Composição bromatológica de Tifton submetido a diferentes lâminas de irrigação e doses de nitrogênio

Abstract

This research had the purpose to evaluate the Tifton 85 (Cynodon sp.) bromatological composition under irrigation levels and nitrogen fertilization. The experiment was conducted in the experimental area of Federal University of the Pampa, Itaqui Campus in Plinthaquoxsoil. The study consisted in the Tifton bromatological evaluation with the following evaluated parameters: mineral matter (MM), crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), hemicellulose (HEM), cellulose (CEL), lignin (LIG), and total digestible nutrients (TDN). The main factor of treatments were the irrigation levels: 0 % of irrigation; irrigation in 50 % crop need; irrigation in 100 % need and 150 % need. The other factor was related to the nitrogen fertilization levels: 0 N kg ha-¹, 150 N kg ha-¹, in an experimental design completely randomized in a factorial arrangement 4x2, in subdivided parcels with three replicates. The cuts were done in January, February andmarch of 2012. The nitrogen fertilization was parceled in three times, being applied 1/3 of N, in the second cut prior to the experiment and the remainder (2/3) also parceled every 28 days, after the first and second cut, January and February respectively. The irrigation need was determinate by the daily evapotranspiration of the culture, obtained by campus meteorological station, as the coefficient of theculture. There was not any significant difference to the irrigation factor (P>0,05) to all parameters. There was a statistical difference in nitrogen fertilization factor, in Hem and MM parameters. There was a significant difference between cuts (P < 0,05) in the first cut for the variables HEM e LIG and in the third cut for the variable MM. The different irrigation levelsdonotshow effects to the main bromatological composition variables, and throughout the stages of plant maturity, there was a decrease in the levels ofCEL, CP, ADF, NDF and an increase of LIG.