Dry matter production, leaf/stem ratio and growth indexes of palisade grass (Brachiaria brizantha cv. Xaraes), cultivated with different rate combinations of nitrogen and potassium

This work aimed to evaluate dry matter production, leaf/stem ratio and growth indexes of palisade grass cv. Xaraes grown under increasing nitrogen and potassium rates. The experiment was carried out in a greenhouse from November, 2004 until February, 2005. The experimental treatments consisted of a 4 x 3 factorial arrangement between nitrogen and potassium rates respectively. Nitrogen rates were 0, 75, 150, and 225 mg dm(-3), whereas potassium rates were 0; 50 and 100 mg dm(-3). The experiment design was completely randomized with four replications. It was verified a positive N fertilization effect both on leaf dry matter yield and total dry matter yield. Potassium influenced these same response variables only at the second harvest. The leaf/stem ratio, leaf area ratio (LAR), specific leaf area (SLA) and, leaf weight ratio (LWR) were affected by treatments only at the third harvest. Increasing N rates reduced these response variables (L/S, LAR, SLA, LWR) while potassium rates behaved in an antagonistic way on LAR and SLA.