Produtividade do capim Massai sob interferência de plantas daninhas em área de renovação

Abstract

The objective was to evaluate weed competition on the composition, production and structure of Panicum maximum Jack. Massai defining the period prior weeds interference (PBWI) and to perform the phytosociological study in the pasture renewal area. A randomized block design was used in 3x4 m plots in six periods weed coexistence periods: 15, 30, 45, 60, 75, and 90 days after the emergency (DAE) and control (non-coexistence). In the forage was avaluated the fractionation (leaf, stem and dead material), natural matter, dry matter (DM), organic matter (OM), crude protein (CP) and neutral detergent fiber corrected for ashes and proteins (NDFap) in each period in coexistent and compared with the check treatment. At 90 days, all treatments were evaluated and the volumetric density of the dry matter (VDDM), ethereal extract (EE), acid detergent fiber (ADF) and lignin (LIG) were evaluated. The data were evaluated in a mixed model and subdivided plot, the means being compared by orthogonal contrast with regression adjustment. The EPI was calculated by regression based on a 5% loss of VDDM. Under the initial density of 495 m² weeds, the Urena lobata species had greater relative importance. The Coexistence with weeds decreased leaf production and increased stem yield at 75 DAE, altering the leaf-stem ratio at 90 DAE, which altered the composition and decreased forage yield. The loss of the VDDM was linear with the increase of the days of coexistence with the weeds being PBWI stipulated in 10 DAE of the Massai grass.