The Role of Phosphate Fertilization on Physiological Responses of the Young Bertholletia excelsa Plants Grown in a P-Deficient Amazon Ferralsol.

Phosphorus (P) reacts with soil minerals, which makes it less available to plants. Considering that Amazonian soils have a low pH and nutrient availability, both of these properties contribute to an increase in P limitation. Here, we investigate how the addition of P to the substrate affects morpho-physiological traits of Brazil nut trees ( Bertholletia excelsa Bonpl.). The experiment was carried out in a greenhouse with 24-month-old saplings, and the P treatments consisted of a control (Ferrasol without P addition) and 100, 200, 400, and 500 mg P kg -1 of added to the soil. When B. excelsa saplings were fertilized with phosphate, the N:P leaf ratio reduced from 50 to 26. Addition of P favored the photochemical efficiency of PSII (F V /F M ), and the application of 200 mg kg -1 increased photosynthesis ( P N ) by 50%. Furthermore, phosphorus enhanced light and nutrient use efficiency. An increase in B. excelsa dry biomass was observed when 200 mg P kg -1 was added, with maximum yield occurring at 306.2 mg P kg -1 . Physiological parameters suggest robust responses by B. excelsa to P fertilization. In addition, our findings reveal the critical role of P on B. excelsa growth in Ferralsol, as well as the potential of P fertilization to improve functional traits of this important Amazonian tree.