Effect of different organic substrates on the initial development of açaí (euterpe oleracea mart.) Seedlings in dystrophic yellow latosol

Objective: To evaluate the effect of different organic substrates (sheep manure, litter from cultivated area, agroforestry system litter, and native vegetation litter) on the initial growth of açaí seedlings under greenhouse conditions. Theoretical Framework: The açaí palm (Euterpe oleracea Mart.) holds great socioeconomic and environmental importance in the Amazon region, especially in the states of Pará, Amapá, and Amazonas. Although it is a hardy species, it is commonly cultivated in naturally low-fertility soils, such as dystrophic Yellow Latossols, which have high acidity and limit the early growth of seedlings. Organic fertilization has shown promise by improving the physical, chemical, and biological properties of the soil. Among organic materials, litter stands out for supplying nutrients gradually and improving soil structure and microbiology. Method: A completely randomized design experiment was conducted with four treatments and eight replications (total of 32 seedlings). Açaí seedlings were transplanted and grown for 90 days in plastic bags, evaluated every 10 days. Measured variables included plant height, stem diameter, number of leaves, and relative chlorophyll content (SPAD). Data were analyzed by ANOVA and grouped using the Scott-Knott test at 5% probability (Sisvar 5.6). Results and Discussion: Seedlings treated with agroforestry system litter (LITSAF) and cultivated area litter (LITCULT) showed superior growth in height (33.90 cm and 31.77 cm), stem diameter (50.95 mm and 48.83 mm), and number of leaves (17.75 and 17.63) compared to sheep manure (29.16 cm; 44.90 mm; 15.00 leaves) and native litter (28.18 cm; 41.30 mm; 14.50 leaves). Chlorophyll index remained similar across treatments (37.79–44.39 SPAD). Litter from SAF and cultivated areas favored açaí seedling growth, outperforming sheep manure and native litter due to higher nutrient release. Chlorophyll index was stable among treatments. These data indicate that such litters are sustainable and effective alternatives for seedling production. Research Implications: This study provides support for more sustainable practices in açaí seedling production, with potential to reduce chemical fertilizer use, optimize nursery costs, and improve field planting success. Originality/Value: This research expands knowledge on using organic residues in açaí seedling production by addressing little-explored sources. Its relevance lies in valuing local and sustainable substrates with direct application in agroforestry and extractivist systems in the Amazon.