Phosphate sources and soil acidity in seedling production of Theobroma Grandiflorum

Abstract

Cupuaçu (Theobroma grandiflorum) is a plant native to the Brazilian Amazon belonging to the Malvaceae family. It is greatly appreciated in the northern region of Brazil, mainly for its flavor and aroma of its pulp. The objective of this work was to evaluate the behavior of cupuaçu (Theobroma grandiflorum) seedlings under phosphate fertilization and soil acidity correction. The experiment was conducted in a greenhouse located at the Institute of Agrarian Sciences (ICA), Soil Science Area, Federal Rural University of Amazonia (UFRA), Belém (PA). A completely randomized experimental design in a 3 x 2 factorial scheme was used, distributed in 4 replications, making a total of 24 experimental units. The factors were: phosphate fertilization (triple superphosphate, simple superphosphate and yoorin); and soil correction (with and without liming). Phosphate fertilizers were applied 0.06 g/plant triple superphosphate with 43% P2O5; 0.15 g/plant Yoorin Master 17% P2O5 and 0.13 g/plant single superphosphate 20% P2O5. In order to meet the nutritional needs of the plant, 0.07 g/plant of urea and potassium chloride were also applied. Soil correction was performed by the base saturation method, raising the exchangeable soil bases to 60%, applying 8.1 g of dolomitic limestone with the PRNT 92%, per experimental unit. The response variables evaluated were: plant height (AP), stem diameter (DC), leaf number (NF), leaf area (AF), green leaf mass (MVF), dry leaf mass (MSF), green root mass (MVR), dry root mass (MSR), root length (CR). The combination of phosphate fertilizers and liming provides the best results for cupuaçuzeiro seedlings. Yoorin thermophosphate with or without correction promotes satisfactory results for the production of cupuaçuzeiro seedlings. Simple superphosphate promotes satisfactory results regarding the phytometry of cupuaçuzeiro seedlings with and without soil correction.