Produção, alocação de biomassa e aspectos nutricionais de um clone de eucalipto em função da densidade de plantio, na região litorânea do RN

Abstract

In this experiment the effect of different population densities on the production and allocation of biomass and nutritional efficiency of a eucalyptus clone was evaluated. Twelve population densities were tested, varying from 498 to 13,333 plants per hectare. The evaluations were performed when the trees were 36 months old, determining the total biomass production and the biomass allocation per plant (kg plant-1 ) and area (t ha-1 ) and content, nutritional efficiency of N, P, K, Ca, Mg and S for the components leaves, branches, bark and wood. Data were submitted to analysis of variance and F test, and regression equations were adjusted with the respective trend lines. The values of total biomass and biomass of the wood per hectare decreased with the reduction of the density of plants, and the values of total biomass and biomass of the wood per plant increased with the reduction in the population density. Proportional allocation of biomass to leaves and branches increased with decreasing plant density, while the biomass proportional allocation to wood reduced, and the bark was not affected. The highest aerial biomass production per plant (118.48 kg plant-1 ) was obtained at the density of 588 ha-1 trees (17 m² plant-1 ). The highest density of plants, 13,333 ha-1 trees, provided the highest yield of total biomass (205.5 t ha-1 ) and wood (159.64 t ha-1 ) per unit area. With the reduction of the population density, it was observed an increase in the N and S content in the branches and wood and in the Ca content in the branches; increase in N content in leaves and N, Ca, Mg and S in the bark. The levels of P and K presented quadratic behavior as a function of population density. The content of macronutrients tended to decrease as the population density decreased. The wood was the component that presented the highest values of nutritional efficiency, which, in general, tended to decrease with reduction in plant density, with Ca being the only macronutrient that did not show effect in this last parameter.