The objective of this work was to verify the effect of different macronutrient concentrations on plant growth and dry biomass allocation in leaves, stems and roots of Myriophyllum aquaticum. The plants were cultivated in plastic pots filled with washed sand and immersed in nutritive solution. The study was carried out in a randomized complete design with four levels of nutrition solution at 0, 25, 50, 75% from the original concentration solution of N, P, K Ca, Mg and S, besides a control (100% of the nutritive solution) with 4 replications for 38 days. The largest production of total biomass was obtained in the control plot. The absence of K affected biomass allocation in the roots. The highest total branch length was found among the levels of Ca at 60 mg L-1. The solution at 100% of the macronutrients provided the largest plant length. The number of branches among the N and P levels followed a linear and growing tendency with the concentrations of these nutrients, but in a larger proportion for phosphorus. The most favorable conditions to plant development were at 100% of the macronutrients in the solution base. The highest N levels were verified in the leaves rather than in the stem while for the other nutrients, the greatest allocation was in the stem. Maximum biomass allocation in this species was observed in stems.
weed; aquatic plant; growth
