Pineapple (Ananas comusus) plant material as supplement for maize residue-based oyster mushroom substrate and reduction of cadmium soil contamination

Abstract

Pineapple (Ananas comusus) production generates hard currency and, as a labor-intensive industry, it creates jobs. The profitability of pineapple farming in South Africa faces several challenges, including low yield potential and cadmium (Cd) contamination of soils, which damaged the reputation of the industry. To increase the income of pineapple farmers, research was conducted to evaluate the utilization of pineapple crop residue for oyster mushroom (Pleurotus ostreatus) production and to establish the Cd levels in the mushrooms produced on Cd-contaminated pineapple crop residue. Treatments were maize residue (M), pineapple residue (P), and a mixture of maize and pineapple residues [at 1:1 ratio (on a dry weight basis), M + P]. Biological efficiencies of 90%, 77.6%, and 29% were recorded for the M + P, P, and M treatments, respectively. The P and M + P substrates significantly increased mushroom yield. Mushroom protein contents were 23.3%, 18.86%, and 18.81% (on a dry weight basis) in the M + P, P, and M treatments, respectively. Mushrooms in the P substrate had the highest Cd level (3.3 mg/kg). In the M + P substrate, Cd reduced to a safe level (0.15 mg/kg). This indicates that mushrooms have biosorption capacity, and could be used to solve the problem of Cd pollution and increase the income of pineapple production.