Analysis Laboratory (LAS) of UFPB, Campus II, Areia - Paraíba. At each harvest, the following variables were evaluated: biometry and fruit weight, 1000 seed weight, seed water content, germination percentage, first germination count, germination speed index, emergence percentage, emergence speed index, length and dry mass of the primary root and aerial part. The statistical design used was entirely random, and the data were subjected to analysis of variance by the F test (P < 0.05) and, when significant, it was applied the polynomial regression analysis as a function of harvest seasons, in linear and quadratic models, using the statistical program R. It was found that the maximum value for length and diameter of the fruits occurred at 46 and 49 DAA, while for fruit weight, the maximum value was reached at 49 DAA. For 1000 seeds weight, the maximum value was reached at 41 DAA, and the maximum water content was at 18 DAA, with a subsequent decrease. The germination percentage, first germination count, germination speed index, emergence percentage, emergence speed index, root and aerial part length occurred at 49 DAA, and the maximum dry mass of the primary root and aerial part occurred at 41 DAA, with the values of all these variables directly related to factors such as climate, temperature and water availability for the plants and fruits. The period of physiological maturity of Tabebuia caraiba (Mart.) Bureau seeds is reached from 41 to 49 days after anthesis, and this is the ideal period for harvest to avoid the loss of fruits and seeds by natural dispersion, and a reduction in the physiological quality of the seeds.