Caracterização biomorfológica, germinação e conservação de sementes de Triplaris brasiliana CHAM. (POLYGONACEAE)

Abstract

The objective of this study was to characterize morphometrically seeds “ant-stick” (Triplaris brasiliana Cham.), and study their physiological behavior depending on the treatment of dormancy, temperature, substrate, moisture degree, storage conditions and describe the different post-seminal stages. After the harvest of the seeds of T. brasiliana in the municipalities of Maceió and Rio Largo, Alagoas , in the period March-April 2013, was determined the degree of moisture and biometric measurements (length and thickness) . The evaluation of the initial physiological quality was performed with intact seeds scarified with sulfuric acid and three substrates (on paper, roll paper and sand) and then was evaluated the effect of temperature on germination (constant 20, 25, 30, 35 to 40°C and alternating 20-30°C). For the identification of suitable substrate moisture, seeds were sown on moistened paper with water volume (mL) of 1.5; 2.0; 2.5; 3.0 and 3.5 times the mass of dry substrate. As for the post-development was evaluated seminal various processes triggered during the growth and differentiation of seedlings, characterization of imbibition curve. Subsequently assessing the degree of tolerance of seeds to desiccation (drying then until reaching 13.6, 11.6, 9.6 and 7.6 % moisture) and analysis of seed vigor was performed by storing a six months in three environments (refrigerator, dry chamber and uncontrolled conditions) and two containers (glass and paper type "Kraft") . The variables analyzed were: germination (G %), speed of germination index (SGI), first count, length of aerial part, root length and dry weight of seedlings. Thus, the design was completely randomized, whether by performing descriptive analysis of biometric data and the initial seed quality tests, the treatments were arranged in a factorial scheme. In the assessments of the substrate volume of water, storage and drying curve, the data were subjected to polynomial regression. Seeds with 15.6 % initial moisture were on average 6.4 cm long and 3.2 cm wide. The axial embryo and the embryonic axis is in the central part of the lower half of the seed, the germination is epigeal and seedlings are fanerocotylar. The sowing of scarified seeds on paper at 30 and 25 ° C was more favorable for germination and seedling growth of T. brasiliana, as well substrate wetting in water volume of 2.5 times its dry mass . The seeds are sensitive to dehydration, preserving physiological quality for longer when stored in the refrigerator and camera, in both packaging used.