Selenium affects the mycelial growth, agronomic traits, and nutritional quality of Stropharia rugosoannulata

Abstract:

[Background] Stropharia rugosoannulata is a new edible mushroom species in China. With simple cultivation methods and high yield and benefits, it plays a key role in the efficient transformation of agricultural wastes and the increase in farmers’ income. [Objective] To explore the effects of selenium on the mycelial growth, agronomic traits, and nutritional quality of S. rugosoannulata and provide a basis for the production of selenium-enriched S. rugosoannulata. [Methods] The mycelial growth rate and dry weight of S. rugosoannulata treated with different concentrations of sodium selenite (Na₂SeO₃) were determined by the plate culture method. The cultivation matrix composed of sawdust, rice husk, and corncob was supplemented with 0–10 mg/kg Na₂SeO₃ for the cultivation test. The agronomic traits, nutritional quality, and antioxidant activity of the first batch of fruiting bodies were evaluated. [Results] The treatments with 0–10 mg/L Na₂SeO₃ had no significant effects on the mycelial growth rate and dry weight, which were 3.74–3.76 mm/d and 40.67–41.33 mg, respectively. However, when the concentration of Na₂SeO₃ reached 15 mg/L or above, the mycelial growth was significantly inhibited. The cultivation tests showed that the addition of 0–10 mg/kg Na₂SeO₃ had no significant effects on the biological efficiency of the mushroom. The 7.5 mg/kg Na₂SeO₃ group showed the best cap diameter, stipe diameter, and fresh weight of single mushroom. Moreover, this group demonstrated the highest content of crude protein, crude polysaccharides, total amino acids, essential amino acids, non-essential amino acids, delicious amino acids, and glutamate. The crude polysaccharides from fruiting bodies in the 7.5–10.0 mg/kg Na₂SeO₃ groups demonstrated significantly higher DPPH and · OH free radical scavenging activities than the blank control group. [Conclusion] The addition of low-dose Na₂SeO₃ could significantly improve the agronomic traits and nutritional quality of the fruiting bodies of S. rugosoannulata, and the optimum dose was 7.5 mg/kg. The findings provide a reliable experimental basis for the production of selenium-enriched S. rugosoannulata.