Growth, Nutrient Accumulation, and Nutritional Efficiency of a Clonal Eucalyptus Hybrid in Competition with Grasses

Abstract

Invasive grasses reduce resource availability, mainly nutrients in the soil, and the growth of eucalyptus plants. Efficient management to increase productivity depends on understanding levels of weed interference in eucalyptus plantations. The nutritional efficiency of eucalyptus plants in competition has been evaluated by plant tissue analysis. The objective was to evaluate the growth, relative accumulation of nutrients, and nutritional efficiency of the eucalyptus clonal hybrid I144 (Eucalyptus urophylla × Eucalyptus grandis), in competition with Megathyrsus maximus cv. BRS zuri, Urochloa brizantha cv. marandu, Urochloa decumbens cv. basilisk and in the control (eucalyptus plants without weed competition). The experiment was carried out with a completely randomized design, with four treatments and ten replications. The height, stem diameter, number of leaves, leaf area, dry matter of leaves and stem, nutrient content in leaves and uptake, transport, and N, P, and K utilization efficiency of the eucalyptus clonal hybrid were evaluated at 110 days after transplantation. The growth parameters and relative contents of macro and micronutrients in the eucalyptus clonal hybrid were lower in competition with M. maximus, U. brizantha and U. decumbens. The efficiency of N, P, and K uptake and transport by the eucalyptus clonal hybrid was 29.41 and 7.32% lower in competition with U. decumbens than in the control treatments, respectively. The efficiency of N, P, and K utilization by eucalypts was 13.73, 9.18, and 22.54% lower in competition with M. maximus, U. brizantha, and U. decumbens, respectively. The reduced growth and nutritional parameters of the eucalyptus clonal hybrid were more evident in competition with U. decumbens. Plant tissue analyses efficiently determined the level of competition for nutrients between species. Crop competition with grasses can decrease the efficiency and use of nutrients, which consequently reduces plant development and productivity.