Elucidating the mechanisms of phosphorus accumulation and use efficiency in açaí palm plants at different cultivation ages

The cultivation of the açaí palm (Euterpe oleracea Mart.) has experienced remarkable growth in the Amazon region. However, knowledge regarding the dynamics of phosphorus (P) in the vegetative and reproductive components of açaí plants across different growth stages remains limited. This study aimed to evaluate the dynamics of P accumulation, efficiency, and the rates of immobilization, recycling, and export in açaí palms cultivated on upland soils at varying plant ages in the Amazon. The experiment was conducted in Tomé-Açu, Pará, Brazil, using a completely randomized strip-plot design with four replicates and six treatments corresponding to planting ages (2-7 years). Data were analyzed using analysis of variance (F test, p < 0.05), followed by regression modeling where significant. The results revealed that P accumulation and efficiency varied across plant organs, with the highest demand observed during the productive phase, when total P requirements reached 106.5 g plant^-1. Maximum rates of P export, recycling, and immobilization were recorded at seven years of age, with immobilization accounting for up to 69.4 kg ha^-1 of P. The stipe demonstrated the highest P use efficiency among the plant organs. Based on the findings, a recommended application of 200 kg ha^-1 of P₂O₅ is suggested for fruit yields exceeding 25 t ha^-1. From a nutritional perspective, the daily P requirement for an adult (700-750 mg) can be met with the consumption of approximately 500 g of açaí pulp. These results contribute to the rational use of phosphate fertilizers, enabling improved yield of açaí palms in the unique soil and climatic conditions of the Amazon region.