Interference Of Urochloa Brizantha On The Growth And Accumulation Of Macronutrients Of Peltophorum Dubium Plants

The presence of weeds in a forest stand may cause losses because they reduce the efficency in the use of growth resources for arboreal species. The point of this paper was to evaluate the initial growth and the nutrient accumulation of Peltophorum dubium (Sprengel) Taubert in coexistence with Urochloa brizantha Stapf. cv. Marandu. Three treatments were used in this research: 0, 2 and 4, equivalent respectively to 0, 23 and 46 plants by m(2) of Brachiaria plants in the field. Pots (having a capacity of 18 liters) filled with soil were used. At 84 days after the Brachiaria transplant, cutting of the aerial part at 2 cm above ground was done, simulating a field mowing and at 168 days the height, diameter, leaf area, mass of dry matter and the nutrient content in arboreal species plants were evaluated. Urochloa brizantha affected negatively the dry matter accumulation and of macronutrients in Peltophorum dubium after 168 days. Plants free from coexistence exhibited higher production of roots, branches, leaves, leaf area, average weight per leaf and nitrogen and calcium contents in roots. Upon completion of the work, it is concluded that the presence of Urochloa brizantha, in the two densities mentioned in this paper, entails a growth limitation of Peltophorum dubium.