Effect of macronutrients on the growth and mineral nutrition of seedlings of Anadenanthera macrocarpa (Benth.) Brenan (angico-vermelho) and Mimosa caesalpiniaefolia Benth. (sansão-do-campo) / Efeito de macronutrientes sobre o crescimento e a nutrição mineral de mudas de angico-vermelho (Anadenanthera macrocarpa (Benth.) Brenan) e sansão-do-campo (Mimosa caesalpiniaefolia Benth.)

Elzimar de Oliveira Gonçalves

The knowledge of the nutritional needs for the production of seedlings and their establishment in their permanent place are fundamental for the success of any planting program of forest species. Therefore, the native forest species call for attention. Because of few nutritional data existing about these species, it is necessary to develop more detailed studies to determine these needs. There are great differences among the nutritional needs of each species and so are the demands of one or other element. But the lack of one of them, obviously, is going to limit plant growth. The objective of this study was to evaluate the effect of different doses of macronutrients (N, P, K, S, Ca and Mg) on the growth and nutrition of seedlings of Anadenanthera macrocarpa (angico-vermelho) and Mimosa caesalpiniaefolia (sansão-do-campo) in three types of soil. The plants were growth in Argisol, Distrophic Latosol and Alic Latosol) in pots with 2.1 dm3 capacity. The experiment was carried out from February to June 2005 in the Viveiro de Pesquisas Florestais (Forest Research Nursery) of the Departamento de Engenharia Florestal (Forest Engineering Department) of the UFV in Viçosa, Minas Gerais State, Brazil. The treatments were delimited according to a Baconian Matrix, where the macronutrients were varied in three different doses plus two additional treatments (zero and base), in a total of 20 treatments with four repetitions. The N, K and S sources were parcelled in four times (0, 30, 60 and 90 days). The plants were harvested in 120 days after seeding and data were analyzed. It was verified that there were differences in plants responses to the macronutrients according to the soil studied. Both species increased the absorption of macronutrients as the rate of availability of these nutrients increased in the soil. This led to a greater concentration of the nutrients in all parts of the plants. However, in some cases, there was not a correspondent growth response. The greatest growth was observed in the seedlings grown in the LVA soil and the nutrients P, N and S were the ones that caused most significant effects. The N doses varied from 50 to 200mg/dm3 for both species. It was observed that Anadenanthera macrocarpa needs less P (from 150 to 250 mg/dm3) than Mimosa caesalpiniaefolia (from 312 to 503 mg/dm3). As for K, Ca and Mg, the recommended doses are the same for both species: 50 mg/dm3; 0.8 cmolc/dm3 and 0.2 cmolc/dm3, respectively. Specifically for Anadenanthera macrocarpa, in terms of critical level, the values which rendered the best plant development were: N (14.4 to 26.8 mg/dm3 in the plant), P (7.5 to 46 mg/dm3 in the soil and 1.1 to 1.4 g/kg in the aerial part), K (14 to 86.5 mg/dm3 in the soil and 6.2 to 8.5 g/kg in the aerial part), Ca (0.8 to 2.2 cmolc/dm3 in the soil and 5 to 19 g/kg in the aerial part), and Mg (0.2 to 0.8 cmolc/dm3 in the soil and 1.7 to 1.9 g/kg in the aerial part). For Mimosa caesalpiniaefolia the values were: N (16 to 17.3 mg/dm3 in the soil), P (77 to 110 mg/dm3 in the soil and 1 to 1.5 g/kg in the aerial part), K (14 to 86.5 mg/dm3 in the soil and 5.7 to 7.1 g/kg in the aerial part), Ca (0.8 to 2.2 cmolc/dm3 in the soil and 10 to 14.4 g/kg in the aerial part), and Mg (0.2 to 0.25 cmolc/dm3 in the soil and 1.3 to 2.4 g/kg in the aerial part). Nevertheless, for both species, for K and Ca studies are suggested with doses within the range of the values found, to better define the critical level. The influence of the application of a given macronutrient on the absorption of the others was more significant for P both for the increase and for the decrease, and the stronger effects were on the aerial part of the plants. However, the increased doses of the nutrients applied did not interfere in the absorption of the other, witch indicates an equilibrium among them, or, the nutritional balance was appropriate.

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