Crescimento da parte aérea e dinâmica do sistema radicular em Handroanthus heptaphyllus submetido à aplicação de fósforo

Abstract

Resumo : Os solos do Brasil apresentam baixa disponibilidade de fósforo (P). Isso reduz a sobrevivência e crescimento de espécies florestais pois esse elemento é fundamental em processos fisiológicos. Assim, tendo em vista a importância ecológica e o potencial econômico do Handroanthus heptaphyllus, o objetivo do presente estudo foi avaliar o crescimento e a morfologia de raízes de H. heptaphyllus, ao longo do tempo, quando cultivado em solo com e sem aplicação de P. A pesquisa foi conduzida em solo Argiloso vermelho em Santa Maria, Rio Grande do Sul. Plantas de H. heptaphyllus foram cultivadas por 36 meses em solos com Baixo P (sem adubação) e Alto P (adição de 90 kg P2O5 ha-1 ). Aos 18, 24, 30 e 36 meses após o plantio foram determinadas as concentrações de P no solo e em folhas. Além disso, foi mensurado a altura e diâmetro do coleto de plantas. Concomitantemente, as raízes das plantas foram escaneadas através da técnica do minirizotron, e nas imagens obtidas foi determinado o número de raízes e a área superficial de raízes

Abstract : Brazilian soils have low phosphorus (P) availability. This reduces the survival and growth of forest species as this element is fundamental in physiological processes. Thus, in view of the ecological importance and economic potential of Handroanthus heptaphyllus, the objective of the present study was to evaluate the growth and morphology of roots of H. heptaphyllus, over time, when cultivated in soil with and without application of P The research was conducted in a red Clay in Santa Maria, Rio Grande do Sul. H. heptaphyllus plants were cultivated for 36 months in soils with Low P (without fertilization) and High P (addition of 90 kg P2O5 ha-1). At 18, 24, 30 and 36 months after planting, P concentrations in soil and leaves were determined. In addition, the height and diameter of the plant collection were measured. Concomitantly, the roots of the plants were scanned using the mini-rizotron technique, and the number of roots and surface area of roots were determined from the images obtained. Phosphate fertilization increased P availability in the soil and, consequently, increased P concentrations in leaves. As a result, it promoted growth in height and diameter of the stem. The number and area of roots was higher in the soil with High P, mainly in the upper layers of the soil. The research highlighted the importance of fertilization for the development of Ipê-roxo seedlings and emphasized the influence of phosphorus on the growth and concentration of nutrients in the plants.