Effects of Carbon, Nitrogen, Particle size and moisture on Oyster Mushroom Production in KwaZulu Natal - Cedara

Dissertation submitted in fulfilment of the requirements for the degree of Master of Science in the Faculty of Science and Agriculture, Department of Biochemistry and Microbiology at the University of Zululand.

Mushrooms are liked for their delicious flavour, high protein content and absence of cholesterol. Farmers require guidance in how they can manipulate the current existing mushroom production methods to fit in their cheaper, local ready available raw materials. Mushroom production can be optimized only if its substrate specific requirements are known and well maintained. Different potential sources of carbon and nitrogen such as wheat bran, teff, lucerne, bagasse, maize, sawdust, juncao and hominy chop were analysed using Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES Analysis). Carbon and nitrogen content was used to set up five carbon/nitrogen (C/N) ratios (15:1, 25:1, 35:1, 70:1 and 100:1). Milling of the raw materials was done in three phases which were 8 mm, 12 mm and 25 mm using different sieves of the multi-purpose milling machine. The raw materials were mixed and the water was added to achieve 65% moisture. The raw materials were bagged and pasteurized at 900C for 14 hours. The substrates were inoculated with Pleurotus ostreatus spawn produced at Department of Agriculture and rural Development (DARD). The rate of the mycelium growth and contamination was monitored and recorded. When the substrates were fully colonised, they were cut on top and randomly placed on the wall and irrigated daily. Fresh mushrooms of each mushroom pack were harvested and weighed. The optimum substrate requirements were determined based on best C/N ratio, particle size, biological efficiency and contamination rate. The highest biological efficiency was achieved with the following substrate composition 31.3% bagasse, 6.3% wheat bran, 12.5% maize, 12.5% sawdust, 12.5% hominy chop, 12.5% juncao, 6.3% lurcerne and 6.3% teff with particle size of 8 mm and C/N ratio of 35:1. There are many agro-waste that can be successful used in production of oyster mushrooms, but its combination to form a required optimum C/N ratio is very important. This study showed that the particle size also played a crucial role in mycelium growth. The study concluded that particle size of the raw material when using plastic bag (150x300 mm) must be at least between 8 and 12 mm and C/N ratio should above 25:1 and below 35:1.