Produção de flores cortadas de zínia em ambientes de cultivo e adubação silicatada

Abstract

The species Zinnia elegans Jacq., belonging to the Asteraceae family, is an ornamental plant characterized by an herbaceous growth habit and upright stature, adapted to tropical climate conditions. Although it demonstrates potential as a cut flower, its utilization in floriculture and landscaping is primarily concentrated in the composition of garden beds and flower borders. Zinnia features a wide diversity of flower colors and possesses long stems, which increases its potential and relevance for commercialization. Even with these attractive characteristics, the information and technologies available for its production are still quite limited. Therefore, to understand and generate information about the production process, specifically considering cut flower production, the objective was to evaluate the growth and development of plants cultivated under different shading screens (full sun, 30% black shading screen, 50% black, 50% red, and 50% blue) and to test varying doses of silicon (0, 25, 50, 75, and 100 mg L⁻¹) applied via foliar spray in Zinnia elegans cv. 'Luz da Lua', aiming to obtain plants with flower stems of commercial quality. Two experiments were conducted: the first to test the different cultivation environments for the production of flower stems, and the second to verify the effectiveness of silicon fertilization. Evaluations monitored plant development and were performed at 21, 30, 60, and 90 days after sowing, observing parameters such as emergence, height, stem base diameter, number of leaves, shoot fresh and dry weight, root fresh and dry weight, length of the longest root, and the yield and quality of the cut flowers, in addition to physiological, biochemical, and anatomical analyses. For the silicon experiment, the flower stems were also evaluated regarding stem height, stem diameter, flower diameter, and stem weight. For the post-harvest period, the water absorption rate and the fresh weight of the stems were assessed, and a score from 0 to 5 was assigned, indicating the commercialization point of the flower stems. Based on the results obtained, it was possible to infer that shading screens influence Zinnia development, with black screens being recommended for cultivation. Regarding silicon, the plants exhibited good development during the experimental period, and for most of the analyzed variables, the 100 mg L⁻¹ dose showed the best performance. For postharvest, the durability of the flowers was approximately six days, and no differences were observed among the doses. Furthermore, the doses did not influence the other post-harvest variables.