Forage yield and growth of “Panicum maximum” cvs. Mombaça and Tanzania-1 and Mulato hybrid Brachiaria under phosphorus application

Abstract

The experiment was carried out in west of Paraná state, in Red Eutroferric Latosoil. The objective was to verify, in the establishment, the available P concentration in soil and critical doses of P to yield of dry matter (DM) and tillering and, in the 2° year, the growth of Panicum maximum cvs. Mombaça and Tanzânia-1 and Brachiaria sp. hibrid Mulato. The treatments were three forages and five P2O5 rates (0, 40, 80, 120 e 240 kg/ha) randomized in three complete blocks in factorial arrange. The phosphorus rates linearly increased the P available in soil extracted by Mehlich-1 method (ŷ =-4,5136 + 1,0241X, R2=0,96, ŷ, in mg/dm3). The P application increased, up to maximum, the DM yield of forages Mombaça (ŷ=6.472 + 74,41X – 0,241X2 R2=0,97), Tanzânia-1 (ŷ =6.923 + 70,95X – 0,249X2, R2=0,88) and Mulato (ŷ =7.393 + 94,42X – 0,341X2, R2=0,72) and the tiller density (TD). The critical phosphorus rates of 54, 44 e 48kg/ha of P2O5, respectively, to Mombaça, Tanzânia-1 and Mulato and P critical concentrations in soil of 51, 41 and 44mg/dm3. In the establishment, the mulato-grass presented highers DM yield and TD (11.169kg/ha and 69 tillers/0,25m2). The DM yield and TD in the mombaça-grass (9.787kg/ha and 54 perfilhos/0,25m2) and the tanzania-grass (9.563kg/ha and 52 perfilhos/0,25m2) were equal. In the 2° year, there were no variations in DM yield. The highest leaf elogantion ratio (LER) and leaf appearance ratio (LAR) were obtained in mombaça-grass and mulato-grass, respectively. The mulato-grass presented lower phylocron.