Açaí and Juçara Residues as Substrate Components for Euterpe edulis Seedling Production: Growth, Nutrient Status and Physiological Responses

Agricultural residues can be used as substrate components for seedling production, contributing to cost reduction and waste management. This study evaluated the growth, nutritional composition, and physiological performance of Euterpe edulis seedlings cultivated under greenhouse conditions. It is one of the first to integrate morphological, nutritional, and physiological indicators to assess agro-industrial residues as substrate components. The experiment followed a randomized block design with five substrates and four replicates: commercial substrate; 100% crushed açaí and juçara seeds; 50% soil + 50% cattle manure; 50% soil + 50% crushed seeds; and 33.3% soil + 33.3% cattle manure + 33.3% crushed seeds. Plant height was not affected by substrate type, while stem diameter and leaflet length were greater in the commercial substrate. Root length was higher in the commercial substrate; however, root dry mass, surface area, and volume did not differ among treatments. Leaf number, leaflet width, leaf area, and Dickson quality index were similar across substrates, indicating comparable seedling quality. The shoot-to-root ratio was higher in seedlings grown in the substrate composed of 100% crushed seeds. Higher nitrogen concentration was observed in seedlings grown in substrates based on crushed residues, without differences in biomass, indicating the absence of a dilution effect. No statistical differences were observed for the remaining nutrients. Physiological parameters indicated adequate photosynthetic performance across treatments. Substrates based on crushed açaí and juçara residues showed comparable performance to the commercial substrate, representing a viable and sustainable alternative for E. edulis seedling production.