Morphogenic and structural characteristics and chemical composition of grass aruana, submitted to nitrogen fertilization

This study aimed at evaluating the morphogenic and structural characteristics of Panicum maximum Jacq. cv. Aruana, as well as its chemical composition after submitting it to different nitrogen levels. The experiment was performed by adopting a randomized block design which included four treatments (0, 75, 150 and 225 kg ha-1 of N) and three replications, in 100 m2 plots. Twice a week, for the 63 days of regrowth, the morphogenic characteristics were determined and estimated, after which the chemical composition was assessed. The aruana grass revealed a quadratic and positive response to the nitrogen fertilization, and showed a remarkable rise in the elongation rates, leaf appearance and senescence, besides the number of live leaves per tiller and final leaf length. However, the nitrogen fertilization reduced the phyllochron and leaf life in the aruana grass, implying the direct effect of nitrogen on the flow of tissues. A quadratic and positive effect of the nitrogen fertilization was observed for the dry mass production, from 5,840.80 kg ha-1 for plants lacking the nitrogen fertilization to 8,862.55 kg ha-1 for those fertilized with 225 kg ha-1 of N. Thus, while the nitrogen fertilization positively affected both tillering and morphogenesis, the N doses used in this study were insufficient to induce any change in the chemical composition of the aruana grass.