Mushroom production is a sustainable practice but requires improvements, such as in Lentinula edodes (Berk) Pegler cultivation, which has high water and labor demands. In this context, this study proposed replacing the traditional primordia induction method by submersion with a water injection method. Two primordia induction methods (submersion and injection) and two cultivation block formats were compared: rectangular cube (2 kg) and cylindrical (3.5 kg). The substrate, composed of eucalyptus sawdust (72%), wheat bran (12.5%), rice bran (12.5%), CaCO₃ (1%), and CaSO₄ (2%), was inoculated with strain LED 19/11 and incubated for 80 days at 26 ± 5 °C and 85 ± 15% humidity. After this period, the blocks were washed and transferred to the production environment. Fruiting was induced either by submersion or water injection, and production was evaluated over four harvest flushes. The 2 kg blocks had higher yields with submersion (16.62%), while the 3.5 kg blocks responded better to injection (13.01%), showing more homogeneous production. Increasing the substrate quantity contributes to greater harvest stability across production cycles. Water injections proved to be a viable alternative, reducing handling and facilitating large-scale production. The use of this technique demonstrates great importance in reducing water use and also the need for labor in cultivation.

The valorization of agro-industrial residues is essential for advancing circular bioeconomy systems. This study integrated the natural colorant and edible mushroom industries by evaluating annatto (Bixa orellana) residues as substrates for Pleurotus ostreatus cultivation. Two experiments were conducted, testing field and industrial residues at three incorporation levels (32.5%, 42.5%, and 52.5%, w/w on a dry weight basis) combined with different supplementation strategies (corn bran, wheat bran, and their mixture) in a completely randomized design. Field residues showed greater yield and biological efficiency, while industrial residues exhibited higher variability. Total yield reached 38.92%, while the lowest value was 24.28%, representing an increase of up to 65% depending on residue origin and supplementation strategy. Biological efficiency exceeded 140% under optimal conditions, with gains above 70% compared to the lowest-performing treatments. Field residues also promoted a higher number of bunches and greater average bunch mass. Overall, substrate origin, supplementation, and residue proportion were decisive for fungal performance, demonstrating that annatto residues are promising low-cost substrates for scalable mushroom production within circular economy systems.