Shading level, reflective material, and seeding depth on the growth of baru seedlings

The baru (Dipteryx alata Vog.) is a native species of Brazilian cerrado, and has been widely used in reforestation, medicine, and food industry. The effects of shading levels, reflective material, and seeding depth on the growth of baru seedlings were investigated in this study. The seedlings were grown in full sunlight, and in three production nurseries constructed with 18%, 30%, and 50% shading screens on growing benches coated or not coated with a reflective material (Aluminet®). The seeds were sown at depths of 2.0 or 4.0 cm in black polyethylene bags of 15.0 × 25.0 cm (1.8 L), filled with substrate formulated from the mixture of sandy soil: bovine manure: vermiculite (5: 3: 2). Each seedling production environment was considered an experiment because there were no replications for shading levels. The experimental design was completely randomized, in a 2 × 2 factorial scheme (two growing benches × two seeding depths), with five replications of eight seedlings. At 53, 86 and 120 days after sowing, the substrate temperature, plant height, stem diameter, shoot dry matter, root dry matter, total dry matter, absolute growth rate, and Dickson quality index was measured. The data were submitted to the joint analysis of the experiments. The means of shading levels were grouped by the Scott-Knott test, while the growing benches and seeding depth were compared by Student's t-test, both at 5% probability level. The use of reflective material (Aluminet®) on growing benches does not improve the growth and quality of baru seedlings. The seeding depth of 2.0 and 4.0 cm did not interfere in the quality of the baru seedlings. High-quality baru seedlings can be produced in environments with 50% shading screen