Caracterização das sementes e uso de nanopartículas na germinação de Seemannia sylvatica (Kunth) Hanst

Abstract

The flowers and ornamental plants segment plays a relevant role in the Brazilian economic market, currently generating around R$19.9 billion in national revenue. Landscaping with native plants has become an alternative for the diversification of this market, contributing to the propagation and protection of native species, which are often under threat of extinction. From this perspective, Seemannia sylvatica (Kunth) Hanst. is a species native to Brazil, belonging to the Gesneriaceae family, which has attractive flowers and notable ornamental value, although little studied and with a status of almost threatened with extinction. Therefore, the objective of this work was to characterize its seeds morphologically, identifying the possible factors that influence germination and propagation, providing information about this species. Furthermore, evaluate the effect of the ultrasonic bath and carbon nanotube on germination and seedling establishment, after storage of these seeds. Also, through the production of seedlings in pots, obtain a new product with information about cultivation, aiming to commercialize this species in the ornamental plant market. Initially, seeds were subjected to characterization to determine: color; dimensions; weight of a thousand seeds; texture and shape; as well as the evaluation of seed germination under conditions of different temperatures, photoperiods, substrates and storage. The ultrasonic bath was used at a frequency of 40 KHz at different time intervals (0, 5, 10, 15 and 20 minutes), and the carbon nanotube at a concentration of 0.2 mg/L. To determine the best pot filling for this species, the seedling production test was carried out in gourds. The seedlings were transplanted into the gourds, with the treatments defined as different quantities of plants per gourd. The Seemannia sylvatica seed is tiny, with an average length of 0.44 mm and an average width of 0.12 mm; it has an elliptical shape and yellow color. The outer integument is shiny with a rough texture and small striations. The weight of a thousand seeds was 3.4 mg. It is a positive photoblastic seed, which requires light for germination to occur, with a photoperiod of 8 hours of daily light being the best for this species. The optimum temperature evaluated for germination was 25 oC, with epigeal germination. The results for the ultrasonic bath and the carbon nanotube generally showed favorable effects on vigor recovery, the percentage of normal seedlings and greater root length, respectively. Knowledge of seed morphology is extremely important for the preservation of plant species, especially those threatened with extinction.