Calcário e macronutrientes no crescimento inicial de Eucalyptus benthamii

EnglishMacronutrient suppression is one way to identify which chemical elements is the most important in the early development of seedlings of forest species. This study evaluated the initial growth of Eucalyptus benthamii seedlings through morphological and physiological variables, submitted to doses of N, P and K, and liming. The experimental design to install the experiment was completely randomized, with a 2x9 factorial scheme, in which levels of factor “A” referred to absence and presence of liming and levels of factor “B”, to the different treatments of NPK. Morphological variables of SD (stem diameter) and H (height) and the physiological variables of A (photosynthesis), E (transpiration), gs (stomatal conductance), Ci/Ca (relationship between intercellular and atmospheric CO2 concentration) and WUE (water use efficiency) were measured. For morphological variables, the absence of N directly affected the means and there was a direct relationship between increase of the dose and increase of SD and H. There was a positive relationship of P mainly in relation to shoot dry matter content (SDMC) and root dry matter content (RDMC). For the physiological variables, there was no direct response with the doses of N or P, with K being the element that most influenced the variables, especially when limestone was applied, resulting in higher averages for photosynthesis, transpiration and stomatal conductance. With the purpose of meeting the morphological and physiological demands, the recommendation for cultivation of Eucalyptus benthamii under the conditions of this study is the doses 150-200-150, without liming application. portuguesA supressao dos macronutrientes e uma das maneiras de identificar qual ou quais dos elementos quimicos e o mais importante no desenvolvimento inicial das mudas de especies florestais. O estudo objetivou avaliar o crescimento inicial de mudas de Eucalyptus benthamii por meio de variaveis morfologicas e fisiologicas, submetidas a doses de N, P e K, e calagem. O delineamento experimental para instalacao do experimento foi em delineamento inteiramente casualizado, com esquema fatorial 2x9, em que os niveis do fator “A” se referiram a ausencia e a presenca de calagem e os niveis do fator “B” aos diferentes tratamentos de NPK. Variaveis morfologicas de DAC (diâmetro a altura do colo) e H (altura) e as variaveis fisiologicas de A (fotossintese), E (transpiracao), gs (condutância estomatica), Ci/Ca (relacao entre a concentracao intercelular e atmosferica de CO2) e WUE (eficiencia no uso da agua) foram determinadas. Para as variaveis morfologicas, a ausencia do N afetou diretamente as medias, havendo uma relacao direta entre o aumento da dose com o aumento das variaveis. Ha uma relacao positiva do P principalmente em relacao a MSPA e MSPR. Para as variaveis fisiologicas, nao houve resposta direta com as doses de N ou P, sendo o K o elemento que mais influenciou as variaveis, principalmente quando o calcario foi aplicado, resultando em maiores medias para fotossintese, transpiracao e condutância estomatica. Com o objetivo de atender as demandas morfologicas e fisiologicas, a recomendacao para o cultivo de Eucalyptus benthamii nas condicoes deste estudo e a dose 150-200-150, sem aplicacao de calagem.