Effects of treated sugar mill effluent and rice straw on substrate properties under milky mushroom (Calocybe indica P&C) production: Nutrient utilization and growth kinetics studies

Abstract

Abstract In this work, we evaluated the potential of treated sugar mill effluent (SME) as a moistener of rice straw substrate for laboratory cultivation of milky mushroom (Calocybe indica P&C). Five different concentrations of SME including, 0% (control using normal water supply) 25, 50, 75, and 100% were tested to enrich the rice straw substrate. Laboratory experiments were performed under controlled temperature (32.5 °C) and humidity (74.0%). The results showed that substrate enrichment with SME significantly increased the nutrient composition of rice straw substrate which further enhanced the C. indica production. After cultivation of C. indica, the maximum removal of substrate nutrients including, organic carbon (36.05%), NO 3 − -N (37.41%), Na + (26.19%), K + (9.80%), PO 4 3 − -P (9.33%), SO 4 2 − (38.65%), Ca 2 + (28.19%), Mg 2 + (37.50%), Cu 2 + (43.70%), Fe 3 + (36.41%), Mn 2 + (35.62%), and Zn 2 + (36.13%) was observed using 50% SME enrichment. The maximum flush yield and bioefficiency were 127.2 g/kg substrate and 75.3% with maximum nutrient uptake rates, respectively within the same treatment. The modified Gompertz model gave the best predicted cumulative mushroom biomass production (y: 148.7 g/kg) and lag phase (0.1070 days) with a good coefficient of determination (R2 ≥ 0.9900), respectively. This work represented the sustainable utilization of treated SME for enhanced production of C. indica while reducing freshwater and fertilizer inputs.