Há interação de selênio e potássio na nutrição e produtividade de gramíneas forrageiras?

Abstract

Currently the use of forage grasses in different activities requires a wide development of the plant to obtain a high productivity and a way to increase productivity is using ionic interactions. Thus, this study aimed to use the interaction between doses of selenium (Se) and potassium (K), to obtain the best development of forage grasses. Presenting as hypothesis that with the interaction of doses of Se and K, brachiaria and capim andropógon obtain greater structural and morphogenic development thus achieving a wide forage production. For this experiment, three doses of K (120, 150 and 180 mg dm-3) and four doses of Se (0, 0.25, 0.75 and 1.5 mg dm-3) were used. For K doses, fertilization was performed in three plots. The first was applied seven days after planting and the other plots with thirty days of interval, all via soil. The doses of Se were applied, via soil, fifteen days before the cuts. Three cuts were made, the first cut forty days after emergence and the other forty days after the previous cut. The collected material was taken for drying, grinding and storage. The species chosen to receive this treatment were Brachiaria ruziziensis and Andropogon gayanus, both forage grasses. 96 pots were used and the seeds were sown directly in the soil without receiving previous treatment. The soil used, a typical dystrophic Red Yellow Latosol (Oxisol), was analyzed and corrected with dolomitic limestone to receive sowing. The plants also received basic fertilizers of N, S, P and micronutrients. For this project were made morphogenic analyzes weekly to monitor the development of plants, readings of stem length, leaf length and leaf senescence. At the end of the experiment were removed the roots that followed for drying, grinding and chemical analysis along with the shoot to quantify the concentration of nutrients. For capim andropógon there was no interaction between the doses of the elements studied, not influencing the productivity of the grass and the morphogenic rates. The contents of Se and K were not influenced by the doses of the elements, not obtaining significant response. For brachiaria there was no response of fertilization in relation to productivity. However, there was interaction between the elements in leaf elongation and senescence rates. As well as for the Se contents of the aerial part, demonstrating a synergistic interaction between the elements. With this it is concluded that brachiaria presented responses to interaction between the elements, which was not observed in capim andropógon. And the elements separately did not influence the productivity of the grasses.