ABSTRACT Our aim was to assess the mineral composition of corn silages produced in four states of Brazil: Goiás, Minas Gerais, Paraná, and Santa Catarina. In total, seventy-three samples were analyzed. Total element content was extracted by HNO3 and H2O2 microwave-assisted digestion, and inductively coupled plasma-mass spectrometry (ICP-MS) was used to determine concentration. Of the 31 elements analyzed (Ag, Al, As, B, Ba, Be, Ca, Cd, Co, Cr, Cs, Cu, Fe, K, Li, Mg, Mn, Mo, Na, Ni, P, Pb, Rb, S, Se, Sr, Ti, Tl, U, V, and Zn), 21 had concentrations above equipment detection limits. No elements reached the maximum tolerable concentration, but concentrations of Ca (0.14-0.15%), Cu (3.4-5.6 mg kg−1), P (0.13-0.16%), S (0.06-0.08%), and Zn (13-19 mg kg−1) were below the adequate concentration for good nutritional balance. The strong and consistent correlation observed between Fe and Ti in silage samples indicated contamination by soil. Mean concentrations of Cu, Mn, Mo, P, S, and Zn were different among states, and canonic analyses successfully discriminate samples according to their state of origin. Minerals from corn silage should be considered when formulating balanced cattle diets. To ensure silage quality, farmers must adopt strategies that reduce contamination by soil during the ensiling process.

RESUMO Espécie da floresta subtropical da América do Sul e restando apenas menos de 3 % de vegetação natural, a Araucaria angustifolia é ainda pouco conhecida sobre a distribuição de elementos em suas acículas. Nesse estudo, utilizamos microscopia eletrônica de varredura (MEV) com espectroscopia por dispersão de energia (EDS) para avaliar a distribuição elementar em acículas de A. angustifolia. Foram selecionadas acículas de plantas (28 meses de idade) cultivadas em experimento de adubação: com suprimento de N, P e K; com N e P; com N e K. Na microanálise quatro tipos de tecidos especializados das acículas (epiderme superior, mesófilo paliçádico, mesófilo esponjoso e epiderme inferior) foram avaliados quanto a composição (C, O, P, K, Ca, S e Al). Quando foram detectados cristais determinaram-se as concentrações de 12 elementos (C, O, P, K, Ca, S, Al, Fe, Mg, Na, Si e Cl). Na baixa disponibilidade de P e K, esses elementos foram encontrados em baixas concentrações na epiderme, no mesófilo e em cristais. Na baixa disponibilidade de P ocorreu acúmulo de Ca e K no mesófilo esponjoso, enquanto que na baixa disponibilidade de K ocorreu acúmulo de Ca no mesófilo esponjoso. Em adição, a baixa disponibilidade de K e P favoreceu a formação de cristais, sendo que em baixa disponibilidade de K, os cristais apresentaram mais Ca e Mg. A disponibilidade de P e K no solo afetou a distribuição de elementos em acículas de A. angustifolia, sendo que o tipo de tecido e a formação de cristais foi chave para a dinâmica de nutrientes nas acículas.

ABSTRACT Araucaria angustifolia is a conifer species found in South American subtropical forests that comprises less than 3% of the native vegetation and little is known concerning the accumulation of nutritional elements in its needles. In this study, scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy (EDS) was used to assess the elemental distribution in needles. Needles were selected from 28 month-old plants grown in a fertilization experiment supplied with: 1) N, P, and K; 2) N and P; and 3) N and K. In microanalysis, four types of specialized needle tissues (adaxial epidermis, palisade mesophyll, spongy mesophyll and abaxial epidermis) were evaluated for elemental composition (C, O, P, K, Ca, S and Al). When crystals were detected, the concentrations of 12 elements were determined (C, O, P, K, Ca, S, Al, Fe, Mg, Na, Si, and Cl). Under low soil P and K, these elements were found in low concentrations in the epidermis, mesophyll, and crystals. Under low soil P, Ca and K accumulated in the spongy mesophyll, while under low soil K only Ca accumulated in this tissue. In addition, low soil P or K availability favored the formation of crystals; crystals under low soil K availability had more Ca and Mg. Soil P and K availability affected the distribution of elements in needles of A. angustifolia, in that type of tissue and formation of crystals were key to the nutrient dynamics in needles.