Condicionamento de sementes de Solanum lycocarpum St. Hil e o desenvolvimento de mudas na fase inicial

Abstract

S. lycocarpum is a Solanaceae widely distributed in the central Brazilian savanna, whose capacity of colonization of degraded areas indicates its great potential on reforestation projects. However, its seeds present dormancy due to endosperm mycropilar restriction to radicle protrusion, leading to a slow and non-uniform germination. This study aimed to evaluate the efficiency of priming technique on S. lycocarpum seed germination and to investigate the physiological alterations caused, during the treatment, in the embryo and endosperm mycropilar. Subsequently, it was evaluated the priming effect on the quality of seedling developed in different sizes of containers, under nursery conditions. Based on the results, it was verified that the imbibition of S. lycocarpum seeds in distilled water for fifteen days, in low temperature, improves the germination velocity index and reduces the time to 50% of final germination. Nevertheless, when the seeds were conditioned in low water potential solutions and higher temperatures, those answers were not observed. S. lycocarpum seeds presented endo-ß-mannanase activity during hydropriming, which was related with the decrease in the rupture force of the endosperm mycropilar. There was an increase of fresh weight of the embryo only after de the conditioning. It´s suggested that the hydropriming affects the weakening of the endosperm mycropilar which, with the increase of the compressive force of the embryo after the conditioning, determined the break of physiological dormancy caused by the endosperm. The hydropriming improved the quality of seedling at the nursery, 90 days after the sowing, increasing the emergency, height, stem diameter and mass of dry matter of the plants. The sizes of containers affected the initial development of seedling, so that the best performance was observed when plants developed in 180 mL plastic tubes.